GroupDIY

Project Specific Discussions => Microphones => Topic started by: poctop on January 24, 2014, 06:31:03 PM

Title: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 24, 2014, 06:31:03 PM
D-Elam 251E with True Pattern Switching on PSU ,  

this was a very fun build.  Specially the Point to Point HZ bridge,  half PCb/half PTP for Optimal Results and Maximum Fun  

Enjoy,
more Info soon at http://www.vintagemicrophonepcbkit.com Or http://groupdiy.com/index.php?topic=49675.0

Schematic ELA M251E
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06402.pdf (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06402.pdf)

Schematic D-E251E
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0643e.pdf

PsU
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06450.pdf


thanks to Trans4funks1 for this nice work.  :)

Microphone DiaGram
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

PSU DiaGram
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06473.pdf

PSU BOM Only
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=721fb79f74
 (http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=721fb79f74)

Elam 251 BOM.  (Missing From BOM 4700pf Polystyrene 630V and 1000pf Polystyrene /630V and 100pf Polystyrene 630V)
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=d2c3022a97 (http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=d2c3022a97)

List Of interesting Tweaks From User and Group Member
I compile them as I go ,

Ok , here is some tweaks you can do from original schemtics,

SuggestedTweaks

100uF or more  on the cathode bypass cap instead of 22uF (C3) bass response
increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)  (C2) bass response
Grid to ground resistor higher  100m or 250m (R4) Bass Response
Increase or decrease output coupling cap to taste to modify low end response  (C1) to taste









(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06486.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06496.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a064a7.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0283f.jpg)


It is needed to get rid of a pair of  high stamping Metal siders to proper with the aid of a metal cutter and a file  :P

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a064c9.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a064da.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a064e8.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a064f9.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06506.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06518.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06529.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0653b.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0654d.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0655a.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0656b.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06579.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0658a.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0659c.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a065ad.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a065bf.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a065d0.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a065e2.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a065f3.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06621.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06633.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06644.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0665a.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0666d.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0667b.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0668c.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0669e.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a066af.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a066c3.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a066d4.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a066e6.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a066f3.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06706.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06718.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993f9b.jpg)


Best,  :)
DAN,
Title: Re: Telefunken Clone (D-Elam 251) Tube Microphone Build Thread
Post by: 3nity on January 24, 2014, 06:47:19 PM
amazing dude!!!
Cant resist, put me down for 1 set of pcbs.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on January 24, 2014, 06:59:32 PM
Yay! What tranny is that? Will the BOM include electrolytic, wet tantalum, etc. like the original?

Why does your headbasket have a cardioid symbol? That's not right haha
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: RuudNL on January 25, 2014, 08:03:56 AM
Is the schematic available?
What is the function of the relays in this version?
(As far as I know there was no relay in the original ELA M 251)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 25, 2014, 08:30:06 AM
Is the schematic available?
What is the function of the relays in this version?
(As far as I know there was no relay in the original ELA M 251)

The Relay are used To control this scheme, its all Floating Ptp for the realy control as this control the capsue.

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993faa.jpg)

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on January 25, 2014, 08:32:42 AM
Is the schematic available?
What is the function of the relays in this version?
(As far as I know there was no relay in the original ELA M 251)

the polarisation switching is done via remote controlled relays. I did te same in my mic, but all point to point, looks a bit wild but works fantastic.

you have to get relays with good isolation resistance.

in the original it's a switch
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 25, 2014, 08:36:46 AM
Yay! What tranny is that? Will the BOM include electrolytic, wet tantalum, etc. like the original?

Why does your headbasket have a cardioid symbol? That's not right haha

The Transfo is a Cinemag 2480 for now , I do have BOM available ,
Best,
dAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 25, 2014, 10:05:24 AM
It almost seems like the board is a piece of garolite with a printed sheet attached to it.  What is it?

I would like to build a 251 for my fist mic mod and I have been looking at switches etc.

Can you explain more about how to use the relays, or do you perhaps plan to release a PCB kit and a schematic of this particular build?

I'm excited to see what you have done! :-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 25, 2014, 11:27:33 AM
It almost seems like the board is a piece of garolite with a printed sheet attached to it.  What is it?

I would like to build a 251 for my fist mic mod and I have been looking at switches etc.

Can you explain more about how to use the relays, or do you perhaps plan to release a PCB kit and a schematic of this particular build?

I'm excited to see what you have done! :-)

the 3 relays are used to Operate all the pattern like the original elam would, but it can be done on the psu as this kind of switch is nearly impossible to find ,
Works awesome ,
Best,
dAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 25, 2014, 11:29:32 AM
Quote
It almost seems like the board is a piece of garolite with a printed sheet attached to it.  What is it?

FR4 PCB,  I Actually Call this mic , the Walter White,  ;D

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 25, 2014, 11:53:31 AM
I do have 6 kit left for those who would like to jump in  :o ,

PM me if interested,

Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Khonnor on January 25, 2014, 11:27:02 PM
Hi!! I'm really interested in this mic but i can't find the link of this kit in your website.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 26, 2014, 09:26:47 AM
I'm very interested in viewing a schematic of how the relays are specifically implemented in this circuit.

I was reading the data sheet for them and I am having difficulty imagining how the various pin outs on the relay fit into the traditional circuit.

I have attached a screen shot of what I think is the part of the data sheet that applies. I have a self made drawing of the 251-E circuit that is essentially a copy of the official AKG version posted in the OP and I would like to, as an exercise in learning, incorporate the relays in a new schematic so that I can fully understand what is going on.


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 05:42:05 AM
I do have 2 set left ,
Best, Dany,
PM for details,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 27, 2014, 09:32:24 AM
Hi DAn et al,

I'll be building this bad boy with BeesNeez bodies and no donor PS etc.

Could someone please point me in the direction of an appropriate trafo 240 primary, dual secondaries? Have googlised it with minimal success.

Or do I need 2 separate trafos? How much power for each?

Thanks for your help.

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 09:39:48 AM
Hi DAn et al,

I'll be building this bad boy with BeesNeez bodies and no donor PS etc.

Could someone please point me in the direction of an appropriate trafo 240 primary, dual secondaries? Have googlised it with minimal success.

Or do I need 2 separate trafos? How much power for each?

Thanks for your help.

Matt

I think the simplest and most efective way is try to get a HT-11 PSU unit from Chunger ,  you will be done in a hour

Yes you would need a 9.5V ish tap and a 200V tap,
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 27, 2014, 09:55:53 AM
Yeah, Im  a bit reluctant to buy the whole kit when the only bit I'll need is the trafo essentially. I want to do these with Galaxy cases and other bits and pieces that I already have.

Also, can you recommend a place to source the 7 pin XLR inserts with retaining grub screw?

Thanks again,

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on January 27, 2014, 10:02:56 AM
Hi Dan, in the original schematic, was the 3.2uF output cap an electrolytic or perhaps wet tantalum? I haven't been able to find anything definitive. I found a wet tantalum but it's value is a little high, and voltage is only 125V. It's also expensive!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 10:22:07 AM
Looks like a wet tantalum to me , but they may have had different type over times ,  as Metal paper, polyester also,
Why Not polyprop
Here is a shot ,.

http://www.youtube.com/watch?v=rJx9TdJSFRI

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993fdb.gif)
Best,
Dan,

your guess now,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 10:23:05 AM
Yeah, Im  a bit reluctant to buy the whole kit when the only bit I'll need is the trafo essentially. I want to do these with Galaxy cases and other bits and pieces that I already have.

Also, can you recommend a place to source the 7 pin XLR inserts with retaining grub screw?

Thanks again,

Matt

Just Ask Chunger he should be able to provide those items for you ,
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 27, 2014, 10:55:04 AM
Hi Dan,
 I am looking forward to receiving the PCB kit I ordered over the weekend. Thanks for making it available. I'm ordering the BOMs from Mouser this morning.

 Do you plan to make a specific schematic available that represents your changes to the AKG schematic you posted above?

 I anticipate difficulty in understanding how those relays are set up and while I know I can simply follow your photos as step by step instructions I will enjoy learning what is actually going on inside the yellow boxes. :-)

 I appreciated being able to view your PSU schematic for the 269 project, and since I am actually going to attempt build/mod a "Walter White" I'd like to have the same opportunity to study the design you used for this PSU PCB.
 
 I'd appreciate any info you can share, even if it is just some sort of hand drawn schematic detail of how the relays fit in to the official AKG switch detail you posted.

 Thank You!

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: toobnoob on January 27, 2014, 12:20:18 PM
Sweet Googly Moogly that looks awesome!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: RuudNL on January 27, 2014, 12:43:13 PM
Why build an ELA M251 clone if you have two of them in your microphone locker? :P

(http://www.vansteenissoftware.nl/DIY/M251.jpg)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 12:59:26 PM
Why build an ELA M251 clone if you have two of them in your microphone locker? :P

(http://www.vansteenissoftware.nl/DIY/M251.jpg)

Then you obviously dont  :P , if you are lucky enough to have them already Then Enjoy,
D :o
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 27, 2014, 02:08:13 PM
There may be some guys that bought their first two for $300 and don't want to spend an extra $10,000 on a third one.

:-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 27, 2014, 03:30:50 PM
Quote
Do you plan to make a specific schematic available that represents your changes to the AKG schematic you posted above?

 I anticipate difficulty in understanding how those relays are set up and while I know I can simply follow your photos as step by step instructions I will enjoy learning what is actually going on inside the yellow boxes. :-)

 I appreciated being able to view your PSU schematic for the 269 project, and since I am actually going to attempt build/mod a "Walter White" I'd like to have the same opportunity to study the design you used for this PSU PCB.
 
 I'd appreciate any info you can share, even if it is just some sort of hand drawn schematic detail of how the relays fit in to the official AKG switch detail you posted.

Dont worry i will adress your request  soon enough.



only 1 set left,
PM for details if interested ,

in the eventuality that i could make another run of those , please post on this thread if i have enough folks i will proceed to round 2
i am just selling my leftover for now hence the number of set is very limited,


Best,
Dan,

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: toobnoob on January 27, 2014, 03:37:06 PM
Next time you do a batch I'd be down for 2 8)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 27, 2014, 04:18:56 PM
I anticipate difficulty in understanding how those relays are set up and while I know I can simply follow your photos as step by step instructions I will enjoy learning what is actually going on inside the yellow boxes. :-)

I'm also not too sure exactly how these are implemented.

From the ELAM schematic the switching pattern is a 3P3T configuration.

So the 3 x DPDT relays are taking over the function of the 3P3T switch.

Now to sit down with a bit of paper and figure out how...

:)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on January 27, 2014, 07:55:19 PM
Going to wait for Chunger new mic shipment.
I'm in for 2  sets in round 2.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 28, 2014, 07:10:24 PM
still 1 left , :)
Let me know
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 28, 2014, 07:36:29 PM
still 1 left , :)
Let me know

Gone ,
thanks ,
Dan,
Stock out,  
Best,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on January 28, 2014, 09:00:30 PM
I'm in for 2 sets for round 2.  Any estimate when they will be available? 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on January 28, 2014, 09:56:21 PM
In for a pair on round 2.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 29, 2014, 05:44:29 PM
Hi Dan,
 What are the 2 diodes labeled D1 and D2 for?

 Will the AMI T-14 fit just as well as the Cinemag in the transformer slot?

 Thanks.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vineyardgray on January 29, 2014, 09:22:29 PM
Count me in for a pair for round 2.   :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 29, 2014, 11:25:43 PM
What are the 2 diodes labeled D1 and D2 for?

The mouser BOM suggests they are relay voltage suppression diodes.

I found this simple relay info:

http://www.autoshop101.com/forms/hweb2.pdf

Page 11/12
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 30, 2014, 06:49:36 AM
So I had a bit of a sketch re the relay switching and this is what I came up with.

The relays are drawn as individual DPDT switches, with the coil connectors not shown.

The connections from the capsule to the main circuit are labelled A, B and C from top to bottom.

As shown in the previous relay schematic, in the de-energised state there is a connection between the poles and the middle pins. In the energised state there is a connection between the poles and the upper pins.

The switch on the PSU would then need to only supply 2 rails of coil voltage for figure of 8 and omni, with the PSU position for cardioid being no connection.

Am I close?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 30, 2014, 07:30:09 AM
Hi Woot,
 Thanks for explaining about the diodes. Now I'm scratching my head wondering why there aren't 3.

 Thanks for making a sketch of the relay network. I'll give it a look. I spent last evening studying some drawings and photos of similar set  ups on another thread here and I was left thinking I could wire it up but not really understand it. You provided some extra details about the routing that are helpful.

 I am very curious to see the PCB and get this figured out. I have my self made drawing of the traditional 251 and I have cleared out the switch and added the relay schematic symbols in anticipation of getting this figured out.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 30, 2014, 09:12:24 AM
So I had a bit of a sketch re the relay switching and this is what I came up with.

The relays are drawn as individual DPDT switches, with the coil connectors not shown.

The connections from the capsule to the main circuit are labelled A, B and C from top to bottom.

As shown in the previous relay schematic, in the de-energised state there is a connection between the poles and the middle pins. In the energised state there is a connection between the poles and the upper pins.

The switch on the PSU would then need to only supply 2 rails of coil voltage for figure of 8 and omni, with the PSU position for cardioid being no connection.

Am I close?

I am Travelling this week so it quite tough to validate this one without my Master Schematic, but from the top of my head this is it ,
it needs indeed 2 different supply control voltage for the different combination and 2 optional supressing diode, as a pair of relay are activated simultaneously for all the patter to work, the tricky part was to ellaborate a way of having this floating from the board and still be solid and have enough room to supply those 2 control lines from the small area the pcb. the mic is super silent too I can confirm that. you really did your homework on this and i bet you had fun doing it.
I did  :),
Best,
Dan,

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 30, 2014, 09:41:06 AM
Hi Dan,
 What are the 2 diodes labeled D1 and D2 for?

 Will the AMI T-14 fit just as well as the Cinemag in the transformer slot?

 Thanks.

Supressing diode indeed,   yes the aMI T14 will fit nicely there,
Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on January 30, 2014, 10:47:06 AM
Thank you for the info Dan.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on January 30, 2014, 12:58:01 PM
Hi Woot,
 Thanks for explaining about the diodes. Now I'm scratching my head wondering why there aren't 3.

I think because there are only 2 voltage rails, and their job is suppressing reverse voltages down them back towards the PS.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on January 31, 2014, 10:50:37 AM
Looks like a wet tantalum to me , but they may have had different type over times ,  as Metal paper, polyester also,
Why Not polyprop
Here is a shot ,.

http://www.youtube.com/watch?v=rJx9TdJSFRI

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/Elam%20Back.gif)
Best,
Dan,

your guess now,

I guess I'm just trying to get as close as possible to the "vintage sound." I have no experience as to how different capacitors can sound. I have read that wet tantalums short when they die, which I guess could be dangerous for the transformer in the mic. Has anyone compared the tone of wet tantalum versus polypropylene?

Dan, I will probably be in for 1 kit when you do another run.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Marc Duchesne on February 01, 2014, 11:34:38 AM
Where's the mic donor body from Dan...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 01, 2014, 11:53:08 AM
Where's the mic donor body from Dan...

do you mean where is the mic donor come from , ?

D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Marc Duchesne on February 01, 2014, 09:24:59 PM
Yep, where have you got the donor body from...

Might be interested to built one...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 03, 2014, 05:04:34 AM
Hi DAn,

Could you tell me the max voltage for the 200v secondary of the power trafo?

How much power do I need for each secondary?

Would this work?

http://www.don-audio.com/g-pultec-power-trafo-sec-220v-9v-5V

Thanks,

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 09:46:51 AM
Yep, where have you got the donor body from...

Might be interested to built one...

It is a Classic Kit from Chunger HT-11A with psu and Elam type headbasket,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 09:49:23 AM
Hi DAn,

Could you tell me the max voltage for the 200v secondary of the power trafo?

How much power do I need for each secondary?

Would this work?

http://www.don-audio.com/g-pultec-power-trafo-sec-220v-9v-5V

Thanks,

Matt

This traffo has enough power no issues if you use the 9V for the heater and the 220V for the B+ ,  you might want to tweak your R1 and R2 resistor to drop it the right amount tough , you can do the math and it will work fine , the resistance were based on the 200V output from the HT-11 psu , also you need to aim it a 110V not 120V ,
i use a 250K pot for this and 75k r1 and 75K R2 ,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 03, 2014, 10:04:35 AM
An alternative body could be the BeesNeez Ela M. It was on sale (100 dollars off) until last weekend. Perhaps Ben and Veronica could prolong the sale for Group DIY members who act quickly? The Australian dollar is relatively cheap now, too, especially for Europeans. The body will still be more expensive than the HT-11A, but it's built like a tank.
It does have a bigger diameter (closer to the original, actually). Well, a little too big should be less of a problem than too small. Would it be a problem, Dan?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 10:21:15 AM
An alternative body could be the BeesNeez Ela M. It was on sale (100 dollars off) until last weekend. Perhaps Ben and Veronica could prolong the sale for Group DIY members who act quickly? The Australian dollar is relatively cheap now, too, especially for Europeans. The body will still be more expensive than the HT-11A, but it's built like a tank.
It does have a bigger diameter (closer to the original, actually). Well, a little too big should be less of a problem than too small. Would it be a problem, Dan?

Too big is actually a good thing for DIYer, what is the lenght of the Beez mic body.
LEt me know i will check the lenght of the pcb  .
Best,
DAN,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 03, 2014, 10:35:15 AM
Oh, I forgot to add that it can be ordered in any of the standard BeesNeez colors, with no upcharge. These are professional paint and powder coating jobs.

Quote
Too big is actually a good thing for DIYer, what is the lenght of the Beez mic body.
LEt me know i will check the lenght of the pcb  .
Best,
DAN,

Sleeve diameter, from the back of my head, is 51 mm or 2 inches. I'd have to check for length (I believe it was mentioned in older adds), but perhaps Ben or Veronica could chime in.

Anyway, here's the current add (without sale):
http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99 (http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 03, 2014, 10:50:22 AM
How tough would it be to fashion an angled pedestal for the capsule mount? That's one of the differences between C12 and 251, as well.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 03, 2014, 11:26:56 AM
Yep, where have you got the donor body from...

Might be interested to built one...

Do you mean building the kit or making an Ela M251 body?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on February 03, 2014, 12:51:44 PM
Oh, I forgot to add that it can be ordered in any of the standard BeesNeez colors, with no upcharge. These are professional paint and powder coating jobs.

Quote
Too big is actually a good thing for DIYer, what is the lenght of the Beez mic body.
LEt me know i will check the lenght of the pcb  .
Best,
DAN,

Sleeve diameter, from the back of my head, is 51 mm or 2 inches. I'd have to check for length (I believe it was mentioned in older adds), but perhaps Ben or Veronica could chime in.

Anyway, here's the current add (without sale):
http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99 (http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99)

Hey guys inside the BeesNeez 251 body there is 119mm of clearance for a PCB. PCB width can be up to 48mm wide. Our 251 body is 51mm the same as the original.

Sorry for the delay in seeing this post, it was a busy weekend.

Thanks,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on February 03, 2014, 01:01:25 PM
As for the sale price, I can bring it back for you guys. However I really need to have numbers. I already have head grilles and bases made, but I do need to make the body tube. This can be done quickly and easily, but before I purchase the metal and re-program the CNC, it would be good to know how many we are talking about. So if you let me know your interest I can start a list. I would also be happy to offer a body and CK12  capsule combo, if you purchase both together I could reduce the capsule price to $400. Ben is completing a large CK12 batch this week so they will be in stock and all current orders shipped.

Thanks, v
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 03, 2014, 01:13:32 PM
That was pretty quick actually!  :)
Thanks, Veronica.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 03, 2014, 03:04:04 PM

This traffo has enough power no issues if you use the 9V for the heater and the 220V for the B+ ,  you might want to tweak your R1 and R2 resistor to drop it the right amount tough , you can do the math and it will work fine , the resistance were based on the 200V output from the HT-11 psu , also you need to aim it a 110V not 120V ,
i use a 250K pot for this and 75k r1 and 75K R2 ,
Best,
Dan,

Thanks Dan
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 03, 2014, 03:15:43 PM
Sleeve diameter, from the back of my head, is 51 mm or 2 inches. I'd have to check for length (I believe it was mentioned in older adds), but perhaps Ben or Veronica could chime in.

This was one of the issues with the Matachung board... it was too long for the BN ELAM body...

I should be receiving my ELAM Walter White board soon, so I can double check it. And if Veronica is saying 119 mm clearance for the PCB, then I think there is still lots of room under that where a trafo like the T14 could fit if needed (in addition to the xlr wiring).

I can confirm as well that the quality and finish of these is very high, and as micaddict mentioned there is probably another 10-15% "discount" in it for both European and US customers owing to the recent fluctuation in the AUD... I know because everything I'd like to buy is now 10-15% more expensive  :'(
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 03, 2014, 03:53:21 PM
So Dan.... what's the current draw of each bit of the circuit??

120v and 6.3V parts?

Thanks !
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 08:34:08 PM
Oh, I forgot to add that it can be ordered in any of the standard BeesNeez colors, with no upcharge. These are professional paint and powder coating jobs.

Quote
Too big is actually a good thing for DIYer, what is the lenght of the Beez mic body.
LEt me know i will check the lenght of the pcb  .
Best,
DAN,

Sleeve diameter, from the back of my head, is 51 mm or 2 inches. I'd have to check for length (I believe it was mentioned in older adds), but perhaps Ben or Veronica could chime in.

Anyway, here's the current add (without sale):
http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99 (http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=99)

Hey guys inside the BeesNeez 251 body there is 119mm of clearance for a PCB. PCB width can be up to 48mm wide. Our 251 body is 51mm the same as the original.

Sorry for the delay in seeing this post, it was a busy weekend.

Thanks,

N.B

PCB Dimension :

Lenght:  126mm
this is a Taper PCB
PCB maximum Width: 38mm
PCB Minimum Width at bottom of pcb Width: 36mm
Side Rail Clearance Minimum Required : 2.5mm

Fit shown is HT-11 Mic body

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/CAM00133%20-%20Copy.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993feb.jpg)

Best
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 08:44:19 PM
So Dan.... what's the current draw of each bit of the circuit??

120v and 6.3V parts?

Thanks !

110V B+ not really much this is plate current  : <1ma

or you can do this  (B+(V))-(Plate Voltage(V))/Plate Resistance = Plate Current.


6.3V Heater in parralelle  6072 Tube Data sheet : 350ma


Hope this helps,
Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 03, 2014, 10:34:10 PM

Lenght:  126mm
PCB maximum Width: 38mm
Side Rail Clearance Minimum Required : 2.5mm

Best
Dan,

Re the Beezneez body...

Yep, so similarly to the Matachung board it is ~7mm too long.... But looking at the board, we may be able to bring it in on each side by a couple of millimetres so it fits into the bottom bit (see photo). The bottom part is approx 22mm deep, some of which will be taken up by the xlr wiring....

Otherwise, I presume I'll have to cut all of the board off from the trafo down and directly wire all of the xlr connectors to their destination... DAn, will there be much of an issue doing this?

Cheers,

MAtt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 10:41:43 PM

Lenght:  126mm
PCB maximum Width: 38mm
Side Rail Clearance Minimum Required : 2.5mm

Best
Dan,


Re the Beezneez body...

Yep, so similarly to the Matachung board it is ~7mm too long.... But looking at the board, we may be able to bring it in on each side by a couple of millimetres so it fits into the bottom bit (see photo). The bottom part is approx 22mm deep, some of which will be taken up by the xlr wiring....

Otherwise, I presume I'll have to cut all of the board off from the trafo down and directly wire all of the xlr connectors to their destination... DAn, will there be much of an issue doing this?

Cheers,

MAtt


finding 3.5mm on each side would be best , but you could jump the connection but it will not be very "elegant",
but after all this is DIY so scraping a bit of metal for this particular body could also be possible ,  ;),
following the next episode,
Best,
Dan,



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 03, 2014, 10:44:56 PM

Lenght:  126mm
PCB maximum Width: 38mm
Side Rail Clearance Minimum Required : 2.5mm

Best
Dan,

Re the Beezneez body...

Yep, so similarly to the Matachung board it is ~7mm too long.... But looking at the board, we may be able to bring it in on each side by a couple of millimetres so it fits into the bottom bit (see photo). The bottom part is approx 22mm deep, some of which will be taken up by the xlr wiring....

Otherwise, I presume I'll have to cut all of the board off from the trafo down and directly wire all of the xlr connectors to their destination... DAn, will there be much of an issue doing this?

Cheers,

MAtt

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/CAM00133%20-%20Copy.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993ffb.jpg)

Here is even more details ,
Lenght:  126mm
this is a Taper PCB
PCB maximum Width: 38mm
PCB Minimum Width at bottom of pcb Width: 36mm
Side Rail Clearance Minimum Required : 2.5mm

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on February 03, 2014, 11:40:45 PM
What are the dimensions of the coupling cap cutout?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 04, 2014, 01:02:28 AM
So Dan.... what's the current draw of each bit of the circuit??

120v and 6.3V parts?

Thanks !

110V B+ not really much this is plate current  : <1ma

or you can do this  (B+(V))-(Plate Voltage(V))/Plate Resistance = Plate Current.


6.3V Heater in parralelle  6072 Tube Data sheet : 350ma


Hope this helps,
Best,
DAN,

Sorry DAn.... I'm really too n00b to figure this out...can you help please?

So are R1 and R2 acting as a voltage divider? Where does the trimmer come in? Is it in series with one of the resistors?

I plugged these numbers into a voltage divider calculator but the answers didn't make any sense to me... for a 200v input and 110v output, it's suggesting around 91k for R2 if R1 is 75 k. This would make sense for a 75 k resistor and a 25k trimmer... But I'm not sure where the 200k trimmer fits in?

For a 220v inout and 110 volt output R1 and R2 are the same value... 100k, 80k, whatever. So what would you suggest?

Thanks for any advice!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 04, 2014, 04:56:32 AM
Well, the slight oversize is a bummer. Of course both Matador and Dan's PCB were based on the long and slender HT-11a body; not necessarily an original Ela M. And Matador's is in fact the C12 PCB to begin with. I guess Dan could theoretically shrink the whole PCB lengthwise by 5.5%, but that would send him back to the drawing table, meaning extra time, energy and money. Not the best scenario for him probably. On the other hand, should very accurate clone bodies (looking like the two originals, earlier posted in this thread) become available, it may be a good thing if there were a PCB fitting the original thing. The same holds for the U67 BTW.
But that's missing the point, of course. I can't speak for Dan, but it seems to me that the whole idea of his PCBs is accurate, classic circuits for affordable, well-available bodies. Those who want the exact look of an Ela M251 will probably want the clear plastic inside, too.
Hey, but the D-49 does come in a square and round version. Hmmm.....  ;)
Just playing around there, Dan. It's your show and a fine show it is!

Conversely, should there still be a BeesNeez collaboration, it might be possible for them to cut slightly longer sleeves from the rough tube. But that would mean adding longer rails, as well. So I guess that would call for a serious amount of bodies to be worthwile.

Oh well, it was worth trying. I like the heavy BeesNeez weapons.

Yes, perhaps a little filing here and there will do the trick. After all, it's DIY.

Carry on. :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 04, 2014, 05:53:08 AM
What are the dimensions of the coupling cap cutout?

41 x 16mm
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 04, 2014, 06:19:09 AM
^^

Sweet, this should also fit:

Auricap XO 400v 26 x 33mm (DxL)
Mundorf M-Cap 400v 17 x 34mm (DxL)

if anyone considering using them...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 04, 2014, 08:36:33 AM
So Dan.... what's the current draw of each bit of the circuit??

120v and 6.3V parts?

Thanks !

110V B+ not really much this is plate current  : <1ma

or you can do this  (B+(V))-(Plate Voltage(V))/Plate Resistance = Plate Current.


6.3V Heater in parralelle  6072 Tube Data sheet : 350ma


Hope this helps,
Best,
DAN,

Sorry DAn.... I'm really too n00b to figure this out...can you help please?

So are R1 and R2 acting as a voltage divider? Where does the trimmer come in? Is it in series with one of the resistors?

I plugged these numbers into a voltage divider calculator but the answers didn't make any sense to me... for a 200v input and 110v output, it's suggesting around 91k for R2 if R1 is 75 k. This would make sense for a 75 k resistor and a 25k trimmer... But I'm not sure where the 200k trimmer fits in?

For a 220v inout and 110 volt output R1 and R2 are the same value... 100k, 80k, whatever. So what would you suggest?

Thanks for any advice!

When i have time i will probe my mic to find out exactely the current draw at 110B+
i have made a dropper resistor caculator with excel that i will share also,
Best,
Dan,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 04, 2014, 09:14:38 AM
Well, the slight oversize is a bummer. Of course both Matador and Dan's PCB were based on the long and slender HT-11a body; not necessarily an original Ela M. And Matador's is in fact the C12 PCB to begin with. I guess Dan could theoretically shrink the whole PCB lengthwise by 5.5%, but that would send him back to the drawing table, meaning extra time, energy and money. Not the best scenario for him probably. On the other hand, should very accurate clone bodies (looking like the two originals, earlier posted in this thread) become available, it may be a good thing if there were a PCB fitting the original thing. The same holds for the U67 BTW.
But that's missing the point, of course. I can't speak for Dan, but it seems to me that the whole idea of his PCBs is accurate, classic circuits for affordable, well-available bodies. Those who want the exact look of an Ela M251 will probably want the clear plastic inside, too.
Hey, but the D-49 does come in a square and round version. Hmmm.....  ;)
Just playing around there, Dan. It's your show and a fine show it is!

Conversely, should there still be a BeesNeez collaboration, it might be possible for them to cut slightly longer sleeves from the rough tube. But that would mean adding longer rails, as well. So I guess that would call for a serious amount of bodies to be worthwile.

Oh well, it was worth trying. I like the heavy BeesNeez weapons.

Yes, perhaps a little filing here and there will do the trick. After all, it's DIY.

Carry on. :)

Accurate bodies for U67 and 251 would sure be nice. I must say, however, that after my own very rudimentary tests (which I will continue), I'm no longer convinced headbaskets have as much to do with sound as many claim.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on February 04, 2014, 11:26:03 AM


Conversely, should there still be a BeesNeez collaboration, it might be possible for them to cut slightly longer sleeves from the rough tube. But that would mean adding longer rails, as well. So I guess that would call for a serious amount of bodies to be worthwile.

Oh well, it was worth trying. I like the heavy BeesNeez weapons.

Yes, perhaps a little filing here and there will do the trick. After all, it's DIY.

Carry on. :)

Hi, I think that Dan's PCB looks great, so making the body tubes and rails longer is not a problem, but I will need numbers to order the metal and to make the changes. I will not go ahead with anything until we have some idea of what we are looking at.

Thanks, V
[email protected]
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 04, 2014, 12:31:24 PM
^^^
 :)

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on February 04, 2014, 07:40:22 PM
Looks like a wet tantalum to me , but they may have had different type over times ,  as Metal paper, polyester also,
Why Not polyprop
Here is a shot ,.
(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/Elam%20Back.gif)
I have only seen wet tantalums in stock 251's over the last 24 years. Any film caps were aftermarket repairs.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 04, 2014, 08:47:59 PM
Good point, David Bock. I have been unable to find any wet tantalums over 125V in the 3.3uF range, and they are very expensive. Do you think it's really worth it sound-wise, and is it dangerous to use a cap of 125V? And wouldn't it be dangerous for the transformer if the wet tantalum goes caput? I read that they short when they fail.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 05, 2014, 12:41:56 AM
^

doing a wet tantalum search on the Vishay website yields some series of caps at higher voltages (180-200+) and appropriate capacitance. Don't know if any are OK for this application.

They may sell them to you although I wonder what the MQ would be :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 05, 2014, 04:38:52 AM
Quote
Hi, I think that Dan's PCB looks great, so making the body tubes and rails longer is not a problem, but I will need numbers to order the metal and to make the changes. I will not go ahead with anything until we have some idea of what we are looking at.

Thanks, V
[email protected]


So .......

Anyone want me to start a feeler thread?



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: braeden on February 05, 2014, 05:16:57 AM
Quote
Hi, I think that Dan's PCB looks great, so making the body tubes and rails longer is not a problem, but I will need numbers to order the metal and to make the changes. I will not go ahead with anything until we have some idea of what we are looking at.

Thanks, V
[email protected]


So .......

Anyone want me to start a feeler thread?



Henk

Very interested in purchasing a CK12 and ELA body.

When are the PCBs available?

Thanks
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 05, 2014, 09:03:52 AM
Quote
Hi, I think that Dan's PCB looks great, so making the body tubes and rails longer is not a problem, but I will need numbers to order the metal and to make the changes. I will not go ahead with anything until we have some idea of what we are looking at.

Thanks, V
[email protected]


So .......

Anyone want me to start a feeler thread?



Henk

Very interested in purchasing a CK12 and ELA body.

When are the PCBs available?

Thanks

They will be returning when there is enough folks to make it happen I guess,
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 05, 2014, 09:05:30 AM
^

doing a wet tantalum search on the Vishay website yields some series of caps at higher voltages (180-200+) and appropriate capacitance. Don't know if any are OK for this application.

They may sell them to you although I wonder what the MQ would be :)

I just tried this. I'm not finding anything over 125V for 3.3uF. Got a link? MQ on mouser is like 25 pieces at $60 each
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on February 05, 2014, 01:52:52 PM
Good point, David Bock. I have been unable to find any wet tantalums over 125V in the 3.3uF range, and they are very expensive. Do you think it's really worth it sound-wise, and is it dangerous to use a cap of 125V? And wouldn't it be dangerous for the transformer if the wet tantalum goes caput? I read that they short when they fail.
I've never seen the wet tant in a 251 short out (I have seen loss of capacitance), though I've seen plenty of tants short out in ATR124 decks taking down the whole machine (smoke optional).
I have also seen original T14/1 xfmrs go open. That wire is mighty fine.
IF your new build mic does not copy the exact footprint of the 251, you should have more room for other cap options. Then you can listen and decide for yourself. But in a vintage 251, space is at a premium so the original cap is a must, unless you are willing to crack the plexiglass body, as some repairs guys are willing to do. FYI there is no electrolytic that will fit in that space that sounds good so don't bother.
Yes you can use a 125v cap, though it's safer with higher tolerances. The occasion of reaching 125v across the cap occurs at power up, when the B+ is there but the tube hasn't fully heated. Reaching full B+ once the tube is heated will likely not happen during normal use, unless you stick it in a kick drum.
I have found NOS went tants (of the value you need for this mic), even recently, so I know they are out there 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 05, 2014, 02:33:05 PM
Good point, David Bock. I have been unable to find any wet tantalums over 125V in the 3.3uF range, and they are very expensive. Do you think it's really worth it sound-wise, and is it dangerous to use a cap of 125V? And wouldn't it be dangerous for the transformer if the wet tantalum goes caput? I read that they short when they fail.
I've never seen the wet tant in a 251 short out (I have seen loss of capacitance), though I've seen plenty of tants short out in ATR124 decks taking down the whole machine (smoke optional).
I have also seen original T14/1 xfmrs go open. That wire is mighty fine.
IF your new build mic does not copy the exact footprint of the 251, you should have more room for other cap options. Then you can listen and decide for yourself. But in a vintage 251, space is at a premium so the original cap is a must, unless you are willing to crack the plexiglass body, as some repairs guys are willing to do. FYI there is no electrolytic that will fit in that space that sounds good so don't bother.
Yes you can use a 125v cap, though it's safer with higher tolerances. The occasion of reaching 125v across the cap occurs at power up, when the B+ is there but the tube hasn't fully heated. Reaching full B+ once the tube is heated will likely not happen during normal use, unless you stick it in a kick drum.
I have found NOS went tants (of the value you need for this mic), even recently, so I know they are out there

Dear Bockaudio, thanks For your Valuable input in this thread,
Best,
Dany,
dD
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 05, 2014, 02:40:22 PM
David rocks.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: granger.frederic on February 05, 2014, 03:45:01 PM
Great work guys
is there any issue with the relays in the high impedance section ?
what's the inter-electrode insulation/capacitance of the relays ?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 05, 2014, 03:58:06 PM
Great work guys
is there any issue with the relays in the high impedance section ?
what's the inter-electrode insulation/capacitance of the relays ?

Thanks, Works Fantastic , All critical connection to the relay are floating off  board.
 
see here:
http://dk.mouser.com/Search/ProductDetail.aspx?R=DS2Y-S-DC6Vvirtualkey66710000virtualkey769-DS2Y-S-DC6V (http://dk.mouser.com/Search/ProductDetail.aspx?R=DS2Y-S-DC6Vvirtualkey66710000virtualkey769-DS2Y-S-DC6V)

Best,  :)
Dan,
dD


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 05, 2014, 05:56:58 PM
Well done Dan in taking over the project... It was too much for me to get done with everything else going on at the moment.

I do think maybe take a look at our last design (version 6.5) as this was the closest i feel to perfection in utilizing the relays.


The cathode bypass components would be floating on back of tube base hence displayed off of the board.

As per the coupling cap being wet tant, i have a few here, they are pretty much the 1501 if i remember correctly and I feel they don't sound bad they just over compress. I didn't like them in my elam builds but thats me.

Cheers

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 05, 2014, 06:01:15 PM
i also feel there should be more space on your build to accommodate longer resistors such as vintage wire wound types which can be sourced.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 05, 2014, 10:56:52 PM
^

doing a wet tantalum search on the Vishay website yields some series of caps at higher voltages (180-200+) and appropriate capacitance. Don't know if any are OK for this application.

They may sell them to you although I wonder what the MQ would be :)

I just tried this. I'm not finding anything over 125V for 3.3uF. Got a link? MQ on mouser is like 25 pieces at $60 each


http://www.vishay.com/capacitors/tantalum/tantalum-wet/

They look like the XTK model. Datasheet is there too...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 05, 2014, 11:22:24 PM
Good point, David Bock. I have been unable to find any wet tantalums over 125V in the 3.3uF range, and they are very expensive. Do you think it's really worth it sound-wise, and is it dangerous to use a cap of 125V? And wouldn't it be dangerous for the transformer if the wet tantalum goes caput? I read that they short when they fail.
I've never seen the wet tant in a 251 short out (I have seen loss of capacitance), though I've seen plenty of tants short out in ATR124 decks taking down the whole machine (smoke optional).
I have also seen original T14/1 xfmrs go open. That wire is mighty fine.
IF your new build mic does not copy the exact footprint of the 251, you should have more room for other cap options. Then you can listen and decide for yourself. But in a vintage 251, space is at a premium so the original cap is a must, unless you are willing to crack the plexiglass body, as some repairs guys are willing to do. FYI there is no electrolytic that will fit in that space that sounds good so don't bother.
Yes you can use a 125v cap, though it's safer with higher tolerances. The occasion of reaching 125v across the cap occurs at power up, when the B+ is there but the tube hasn't fully heated. Reaching full B+ once the tube is heated will likely not happen during normal use, unless you stick it in a kick drum.
I have found NOS went tants (of the value you need for this mic), even recently, so I know they are out there

Thanks for that info! May I ask where you found those NOS wet tants, or am I off on a treasure hunt? I didn't see the right ones at Surplus Sales.

^

doing a wet tantalum search on the Vishay website yields some series of caps at higher voltages (180-200+) and appropriate capacitance. Don't know if any are OK for this application.

They may sell them to you although I wonder what the MQ would be :)

I just tried this. I'm not finding anything over 125V for 3.3uF. Got a link? MQ on mouser is like 25 pieces at $60 each


http://www.vishay.com/capacitors/tantalum/tantalum-wet/

They look like the XTK model. Datasheet is there too...

Thanks! Strange they did not show up when I used the Search Filters, but I see them now. This could be a good option if Vishay will sell them in low minimum quantities.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 06, 2014, 02:22:48 AM
I think they are actually 1501's

TE-1501 capacitor

http://www.ebay.com/itm/SPRAGUE-30D-TE-1501-CAPACITOR-2-150-DC-NNB-/360167699030

the 1501 is what telefunken usa use in their reissues, although thats not really saying much. sorry
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 06, 2014, 03:17:28 PM
I think they are actually 1501's

TE-1501 capacitor

http://www.ebay.com/itm/SPRAGUE-30D-TE-1501-CAPACITOR-2-150-DC-NNB-/360167699030

the 1501 is what telefunken usa use in their reissues, although thats not really saying much. sorry

thanks Jess for the pointer,
Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on February 06, 2014, 03:35:26 PM
Stuffing the board now. Maybe I missed something.
What's all this about a WET Tant? Should I get the part in the above E-bay Link?
Where does it go?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 06, 2014, 03:46:18 PM
The TE-1501 appears to be aluminum cap, not wet tant. It's for the coupling cap. It does indeed look like the caps Telefunken USA uses quite a bit in their reissues.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 06, 2014, 04:21:29 PM
I'm not sure how it applies but here is info on the Sprague:


http://www.vishay.com/docs/42042/te.pdf

http://www.mouser.com/ProductDetail/Vishay-Sprague/TE1501-E3/?qs=sGAEpiMZZMtZ1n0r9vR22beeiJoI0EpCZ9lzI8RKauE%3d
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 06, 2014, 08:29:07 PM
Here is a drawing of the factory two five one with the figure 8 routing through the the switch. It helped me to look at this to confirm that I had drawn the relays correctly.

I will appreciate it if any or every one can check my work in progress and offer correction(s) if they spot any mistakes.


For Reference.
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199400b.jpg)

I Posted the Schematics for you to compare see page 1,
Best,
DAn,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 07, 2014, 07:04:33 AM
Thanks very much Dany!

I look forward to going through step by step.  :-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 07, 2014, 01:24:21 PM
Hi Dany,
 I was looking at your D-E251E schematic and comparing it too the AKG ELA M251E schematic, both of which are linked to in the first post of this thread.

 I am curious about the polarity shown in the D-E251E schematic for the Cathode Capacitor that you have labeled C3, 22uf 6V. The traditional AKG schematic has the polarity shown the other way so I am bit confused and thought I should ask about it.

 ?

 Thank You.

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 07, 2014, 02:45:56 PM
Hi Dany,
 I was looking at your D-E251E schematic and comparing it too the AKG ELA M251E schematic, both of which are linked to in the first post of this thread.

 I am curious about the polarity shown in the D-E251E schematic for the Cathode Capacitor that you have labeled C3, 22uf 6V. The traditional AKG schematic has the polarity shown the other way so I am bit confused and thought I should ask about it.

 ?

 Thank You.

ErraTum

Many Thanks For Catching This , it is indeed inverted , this will be corected in the production batch as this are prototype pcb  , the silkscreen for C3 on the tube socket board should be inverted
so the (+) on the pcb should be the negative (-) side , for those who have got the proto pcb form the intial run , i sent an email to all of you to warn about this erratum ,
To fix this orient the capacitor C3 + lead on the negative on the pcb  

Best,
Dan,




Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on February 07, 2014, 04:05:14 PM
Got it. C3 inverted.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 07, 2014, 04:25:18 PM
I've started a separate, feeler thread concerning a Beesneez body, taylored for this project.

http://groupdiy.com/index.php?topic=55176.0 (http://groupdiy.com/index.php?topic=55176.0)



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on February 07, 2014, 08:22:36 PM
The TE-1501 appears to be aluminum cap, not wet tant. It's for the coupling cap. It does indeed look like the caps Telefunken USA uses quite a bit in their reissues.
I really do urge you to either find the wet tant or make space for PIO.
IIR I have consistently found WT's at assorted Surplus places.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 08, 2014, 07:27:53 AM
Hi David,
 Thank you for expressing this with emphasis.

 I have been looking around online for Wet tantalum and Paper in Oil caps in the 125vDC to 450vDC range and can only find limited selections.

 It seems like if you are willing to find them you can find them.

 I have a question regarding the capacitance value. I recall seeing discussion regarding opinions about values other than 3.2uf but I am having trouble finding reference to the discussion in my notes.

 I am wondering, since it is not particularly easy, or affordable, to locate an assorted supply of Wet Tantalum capacitors, if you or someone can offer a general overview of the implications of using values different than 3.2uf.


Thank you.
 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on February 08, 2014, 01:58:38 PM
I have a question regarding the capacitance value. I recall seeing discussion regarding opinions about values other than 3.2uf but I am having trouble finding reference to the discussion in my notes.

You could increase the grid resistor and reduce the output cap value. Go up to 250M and down to 1uF.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: OPR on February 11, 2014, 07:42:18 AM
+1
Quote
250M and down to 1uF.
particularly if your using a Chinese Ck12 capsule as they don't have the LF response of the real capsule or an accurate clone.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 12, 2014, 12:46:07 PM
Well done Dan in taking over the project... It was too much for me to get done with everything else going on at the moment.

I do think maybe take a look at our last design (version 6.5) as this was the closest i feel to perfection in utilizing the relays.


The cathode bypass components would be floating on back of tube base hence displayed off of the board.


Hi Jess,
 I took a look at the board you posted an example of to learn how you planned to use the relays and I can not figure out how it can work. I drew a schematic, as I did with Dany's layout, and I am hoping I am missing something you can explain. I can't unlock the puzzle of how the board you posted a image of provides all 3 patterns.

 Any clues?

 Thank You.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 12, 2014, 05:55:41 PM
Well done Dan in taking over the project... It was too much for me to get done with everything else going on at the moment.

I do think maybe take a look at our last design (version 6.5) as this was the closest i feel to perfection in utilizing the relays.


The cathode bypass components would be floating on back of tube base hence displayed off of the board.


Hi Jess,
 I took a look at the board you posted an example of to learn how you planned to use the relays and I can not figure out how it can work. I drew a schematic, as I did with Dany's layout, and I am hoping I am missing something you can explain. I can't unlock the puzzle of how the board you posted a image of provides all 3 patterns.

 Any clues?

 Thank You.

did you get the schematic I posted ?
Best,
dD
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 12, 2014, 07:15:30 PM
Hi Dany,
 Yes I downloaded it right after you posted it. It was very helpful. Thank for posting it. I had thanked you and I sent you that message about C3 too.

 I am interested in the idea that there may be several relay switching solutions to achieve the same goal and I enjoy the exercise of thinking it through.

 Thank You.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 12, 2014, 07:50:05 PM
Hi Dany,
 Yes I downloaded it right after you posted it. It was very helpful. Thank for posting it. I had thanked you and I sent you that message about C3 too.

 I am interested in the idea that there may be several relay switching solutions to achieve the same goal and I enjoy the exercise of thinking it through.

 Thank You.

Yes Thanks again for catching C3  :) , Very helpfull too ,
I was just curious to see if you were refering to Jesse Board saying that i could not work out so was  just checkin if you had found another mistake in the pattern switching on mine  I really checked that part a million time and with the built mic  ;D
I am all ear if you can find an easier way.
Best,
dD

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 12, 2014, 07:59:35 PM
Hi Dany,
 I learned a lot by working through your example. I think you nailed it.

 :-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 12, 2014, 11:27:24 PM
Hi DAn,

Received the boards with thanks. They are great! So it is with apologies that I present this.... This is the standard ELAM 251 body from BeezNees.

Lots of curiosity, much impatience and some precision dremeling :)

The only thing I can see is that the copper ground layer is exposed on the left and will therefore short to the mic body. Is this OK, or ideally should it be isolated?

Or if this is really a bad idea, then please let me know and I'll leave the other one alone. ;)

Thanks,

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 12, 2014, 11:28:33 PM
Just needs a tidy up filing...

For anyone wondering that's approximately 10mm up the board.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on February 13, 2014, 02:14:53 AM
Woot, Thanks for the pix.
Are you using the same body that's listed in this FEELER?

http://groupdiy.com/index.php?topic=55176.0 (http://groupdiy.com/index.php?topic=55176.0)

I've got the same board and am considering this Beeneez body.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 13, 2014, 05:54:07 AM
The body in the feeler (if we get enough takers) will be an exact fit. This means it will be longer if necessary, it will have corresponding holes in the rails etc.

 :)

Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 13, 2014, 05:57:01 AM
BTW, do we need an opening for a pattern switch?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 13, 2014, 06:11:25 AM
I did this with the original size body from BeesNeez, the bodies in the feeler don't exist yet ;)

I haven't confirmed that the AMI T14 or any other trafo will fit snugly down in that recess with the XLR but I can't see it being an issue just from eyeballing it. When I do the install, I'll update everyone accordingly.

I can see the benefit from having a custom made body, but given that Veronica said there would be an MQ, and the usual time it takes to get these things rolling, I just thought I'd do a simple hack job, to see whether it could work if the other plan fell through.

 8)

The other problem I foresee is that it won't matter where you drill the holes as the board in current dimensions doesn't over lap the struts. Make it wider, then it'll be too fat for the Alcatron et al mic bodies.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 13, 2014, 06:42:12 AM
Quote
The other problem I foresee is that it won't matter where you drill the holes as the board in current dimensions doesn't over lap the struts. Make it wider, then it'll be too fat for the Alcatron et al mic bodies.

Yeah, I've thought about that one. Well, in any case the collaboration will result in the best, practical solutions I'm sure.
Hey, removable ears on the PCB maybe?   ::)

So, what do you guys think would be the best place to discuss these details; this thread or the feeler?
I would think the latter, but I'm not sure.


Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 08:55:44 AM
Quote
The only thing I can see is that the copper ground layer is exposed on the left and will therefore short to the mic body. Is this OK, or ideally should it be isolated?

Or if this is really a bad idea

the ground plane is actually made to make contact with the mic body , but the intended purpose is trough the mounting hole on the side tough ,
the upper parts where the relay sits is the critical place because there are the relays pads there and some component pad those should be clear rfom the mic railing at all times,  bythe look of it i think it will fit nice.

Hope this helps,
BEst
dD
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 13, 2014, 10:38:42 AM
After building 2 fantastic Tim Campbell equipped sounding ELAM's this past weekend, I just wanted to mention that with the HT-11A bodies, the relays are a VERY tight fit and the 2 outside ones will rub against the body tube.  I was somewhat able to alleviate this by angling the 2 outside relays in so that their outside corners sat a little closer towards the center K2 relay.  Also I cut the leads for C4, R6, and R4 short enough that they did not protrude through the board so that they relay wouldn't have to sit any farther out than it needed.  Finally I was able to carefully file the corners of the relay in at a 45 degree angle.  My boards still flex just a bit when assembling the mic from the relays hitting the body tube though  :-\

Anyways hope that helps with anybody that has yet to use these boards in conjunction with the HT-11A's.     
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 13, 2014, 11:11:53 AM
The other problem I foresee is that it won't matter where you drill the holes as the board in current dimensions doesn't over lap the struts. Make it wider, then it'll be too fat for the Alcatron et al mic bodies.

So how do you plan to attach the PCB?

BTW, do we need an opening for a pattern switch?

Room for a pattern switch would be great. However (and I could be very wrong), I thought I read somewhere that the proper switches do not exist anymore. Again, I could be way off base here.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 11:33:13 AM
After building 2 fantastic Tim Campbell equipped sounding ELAM's this past weekend, I just wanted to mention that with the HT-11A bodies, the relays are a VERY tight fit and the 2 outside ones will rub against the body tube.  I was somewhat able to alleviate this by angling the 2 outside relays in so that their outside corners sat a little closer towards the center K2 relay.  Also I cut the leads for C4, R6, and R4 short enough that they did not protrude through the board so that they relay wouldn't have to sit any farther out than it needed.  Finally I was able to carefully file the corners of the relay in at a 45 degree angle.  My boards still flex just a bit when assembling the mic from the relays hitting the body tube though  :-\

Anyways hope that helps with anybody that has yet to use these boards in conjunction with the HT-11A's.   

would you be able to post some picture of this achievement in my case i did not have to file anything to make it fit, lets make sure when you install the relay that they are fully engaged and as close as the board as possible and not slighlty crooked , it is very easy to leave a gap there or position the relay just sidewayss,  what i usually do is that i solder one pin of the relay and then heat it up again and push down on the relay to give it his proper position and then i solder the rest of the pins, also make sure your ouput cap is not too fat to make the board flex when you install it , I agree tough it is a close fit but it should slide in properly as in my build.
also make sure the orientation of the pcb is not slighlty deviated also  cause i also notice once that the rail on the HT-11A can have a slight tolerance sideways that you can fix by just pusing them straight. once this is perfectly straight it should slide in but it is indeed a very close , so you have to make sure all the small details are on your side.  ;)
 
Again, Congrats for your build and i would be delighted to see picture of those babies on this thread,  :) :) :)

and an audio sample would just be divine with CT inside

Best,  :)
Dan,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 13, 2014, 01:08:21 PM
Dan,

The relays were mounted absolutely flush against the board, and the board aligned with the frame rails.  I also dremeled out space for the output cap so it doesn't touch at all.  The mic pictured is my first attempt, but my 2nd one that went smoother (but still touching and with the angled relays) was already sent off to a friend before I could take pictures.  I also noticed that the mounting tab was also a culprit.  After carefully using pliers to angle the board closer to the frame rails towards the headbasket, it helped a bit as well.  You can see in the last picture how close the top outside edges of the relays come to where the body tube fits in the headbasket.   

Anyways here's my build...no clips as of yet.  I just did a comparison with my C12 TC build and noticed the ELAM had more proximity/bass response, as well as a slightly mid scooped sound that I suppose would deem it more aggressive compared to the more neutral C12.  I'll try to have a singer in soon to do some more comparisons to post.

Kevin

(http://i1096.photobucket.com/albums/g330/kcguitarz/Mobile%20Uploads/100_5674_zpsb2ff1cda.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/Mobile%20Uploads/100_5674_zpsb2ff1cda.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/Mobile%20Uploads/100_5675_zps3f854bcf.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/Mobile%20Uploads/100_5675_zps3f854bcf.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/Mobile%20Uploads/100_5677_zpsd0ca02c6.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/Mobile%20Uploads/100_5677_zpsd0ca02c6.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/Mobile%20Uploads/100_5683_zpsd8c27453.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/Mobile%20Uploads/100_5683_zpsd8c27453.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/Mobile%20Uploads/100_5681_zps876cd920.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/Mobile%20Uploads/100_5681_zps876cd920.jpg.html)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 01:31:53 PM
Many thanks Kevin for your post , Not that i want to be too fussy  ;) , but i can notice on your build that the railing and spacing is not symetrical ,
Like I said if you align it perfeclty straight it will go in without having to modify anything ,  and also not sure if you have used the same cap as i have in my picture but this one is definetly a little too fat and comes in contact with the tube , i replaced this one in the bOM for a little smaller ones that is 3.3uf polyester that will fit in no problem. but I might see if i could make even more room for this particular one in the release revision as it is rolling out now and caps is a matter of taste and fit.
on another note what i did to be able to install the 2 screws as one thread is on the other side I used a pair of plier and bent the ears a bit so i could reach the thread on the other side of the mic body  ;)

Again Really appreciate your input and hope you will enjoys these , wow 2 already. :)
Best,
Dan,

Caution to Symetrical pcb installation ,
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281994058.jpg)


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on February 13, 2014, 01:58:10 PM
Cool paint job, too ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 13, 2014, 02:42:31 PM
Sorry Dan.  It's aligned.  You can also see where I routed out the space for the fat cap.  Anyways all is well and it sounds great so that's all that matters I guess.     

(http://i1096.photobucket.com/albums/g330/kcguitarz/20140213_132951_zpsgzuydbrr.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/20140213_132951_zpsgzuydbrr.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/20140213_133035_zpstmgui4q1.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/20140213_133035_zpstmgui4q1.jpg.html)

And thanks Melodeath...I actually had them powdercoated.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 13, 2014, 02:59:20 PM
So how do you plan to attach the PCB?

Looking at the 2 main mounting holes that DAn used on the Alcatron body (the two nearby the top of the cap), they are almost adjacent to the middle tapped holes on the BN rails. I'm thinking with a little more downwards adjustment and a couple of little metal tabs, should be able to make a nice sturdy mount.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 03:04:42 PM
Sorry Dan.  It's aligned.  You can also see where I routed out the space for the fat cap.  Anyways all is well and it sounds great so that's all that matters I guess.     

(http://i1096.photobucket.com/albums/g330/kcguitarz/20140213_132951_zpsgzuydbrr.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/20140213_132951_zpsgzuydbrr.jpg.html)
(http://i1096.photobucket.com/albums/g330/kcguitarz/20140213_133035_zpstmgui4q1.jpg) (http://s1096.photobucket.com/user/kcguitarz/media/20140213_133035_zpstmgui4q1.jpg.html)

And thanks Melodeath...I actually had them powdercoated.

Awesome Kevin , you are right , i am just aiming to make the best changes to the pcb i can , i will definitively look into creating that space for the fat cap ,
Thanks For your input in this project, :)  i will also recheck mine to make sure i have not overseene somthing ,

Best,
Dan,
dD
 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on February 13, 2014, 03:56:31 PM
Dan,

If there's room to extend the cap spacing to 48-50 mm, there are some interesting looking, super inexpensive Soviet mylar caps on ebay. One audiophool site says they're in between modern mylar and PIO... who knows, but worth a try.

http://www.ebay.com/itm/3-3uF-160V-PETP-Capacitors-K73-16-Lot-of-50-/400508921279
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 04:02:41 PM
Dan,

If there's room to extend the cap spacing to 48-50 mm, there are some interesting looking, super inexpensive Soviet mylar caps on ebay. One audiophool site says they're in between modern mylar and PIO... who knows, but worth a try.

http://www.ebay.com/itm/3-3uF-160V-PETP-Capacitors-K73-16-Lot-of-50-/400508921279

I will try to do my best ,  ;)
DAn,
dD
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 13, 2014, 07:13:31 PM
Kevin you were Right all along , I dissambled to mic to make sure I wasnt crazy  :o , and understood that the first time i tried to put the sleeve the fat cap was in there too ! ,
so i tought that this was the only reason why it wouldnt but nop in, However been ale to assemble to whole mic with no mod just by prying a little bit on the rail and headbasket togheter I am even thinking that is is (actually a good thing) rendering the mic body less microphonic in regards to the Shell  ;) at the end but it still bends a bit so i removed the cap and tried again and it bent still a little hair. i Have check upon reducing the spacing on the relay position but even still the sleeve will be rubbing just a tiny glimpse ,  so smoothing the edge should be fixing the issue ,

I am checking on opening the output cap a little more still  :o  Space is a Premium !

thanks to Dremel  8)

Thanks Again For pointing this out ,
Best,
Dan,


 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 14, 2014, 12:34:15 AM
No problem at all Dan!  Glad to help the community out on this first run of ELAM's with the integral switching relays.  (Those TC capsules were waiting over a year for these boards to finally come out!)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 15, 2014, 12:54:10 PM
As requested , a little helper to find the pefect dropping resistor for the B+ line in function of your output transfomer voltage,
Just change the number in the Red cell to match you need,
Best,
DAn,
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199406c.xlsx (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199406c.xlsx)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 15, 2014, 08:08:48 PM
^^^ Thanks heaps for this DAn, and for measuring the plate current.

So obviously the total current draw entered in the excel here is the plate current (0.50mA) plus the 6072 heater current (0.35mA) = 0.85mA yeah?

 8)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 15, 2014, 08:15:40 PM
^^^ Thanks heaps for this DAn, and for measuring the plate current.

So obviously the total current draw entered in the excel here is the plate current (0.50mA) plus the 6072 heater current (0.35mA) = 0.85mA yeah?

 8)

Nop this will be only for the B+ line from the traffo 200V , No heater current there  0.85ma  ( 0.5ma B+ and 0.35ma bleeding trough the 470K resistor of this same line,

the heater current is on the second system where usually the 9.5V attached,

Note that the heater current is 350ma and not 0.35ma  ;)

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 15, 2014, 08:20:37 PM
^^^ Thanks heaps for this DAn, and for measuring the plate current.

So obviously the total current draw entered in the excel here is the plate current (0.50mA) plus the 6072 heater current (0.35mA) = 0.85mA yeah?

 8)

Nop this will be only for the B+ line from the traffo 200V , No heater current there  0.85ma  ( 0.5ma B+ and 0.35ma bleeding trough the 470K resistor of this same line,

the heater current is on the second system where usually the 9.5V attached,

Note that the heater current is 350ma and not 0.35ma  ;)

Best,
Dan,

Where is the headslap emoticon ??    ::) this'll do.... ha ha

Got you.... was scratching my head about where the extra 0.35mA came from....
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 18, 2014, 09:52:47 AM
As I received many PMs on this , here is the status.

I currently am polishing the last details on this project , please post on this thread if you would like to be enlisted for the next run as the qty will be limited,
thanks
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Category 5 on February 18, 2014, 10:01:54 AM
Put me down for 1 Dan.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Le Roux on February 18, 2014, 10:18:52 AM
One for me please.

Neil
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: sliebers on February 18, 2014, 04:48:42 PM
One for me too please.

Scott
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 18, 2014, 05:07:24 PM
One please
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Charles Turkmen on February 19, 2014, 07:06:49 AM
One for me too please Dany !

Thanks,
Charles
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: electrisizer on February 19, 2014, 09:19:46 AM
really interested in two, but audio clips would be nice...
especially in comparison to an c12 (clone). perhaps someone could make an overhead drum recording? voice would be nice too  8)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 19, 2014, 09:29:47 AM
really interested in two, but audio clips would be nice...
especially in comparison to an c12 (clone). perhaps someone could make an overhead drum recording? voice would be nice too  8)

+1     KCguitar Alias(Kevin) is in a Really great position to do this has he has 2 CT12 in hand 2 E-251 and some C12 with them ,
but i cannot promise somthing i dont have or cant do at the moment  ;)
Just toughts,

Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 19, 2014, 09:38:02 AM
Dan,

If there's room to extend the cap spacing to 48-50 mm, there are some interesting looking, super inexpensive Soviet mylar caps on ebay. One audiophool site says they're in between modern mylar and PIO... who knows, but worth a try.

http://www.ebay.com/itm/3-3uF-160V-PETP-Capacitors-K73-16-Lot-of-50-/400508921279

OK ,  I messed up all night with thenth of millimeters to optimze the relay position at the very best ie 0.25mm spacing between them and for the output cap i have been able to reach ........ 50.16mm  :)

Your Honor,  I rest My case  8)
Best,
Dan,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 19, 2014, 11:56:07 AM
I'll have a female singer over to demo the C12 and ELAM for some jazz covers later today that I will post up.  Sorry I don't have a drum set at my home studio. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lowfreq on February 19, 2014, 03:50:15 PM
Ooh, Ooh. 2 for me please!! :D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kcguitar on February 19, 2014, 10:59:07 PM
Ok, here we go folks with the C12/ELAM shootout.  My CT12 equipped Chunger C12 vs CT12 equipped poctop ELAM.  Both mics were run into a vintage 1099 (1073 with fixed line gain) with no EQ or compression and straight to my SSL madi converters.  First is the C12, second is the ELAM.  I purposely mixed the backing track low fyi.  Results were what I expected...   

https://soundcloud.com/paradyne-studios/i-love-you-c12-then-elam-mic
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on February 20, 2014, 12:05:23 AM
YMO, On her voice, I thought the elam was fuller sounding. Good Job.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 20, 2014, 06:46:32 AM
Yep, apparently both are good examples of the species, because apart from sounding classy, they differ exactly in the way I would have expected.

C12 sounds a hair more natural and/or maybe slightly more detailed. Ela M is very much in the ballpark, but sounds more like a record (more finished; more beautiful if you will).

Both are plenty bright enough, but C12 has a touch more air (as can be expected). So Ela M is subtly rounder way up high, but also a bit fuller in the lows. Could this have to do with the hard switched pattern in the latter?
(I assume both are in cardioid?)


Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 20, 2014, 06:49:41 AM
Oh, and thanks for posting!!!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 20, 2014, 08:26:01 AM
Ok, here we go folks with the C12/ELAM shootout.  My CT12 equipped Chunger C12 vs CT12 equipped poctop ELAM.  Both mics were run into a vintage 1099 (1073 with fixed line gain) with no EQ or compression and straight to my SSL madi converters.  First is the C12, second is the ELAM.  I purposely mixed the backing track low fyi.  Results were what I expected...   

https://soundcloud.com/paradyne-studios/i-love-you-c12-then-elam-mic

Many thanks For doing that Kevin , appreciate it , and this is super good to have handy ,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: chaserose1 on February 21, 2014, 02:51:18 AM
I would like 2 sets
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kvothe on February 21, 2014, 01:47:00 PM
I would very much like one, too!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on February 21, 2014, 06:14:28 PM
Got one set of the first batch,
but I'll need another set for a pair.
Thanks
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: synchroman on February 24, 2014, 03:51:36 PM
I would like to buy QTY 4
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Category 5 on February 24, 2014, 10:18:18 PM
Def in on this one.  The ELA M sounded smoky and pillowy compared to the C12 which was silky and smooth like bead blasted aluminum.  I love describing sound with analogies.  lol.  The ELA M could have even been a U47.  What I mean is, it was different from the C12 in the same way a 47 is.  I wouldn't kick either mic out of bed if you catch my drift.  ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on February 26, 2014, 11:58:56 PM
Hey DAn,

A question re IPA - there are obviously a lot of sensitive components in the build.... relays/polyprops that won't take kindly to being doused in IPA.

Is it necessary to go over the connections to remove any flux residue etc?

Ta

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 28, 2014, 11:19:14 PM
Whats happening Dan!...

Just finished my build... spread it out over a couple of days. Few things for future board

You should increase the solder padding size on the pcb
Include support strut terminals for tube base.
Relays closer together as someone else pointed out.

At the moment my build consists of:

Tim Campbell Capsule
MKT 1813 nos coupling cap
T14 AMI

I haven't tested for audio yet but on the meter I got:

B+ 110v at mic
H 6.3v at tube
Plate 65.7v at tube

Theres a couple of vintage 251's here at paramount I'll shoot it out against over the next couple days.

Bless,
J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 28, 2014, 11:31:23 PM
p.s

Theres so many different quotes on b+ voltage on discussion boards and schematics. Whats the official word. are we working with 110 or 120?

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 03, 2014, 06:35:10 AM
ok so just a quick shootout of my speaking voice and some shakers and tamb against a vintage elam251. It has a SP sticker on it so i'm sure he modded it or obviously worked on it to some degree and i didn't open it up to see what that might have been.

I threw them up in the control room, one pop filter 4" from head basket and my lips approx 2" from pop filter.

Tim Capsule
MKT 1813 2.2uf (Nos Green)
Styro 4800pf
AMI T14
Matador/Chunger Dual Layer Headbasket (Rear side powder coated black)
5 Star GE 6072
Dans resistor pack.
120v b+ / 65.6v Plate / 6.3v Heater

Both mics are running through a matched pair of vintage 1081 with no EQ at 30db gain / no compressor. I had to gain up my elam roughly 2db in PT to match.

Pro Tools Session:

www.JessJackson.com/sessions/251Test.zip

Ill reserve my comments for now, I know what I think but i'm more interested in your observations.

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on March 03, 2014, 07:31:07 AM
I want to know more about your nearly perfect relay switching layout. I tried to make sense of it using your last PCB screen shot...

:-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on March 03, 2014, 09:41:54 AM
Jess, the link is not working.
Well, not for me anyway.



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on March 03, 2014, 09:48:04 AM
One too many s's in sesssions
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 03, 2014, 10:04:14 AM
Thanks so much for the test, JessJackson. The real 251 seems to have a good bit more top-end, as well as a deeper bass response (it's pretty noticeable when you say "BASS").

I also noticed that the real 251 must have a slower transient response, because while the transient peaks match pretty well in the clips, the volume is 1db shy on your clone when you are talking, which makes the real 251 sound "fuller."
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on March 03, 2014, 12:13:10 PM
Link doesn't work for me.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 03, 2014, 12:20:16 PM
Just take one "s" out: www.JessJackson.com/sessions/251Test.zip
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 03, 2014, 02:17:25 PM
Sorry fixed the link. it was late.  :P
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 03, 2014, 02:29:28 PM
Thanks so much for the test, JessJackson. The real 251 seems to have a good bit more top-end, as well as a deeper bass response (it's pretty noticeable when you say "BASS").

I also noticed that the real 251 must have a slower transient response, because while the transient peaks match pretty well in the clips, the volume is 1db shy on your clone when you are talking, which makes the real 251 sound "fuller."

Exactly my thoughts with the exception that I think the top end just seems brighter due to the mids being slightly scooped (or bumped on my clone depending on how you look at it). One thing i notice. the quasi 3D ness everyone loves about the vintage c12s and elams is missing on the clone. and yes more bass in the original, id put the bass down to the coupling cap or transformer most likely. I'd GUESS the 3Dness comes from harmonic distortions created by maybe the transformer type and or coupling capacitor type. The Telefunken USA mic's are lacking this also and they don't use wet tantalums so i'm gonna give that a shot.

I've ordered some 3.6uf nos wet tantalums on ebay to try out the original coupling caps. I could also try with the Haufe t/14 from my c12. I've also been trying to source some original ingelen tubular dogbone ceramic caps as used in the original but can't find correct values anywhere http://www.ebay.com/itm/23-vintage-INGELEN-ceramic-capacitors-1500pF-10-antique-radio-/390542882687?pt=Vintage_Electronics_R2&hash=item5aee2b777f

let me know if any of you are sitting on these little gems.


I'm really happy with dans work though.. ITS VERY CLOSE
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on March 03, 2014, 03:32:51 PM
Quote
I could also try with the Haufe t/14 from my c12.

AFAIK the Haufe has limited bandwidth if compared to the AMI, so I wouldn't expect that do the trick.
But as always, the proof is in the pudding.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on March 03, 2014, 03:52:30 PM
Yep, the link is working now, so I did a quick listen on cans.
They're more alike actually than I expected after the talk above.
I think with some fine tuning you should be able to get pretty close.
Also keep in mind that the tuning of (original) CK12 capsules is all over the map. And as we know, the capsule is the biggest factor at play.



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on March 03, 2014, 04:13:02 PM
Exactly my thoughts with the exception that I think the top end just seems brighter due to the mids being slightly scooped (or bumped on my clone depending on how you look at it). One thing i notice. the quasi 3D ness everyone loves about the vintage c12s and elams is missing on the clone. and yes more bass in the original, id put the bass down to the coupling cap or transformer most likely. I'd GUESS the 3Dness comes from harmonic distortions created by maybe the transformer type and or coupling capacitor type. The Telefunken USA mic's are lacking this also and they don't use wet tantalums so i'm gonna give that a shot.

Thoughts:

1) I read a little about the Stephen Paul mods, which involve rediaphragming with 1.5 or 3 micron material. Results of modding the CK12 seem to be extended top end and a scoop in the low mids. Maybe this could account for the relative lack of top and lo-mid bump in the clone.

2) Could the lack of air in the clone also have to do with the high impedance part of the amp?

3) The "reach" or 3dness in the original is more important IMO than the tone stuff. I've never done a capsule shootout in person, but in (blind) M7 shootouts I've heard online, a lot of the last 10% of depth seems to follow the Neumann capsules. Could this have to do with Tim's capsule?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on March 03, 2014, 06:02:48 PM
You really need to know how far the SPA mods went in the vintage mic- it could be radically far from original production, rendering your test "meaningless". Extreme capsule mods were the game there, so you need to see if that work was done. They usually wrote something on the backplate, which would be visible to the naked eye without disassembling the capsule.
Don't use ceramic caps in mics. It's the ONE thing that modern production has over older mics, as ceramics can be an excellent noise source in a mic.
And if a person could hear the frequency that the 100pF shunt operates at, that person might be...a bat.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 03, 2014, 06:56:04 PM
I agree with the test being "meaningless" based on the fact that the test 251 has a SP sticker on the back. I'm not about to open up the 251, the owner and tech will get their little knickers in a twist (whats up tom!)... I'll rent another one and see if someone locally has a vintage spec 251.

I highly doubt its the capsule. I have a reskinned ck12 in my vintage c12 that sounds almost identical.

I probably wouldn't change the 100pf to ceramic,  i'm sure styroflex caps were around back then so I wouldn't pay much attention to new vs old. I will change the 4,800pf to see what audio properties different materials hold. Yes the noise may be higher slightly but it may also contribute to the vintage sound. To be honest mate thats kinda like growing up in the digital era and telling everyone not to print to tape ever. If you don't try you'll never know. Less noise isn't always a good thing.

First things first though, this wet tantalum capacitor.

one thing i did notice though, I did a test going back and forth from the 251's to the vintage u67 and found the u67 so scratchy and harsh in the top end in comparison, yet i love the upfront transient speed of the u67 in the mids, everything is just loud on that mic yet a little nasely and harsh next to the 251. u67 outputs about 10db louder than both 251's

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 03, 2014, 07:23:27 PM
JessJackson, have you done a C12 clone and compared it to your vintage?

I look forward to your future tests with a rented 251. I had forgotten that the 251 in the current test was an SP mod, so who knows how it differs from an original.

Are the NOS wet tant caps you bought on Ebay the Sprague 109D? Those are current production, but I saw them listed as "NOS" on ebay. Regardless, very good price up there. I may grab 'em too.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 03, 2014, 08:00:39 PM
JessJackson, have you done a C12 clone and compared it to your vintage?

I look forward to your future tests with a rented 251. I had forgotten that the 251 in the current test was an SP mod, so who knows how it differs from an original.

Are the NOS wet tant caps you bought on Ebay the Sprague 109D? Those are current production, but I saw them listed as "NOS" on ebay. Regardless, very good price up there. I may grab 'em too.

No never bothered with the clone test. i gutted it and turned it into this elam clone instead. The c12 sound is too bright for me. its pleasant but doesn't sit in a mix well. I've got a lot of records on the radio recorded with it but the vocal mixes were always struggled.

I'll also test my 67 clone against the vintage one here today probably.

yeah, the tants were 109d's. if anyone has any nos, id appreciate one, cheers.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on March 04, 2014, 05:57:49 AM
Well done Dan in taking over the project...

I do think maybe take a look at our last design (version 6.5) as this was the closest i feel to perfection in utilizing the relays.


Hi Jess,
 I took a look at the board you posted an example of to learn how you planned to use the relays and I can not figure out how it can work. I drew a schematic, as I did with Dany's layout, and I am hoping I am missing something you can explain. I can't unlock the puzzle of how the board you posted a image of provides all 3 patterns.

 Any clues?

 Thank You.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 04, 2014, 03:12:35 PM
JessJackson, have you done a C12 clone and compared it to your vintage?

I look forward to your future tests with a rented 251. I had forgotten that the 251 in the current test was an SP mod, so who knows how it differs from an original.

Are the NOS wet tant caps you bought on Ebay the Sprague 109D? Those are current production, but I saw them listed as "NOS" on ebay. Regardless, very good price up there. I may grab 'em too.

No never bothered with the clone test. i gutted it and turned it into this elam clone instead. The c12 sound is too bright for me. its pleasant but doesn't sit in a mix well. I've got a lot of records on the radio recorded with it but the vocal mixes were always struggled.

I'll also test my 67 clone against the vintage one here today probably.

yeah, the tants were 109d's. if anyone has any nos, id appreciate one, cheers.

Keep us updated on the 109d swap, and that 67 test
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: electrisizer on March 05, 2014, 11:52:44 AM
ok so just a quick shootout of my speaking voice and some shakers and tamb against a vintage elam251.

Ill reserve my comments for now, I know what I think but i'm more interested in your observations.


original: big sound, 3d image, real world... clone lacks it a bit :-\
i hear it not only on the voice recording but on shakers too.
wanted to build a pair of 251 for overhead recordings but i have to think about...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on March 06, 2014, 01:18:50 PM
Have you tried 5840/will it be a drop-in replacement?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 07, 2014, 12:38:15 AM
Ok, I rented another vintage 251. This one was also NOT COMPLETELY ORIGINAL!! damn.

It had what a (black Dale RFX-1/2 100meg 2% 6721) at Grid and a (Yellow 1uf s&ei mfg.10% 200vDC 7030) output cap. No sign of who did the mod. Capsule looked original through the head basket.

www.JessJackson.com/sessions/New251Test.zip

You'll find that my mic most likely will need you to boost it with clip gain or whatever by 0.3 - 0.4db. I had replaced my output cap with a Wet Tantalum 125v 3.6uf

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 07, 2014, 09:56:09 AM
Thanks again for the test. I listened blind after turning the clone up by 0.36dB.

For the first voice I preferred your clone. I would have guessed it was the original if I had to at that point. It was brighter, but in the right "air" spots, not the sibilance spots. It made it sound more 3D and real, while being less harsh. Then the voice switched to someone else and I felt the exact opposite. Now the clone was more sibilant. Very interesting.

So the usual 30M resistor was swapped with 100M?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 07, 2014, 03:06:52 PM
Thanks again for the test. I listened blind after turning the clone up by 0.36dB.

For the first voice I preferred your clone. I would have guessed it was the original if I had to at that point. It was brighter, but in the right "air" spots, not the sibilance spots. It made it sound more 3D and real, while being less harsh. Then the voice switched to someone else and I felt the exact opposite. Now the clone was more sibilant. Very interesting.

So the usual 30M resistor was swapped with 100M?

Maybe import my new test audio into my old test session?... everything was the same setting.

Yeah just swapped out for 100m flat and square shaped like the ohmites.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Melodeath00 on March 07, 2014, 03:40:47 PM
Thanks again for the test. I listened blind after turning the clone up by 0.36dB.

For the first voice I preferred your clone. I would have guessed it was the original if I had to at that point. It was brighter, but in the right "air" spots, not the sibilance spots. It made it sound more 3D and real, while being less harsh. Then the voice switched to someone else and I felt the exact opposite. Now the clone was more sibilant. Very interesting.

So the usual 30M resistor was swapped with 100M?

Maybe import my new test audio into my old test session?... everything was the same setting.

Yeah just swapped out for 100m flat and square shaped like the ohmites.

I don't use Pro Tools, so I cannot use your session file. I am importing the two audio files into my DAW and comparing from there. I'm not sure what you mean by "everything was the same setting" as the old test session. I turned up your clone .36dB because you indicated in your post it needed to be turned up.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 07, 2014, 04:40:46 PM
Thanks again for the test. I listened blind after turning the clone up by 0.36dB.

For the first voice I preferred your clone. I would have guessed it was the original if I had to at that point. It was brighter, but in the right "air" spots, not the sibilance spots. It made it sound more 3D and real, while being less harsh. Then the voice switched to someone else and I felt the exact opposite. Now the clone was more sibilant. Very interesting.

So the usual 30M resistor was swapped with 100M?

Maybe import my new test audio into my old test session?... everything was the same setting.

Yeah just swapped out for 100m flat and square shaped like the ohmites.

I don't use Pro Tools, so I cannot use your session file. I am importing the two audio files into my DAW and comparing from there. I'm not sure what you mean by "everything was the same setting" as the old test session. I turned up your clone .36dB because you indicated in your post it needed to be turned up.

I just meant that you can compare this to my other previous test before replacing the capacitor, I had the same pre amp settings and same distance from the mic. Therefore see how much of a difference the capacitor made. Obviously the takes and speaking performance differs.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on March 07, 2014, 05:33:00 PM
^^ much better IMO! Much less anaemic than the original setup. Very nice.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kpearsall on March 08, 2014, 03:07:33 AM
One for me please
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: SKJGProject on March 08, 2014, 09:42:47 AM
+1 for me as well
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on March 08, 2014, 07:53:30 PM
I would be up for one also.  ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: la2a4life on March 09, 2014, 01:06:15 PM
+1 for me as well!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bockaudio on March 10, 2014, 03:19:49 PM
"Yes the noise may be higher slightly but it may also contribute to the vintage sound. To be honest mate thats kinda like growing up in the digital era and telling everyone not to print to tape ever. If you don't try you'll never know. Less noise isn't always a good thing.
"

Tape noise and the un-reliabilty + noise of a ceramic cap for the AC bypass in a condenser mic are not even close to the same thing. Generally, the noise from the ceramic in that application is one that manifests years later. As an example, the ceramic cap used in the U47 was fine when the mics were new in the '50's, noisy by the 1980's.
I have never instructed anyone to not record to tape, quite the opposite. As well I own an ATR 124 & Mtr12,  so I really don't understand the comment.


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 10, 2014, 04:31:22 PM
"Yes the noise may be higher slightly but it may also contribute to the vintage sound. To be honest mate thats kinda like growing up in the digital era and telling everyone not to print to tape ever. If you don't try you'll never know. Less noise isn't always a good thing.
"

Tape noise and the un-reliabilty + noise of a ceramic cap for the AC bypass in a condenser mic are not even close to the same thing. Generally, the noise from the ceramic in that application is one that manifests years later. As an example, the ceramic cap used in the U47 was fine when the mics were new in the '50's, noisy by the 1980's.
I have never instructed anyone to not record to tape, quite the opposite. As well I own an ATR 124 & Mtr12,  so I really don't understand the comment.

The ceramic caps in the vintage elam 251 from the same era are fine. That mic has less noise than my current build. I'd imagine its a case by case situation.

Ceramic caps do deteriorate though. I few NOS ones have literally crumbled between my fingers.

J
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: sedit1 on March 15, 2014, 02:36:11 AM
As I received many PMs on this , here is the status.

I currently am polishing the last details on this project , please post on this thread if you would like to be enlisted for the next run as the qty will be limited,
thanks
Best,
Dan,

I'm in for one also!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 17, 2014, 08:45:09 AM
Thanks To my Brother,I should be getting another batch really soon,
Stay tuned,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on March 17, 2014, 10:26:51 AM
Thanks To my Brother,I should be getting another batch really soon,
Stay tuned,
Best,
Dan,

I am for one too when it happens!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on March 17, 2014, 08:17:28 PM
Thanks To my Brother,I should be getting another batch really soon,
Stay tuned,
Best,
Dan,

Will it be the same as the initial run or have you changed anything?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 17, 2014, 08:37:08 PM
Quote
Will it be the same as the initial run or have you changed anything?

Updates Are.

Silk Error Polarity Cathode Bypass Cap  Fixed,
Relay Tightest as possible I guess  :o
Output Cap Receptacle Enlarged.

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/D251E.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199408f.jpg)

best,
dAn,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on March 18, 2014, 05:29:07 AM
Fun build, thanks DAn!!

Here are some photos with the hack build with the Beesneez body. Fiddly! Looking forward to the longer/custom one!

Will install TC capsule and report back when fired up.

Only thing is how to secure the PCB to the rails. I passed some cable ties all around which was secure but then I couldn't get the case over...

Otherwise you can see how close the relay legs are to the rails, so it has to be well secure or they'll short.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on March 18, 2014, 05:31:58 AM
Tight!

Notice that I shortened the screw on the left, as it is at risk of shorting with the S+ pad. On the other side is the ground pad, so no need to shorten the screw there.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on March 18, 2014, 05:33:25 AM
More gutz - notice extra hole for securing cap with cable tie.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 18, 2014, 08:07:42 AM
More gutz - notice extra hole for securing cap with cable tie.

thanks for your post  :) , I am glad you made it with the hack of the beesneez Mic body ,
Ultimately the PCB were made to fit the HT-11 Mic body Kit that Chunger will be having soon again ,

http://groupdiy.com/index.php?topic=50015.0

Veronica and Ben are as well probably working out an adaptation at the moment for future builder I guess,

http://groupdiy.com/index.php?topic=55176.0
Best,
Dan,

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on March 18, 2014, 08:39:00 AM
Dany, did you send the updated version to Ben and Veronica, too?
Outside measurements are likely the same, but perhaps it helps if they have the definitive version?



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 18, 2014, 09:06:30 AM
Dany, did you send the updated version to Ben and Veronica, too?
Outside measurements are likely the same, but perhaps it helps if they have the definitive version?



Henk

The Outside Footprints is the exact same mouting hole ....etc.. as this was intented at first for the Ht-11A ,
the minor modification should not affect the adaptation outcome  ;)
Thanks for checking Henk,  :)
Best,
DAN,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on March 18, 2014, 10:59:14 AM

The Outside Footprints is the exact same mouting hole ....etc.. as this was intented at first for the Ht-11A ,
the minor modification should not affect the adaptation outcome  ;)
Thanks for checking Henk,  :)
Best,
DAN,

The new PCBs won't fit the HT-11A?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 18, 2014, 11:09:17 AM

The Outside Footprints is the exact same mouting hole ....etc.. as this was intented at first for the Ht-11A ,
the minor modification should not affect the adaptation outcome  ;)
Thanks for checking Henk,  :)
Best,
DAN,

Quote
The new PCBs won't fit the HT-11A?

The PCB are made For the Ht-11A No Worries,
Best,
DAN,



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Woot on March 18, 2014, 06:57:48 PM
Thanks DAn,

I think a couple of little square tabs sticking out from the rails so we can utilise the original mounting holes would work a treat... but Veronica and Ben are the experts, I'm sure they'll figure it out perfectly.

Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 24, 2014, 08:21:53 AM
New Run is on the way ,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on March 24, 2014, 12:58:18 PM
New Run is on the way ,
Best,
Dan,

So how do we order the PCBs?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 24, 2014, 01:24:33 PM
New Run is on the way ,
Best,
Dan,

So how do we order the PCBs?

Not Yet,
I will report back when they are in stock , that should be pretty soon,
Best,
DAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on March 26, 2014, 05:23:46 PM
I'm loving mine cutting with it every day for an upcoming E.P.

Does anyone have an extra outer body or knows where to get some piping from the exact dimensions of the outer body. i'd like to extend it longer similar to c12 in size and i want to put a trouchel connector on the bottom.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on March 28, 2014, 12:31:49 PM
I'm loving mine cutting with it every day for an upcoming E.P.

Does anyone have an extra outer body or knows where to get some piping from the exact dimensions of the outer body. i'd like to extend it longer similar to c12 in size and i want to put a trouchel connector on the bottom.

You mean like an extra sleeve from the APEX 460 for example?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 03, 2014, 09:31:52 AM
I should have them as of tommorow ,
Best,  :)
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on April 03, 2014, 04:39:50 PM
I'm loving mine cutting with it every day for an upcoming E.P.

Does anyone have an extra outer body or knows where to get some piping from the exact dimensions of the outer body. i'd like to extend it longer similar to c12 in size and i want to put a trouchel connector on the bottom.

You mean like an extra sleeve from the APEX 460 for example?

yeah exactly!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on April 03, 2014, 05:56:59 PM
I have one extra, pm me
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 03, 2014, 08:48:14 PM
they Arrived,
Best,
DAN ,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: baadc0de on April 04, 2014, 12:26:34 AM
they Arrived,
Best,
DAN ,

Where to order? Price?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 04, 2014, 12:37:03 AM
they Arrived,
Best,
DAN ,

Where to order? Price?

I updated the website ,
should work fine now, had so Many issues with it Lately

http://www.vintagemicrophonepcbkit.com/order2.html

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on April 07, 2014, 01:07:10 PM
Dany, I have a question... Have you experimented with trying to use double coil latching relays instead of single side stable? It may be possible by the use of a shorting switch and a 558 timer to generate the pulses for the correct latching.
For example in my current build, the XLR cable has approx 1.2Ohms resistance. In figure of 8 we are adding 66mA (for a drop of almost 100mV in the heater voltage) compared with cardioid mode. Also, holding an energized coil next to a Hi-Z section does look problematic... What are your thoughts on this?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 07, 2014, 01:45:08 PM
Dany, I have a question... Have you experimented with trying to use double coil latching relays instead of single side stable? It may be possible by the use of a shorting switch and a 558 timer to generate the pulses for the correct latching.
For example in my current build, the XLR cable has approx 1.2Ohms resistance. In figure of 8 we are adding 66mA (for a drop of almost 100mV in the heater voltage) compared with cardioid mode. Also, holding an energized coil next to a Hi-Z section does look problematic... What are your thoughts on this?

the cable resistance you need to account by adjusting the heater voltage with the Voltmeter on the mic pcb itself there is a pad for such measurement on the mic pcb
the heater Voltage is regulated from the psu so this tiny pull of current for the pattern the regulator will take care of that, as per the voltage used in the relay this is DC voltage so same as polarisation or B+ so this is not a problem.  the H-Z section is most sensible to passage of current to an easier path then the one defined on the circuit such as grease and dirt from flux allowing then a path to ground or another part of the cicruit , Since implied parts of the relay are isolated from the pcb this is not an issue at all, no to be confused with high impedance corresponding issues versus nanoscopic stray field,  Once I received my upgraded tube i will post a simple clip of the noise figures wich are totally in range with the other design I have made so far or I would not have simply issued this one :).  Mostly this design have been sucessfully implemented in the Blackspade Line of microphone so you dont have to worry at all,  I am not sure if you have completed your build yet but give it a try yourself you will be convinced then and keep me posted.

hope this helps,
Best,
DAN,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on April 07, 2014, 02:42:37 PM
esistance you need to account by adjusting the heater voltage with the Voltmeter on the mic pcb itself there is a pad for such measurement on the mic pcb
[...]
the heater Voltage is regulated from the psu so this tiny pull of current for the pattern the regulator will take care of that
hope this helps,
Best,
DAN,

Yeah, I know I can adjust the heater voltage to account for losses in the cable... what I am saying is that there is going to be 100mV difference between the switch placed in cardiod mode vs figure of 8. (there will be a 350mA drain in cardioid and 416mA in figure of 8 because of the relays). I am not sure how much the tube will be affected by that though.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 07, 2014, 02:50:56 PM
esistance you need to account by adjusting the heater voltage with the Voltmeter on the mic pcb itself there is a pad for such measurement on the mic pcb
[...]
the heater Voltage is regulated from the psu so this tiny pull of current for the pattern the regulator will take care of that
hope this helps,
Best,
DAN,

Yeah, I know I can adjust the heater voltage to account for losses in the cable... what I am saying is that there is going to be 100mV difference between the switch placed in cardiod mode vs figure of 8. (there will be a 350mA drain in cardioid and 416mA in figure of 8 because of the relays). I am not sure how much the tube will be affected by that though.


The Supply for the relay is taken from the regulated heater supply so it should remains constant despite the extra draw.
Best,
dAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on April 07, 2014, 04:13:18 PM


The Supply for the relay is taken from the regulated heater supply so it should remains constant despite the extra draw.
Best,
dAN,
The voltage before the cable will be constant, true... but the losses on the cable will be higher, the higher the current draw...Unless there is something I am missing the cable will have 10% more losses in figure of 8 than in cardioid...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 07, 2014, 08:08:11 PM
esistance you need to account by adjusting the heater voltage with the Voltmeter on the mic pcb itself there is a pad for such measurement on the mic pcb
[...]
the heater Voltage is regulated from the psu so this tiny pull of current for the pattern the regulator will take care of that
hope this helps,
Best,
DAN,
The voltage before the cable will be constant, true... but the losses on the cable will be higher, the higher the current draw...Unless there is something I am missing the cable will have 10% more losses in figure of 8 than in cardioid...
Yeah, I know I can adjust the heater voltage to account for losses in the cable... what I am saying is that there is going to be 100mV difference between the switch placed in cardiod mode vs figure of 8. (there will be a 350mA drain in cardioid and 416mA in figure of 8 because of the relays). I am not sure how much the tube will be affected by that though.


The Supply for the relay is taken from the regulated heater supply so it should remains constant despite the extra draw.
Best,
dAN,

Quote
The voltage before the cable will be constant, true... but the losses on the cable will be higher, the higher the current draw...

Correct,

I made a little calculation with 1.2ohm cable feed whis is probably on the high side, the worst case scenario between 350ma to 416ma figure 8.

Then Figures 8 the difference would be 79.2 mV

Then Cardiod and Omni would be  39.6 mV

Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on April 07, 2014, 08:20:04 PM
Correct,

I made a little calculation with 1.2ohm cable feed whis is probably on the high side, the worst case scenario between 350ma to 416ma figure 8.

Then Figures 8 the difference would be 79.2 mV

Then Cardiod and Omni would be  39.6 mV

Best,
Dan,

Negligible then. I understand you consider that any magnetic field radiated by the coil from the ripple of H+ will be small even close to the HiZ points.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 07, 2014, 10:03:18 PM
Correct,

I made a little calculation with 1.2ohm cable feed whis is probably on the high side, the worst case scenario between 350ma to 416ma figure 8.

Then Figures 8 the difference would be 79.2 mV

Then Cardiod and Omni would be  39.6 mV

Best,
Dan,



Negligible then. I understand you consider that any magnetic field radiated by the coil from the ripple of H+ will be small even close to the HiZ points.

Voltage will stabilise once the pattern changes they should not be more ripple  in h+ as the one at the output from the psu once the Voltage is set,
 
Best,
Dan,
 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on April 08, 2014, 09:12:36 AM
Does an electro magnet emit ripple when it is designed to use DC rather than AC?

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on April 09, 2014, 10:33:27 AM
Any reason the pattern switch has to be shorting?

Can see a possibility where, for an instant, current is flowing to both relay positions at once, making the relays themselves act as a shorting switch. Or does it not matter?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 09, 2014, 11:24:03 AM
Any reason the pattern switch has to be shorting?

Can see a possibility where, for an instant, current is flowing to both relay positions at once, making the relays themselves act as a shorting switch. Or does it not matter?

Supply for the relay are independently controlled via the psu switch,  current is not allowed to flow trough the unsollicited relay.
only in the case of fig 8   a pair of relay will be activated at once for cardiod and omni only 1 relay is sollicited at the time.
hope this helps,
Best,
dAN,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on April 09, 2014, 03:43:38 PM
Any reason the pattern switch has to be shorting?

Can see a possibility where, for an instant, current is flowing to both relay positions at once, making the relays themselves act as a shorting switch. Or does it not matter?

Supply for the relay are independently controlled via the psu switch,  current is not allowed to flow trough the unsollicited relay.
only in the case of fig 8   a pair of relay will be activated at once for cardiod and omni only 1 relay is sollicited at the time.
hope this helps,
Best,
dAN,

Right, I'm just wondering whether, with a shorting switch, there may be an instant when, eg, both the cardiod and omni relays are activated, which might make pattern switching quieter.

Essentially I'm asking whether it's ok to use a non-shorting switch, since I have a few of those.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 09, 2014, 03:54:11 PM
Any reason the pattern switch has to be shorting?

Can see a possibility where, for an instant, current is flowing to both relay positions at once, making the relays themselves act as a shorting switch. Or does it not matter?

Supply for the relay are independently controlled via the psu switch,  current is not allowed to flow trough the unsollicited relay.
only in the case of fig 8   a pair of relay will be activated at once for cardiod and omni only 1 relay is sollicited at the time.
hope this helps,
Best,
dAN,

Right, I'm just wondering whether, with a shorting switch, there may be an instant when, eg, both the cardiod and omni relays are activated, which might make pattern switching quieter.

Essentially I'm asking whether it's ok to use a non-shorting switch, since I have a few of those.

Ah OK i just realized what you meant ,  yes the shorting type pattern switch is all i could find for this configuration  at mouser, i was aiming at first with the non-shorting as this is what i am used to , but finally tested the shorting switch and the pattern swap was quiet and  no poping issue,  at this time both can be used without issue.
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 17, 2014, 10:29:04 AM
Hi All, As i have gotten a couple of PM regarding this , i will try to unconfuse folks ,

this message pertains that the Errata on the front page has been removed the inversion of C3 on the tube socket pcb has been corrected for the production run that some of you already bought , this errata only applied to those that purchased the inital proto run that was about only 10 pcb of those ,

currently the pcb that is offered is all corrected and good to go ,

here is the summary of what have been done as far of improvement or changes ,
this same pcb is the one that is currenlty available ,

Best,
DAn,

Quote
Will it be the same as the initial run or have you changed anything?

Updates Are.

Silk Error Polarity Cathode Bypass Cap  Fixed,
Relay Tightest as possible I guess  :o
Output Cap Receptacle Enlarged.

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/D251E.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281994127.jpg)

best,
dAn,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on May 24, 2014, 06:57:11 PM
Hi Guys!

I just wanted to report another build of the D-251 here!

First of all, big thanks to poctop for his efforts on this PCB design.
Very well laid out and easy to follow build.

I built this with, and as a comparison to the D-C12 microphone, which is a very straight forward build.
I actually thought this would be significantly more difficult than other DIY-projects, but it actually looks more complicated that it is.
All in all a very rewarding build that I can only recommend!

Now I only have to wait for Chungers donor bodies and transformers!

Thanks to everyone in this forum who is putting in a lot of effort and making this possible!
PCBs, bodies, transformers, capsules and custom parts, none of this would be possible without your joint efforts.
I really appreciate this.

Best,
Michael

(http://groupdiy.com/Users/Violator/Desktop/D-251 Back.jpg)
(http://groupdiy.com/Users/Violator/Desktop/D-251 Upper.jpg)
(http://groupdiy.com/Users/Violator/Desktop/D-251:D-12 Upper.jpg[img][img]/Users/Violator/Desktop/D-251:D-12 Back.jpg)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 29, 2014, 03:39:05 PM
I'm gathering up all the parts for this build and was wondering if anyone had any opinions on which capsule would work best from the choices I can afford right now. Here are the choices I am considering.

1. micriphone-parts RK-12 : 3-micron Japanese mylar - $109
2. AA AK-12 : 6 micron German mylar - $99
3. Chugers 34MM Edge Terminated Capsule : unknown mylar thickness - $76

Any thoughts? Thanks.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 29, 2014, 03:50:53 PM
I'm gathering up all the parts for this build and was wondering if anyone had any opinions on which capsule would work best from the choices I can afford right now. Here are the choices I am considering.

1. micriphone-parts RK-12 : 3-micron Japanese mylar - $109
2. AA AK-12 : 6 micron German mylar - $99
3. Chugers 34MM Edge Terminated Capsule : unknown mylar thickness - $76

Any thoughts? Thanks.

None of them would work I think. You need a four wire capsule with isolated backplanes... At least if you want the figure of 8 mode to work
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 29, 2014, 04:46:47 PM
2 of the sites specifically mention the Elam 251 on their capsule page. Is there a way to use these at all with this pcb? Do you have any recommendations on any capsules that will work aside from beesknees, Tim or tskguy as I cannot afford any of these any time in the foreseeable future? It looks like the RK-87 from microphone parts and the AK-67 from AA have isolated backplanes.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 29, 2014, 05:59:26 PM
2 of the sites specifically mention the Elam 251 on their capsule page. Is there a way to use these at all with this pcb? Do you have any recommendations on any capsules that will work aside from beesknees, Tim or tskguy as I cannot afford any of these any time in the foreseeable future? It looks like the RK-87 from microphone parts and the AK-67 from AA have isolated backplanes.

They lied, they may support ELAM250, but 251 config won't work without circuit modifications.

Without isolated back-planes this is what will happen in figure of eight mode. Because the backplanes are electrically connected you will ground the tube grid, this will create a negative voltage in the grid compared to the cathode and effectively shut down any current in the tube.

I am not sure what will happen in the capsule, the front and back membranes are poralized with +/- 60V but with both of the backplanes grounded I guess that any signal will be seen as ripple in B+, I don't think it will get damaged.

So in summary, with a three wire design you lose the figure of 8 pattern. Yo wont have a ELAM 251, you will get an ELAM 250.

With a K87 capsule though, you will get back figure of eight, but a K87 capsule has a frequency response that peaks around 6dB at 11KHz, so you need to increase the EQ cap between the plate and ground to around 400pF to compensate. It is going to roll-off sharply at 12-13K, so it will lose some air.


NOTE:

Several manufacturers, choose to keep the polarization topology of the C12 (with the 9 polarization patterns) and modify the wiring of the tube for self-biasing. This is similar to Matador's approach to the C12 to ELAM, but it is different from the actual ELAM circuit that poctop implemented. There is also the difference in which the output of teh capsule is in the membranes in the C12 and in the backplanes in the ELAM
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 29, 2014, 06:21:26 PM
Looks like the RK-12 has that peak also. Any other capsule options?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 29, 2014, 07:11:58 PM
I have two RK-12s myself, it is certainly brighter than my Beesneez CK12 but does not sound bad at all.

The peak of the RK12 is nowhere as brutal as the K87/K67 ones.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 29, 2014, 07:57:17 PM
Thanks for all your help and knowledge. So is the most afordable option for this mic the cek-12 from peluso? There has to be something in the $100 range that is decent.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 29, 2014, 08:06:44 PM
Thanks for all your help and knowledge. So is the most afordable option for this mic the cek-12 from peluso? There has to be something in the $100 range that is decent.

CEK12 is still a 3 wire capsule, and it goes for around $240. It has a significant 11Khz peak as well, higher than RK12 but not as big as the K89/69.

In all honestly... all "cheap" capsules are really similar, chunger's and RK12 are good. Never personally heard the AK-12. I have a spare RK12 that I could give out to you for a discount (I bought I matched set or RK12s a while ago, but decided to buy a Beesneez CK12 and Tim Campbell's CT12 when I got the cash for them).

I think you need to know how much you need the figure of eight to take a decision.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 29, 2014, 09:05:33 PM
Cek-12 is a 4 wire AFAIK. 2 red wires, 2 blue wires. I would not mind doing mid-side with it. I guess I need to do a bit more research and figure out what I want to do. Thanks for the offer. Maybe I can do it with no figure of 8 and when I get the money to upgrade then buy a beesknees or a TC. There is also this...

http://micandmod.com/en/capsules/105-microphone-capsule-ck-12.html (http://micandmod.com/en/capsules/105-microphone-capsule-ck-12.html)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 30, 2014, 12:25:18 AM
Ding,

I would recommend that you have a look at http://groupdiy.com/index.php?topic=55376.60 (http://groupdiy.com/index.php?topic=55376.60) before deciding to deal in any way with micandmod.
And in any case, it is a ruse, the CEK12 may well have 4 wires, but the backplanes are not isolated.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on May 30, 2014, 08:50:21 AM
...it appears the very prototype Dan built in this thread is currently being offered for sale in the Black Market forum, and it lists the capsule as the "Ningbo Tongxin" C12 which is the microphone-parts.com/micandmod variant...

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 30, 2014, 09:13:29 AM
Interesting. I guess we will need to hear from the man himself.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 30, 2014, 11:45:54 AM
I just got conformation from Scotty at advanced audio microphones. Here is what he told me.

Quote
The AK12 has 4 wires. Two back plates, and two edge fed diaphragms.
 
Cheers,
 
Scotty

Sounds like a contender.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on May 30, 2014, 12:11:11 PM
I just got conformation from Scotty at advanced audio microphones. Here is what he told me.

Quote
The AK12 has 4 wires. Two back plates, and two edge fed diaphragms.
 
Cheers,
 
Scotty

Sounds like a contender.

...same as Chunger's capsule...from Chunger's Studio 939 site:

"Due to the popularity of our C12 microphone kits, we have imported a high quality 34mm K67-based edge terminated capsule suitable for budget conscious builders. These capsules are 6 micron and backplate isolated, so they are suitable for use in the original ELA M251 polarizing scheme as well as our 9 pattern C12 configuration. The build quality and sonics on these capsules are quite good, but in this grade of Chinese manufactured capsule, we will find variation from unit to unit. This model was selected as an ideal entry level option."
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on May 30, 2014, 12:28:00 PM
Hello all and thanks to everyone who has emailed there support of this build. We are now ready to start taking orders for the Beesneez ELA M251 body kit (adjusted to fit this build) and the Beesneez CK12 capsule. Once the orders are finalised we will begin production in July. I will be keeping you updated as we go along with how things are going. To place your order and secure your body kit and capsule please follow this link [url]http://www.beesneezmicrophones.com.au/store/ela-m251-body-kit-and-ck12-bundle.html/url]

As you can imagine to make this smoother the sooner we are able to secure the orders the sooner we can begin production.

Cheers,
V
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 30, 2014, 02:05:17 PM
 :D



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmnieto on May 30, 2014, 02:22:08 PM
I just got conformation from Scotty at advanced audio microphones. Here is what he told me.

Quote
The AK12 has 4 wires. Two back plates, and two edge fed diaphragms.
 
Cheers,
 
Scotty

Sounds like a contender.

It seems that I was wrong :) Definitely don't go for the RK12. Use Chunger's or the AK12
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on May 30, 2014, 03:05:36 PM
I have also made the body kit available with the Shock Mount but no capsule. Here is the link for that one: http://www.beesneezmicrophones.com.au/store/ela-m251-styled-microphone-body-kit.html
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on June 06, 2014, 09:36:01 AM
Looks like the switch is missing from the PSU mouser cart. Anyone know which is the one?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on June 06, 2014, 09:39:17 AM
Looks like the switch is missing from the PSU mouser cart. Anyone know which is the one?

Wich Switch ,
D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on June 06, 2014, 09:40:46 AM
Found it. It was in the mic body BOM. I was referring to the PSU pattern switching switch.

http://www.mouser.com/Search/ProductDetail.aspx?R=A10315RSZQvirtualkey61170000virtualkey611-A10315RSZQ (http://www.mouser.com/Search/ProductDetail.aspx?R=A10315RSZQvirtualkey61170000virtualkey611-A10315RSZQ)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on June 06, 2014, 09:46:11 AM
Found it. It was in the mic body BOM. I was referring to the PSU pattern switching switch.

http://www.mouser.com/Search/ProductDetail.aspx?R=A10315RSZQvirtualkey61170000virtualkey611-A10315RSZQ (http://www.mouser.com/Search/ProductDetail.aspx?R=A10315RSZQvirtualkey61170000virtualkey611-A10315RSZQ)

Excellent ,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on July 14, 2014, 02:21:10 AM
In your test build, it looks like a Cinemag output transformer. What model number?
I'm using T-14 tranformers in my c-12 builds, and thought I might try a different O.P.T. in the 251s
Has there been any comparsions between the T-14 and Cinemag in this build?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on July 14, 2014, 07:55:31 AM
In your test build, it looks like a Cinemag output transformer. What model number?
I'm using T-14 tranformers in my c-12 builds, and thought I might try a different O.P.T. in the 251s
Has there been any comparsions between the T-14 and Cinemag in this build?

this is a 2480  (11:1)  in my test build , I havent the chance to try the T14 yet but it is on my wish list ,
Best,
dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bancho on July 18, 2014, 04:10:09 AM
Ok, I see there is some confusion about the transformer ratios and therefore different choices (maybe just for me...?).
The original Haufe has the ratio 14:1, AMI T14 and CM-13114 are 12:1... as I understand there is difference in sound if the ratios are different... does this something to do wit circuit/capsule used? Did anyone try how different transformers sound with Beezneez CK12 capsule?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: RuudNL on July 18, 2014, 11:07:46 AM
Just an addition to the capsule discussion from my side:
I have used a Mic&Mod CK-12 in an ELA M-251 'like' design and I must say the quality is excellent!
(Insulated backplates, two backplate connections.)
Personally I never had a problem with Mic&Mod.
Even when a capsule failed after some time, they replaced it with a new one without any costs.
The CK-12 capsule may also have a treble peak (as has the RK-12), but it is a small amount of boost, nothing like a K67/87 capsule.
I prefer a microphone that is a little on the 'bright' side above a ruler flat or even a somewhat 'dull' sounding microphone.
In practice most of the time you will end up with adding some treble, to increase the presence of a sound source. (Anyway: I do...)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: KDE on July 21, 2014, 01:51:52 PM
I have also made the body kit available with the Shock Mount but no capsule. Here is the link for that one: http://www.beesneezmicrophones.com.au/store/ela-m251-styled-microphone-body-kit.html
Sorry if this question has already been answered somewhere else but how close to the original mic does your body kit come? Will the head basket be exactly the same? Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on July 21, 2014, 08:53:45 PM
Hi the body kit will have the same head basket as the Tribute 2 Microphone. These are being made that the moment, so if you wish to order let me know asap. The body kit is of the same build and quality as the rest of the Beesneez range.

thanks, Veronica
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on July 22, 2014, 11:23:52 PM
Looked throught the entire post to find out how to wire the XLR and AMI to the the Mic P.S.B.
GND,OMH,FB,H+,A-,A+,P+,P-,S-,S+,B+
Other than the picture in "Reply 121" which kinda helps, I wasn't able to find a concrete answer.
Using the white boards. Any Help?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on July 23, 2014, 12:48:35 AM
Looked throught the entire post to find out how to wire the XLR and AMI to the the Mic P.S.B.

GND, = gnd
OMH dont recall this one ???
,FB front backplate
,H+ heater
,A- audio -
,A+ audio +
,P+ Primary +
,P- Primary -
,S- secondary -
,S+ secondary +
,B+  Plate Voltage


Other than the picture in "Reply 121" which kinda helps, I wasn't able to find a concrete answer.
Using the white boards. Any Help?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on July 23, 2014, 01:59:58 AM
Thanks for the terms. but where do they connect to the XLR and AMI transformer.

GND, = gnd ( GND tab on XLR )
OMH dont recall this one
,FB front backplate ( to front capsule backplate )
,H+ heater ( what pin # on XLR )
,A- audio - ( what pin # on XLR )
,A+ audio + ( What pin # on XLR )
,P+ Primary + ( Red on AMI )
,P- Primary -   ( Red on AMI )
,S- secondary - ( Blue on AMI )
,S+ secondary + ( Blue on AMI )
,B+  Plate Voltage ( What pin # on XLR )

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on July 24, 2014, 05:23:18 PM
Thanks for the terms. but where do they connect to the XLR and AMI transformer.

GND, = gnd ( GND tab on XLR )
OMH dont recall this one
,FB front backplate ( to front capsule backplate )
,H+ heater ( what pin # on XLR )
,A- audio - ( what pin # on XLR )
,A+ audio + ( What pin # on XLR )
,P+ Primary + ( Red on AMI )
,P- Primary -   ( Red on AMI )
,S- secondary - ( Blue on AMI )
,S+ secondary + ( Blue on AMI )
,B+  Plate Voltage ( What pin # on XLR )

I always run my cable the same way on the xlr cable pinout,
1-audio +
2-audio -
3 shield up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay voltage )
7 circuit ground

For AMI T14 it will be :

Blue , Blue    will be primary + and Primary -
red , red       will be secondary + and secondary -

hope this helps ,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on July 24, 2014, 07:04:28 PM
Thanks, Dan.
I'll use that as a standard hookup.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on July 27, 2014, 07:32:36 PM
Hi guys!

Now I am actually really confused..  ??? I can't seem to make sense of the PIN-connections here.
I look at the PSU in the build, at #121 and at your cable wiring suggestion here, poctop, and they don't look the same.
What am I missing?

We have the following labeling on the PSU/MIC that need to find the right PIN on the two XLRs:

PSU
Label          7-PIN          3-PIN
__________________________________
B+
H+
Bias
POL
GND
Relay
GNDC
POLV
Pmic
PGND
Switch 1
Switch 2
Switch 3
Switch A


MIC
Label          7-PIN
___________________________
A+
A-
H+
F8
OMN
GND
B+


If we could get the "correct" pinout for each label it would make things a lot easier, and we could all use the same standard in our 251-builds.
Right now, I'm not certain what PINs to connect to what label on the PSU/Mic since I am confused by the pictures and lack of clear information.

Please feel free to use any way of describing this that you find best, as long as we understand what PIN goes where on the PSU and Mic..

Thx a lot! :=)

//Michael
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on July 28, 2014, 10:28:31 AM
Thanks for the terms. but where do they connect to the XLR and AMI transformer.

GND, = gnd ( GND tab on XLR )
OMH dont recall this one
,FB front backplate ( to front capsule backplate )
,H+ heater ( what pin # on XLR )
,A- audio - ( what pin # on XLR )
,A+ audio + ( What pin # on XLR )
,P+ Primary + ( Red on AMI )
,P- Primary -   ( Red on AMI )
,S- secondary - ( Blue on AMI )
,S+ secondary + ( Blue on AMI )
,B+  Plate Voltage ( What pin # on XLR )

I always run my cable the same way on the xlr cable pinout,
1-audio +
2-audio -
3 shield up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay voltage )
7 circuit ground

For AMI T14 it will be :

Blue , Blue    will be primary + and Primary -
red , red       will be secondary + and secondary -

hope this helps ,
Dan,

I actually made a little mistake here as there is 2 wire for the relay control , i will be making a drawing in a short moment ,
to make this all clear , for the mean time i will dit this post to add the proper xlr config for this particular build,
 
edit:

1-audio +
2-audio -
3- (Relay control 1)
cable shield up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  )
7 circuit ground
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on July 29, 2014, 03:42:42 PM
These drawings may be helpful:

(http://harmoniccycle.com/hc/images/sound/mic/Walter-White/ELA-M-251-vintagemicrophonepcbkit_D-251.jpg)

(http://harmoniccycle.com/hc/images/sound/mic/Walter-White/ELA-M-251-vintagemicrophonepcbkit_D-251_PSU.jpg)

If anyone finds any mistakes in these drawings please make a note of it so that they can be corrected.


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on July 31, 2014, 06:21:38 PM
Thanks, trans4funks1!

This was exactely the info I was searching for. Very easy to follow, well done!

I finally came around tonight to do the wiring, and gave the 251 a nice Gotham cable too.  :)
Just right after calibration, this mic sounds heavenly right away!

I will let it burn in for a few days and then take it to the studio for testing.

Best,
Michael.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on August 01, 2014, 03:25:10 PM
Hi Michael,
 I'm glad it worked out  well.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on August 01, 2014, 04:20:52 PM
Hi Michael,
 I'm glad it worked out  well.

trans4funks1  your the best ,
Thanks for your help in this matter,
Best
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dougch on August 14, 2014, 12:37:27 AM
I have a couple of questions about the component values. Looking at the picture gallery on the Telefunken USA site, I see that they are using what appears to be 50M resistor on the grid, the 8M resistors are changed to 10M, the 4800pF cap is changed to 10000pF (0.01uF), coupling cap is 2uF and there is no sign of the 100pF cap. Do these changes have a major or minor influence on the circuit as a whole? If this question is too broad, forgive me, I am just curious.

I am also curious about building a M251 model with a 5840 for the tube. Would this be difficult? This would be a second build.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on August 15, 2014, 04:27:09 PM
Hi Guys!

I just picked up my 251 from the powder coater today.
After a week of bad sleep I can say that I am happy with how mintness the of the mic turned out!  ;D
Beige with a tint of green, pretty much like an original ELA M, just as I wanted. VERY happy camper!

Now I definitely want to powder coat my other mics too..
The light ivory you use, Kidvybes, looks very tempting indeed for the C12 stereo pair.

Best,
Michael
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 15, 2014, 06:44:42 PM
Hi Guys!

I just picked up my 251 from the powder coater today.
After a week of bad sleep I can say that I am happy with how mintness the of the mic turned out!  ;D
Beige with a tint of green, pretty much like an original ELA M, just as I wanted. VERY happy camper!

Now I definitely want to powder coat my other mics too..
The light ivory you use, Kidvybes, looks very tempting indeed for the C12 stereo pair.

Best,
Michael

...Looks Great, Michael!...glad it turned out to your liking!

BTW, I used "Cream" on my C12...my other 2 mics were closer to that color you just got...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Dylan W on August 15, 2014, 06:55:31 PM
This looks great. Do you know what the color code/name is that they used?

 
Hi Guys!

I just picked up my 251 from the powder coater today.
After a week of bad sleep I can say that I am happy with how mintness the of the mic turned out!  ;D
Beige with a tint of green, pretty much like an original ELA M, just as I wanted. VERY happy camper!

Now I definitely want to powder coat my other mics too..
The light ivory you use, Kidvybes, looks very tempting indeed for the C12 stereo pair.

Best,
Michael
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 15, 2014, 07:22:20 PM
This looks great. Do you know what the color code/name is that they used?

...here's one of the more popular powder-coat supplier charts:
http://www.nortekpowder.com/pdfs/NortekColorCatalog-2011.pdf

...kinda looks like the "Light Ivory" on this chart...I used that shade on two of my mics, and it matches BeesNeez ELAM-style "Seamist" body color exactly...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on August 15, 2014, 07:39:28 PM
Thx! It actually looks just a bit darker on the photo than it really is due to the low light.
In daylight it looks more like a beige with just a tint of green in it. Very nice with a vintage vibe.
I will post better pictures soon..

Dylan W, I chose from the chart in Kidvybes link, and the color code is RAL 1000
Homepage: http://www.ralcolor.com

I definitely like the RAL 1015 Light Ivory. Contender for the C12!

//Michael
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on September 21, 2014, 09:07:01 AM
looks like the panasonic relays are rate with 100m isolation resistance, I doubt thats good enough, but it is not so difficult to find relays with 1g or higher insulation resistance
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on September 21, 2014, 11:27:37 AM
looks like the panasonic relays are rate with 100m isolation resistance, I doubt thats good enough, but it is not so difficult to find relays with 1g or higher insulation resistance

I was actually suggested those by Oliver , but if you can find  better I am open to suggestion as always ,
they were chosen as a compromised between power package and isolation ,

Let me know,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on September 21, 2014, 11:57:38 AM
I like to find some relays with actual solder tabs that were small enough for me to fit into a Beez Neez 60mm body or a Chi-Com 47 donor.

If anyone has a suggestion I'll appreciate it. I keep realizing my eyes are fuzzy when I am searching through the catalogs.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on September 22, 2014, 03:05:07 PM
yes looking through a catalogue is a horror. I found these 1000g isolation resistance !!
http://de.farnell.com/standexmeder/dip05-2a72-21l/reed-relais-5v-2xschliesser-ohne/dp/1079443 (http://de.farnell.com/standexmeder/dip05-2a72-21l/reed-relais-5v-2xschliesser-ohne/dp/1079443)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on September 22, 2014, 03:38:55 PM
yes looking through a catalogue is a horror. I found these 1000g isolation resistance !!
http://de.farnell.com/standexmeder/dip05-2a72-21l/reed-relais-5v-2xschliesser-ohne/dp/1079443 (http://de.farnell.com/standexmeder/dip05-2a72-21l/reed-relais-5v-2xschliesser-ohne/dp/1079443)

great find,  :) thanks for that,
finding something equivalent in term of package as the panasonic would be even greater
Best,
Dan,


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on September 22, 2014, 03:54:31 PM
finding something equivalent in term of package as the panasonic would be even greater

d'accord looks like all high resistance relais are reed :( I keep searching

nb
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on September 22, 2014, 04:27:14 PM
soooo twenty datasheets later I must confess all DIL packages have max 1 Gigaohm insulation resistance, and this is before the first switching, after that it goes down even lower, mmmh
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on September 22, 2014, 06:18:36 PM
As you can see here those Relay have been used in the BlackSpade UM25 Line From Oliver ,  as they were suggested to me ,
this was actually my reference .

(https://dl.dropboxusercontent.com/u/43869772/Elam%20251/BlackSpade.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d02819943b0.jpg)

Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on September 25, 2014, 11:20:33 PM
Hi guys, here is the body that we have been making for this build. It had been some work to get perfect. The bases are being nickel plated today and the body's are getting there powder coat. I have a few spares if anyone would still like one. There is no compromise on quality here, they are all Australian made.  I have also had a few PSU cases sold for this build with our toroidal transfer and Neutrick connectors. This should sound amazing.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on September 26, 2014, 07:32:17 AM
Is that one of your 60mm bodies adapted with a base that uses straps that are angled inwards towards the pcb's mounting holes?

Looks good!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mics on September 26, 2014, 05:18:15 PM
Is that one of your 60mm bodies adapted with a base that uses straps that are angled inwards towards the pcb's mounting holes?

Looks good!

Hi there.  This is a 51mm body that has been made for this build.  The rails are stainless and fit the pcb perfectly.  Thanks.

Ben
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Andydrum82 on October 02, 2014, 02:04:50 AM
Here's my Elam build coming along. I'm using a Beesneez PSU & body kit/capsule. Big thanks to Ben & Veronica for coming on board with this one 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on October 02, 2014, 04:40:37 PM
This wiring  has not been clearly posted and I can't tell by the pictures.
I'm wiring up the 7 Pin XLR on the mic to the Mic P.C.B.  I have two  connections left,  FB and OMN.
Are these  where the two connections from the selector switch on the Power supply connect to?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 02, 2014, 06:29:36 PM
This wiring  has not been clearly posted and I can't tell by the pictures.
I'm wiring up the 7 Pin XLR on the mic to the Mic P.C.B.  I have two  connections left,  FB and OMN.
Are these  where the two connections from the selector switch on the Power supply connect to?

FB is actually F8 and OMN is the Omni pattern,

those 2 pads will accommodate wiring from the pattern switch , one position of the pattern switch will remain empty as there is no power required for the realy in cardiod ,

then  the 6V power from psu pcb pad (Relay) will be sent via pattern switch to OMN and F8 up on the mic pcb to control the pattern ,

Hope this helps,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on October 02, 2014, 06:54:12 PM
Quote
FB is actually F8
That's why I use a magnifier when I solder.
So , the Figure 8 side of the switch goes to F8, and the omni side goes to OMN.
Thanks. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 02, 2014, 07:12:23 PM
Quote
FB is actually F8
That's why I use a magnifier when I solder.
So , the Figure 8 side of the switch goes to F8, and the omni side goes to OMN.
Thanks.

Correct ,  :),
Best,
DAn,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on October 02, 2014, 07:51:25 PM
Another pair ready to  go.
Just need to install my T.C. capsules and the tubes.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 02, 2014, 07:56:58 PM
Another pair ready to  go.
Just need to install my T.C. capsules and the tubes.

Nice ,   ;)  hoping you will let us know how you like them.
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on October 03, 2014, 07:04:57 AM
What sort of notes are written on those capsule boxes?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 03, 2014, 12:27:01 PM
What sort of notes are written on those capsule boxes?

Probably instruction for connection and a super important notice do not remove until soldering is done  8),
D.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on October 03, 2014, 03:17:31 PM
Yes.
" Do not remove until making connections"
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on October 04, 2014, 08:47:19 AM
Thanks for explaining. Mine didn't come with that note, but I got the message. :-)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on October 05, 2014, 02:05:53 PM
hi poctop

another dozend datasheets later i found a compatible, cheap relais with 1gigaohm at 500vdc ... what you think any downsides of this candidate ?

http://de.rs-online.com/web/p/monostabile-relais/0351819/ (http://de.rs-online.com/web/p/monostabile-relais/0351819/)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 06, 2014, 08:49:10 AM
hi poctop

another dozend datasheets later i found a compatible, cheap relais with 1gigaohm at 500vdc ... what you think any downsides of this candidate ?

http://de.rs-online.com/web/p/monostabile-relais/0351819/ (http://de.rs-online.com/web/p/monostabile-relais/0351819/)

This looks like a very good candidate,  I went in and check upon the specsheet again for both ,
it seems this one is only a 1 mm higher than the other one used in the Bom , and the package is perfect
the spec sheet for the panasonic says Minimum 100M at 500VDC  and the one you have found is Min 1Gig at 500VDC,
wich is very good indeed, 
Since we are very far of those critical limit , it is hard to predict a normal operation Value. but i would expect them to be higher than that a much lower normal operation.

In term of power and current draw they are very very similar.
I went ahead and try sourcing it trough mouser or digikey and they seems to be out of reach or non stock at those location ,
even newark has no stock. 

I would consider the low Power one V23105A5002A201 to be a good candidate for further testing and experimentation.
if you can get a hold of them that would be very interesting to see if there is a noticable difference with those,

Again Thanks For the suggestions and findings  hoping you will let us know the outcomes,

Best ,
Dan,



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on October 06, 2014, 11:25:30 AM
once again, do we need latching or non latching ?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 06, 2014, 11:29:08 AM
once again, do we need latching or non latching ?

Non Latching ,
Best,
Dany,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on October 10, 2014, 07:50:34 PM
I stopped writing on the covers and instead include this.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on October 16, 2014, 09:43:42 AM
[url][http://www.banzaimusic.com/Tyco-Axicom-D2N-5V.html/url]

1g insulation resistance
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Andydrum82 on December 25, 2014, 07:43:49 PM
The body & capsule arrived from beesneez this week it top quality 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Andydrum82 on December 25, 2014, 07:46:10 PM
I finished wiring it all up this morning.  Here's the back. I haven't bought a tube yet so I can't test it.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Andydrum82 on December 25, 2014, 07:47:25 PM
Here's a picture of the front
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on December 25, 2014, 09:58:32 PM
Beautiful!!!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Veronica Sneesby on December 26, 2014, 08:10:34 PM
Hey, the mics are coming together nice. Thanks for sharing the photos. We love seeing you all enjoy the body kits and CK12's
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 08, 2015, 05:32:48 PM
Actually there is no standard for 7 pin wiring  so you can actually make your own scheme if you will
just make sure it follows the logic from the psu to the mic pcb and you will be fine ,
I just have an habit of following the Neumann scheme for my cable ,  I have wired my cable like this ,
but since this one have 2 pattern control it deviates a little bit from it , but as said if you are using a Gotham cable
reserve the blue wire for Circuit ground and the red wire for the heater as those are the biggest gauge to handle more current
as said you can define your own cable configuration from psu to mic as long as it is following the logic.

here is an example :

1-audio +
2-audio -
3- (Relay control 1) to OMN
cable shield  = up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  ) to Fig 8 on mic pcb ,
7 circuit ground
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on February 08, 2015, 05:38:16 PM
Actually there is no standard for 7 pin wiring  so you can actually make your own scheme if you will
just make sure it follows the logic from the psu to the mic pcb and you will be fine ,
I just have an habit of following the Neumann scheme for my cable ,  I have wired my cable like this ,
but since this one have 2 pattern control it deviates a little bit from it , but as said if you are using a Gotham cable
reserve the blue wire for Circuit ground and the red wire for the heater as those are the biggest gauge to handle more current
as said you can define your own cable configuration from psu to mic as long as it is following the logic.

here is an example :

Perfect, Thanks a ton.  I'll upload pictures after the build is complete.  Should be sometime later today.



1-audio +
2-audio -
3- (Relay control 1) to OMN
cable shield  = up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  ) to Fig 8 on mic pcb ,
7 circuit ground
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 08, 2015, 06:37:48 PM
Actually there is no standard for 7 pin wiring  so you can actually make your own scheme if you will
just make sure it follows the logic from the psu to the mic pcb and you will be fine ,
I just have an habit of following the Neumann scheme for my cable ,  I have wired my cable like this ,
but since this one have 2 pattern control it deviates a little bit from it , but as said if you are using a Gotham cable
reserve the blue wire for Circuit ground and the red wire for the heater as those are the biggest gauge to handle more current
as said you can define your own cable configuration from psu to mic as long as it is following the logic.

here is an example :

Perfect, Thanks a ton.  I'll upload pictures after the build is complete.  Should be sometime later today.



1-audio +
2-audio -
3- (Relay control 1) to OMN
cable shield  = up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  ) to Fig 8 on mic pcb ,
7 circuit ground

Please do,
we always like to see Picture of completed build here,
Best,
dAn,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on February 10, 2015, 05:10:43 PM
Just doing some final adjustments on the PSU before plugging in.  I'm noticing that the B+ voltage at terminal Block 1 is at 200v, which seems high based on what I'm reading.  Using trimming resistor R4, I can get the voltage down to about 173v before the resistor bottoms out.  Any thoughts here, or is sending 200v ok (I thought we were aiming for 120v)?  Thanks in advance!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: shaggy on February 10, 2015, 11:53:40 PM
Just doing some final adjustments on the PSU before plugging in.  I'm noticing that the B+ voltage at terminal Block 1 is at 200v, which seems high based on what I'm reading.  Using trimming resistor R4, I can get the voltage down to about 173v before the resistor bottoms out.  Any thoughts here, or is sending 200v ok (I thought we were aiming for 120v)?  Thanks in advance!

No load? (Mic not plugged in.)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on February 11, 2015, 11:11:25 AM
Just doing some final adjustments on the PSU before plugging in.  I'm noticing that the B+ voltage at terminal Block 1 is at 200v, which seems high based on what I'm reading.  Using trimming resistor R4, I can get the voltage down to about 173v before the resistor bottoms out.  Any thoughts here, or is sending 200v ok (I thought we were aiming for 120v)?  Thanks in advance!

No load? (Mic not plugged in.)

Correct.  While I'm posting, it seems that the mic works fine in Cardioid and Omni, but when I turn the power supply to Figure 8 I get nothing.  I've checked to see that the voltage moves from pin to pin as I change polar patterns.  Is this a PTP issue or possibly a capsule wiring issue?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on February 11, 2015, 11:36:16 AM
Or a short between the backplates.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: trans4funks1 on February 11, 2015, 01:10:53 PM
I revised the schematic drawings today to display poctops wiring pin out suggestions.

(http://harmoniccycle.com/hc/images/sound/mic/Walter-White/ELA-M-251-vintagemicrophonepcbkit_D-251.jpg)

(http://harmoniccycle.com/hc/images/sound/mic/Walter-White/ELA-M-251-vintagemicrophonepcbkit_D-251_PSU.jpg)

As always, if someone notices a need for a correction or edit in the drawings please send me a note so that I can make them as accurate and useful as possible.

Thank you.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 11, 2015, 03:12:12 PM
I am to reprint a little batch of those ,
let me know if any interest so i could adjust qty to fit the need,
Best,  :)
DAn,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: mgronroos on February 11, 2015, 03:49:32 PM
I agree that we could need some easy-to-read wiring diagrams for all the projects that require an extrernal PSU.
It is not that many mics, so I think it would be manageable to make one for every type.

I wouldn't have felt secure about the wiring of my 251 if it wasn't for your schematic drawing, Trans4funks1, so I very much appreciated it. Thx Again!  :)
And feel free to post your revised version when they are done since I am about to build two more of these babies.   ;)

Cheers!
//Michael
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 11, 2015, 08:41:44 PM
thanks to Trans4funks1 for this nice work.  :)

Microphone DiaGram
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

PSU DiaGram
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d02819944c5.pdf

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on February 13, 2015, 07:36:42 PM
Gonna have to swallow my pride here folks.  I just finished up building two of these mics:  One works in cardioid and omni (but NOT figure 8, mic goes silent in Figure 8 mode) and the other one isn't passing signal at all.  I built them side by side, and I can find no differences in the two builds.  I've spent my day checking voltages and continuity and can't find anything.  Is anyone able to think of something I haven't?  Technically if one is working in cardioid and omni then the other should be too.  This has me all sorts of puzzled.  Any help would be greatly appreciated.

CB
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on February 13, 2015, 08:03:23 PM
Use a continuity tester to make sure you don't have a short between the backplates or membranes of the capsules.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on February 13, 2015, 08:36:11 PM
OK,  So I have the second mic working now, that was due to a small solder issue between the leg of the tube socket and the resistor.  Now this mic is passing signal in all patterns, but cardioid output is very low.  In Omni the Front capsule is louder than the rear, and in Figure 8 the rear capsule is louder than the front.  I'm going to keep digging into it, but I'm guessing some of the solder points in the PTP portion of the build need to be touched up.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Le Roux on February 19, 2015, 03:08:35 PM
Just finished a 251 with a Tim Campbell capsule, AMI output transformer, and hand picked tube from Christian.
Sounds fantastic!
I have one small issue though. A small amount of crackling around 8khz-16khz.
Tube breakin for 4 days, and even swapped out for the tube out of my C12. Same thing. Any ideas? I'm not sure where to look, other than starting to swap out some caps?
Thanks
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on February 19, 2015, 09:08:08 PM
When does it make this noise? Just standing? While you're speaking into it? Could it be power supply or computer related?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Le Roux on February 19, 2015, 09:20:38 PM
It makes the noise all the time.

Power supply is plugged into UPS, and I tried several other mics/psu and no issues.

Its a subtle click, crackling, but can be heard in recordings. Other than that, lots of gain, lots, and sounds fantastic!

With more playing around, I notice the crackling goes away in omni, but still present in the other patterns.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Le Roux on February 25, 2015, 04:51:55 PM
Alright, problem fixed!

I had omni on pin 3, which was my shield, swapped pin 3 to ground, all quiet!
Sounds awesome!!
Thanks for the project!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 25, 2015, 04:55:05 PM
Alright, problem fixed!

I had omni on pin 3, which was my shield, swapped pin 3 to ground, all quiet!
Sounds awesome!!
Thanks for the project!

Glad you made it ,
Lots of the time in complex problem lies the simplest Solution ,
send a Pic over so we can see this new Toy, :)
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: CBarx on March 05, 2015, 01:06:27 PM
Use a continuity tester to make sure you don't have a short between the backplates or membranes of the capsules.

Tim, turns out that one of these capsules has a short between the backplates.  It's not in the wiring, it's in the capsule itself.  Is there anything I can do to fix this, or do I just have to get a new capsule?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on March 05, 2015, 07:38:37 PM
This isn't something you can fix. You must send it back to the manufacturer.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 06, 2015, 11:31:09 PM
I will be receiving a small batch of D-251 PCB next week,  Let me know if you are interested,
Best,
dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on March 12, 2015, 02:49:05 AM
I'd be interested in a pcb set. Just ordered a Beezneez body and ck12. Also have an ac701 tube and an original ( I think)  t14/1 ready to go.  Also have a telefunken elektroakustik psu.  Should be almost set!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 12, 2015, 08:31:19 AM
I'd be interested in a pcb set. Just ordered a Beezneez body and ck12. Also have an ac701 tube and an original ( I think)  t14/1 ready to go.  Also have a telefunken elektroakustik psu.  Should be almost set!

PCB just Arrived but not updated on webstore yet,  they should be available as of tommorow,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on March 12, 2015, 06:36:59 PM
PCB's Kit Back in Stock,
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on March 13, 2015, 12:18:06 AM
Just sent money. Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HHH on March 22, 2015, 02:48:55 AM
Edit:
I was asking if someone could please explain the effect of using a paper in oil [PIO] output cap [as is sometimes used in a C12] versus using polystyrene - but I was since able to find some info.  Apparently they are very close. But some people seem to prefer the PIO more.  However there doesn't seem to any of the preferred K40 series Russian PIO's on ebay in the larger 1uf though 3uf size. There're some K75's, but they are a combo of polythelene film, paper and oil. Nevertheless some people think they sound pretty good too.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HHH on March 23, 2015, 03:39:39 AM
Thought I'd add that the polyethylene in the K75 series is "polyethylene terephthalate", which is a common polyester. And polyester caps are widely considered the favorite of guitar amp builders for their clear warm and pleasing sound.  Mylar [a product name] is actually polyester too.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: LHS on March 28, 2015, 03:11:40 AM
Has anyone tried successfully to remove the apex 460 logo without painting over it? I'm hoping there's a chemical that I can wipe it off with?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on March 30, 2015, 11:10:14 PM
If it's silkscreen: acetone.

Won't damage the nickel plating.

Has anyone tried successfully to remove the apex 460 logo without painting over it? I'm hoping there's a chemical that I can wipe it off with?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on May 07, 2015, 05:21:06 PM
I'm gathering all of the parts to build two of these mics, 1with a 6072 and 1 with an Ac701k. For the Ac701k in this circuit It would appear that I would need to use a 200K plate resistor (instead of the 100K in the schematics here), a 3k6 cathode resistor (instead of  1K8 ), and 8M for R4 ( instead of the 30M). Also I'd need to set Heaters to 4V and maybe use lower voltage relays? Perhaps a 769-DS2E-S-DC3V (http://www.mouser.com/ProductDetail/Panasonic-Industrial-Devices/DS2E-S-DC3V/?qs=sGAEpiMZZMs3UE%252bXNiFaVG3FKEHiD4jOgP2YhcnFJhc%3d) with some added resistance to drop 4V Heaters to 3V for this relay? or would it make more sense to just use a trimmer after the 6.3 volt relay pad for the heaters? Any thoughts here?
Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:47:46 AM
I've finished my build.  Beesneez Mic Body and Beesneez CK12 capsule, Cinemag CM-13114 transformer, Electro-Harmonix 6072A/12AY7 GOLD Tube, PSU from Chunger.

Front inside:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:48:04 AM
Rear inside:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:48:29 AM
Rear assembled:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:48:45 AM
PSU:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:51:27 AM
Closeup front:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: vinylwall on May 08, 2015, 07:51:44 AM
Closeup rear:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: taliska on May 10, 2015, 02:03:21 PM
Hi All,

I've had these pcbs lying around for a while now, and am just getting around to putting them together. It all looks rather straightforward, but as I haven't seen anyone mention it, I've got to ask about the (mechanical) stability of the relays...

As far as I can tell, the relays are really only supported (mechanically) by a single pin to board solder on the outer relays and get the rest of their mechanical support from the point to point soldering.

Has anyone tried shaking their built pcbs to see if they get any vibration of the relays because of that? I haven't got to that point in my build yet, but it seems like that could be a potential issue...(that could probably be fixed with a bit of glueing if it's a problem).

So, thoughts? Is it a problem in practice?

Cheers,

Kaz
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Winetree on May 10, 2015, 03:41:13 PM
"As far as I can tell, the relays are really only supported (mechanically) by a single pin to board solder on the outer relays and get the rest of their mechanical support from the point to point soldering.
Has anyone tried shaking their built pcbs to see if they get any vibration of the relays because of that?"

Haven't noticed any vibration problems. But I did have to make sure the relays were tight together and had to sand the 2 outer edges at 45 degrees in order to fit the mike tube over them. Also there was noted some problems with vibration noise with the 2 large poly caps on the top  back side of the P.S.B. Glue them down.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: taliska on May 10, 2015, 04:06:19 PM
"As far as I can tell, the relays are really only supported (mechanically) by a single pin to board solder on the outer relays and get the rest of their mechanical support from the point to point soldering.
Has anyone tried shaking their built pcbs to see if they get any vibration of the relays because of that?"

Haven't noticed any vibration problems. But I did have to make sure the relays were tight together and had to sand the 2 outer edges at 45 degrees in order to fit the mike tube over them. Also there was noted some problems with vibration noise with the 2 large poly caps on the top  back side of the P.S.B. Glue them down.

Cool. Yeah, hadn't thought about those caps (yet!), but good call on that. I'll pick up some glue for stabilising everything before progressing any further...

Cheers,

Kaz
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PhatPlanetStudios on May 12, 2015, 08:36:19 AM
Good day 251'ers,
So I've completed my build with a GE 5-star, Beesneez capsule and body and the new mic all powered up and functioned without a hitch!  Great docs, pics and posts made the build a breeze. Thanks to all!  Upon initial listening, the 251 clone sounds thin, bright and lacks low end. Sitting next to our vintage Telefunken U47, the 251 doesn't even come close in sound quality.  Pretty disappointed, so now I'm trying to figure out what I did wrong.  Some questions are;  B+ (grid) voltage.  Diagram says 120V & I've seen 110V in the posts.  Any impact in sound quality with the grid voltage?  Are there any key component changes that differ from the Mouser BOM+Styroflex Caps that I should be aware of?  Any insight would be greatly appreciated.  Thanks guys!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on May 12, 2015, 08:52:11 AM
Good day 251'ers,
So I've completed my build with a GE 5-star, Beesneez capsule and body and the new mic all powered up and functioned without a hitch!  Great docs, pics and posts made the build a breeze. Thanks to all!  Upon initial listening, the 251 clone sounds thin, bright and lacks low end. Sitting next to our vintage Telefunken U47, the 251 doesn't even come close in sound quality.  Pretty disappointed, so now I'm trying to figure out what I did wrong.  Some questions are;  B+ (grid) voltage.  Diagram says 120V & I've seen 110V in the posts.  Any impact in sound quality with the grid voltage?  Are there any key component changes that differ from the Mouser BOM+Styroflex Caps that I should be aware of?  Any insight would be greatly appreciated.  Thanks guys!

My first Reflex would be to try a  cheap chinese CK12 capsule type to rule out any capsule problem at first ,
it is not impossible that somthing is wrong with the capsule as it plays a major role in a microphone ,
Hope this helps,  if not i would defo check the wiring and component value in the HZ bridge, a little substition in a high Megohm range would totally kill it. i would also be intested to see what the capsule looks like when it is polarized.. i would also check to make sure that your 2 backplate are properly isolated this could messup the polarisation scheme for the pattern.
Dan.


Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dmp on May 12, 2015, 10:44:38 AM
Doublecheck the transformer wiring also - that can lead to thin sound
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on May 12, 2015, 10:59:04 AM
Doublecheck the transformer wiring also - that can lead to thin sound

+1

lowest resistance pair to S+ S- and Higher resistance Pair to P+ P-
D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on May 12, 2015, 03:05:54 PM
Any thoughts/ tips on adjustments to the circuit to work with an ac701k?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on May 12, 2015, 03:15:07 PM
Any thoughts/ tips on adjustments to the circuit to work with an ac701k?

i have seen a thread on this Non-export elam 251 Build here somwhere ,

edit : found it  http://groupdiy.com/index.php?topic=57902.0

Best,
d
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PhatPlanetStudios on May 16, 2015, 02:13:46 PM
Good day 251'ers,
So I've completed my build with a GE 5-star, Beesneez capsule and body and the new mic all powered up and functioned without a hitch!  Great docs, pics and posts made the build a breeze. Thanks to all!  Upon initial listening, the 251 clone sounds thin, bright and lacks low end. Sitting next to our vintage Telefunken U47, the 251 doesn't even come close in sound quality.  Pretty disappointed, so now I'm trying to figure out what I did wrong.  Some questions are;  B+ (grid) voltage.  Diagram says 120V & I've seen 110V in the posts.  Any impact in sound quality with the grid voltage?  Are there any key component changes that differ from the Mouser BOM+Styroflex Caps that I should be aware of?  Any insight would be greatly appreciated.  Thanks guys!

My first Reflex would be to try a  cheap chinese CK12 capsule type to rule out any capsule problem at first ,
it is not impossible that somthing is wrong with the capsule as it plays a major role in a microphone ,
Hope this helps,  if not i would defo check the wiring and component value in the HZ bridge, a little substition in a high Megohm range would totally kill it. i would also be intested to see what the capsule looks like when it is polarized.. i would also check to make sure that your 2 backplate are properly isolated this could messup the polarisation scheme for the pattern.
Dan.

Thanks for the insight so far Dan,
We've done some tests of the mic now.  Transformer checked & is correct, Capsule backplates are indeed isolated, I do not have another capsule to exchange with yet though.  Testing so far shows that in comparison to a Brauner VM1 & a Manley Gold Reference, all set to Cardioid & measured with exact same conditions;  the LOW end of the 251 is rolled off by 5-10dB below 200 Hz.  Above 200Hz, all three mics were very well matched.  In addition, testing the 251 in Omni & Figure 8, showed the rear side of the capsule measured 3dB lower than the front.  Would this lowered output of the rear affect the Cardioid measurement with proximity & low-end character?  We checked values of all resistors and they match and are consistent with the build, and schematic.  Look at the attached measurement shot:  Blk, top trace is:  Manley,  Middle, Red trace is Brauner,  Bottom Teal trace is 251.  If anyone can think of anything else we should be looking at, please let us know.  Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: lauritz on May 18, 2015, 04:36:05 AM
I can see somebody had this problem before me...but it seems as though the problem was'nt resolved in this thread, or maybe i missed it.

With the mic unplugged, i can't get the B+ voltage low enough...only goes down to 165 v minimum. I've checked the values of r1 and r2 and they match at 75k ohm. The power transformer output is a little above 200V -maybe 208 V.  Should i just swap in higher value resistors for r1 and r2 or is there a problem somewhere, any insights?

I'm reluctant to plug in the microphone, since i have a 150V tantalum cap sitting at the input in the microphone, and i don't wanna blow it....

thanks in advance.

Lauritz
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: granger.frederic on May 18, 2015, 10:04:55 AM
Dear Lauritz/PhatplanetStudio,

 congratulations you have a near perfect Elam 251 plot : see the original plots at http://recordinghacks.com/pdf/telefunken/ElaM-250-251-Manual.pdf , 

you're near the specs...

but if u want to be sure , double check B+ with the mic plugged : max 110V , check the heater : 6.3V , check that all the HiZ sections are perfectly cleaned , check the capsule voltage before the 8Mohms resistors : around 60V

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....

with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)

regards
Fred

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on May 18, 2015, 02:23:00 PM
I have finally finished the first of my 2 elam's. Seems to be working great. I'm taking it to my studio to test it out.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: lauritz on May 20, 2015, 05:57:15 AM
Dear Lauritz/PhatplanetStudio,

 congratulations you have a near perfect Elam 251 plot : see the original plots at http://recordinghacks.com/pdf/telefunken/ElaM-250-251-Manual.pdf , 

you're near the specs...

but if u want to be sure , double check B+ with the mic plugged : max 110V , check the heater : 6.3V , check that all the HiZ sections are perfectly cleaned , check the capsule voltage before the 8Mohms resistors : around 60V

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....

with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)

regards
Fred

Thanks a lot for your thoughts on the matter...i see now from the schematic that there is a 100k resistor on the way to the anode. With approx. 0,5mA current it leads to a 50V voltage drop, so i guess 160V is more than low enough -measuring directly at the output of the power supply.

Another quick question...i am saving up money for a Tim Cambell capsule, so i don't have a capsule yet. Would there be any problems just putting in 2 capacitors with electrical equivalent values( as the capsule ) and do circuit checks like that? Do i even need that, or could i just power up the mic without the capsule installed?


thanks

best
Lauritz

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on May 20, 2015, 08:27:09 AM
Dear Lauritz/PhatplanetStudio,

 congratulations you have a near perfect Elam 251 plot : see the original plots at http://recordinghacks.com/pdf/telefunken/ElaM-250-251-Manual.pdf , 

you're near the specs...

but if u want to be sure , double check B+ with the mic plugged : max 110V , check the heater : 6.3V , check that all the HiZ sections are perfectly cleaned , check the capsule voltage before the 8Mohms resistors : around 60V

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....

with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)

regards
Fred

Thanks a lot for your thoughts on the matter...i see now from the schematic that there is a 100k resistor on the way to the anode. With approx. 0,5mA current it leads to a 50V voltage drop, so i guess 160V is more than low enough -measuring directly at the output of the power supply.

Another quick question...i am saving up money for a Tim Cambell capsule, so i don't have a capsule yet. Would there be any problems just putting in 2 capacitors with electrical equivalent values( as the capsule ) and do circuit checks like that? Do i even need that, or could i just power up the mic without the capsule installed?


thanks

best
Lauritz

Quote
Thanks a lot for your thoughts on the matter...i see now from the schematic that there is a 100k resistor on the way to the anode. With approx. 0,5mA current it leads to a 50V voltage drop, so i guess 160V is more than low enough -measuring directly at the output of the power supply.

Not Really , you need the output from the psu when the mic is connected and loaded to be 110V,
you cannot account for this with the plate resistor , cause everything parameter on the bias and plate will be off
the best way to do this is to emulate a dummmy load with calculating the resistor required to test it under load wihout the need of the mic both for heaters and B+  , this way you dont over blow the tube , if you have a little higher voltage you can increase a little more R1 and R2
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: lauritz on May 21, 2015, 03:52:58 AM
Quote
Not Really , you need the output from the psu when the mic is connected and loaded to be 110V,
you cannot account for this with the plate resistor , cause everything parameter on the bias and plate will be off
the best way to do this is to emulate a dummmy load with calculating the resistor required to test it under load wihout the need of the mic both for heaters and B+  , this way you dont over blow the tube , if you have a little higher voltage you can increase a little more R1 and R2
Best,
Dan,

Ok Dan, thanks for the correction :) I will sit down and have a thorough look at the schematic soon, and try the dummy load test you suggest. It surprises me that no one asked about this earlier in this thread...but i guess it's just me who's a beginner, or maybe just overly concerned about the wellbeing of the components 8)

best
Lauritz

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kosi on June 08, 2015, 04:41:14 PM
Hi Dan, I'm located in europe.
would this toroidal work ?

http://www.tube-town.net/ttstore/Transformer/Power-Transformer/Toroidal/Toroidal-30VA::2192.html?language=en
Pri: 0 - 220 - 230 - 240 V (black-yellow-purple-red)
Sec 1: 200 V @ 0,1 A (red )
Sec 2: 6,3 V @ 1,5 A (green)

It'a the same, that I used for the PSU of the MKU47

thanks
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kosi on June 08, 2015, 04:43:31 PM
Could anybody tell me: 
which XLR connector uses the BeesNeez Bodykit ?

thanks  :D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on June 08, 2015, 08:38:01 PM
Standard 7-pin XLR insert.

Could anybody tell me: 
which XLR connector uses the BeesNeez Bodykit ?

thanks  :D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PhatPlanetStudios on June 24, 2015, 12:30:19 AM
Our Baby is born!  Our Elam 251 clone lives and breathes!  Thanks so much to poctop, our gracious host to this journey into microphone history!  I couldn't have done it without him, he's such a great engineer, great help, and is super cool! 

It turned out to be a fabulous sounding mic and it was just recently used on a word-class opera recording.  The build was great, and it worked from the get-go.  A little tweaking was done, and then we were ready to put it to work.  It was stressful before we got the approval of artist and engineers, but now a great joy that it's been accepted by the pros.  There was a mic shootout between Brauner VM1 and Bock 251, and our DIY Elam 251 beat them both. 

Here's the specs;
PCB:  vintagemicrophonepcbkit.com
Body & head basket:  Beesneez
Capsule:   Beesneez
Transformer:  AMI
Tube:  NOS GE 5-star
All Silver Solder used
PSU Cable: Gotham audio
Internal wiring:  Silver coated copper, teflon jacket
Components:  Mouser & VM-PCBkit

You may look at the build photos and WAV samples of the mic shootout.  Note they're dry WAV files.  Add reverb for max enjoyment....
https://www.dropbox.com/sh/rysai5anrce6ota/AABnr3CkU_fPXH0U1Cy9UNH-a?dl=0
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on June 24, 2015, 09:03:50 AM
Hello PhatPlanet Studios,

Lovely build, sounding mic and singer!!  I am looking to build one myself maybe with a few slightly different components.

I noticed you mentioned the mic needed some tweaking. I wondered if you could be a bit more specific? I noticed granger.frederic made some pointers in post #206 did you use any of them for tweaking or was it other things?

Did the frequency plot look different once you had finished tweaking?

Thanks for your time,

Regards,

  Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PhatPlanetStudios on June 24, 2015, 11:28:14 AM
Hello Matt,
Thanks for the compliment!  After the initial build and sweep test, the mic was shy in the bass for our taste.  It dropped significantly below 200hz.  I got some great advice from Dany and I ended up changing the tantalum (C3) to a 100mF.  I then ran a sweep test and it appeared to improve the bass response nicely.  I had intention to change out the large cap (C1), but never found the time to setup the sweep test (before and after).  We then had to go into using the mic on the session.  After hearing the result, I haven't gone back in for additional mods.  I think I'll build another mic so I can run some further tests.  This mic is making everyone happy around here, so i don't want to mess it up!


Hello PhatPlanet Studios,

Lovely build, sounding mic and singer!!  I am looking to build one myself maybe with a few slightly different components.

I noticed you mentioned the mic needed some tweaking. I wondered if you could be a bit more specific? I noticed granger.frederic made some pointers in post #206 did you use any of them for tweaking or was it other things?

Did the frequency plot look different once you had finished tweaking?

Thanks for your time,

Regards,

  Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gijsvanwel on July 16, 2015, 03:13:12 PM
Hello fellow builders,

I just finished my build and it sounds awesome!

Specs:
Peluso cek12
Cinemag cm 13114
NOS ge jan 6072a

Im getting very loud pops when using The pattern switch (with preamp gain turn to 0 it still clips) Is there any way to ground the pattern switch or should i just set it to the pattern i want to use before turning on the psu?

My b+ and heater voltages are 110v and 6.3v measured in the mic.

Any help would be much appreciated.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on July 16, 2015, 03:32:55 PM
Hello fellow builders,

I just finished my build and it sounds awesome!

Specs:
Peluso cek12
Cinemag cm 13114
NOS ge jan 6072a

Im getting very loud pops when using The pattern switch (with preamp gain turn to 0 it still clips) Is there any way to ground the pattern switch or should i just set it to the pattern i want to use before turning on the psu?

My b+ and heater voltages are 110v and 6.3v measured in the mic.

Any help would be much appreciated.

a Thump when switching pattern is totally normal.
Best,
Dan,
Thanks for posting ,
BEst,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: o3misha on July 16, 2015, 04:21:52 PM
I am confused...According to schematic you have to get 120 VDC on the 100k resistor.

http://recordinghacks.com/pdf/telefunken/ElaM-250-251-Manual.pdf

Guys, original Haufe t14/1 has 11,5:1 ratio. I saw the document from Haufe.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stevesteve50 on August 13, 2015, 05:35:38 PM
Hello,

I ordered the styroflex capacitor kit with my PCB through vintagemicrophonepcbkit.com. I received one  labeled 1000J 630V, and two labeled 5000J 630V. The package had C12 written on it, though i had ordered for the D-251 build. Is it possible that I was sent the film capacitors for the C12 instead of the 251? What options do I have in getting the correct parts if so?

Steve
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on August 14, 2015, 09:05:44 AM
Hello,

I ordered the styroflex capacitor kit with my PCB through vintagemicrophonepcbkit.com. I received one  labeled 1000J 630V, and two labeled 5000J 630V. The package had C12 written on it, though i had ordered for the D-251 build. Is it possible that I was sent the film capacitors for the C12 instead of the 251? What options do I have in getting the correct parts if so?

Steve

Please send me by PM you Order Number of Paypal I will check your order and validate this ,
Yes this is the C12 Styros Kit indeed,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stevesteve50 on August 19, 2015, 04:49:20 PM
Hi Folks,

I finished soldering up the mic last night. I double checked voltages before I hooked up the capsule. I'm doing all testing on a chinese capsule w a single backplane before I hook up the Tim Campbell. Here's the issue I'm having:

There is a very loud hum/buzz that is much louder than any of the audio passing through. It is not a specific frequency, but a broad range. It sounds like putting your finger on the end of a guitar cable plugged into an amp.

Audio does pass through on omni and cardiod modes. Audio does not pass through on figure 8 mode. (buzz in constant on all modes)

I have been trying to find a thread that would help me troubleshoot the issue but haven't found one yet. I was hoping that someone could either point me in the direction of a thread that covers this issue, or perhaps help troubleshoot.

Many thanks!

Steve
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tonzauber on August 19, 2015, 05:00:46 PM
Do you have the circuit in the housing when you test it? Else it will be just a giant rf receiver...

Make sure that all your housing connections are fit tightly, so that you have a good ground connection.

If the microphone works in cardioid and omni, there is no reason that it should not work in figure of eight as well. Measure the voltages that show up on the back diaphragm connection. In Fig.8 it should be 120V, in Cardioid 60V, in Omni 0V.

I had something similar, but it did work in omni only - no pattern switching at all. It was a cold solder joint in the path of the polarization voltage of the backplate.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: chefducuisine on August 19, 2015, 05:01:48 PM
Steve,

to me this sounds like if you are testing the mic with the housing / body tube removed and or without the headbasket.
Another reason could be a missing ground connection.

Edit: Just saw 'tonzauber' was a bit faster with a similar suggestion... :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on August 19, 2015, 07:13:33 PM
Yeah, I'd double check the relay wiring if it isn't working in fig 8. May have something switched up here.
On a side note, this mic sounds amazing with an ac701 tube!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stevesteve50 on August 19, 2015, 10:19:30 PM
Do you have the circuit in the housing when you test it? Else it will be just a giant rf receiver...

Thanks! I didn't realize the rf it would pick up would be that drastic.  :o :-[ Issue solved.

If the microphone works in cardioid and omni, there is no reason that it should not work in figure of eight as well. Measure the voltages that show up on the back diaphragm connection. In Fig.8 it should be 120V, in Cardioid 60V, in Omni 0V.

The mic seems to be working fine in both cardiod and omni now, however, voltages on the rear capsule are as follows:
Fig.8 22.3 VDC, Cardiod 0VDC, Omni 32VDC

The front of the capsule is constant at 32VDC
The plate voltage varies between 59-62VDC depending on the pattern
B+ is set to 120
Heater is set to 6.2

The patterns are wired and respond correctly, but the voltages aren't matching up. What could be going on?

Correct me on my first post. When I select the Fig.8 pattern, there is almost no signal at all that can be heard except a very faint hum. I'm using a chinese capsule with a single backplate. I've connected the backplate on the capsule to both the "front" and "rear" backplane terminals on the mic pcb. Could this have something to do with the issue? The relays K1 and K3 are receiving 6.3 when the Fig.8  switch is engaged

Thanks again for the help!

Steve

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: chefducuisine on August 20, 2015, 11:10:30 AM
Hi Steve,

you cannot measure voltages on the capsule directly as you are in the high impedance section of the microphone.
In other words: The input resistance of your Multimeter is loading down the voltages resulting in the values you measure.

Plate voltage, heater and B+ look OK to me.

For the 251 you'll need a capsule with separate backplates, otherwise Figure of Eight won't work. Check the upper right part of the schematic named 'Kapsel f. ELA M251E'.
http://www.xaudia.com/xaudia/Schematics/Pages/ELAM_files/Media/m251e/m251e.jpg (http://www.xaudia.com/xaudia/Schematics/Pages/ELAM_files/Media/m251e/m251e.jpg)

Summary:
Congratulations - you have a working 251 !!! 8)
At the moment you are limited by the capsule itself (loosing Figure of Eight).
Remove it and get a good one - this mic deserves it! ;)

(I recommend Tim's CT-12, BeezNeez also has a nice one - check the white market).
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 20, 2015, 05:50:26 PM
I'm not yet certain, but it looks as though Blackspade Audio may be offering their new custom 251-inspired body for sale for kit use, apart from the finished/built version RS-series mics...here's some pics...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 20, 2015, 05:52:01 PM
...website: http://blackspademics.com/
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 20, 2015, 05:52:54 PM
...and...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stevesteve50 on August 20, 2015, 06:07:50 PM
Hi guys,

I installed the CT-12 and checked voltages, and got it fired up. It sounds awesome!

The back capsule is quiet, dull, and dark sounding in omni and figure 8 modes. Could I have missed something here?
If there is a problem is there any way that I am damaging the capsule by having it powered up.

Thanks a million for the help!

Steve
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PhatPlanetStudios on August 20, 2015, 06:13:20 PM
...and...
  Looks like the Apex 460 body to me.  I recognize the headbasket.  Lots of boutique mic makers are repackaging the Apex bodies.  It's easy!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kidvybes on August 20, 2015, 09:19:19 PM
Looks like the Apex 460 body to me.  I recognize the headbasket.  Lots of boutique mic makers are repackaging the Apex bodies.  It's easy!

...these bodies are all custom fabricated in Switzerland and have nothing to do with the SYT1100 (Apex 460) bodies...entirely different proportions (shorter length, wider tube diameter) and construction: http://blackspademics.com/pages/fabrication
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lowfreq on August 21, 2015, 12:51:09 AM
Wow!! Those mic bodies look great.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on August 21, 2015, 06:29:09 AM
Hey Steve,
It sounds like you have a short or are missing a connection to your rear backplate or membrane.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: chefducuisine on August 21, 2015, 02:00:59 PM
Steve,

please check if you used four wires (FC, FB, RC, RB) with Tim's capsule and if those wires are connected as on page one of this threat.
If got the CT-12 in mine for about 3-4 months and I can confirm it is working on all patterns.

Regards,
Chris
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stevesteve50 on August 21, 2015, 07:06:46 PM
Hey Steve,
It sounds like you have a short or are missing a connection to your rear backplate or membrane.

Thanks for the response Tim. I confirmed the continuity between the rear backplane and rear capsule connection and the corresponding  terminals.
I've traced part of the issue to what appears to be a malfunctioning relay. Relay K2 is receiving 6v when omni is engaged, and the negative terminal is grounded. However, it does not engage when it receives voltage. I have a new relay being sent and will install it.

However, I can't understand how a malfunctioning K2 would affect figure 8 mode, so assuming there is also another issue.

When figure 8 is switched on, relays K1 and K3 both engage.  I show continuity between the rear backplate and ground, and the rear capsule shows 22VDC on my meter.

The front capsule measures constant at 32VDC.


Edit: I've traced the issue to what seems to be an intermittently faulty 7 pin cable. Didn't think a new cable would have this issue.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Celinara on October 12, 2015, 11:12:59 PM
So I managed to get everything put together, and on the power supply, when testing the voltages, I had the heater at 6.3V but the B+ voltage never stayed at one fixed amount. It kept infinitely rising. (I turned off power to keep it from getting out of hand). When I checked over everything then tried again, the same thing happened with the B+ but the heater voltage dropped to 0.03V. Any ideas as to what is causing this?

Thanks!~
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on October 12, 2015, 11:30:15 PM
So I managed to get everything put together, and on the power supply, when testing the voltages, I had the heater at 6.3V but the B+ voltage never stayed at one fixed amount. It kept infinitely rising. (I turned off power to keep it from getting out of hand). When I checked over everything then tried again, the same thing happened with the B+ but the heater voltage dropped to 0.03V. Any ideas as to what is causing this?

Thanks!~

B+ will ramp up and overshoot then fall back down and settle, how high did it get?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Celinara on October 19, 2015, 02:22:40 PM
I 100% confirmed the voltage issues were due to a faulty switch. I have a new one on order, and for the time have the omni side disconnected. The mic does work now, and im getting audio through. Only problem is, its very hissy, lots of static. Yes I am testing it with the sleeve and headbasket on. Where are the most common sources of static? I used No-Clean Rosin core solder if that makes any difference.

Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on October 19, 2015, 09:32:20 PM
I 100% confirmed the voltage issues were due to a faulty switch. I have a new one on order, and for the time have the omni side disconnected. The mic does work now, and im getting audio through. Only problem is, its very hissy, lots of static. Yes I am testing it with the sleeve and headbasket on. Where are the most common sources of static? I used No-Clean Rosin core solder if that makes any difference.

Thanks!
Tubes can commonly make a cranckle/pop noise.  Just because it's designed for low noise doesn't mean it's a quiet.  They vary wildly from piece to piece.  If it wasn't specifically selected for microphone use, let it run for a while as tube noise can sometimes subside (and sometimes become worse).
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 12:51:54 PM
...and...

How much is the body and basket?

And to all the others, including Dan :D Will pcb fit inside the beesneez elam body?

Mike
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 26, 2015, 12:54:27 PM
...and...

How much is the body and basket?

And to all the others, including Dan :D Will pcb fit inside the beesneez elam body?

Mike

Beesneez have a special edition Mic body to fit my pcb , ask them ,
they will be able to help,
http://www.beesneezmicrophones.com.au/store/ela-m251-body-kit-and-ck12-bundle.html

Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 01:39:58 PM
...and...

How much is the body and basket?

And to all the others, including Dan :D Will pcb fit inside the beesneez elam body?

Mike

Beesneez have a special edition Mic body to fit my pcb , ask them ,
they will be able to help,
http://www.beesneezmicrophones.com.au/store/ela-m251-body-kit-and-ck12-bundle.html

Best,
Dan,

Thanks Dan, and about the specs, what was it modelled after? I mean yeah, obviously the 251 but are the components matched with the original? Caps, resistors et cetera, value and type wise?

Because to my ear, the D251 sounds less full than all the others; however I don't know how the original sounds and what it sound was before the aging took place.

It'd be damn fine  if someone really compared the original with a beeznees clone for example.

However, I will probably still be building one  8)

Mike
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 26, 2015, 01:43:45 PM
Quote
Because to my ear, the D251 sounds less full than all the others; however I don't know how the original sounds and what it sound was before the aging took place.

It'd be damn fine  if someone really compared the original with a beeznees clone for example.

Well it all depends on tubes and capsule and component and bypass cap and transformer , this is a very general statement  ???
maybe I don't understand it right ,  I am just a circuit solution provider.
Dan
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 01:54:45 PM
Quote
Because to my ear, the D251 sounds less full than all the others; however I don't know how the original sounds and what it sound was before the aging took place.

It'd be damn fine  if someone really compared the original with a beeznees clone for example.

Well it all depends on tubes and capsule and component and bypass cap and transformer , this is a very general statement  ???
maybe I don't understand it right ,  I am just a circuit solution provider.
Dan

Heh, I've refered to a user comment here and a comparison, which in the latter falls a little short low end / guts wise.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on October 26, 2015, 02:10:33 PM
The lack of low-end/guts comes from the 22uf, 30MΩ, and double 8MΩ combo. All of those can be increased to get more out of the mic. By how much and to what, and changing all of them or just a select few, is what'll make the difference between a great mic and an average one. In terms of parts, it'll only cost you about $10 to try all the possible combinations, so worth a try.

In general though, there's a lot more to be had from all the mic builds on this forum by going off-script and experimenting vs. religiously following the original schematics and kit builder BOM's.

For best results, less paint-by-number, and more DIY ;)

Heh, I've refered to a user comment here and a comparison, which in the latter falls a little short low end / guts wise.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 02:24:43 PM
The lack of low-end/guts comes from the 22uf, 30MΩ, and double 8MΩ combo. All of those can be increased to get more out of the mic. By how much and to what, and changing all of them or just a select few, is what'll make the difference between a great mic and an average one. In terms of parts, it'll only cost you about $10 to try all the possible combinations, so worth a try.

In general though, there's a lot more to be had from all the mic builds on this forum by going off-script and experimenting vs. religiously following the original schematics and kit builder BOM's.

For best results, less paint-by-number, and more DIY ;)

Heh, I've refered to a user comment here and a comparison, which in the latter falls a little short low end / guts wise.

Yeah so I've been wondering whether the caps and resistors are based on the original or rather freely chosen?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 26, 2015, 02:26:37 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response



Tweak #3

Hi there, I actually did buy the resistors but not yet installed them, in the meantime though I did switch the .22 uf Tantalum to a 100uf Tantalum and did not hear a change. Then later switched the 100uf Tantalum to a 100uf gold panasonic electrolytic and man the bottom really came up then. I did not have much time to test it on acoustic guitar yet, but the low on my vocal was much more without being muddy or too much. I will try the resistor change to lower the voltage down to 55V soon, I was sort of wanting to see if what I had calculated was correct first. I guess it won't damage  anything to try! I will keep you posted as I proceed!
Thanks again
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 03:06:47 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Thanks :)

But the pcb is 1:1 based on the original schematic or did you take any freedom in changing parts / signal structures?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 26, 2015, 03:11:35 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Thanks :)

The Circuit is exact replica of Ela-M251 but you can go ahead and change the component value up to your taste  ;)
the Silkscreen Value of the pcb are the published Value of the Elam251 Schematic,   But feel free to expirement.
this is DiY afterall  :)

Best,
Dan,



 



But the pcb is 1:1 based on the original schematic or did you take any freedom in changing parts / signal structures?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 03:23:02 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Thanks :)

The Circuit is exact replica of Ela-M251 but you can go ahead and change the component value up to your taste  ;)
the Silkscreen Value of the pcb are the published Value of the Elam251 Schematic,   But feel free to expirement.
this is DiY afterall  :)

Best,
Dan,



 



But the pcb is 1:1 based on the original schematic or did you take any freedom in changing parts / signal structures?

Thanks, that's what I wanted to know :) So now, I don't have to compare it with the original and can already make DIY changes to shift the sound to my liking. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on October 26, 2015, 03:26:31 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Thanks :)

The Circuit is exact replica of Ela-M251 but you can go ahead and change the component value up to your taste  ;)
the Silkscreen Value of the pcb are the published Value of the Elam251 Schematic,   But feel free to expirement.
this is DiY afterall  :)

Best,
Dan,



 



But the pcb is 1:1 based on the original schematic or did you take any freedom in changing parts / signal structures?

Thanks, that's what I wanted to know :) So now, I don't have to compare it with the original and can already make DIY changes to shift the sound to my liking.

That is the ultimate Goal , of microphone Building :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on October 26, 2015, 03:58:45 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Thanks :)

But the pcb is 1:1 based on the original schematic or did you take any freedom in changing parts / signal structures?
Dany being the very stand up chap that he is, is being very helpful and diplomatic.
The Schematic to both are in the first post. How about you take a look to see if they are the same? ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on October 26, 2015, 07:25:55 PM
Dany being the very stand up chap that he is, is being very helpful and diplomatic.
The Schematic to both are in the first post. How about you take a look to see if they are the same? ;)
  Well put.  I'll add that without using original transformers, capsule, caps, etc, we aren't building an exact sounding replica so don't get too hung up on the minutia.  I've found that, when using modern components, sometimes deviating a little from the original actually gets you closer to that original sound, depending if the components you're using are giving you a brighter/darker/etc sound.  And, I know this is blasphemy, but sometimes you can even make adjustments that sound better to your ears than original spec.  I've stopped thinking of original tone as being the ultimate goal and have found greater success in taking a piece of gear I like and building it to sound exactly how I (or my customer) want it to sound.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on October 26, 2015, 08:11:31 PM
And thanks for the tweaking tips for possible low end improvements.   8)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 26, 2015, 09:14:05 PM
Dany being the very stand up chap that he is, is being very helpful and diplomatic.
The Schematic to both are in the first post. How about you take a look to see if they are the same? ;)
  Well put.  I'll add that without using original transformers, capsule, caps, etc, we aren't building an exact sounding replica so don't get too hung up on the minutia.  I've found that, when using modern components, sometimes deviating a little from the original actually gets you closer to that original sound, depending if the components you're using are giving you a brighter/darker/etc sound.  And, I know this is blasphemy, but sometimes you can even make adjustments that sound better to your ears than original spec.  I've stopped thinking of original tone as being the ultimate goal and have found greater success in taking a piece of gear I like and building it to sound exactly how I (or my customer) want it to sound.

Agreed but having the low end off is more defective than comparable in taste, that's why I've mentioned this to Dan, cause he's the man.

Also, is there a kit for the PSU anywhere for sale? Like the chassis, parts et cetera? Or at least just the chassis?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on October 27, 2015, 02:07:43 AM
Also, is there a kit for the PSU anywhere for sale? Like the chassis, parts et cetera? Or at least just the chassis?
Odd, I posted a reply to this earlier and saw it post but it's deleted now so I guess I'll try again.
Dan Duerloo/Collective cases has a really sturdy mic PSU chassis that I love. 
http://collectivecases.com/?product=psu-cases (http://collectivecases.com/?product=psu-cases)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: TLRT on October 27, 2015, 04:14:00 AM
I have an empty micandmod case with connectors if somebody needs it...(I'm in the EU)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: DjaiTeam on October 27, 2015, 06:17:02 AM
Hi TLRT, pm'ed you about the psu case.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 29, 2015, 02:47:01 PM
Someone around here selling beeznees bodies / similar high quality bodies for this project and chassis' for the psu?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: atticmike on October 29, 2015, 07:10:32 PM
Can this be used for the build?:

http://store.t-funk.com/p/m-950s-dual-tube-microphone-power-supply-ela-m-251?pp=24

Fine price for a dual PSU.

Update:  Damn it, no switch for the positions

How about this one?:

(https://dl.dropboxusercontent.com/u/70609905/t.JPG)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on October 29, 2015, 07:29:09 PM
Seems like a waste of money for a diy-er since you can make a better one for a lot less.  As I posted above, Dan D has a good case for this.

Can this be used for the build?:

http://store.t-funk.com/p/m-950s-dual-tube-microphone-power-supply-ela-m-251?pp=24

Fine price for a dual PSU.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on October 29, 2015, 07:32:46 PM
Someone around here selling beeznees bodies / similar high quality bodies for this project and chassis' for the psu?
Yep, that someone is Beesneez :o
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on November 21, 2015, 11:59:42 PM
Speaking of the Beesneez 251 bodies, does anyone know if a swivel mount that could be used with these? The Beesneez mic body is so heavy, I'm afraid it will fall out of the shock mount if put upside down.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: kosi on November 30, 2015, 07:30:24 PM
Just finished my ELA !
I had a little problem with my heater voltage.  As I'm using a different toroid, (200V and 6,3V) I replaced R7 and R8 on the psu with wire. Then I got 6,2 V, which seemed good enough.
But in Fig8 and Omni I had a hum, which disappeared, when I decreased H+ to 5.95V
Mic sounds fine, but has a pretty high noise floor...

Would you recommend to bring the heater up to 6.3V ?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 08, 2015, 09:15:07 AM
Hi there, doing my first DIY mic and chose the 251 kit from Mic and Mod. I am not so good with schematics and am looking for a clear explanation from the 7pin connector to the PCB on the mic. So far I am not sure how to wire them. Can someone let me know the pin out on the connector goes to where on the PCB.

Thanks much!

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on December 08, 2015, 10:40:29 AM
Hi there, doing my first DIY mic and chose the 251 kit from Mic and Mod. I am not so good with schematics and am looking for a clear explanation from the 7pin connector to the PCB on the mic. So far I am not sure how to wire them. Can someone let me know the pin out on the connector goes to where on the PCB.
Thanks much!

Andy

Hi, have you looked at the mic diagram file at page 1?  Your info should be there.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 09, 2015, 11:12:24 AM
Hi there and thanks for the info, I got it figured out. I just finished all the soldering and then when I tried to put it together the body is not even close to fitting because of the relay switches! I saw an earlier post where someone shaved down the edges of the relays, is this the best way to get the body to fit on?

Thanks for any suggestions!

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on December 09, 2015, 11:33:40 AM
Hi there and thanks for the info, I got it figured out. I just finished all the soldering and then when I tried to put it together the body is not even close to fitting because of the relay switches! I saw an earlier post where someone shaved down the edges of the relays, is this the best way to get the body to fit on?

Thanks for any suggestions!

Andy

Are your relays mounted flush? I'd check that before resorting to filing. It's tight, but mine fit.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on December 09, 2015, 07:24:26 PM
Hi there and thanks for the info, I got it figured out. I just finished all the soldering and then when I tried to put it together the body is not even close to fitting because of the relay switches! I saw an earlier post where someone shaved down the edges of the relays, is this the best way to get the body to fit on?

Thanks for any suggestions!

Andy

mine are mounted flush and i just took the edges down slightly with a soldering iron.

Jess
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 15, 2015, 05:19:56 AM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Hi Dan, I just finished up a 251 and it sounds very good, but I do hope to get a bit fuller low end. I am interested in the mods you have mentioned here, but as this is my first build I am still not able to understand the circuit and or schematic very well. I wonder if you could possibly let me know which resistors and caps could be changed by their part number..

decrease capsule voltage to 55V (reduce the 0.5MOhms to ground) R?
increase the 30Mohms grid resistor to 300Mohms R?
put a 100uF on the cathode instead of 22uF C?
output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste) C?
Grid to ground resistor higher  100m or 250m R?
Increase or decrease output coupling cap to taste to modify low end response C?

I do appreciate it very much, I so enjoyed the build and look forward to many more! Keep up the good work! I have also posted a pro tools session of my build next to a new Telefunken 251 if you are interested to hear!

Thanks

Andy



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on December 15, 2015, 09:06:09 PM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Hi Dan, I just finished up a 251 and it sounds very good, but I do hope to get a bit fuller low end. I am interested in the mods you have mentioned here, but as this is my first build I am still not able to understand the circuit and or schematic very well. I wonder if you could possibly let me know which resistors and caps could be changed by their part number..

decrease capsule voltage to 55V (reduce the 0.5MOhms to ground) R?
increase the 30Mohms grid resistor to 300Mohms R?
put a 100uF on the cathode instead of 22uF C?
output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste) C?
Grid to ground resistor higher  100m or 250m R?
Increase or decrease output coupling cap to taste to modify low end response C?

I do appreciate it very much, I so enjoyed the build and look forward to many more! Keep up the good work! I have also posted a pro tools session of my build next to a new Telefunken 251 if you are interested to hear!

Thanks

Andy

The documentation on the first page is very complete. There is enough there to figure out this info if you know tube circuitry. I'm only trying to help you help yourself here so I recommend reading up on how tubes work in a circuit and what each part of a valve does. I found this reading to be very informative. http://www.valvewizard.co.uk/Common_Gain_Stage.pdf (http://www.valvewizard.co.uk/Common_Gain_Stage.pdf)
Try getting thru some of it and I feel those mods will start to make sense. Some of this is boring to get thru and some takes several times of reading to get for me. But it covers some stuff pretty well.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 16, 2015, 07:37:30 AM
Ok , here is some tweaks you can do from original schemtics,

Tweak #1

If your capsule is a bit low end shy for your taste, try to decrease capsule voltage to 55V (reduce the 0.5MOhms to ground),  increase the 30Mohms grid resistor to 300Mohms and put a 100uF on the cathode instead of 22uF. U could increase the output coupling capacitor up to 3.3uF as well ....
with the high end response, assuming your plot is accurate , i would increase the output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste)


Tweak #2

1. Grid to ground resistor higher  100m or 250m
2. Increase or decrease output coupling cap to taste to modify low end response


Hi Dan, I just finished up a 251 and it sounds very good, but I do hope to get a bit fuller low end. I am interested in the mods you have mentioned here, but as this is my first build I am still not able to understand the circuit and or schematic very well. I wonder if you could possibly let me know which resistors and caps could be changed by their part number..

decrease capsule voltage to 55V (reduce the 0.5MOhms to ground) R?
increase the 30Mohms grid resistor to 300Mohms R?
put a 100uF on the cathode instead of 22uF C?
output LP filter by increasing the 120pF to 220pF or even 330pF ... (or more to taste) C?
Grid to ground resistor higher  100m or 250m R?
Increase or decrease output coupling cap to taste to modify low end response C?

I do appreciate it very much, I so enjoyed the build and look forward to many more! Keep up the good work! I have also posted a pro tools session of my build next to a new Telefunken 251 if you are interested to hear! I do have one question  still though I wonder about. When he says to lower the capsule  voltage to 55V, I am assuming that would be the B+ 120Voltage? If that is correct then would I also then need to change the 30M grid resistor to 300M at the same time? It seems that would be the case in my thinking, but I am not sure. I was out part hunting to day and a 300M resistor is really not easy to find! Thanks for any suggestions!

Andy

Thanks

Andy

The documentation on the first page is very complete. There is enough there to figure out this info if you know tube circuitry. I'm only trying to help you help yourself here so I recommend reading up on how tubes work in a circuit and what each part of a valve does. I found this reading to be very informative. http://www.valvewizard.co.uk/Common_Gain_Stage.pdf (http://www.valvewizard.co.uk/Common_Gain_Stage.pdf)
Try getting thru some of it and I feel those mods will start to make sense. Some of this is boring to get thru and some takes several times of reading to get for me. But it covers some stuff pretty well.

Thanks so much for that Ding! I actually learned more from that article than I ever  dreamed I could. Lots of things did make perfect sense as I went through. I will continue to study it and for sure will get more comfortable with the mods in time!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on December 16, 2015, 07:54:32 AM
Seems one member had great results in getting better bass response by just changing the tantalum (C3) to 100mf. Enough that he didn't feel he needed to up (C1) the big output coupling cap on the main body. I would start there and see what that sounds like.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 16, 2015, 11:32:35 AM
I finished my Elam 251 copy and had a chance to do a quick recording next to a new telefunken 251. I was pleased with the results but really hope to get a bit more low end out of mine. The Telefunken 251 really sounds great to me, love mixing vocals recorded through that mic. I will update the file  if I can get it sounding closer!

https://www.dropbox.com/s/rzenqzqn1ha7nyv/Copy%20of%20251%20mic%20test.zip?dl=0
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on December 16, 2015, 01:34:22 PM
What capsule are you using  Andy?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 16, 2015, 10:39:27 PM
What capsule are you using  Andy?

Hey Tim, The mic I built was a complete kit from mic&mod in France. This was my first build so I wanted to get some experience with these before trying one on my own.  The capsule is the newest one that they send with the kit which is made in France from my understanding. I hope with a bit of circuit change I can warm it up a little on the bottom, but I doubt I can match the smooth high that is coming from the telefunken without a capsule change. I am considering to get a Beezneez capsule down the road, but first I will try some DIY ing to see what I might can get out of it...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 17, 2015, 12:41:46 PM
I have my Elam for 5 years(mic parts capsule,RcA 12ay7 tube,Duka pcb)  for now,and I try lots of tubes and trannies on it!

I was waiting for right trannie from that !I tried Beyer,Pikatron,Lundahl and tried lots of differnte tubes!
I looked to the Oliver T14/1(listen the samples), then recently Banzai selling new Haufe T14/1,but I always been sceptic about it cause lots of guru people who knows and heard this mike told that new Haufe isnt the same like old one,even the T14/1 from Oliver TAB dont sound like original!

So recently I find the real Haufe T14/1 from '60-s on web!The price was funny....

I was solder this Haufe T14/1 in my Elam and I was totaly stunned!Totaly differente sound!

Always my Elam was need lots of gain, now no need for lots of gain! And sound amazing!

I think that is very important what to put in this microphone!

Now I start to  saving for Tim Campbell CT12 capsule,and maybe GE 6072 five star!But I satisified with RCA!


http://groupdiy.com/index.php?topic=47469.msg597086#msg597086
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on December 17, 2015, 03:10:05 PM
I have my Elam for 5 years(mic parts capsule,RcA 12ay7 tube,Duka pcb)  for now,and I try lots of tubes and trannies on it!

I was waiting for right trannie from that !I tried Beyer,Pikatron,Lundahl and tried lots of differnte tubes!
I looked to the Oliver T14/1(listen the samples), then recently Banzai selling new Haufe T14/1,but I always been sceptic about it cause lots of guru people who knows and heard this mike told that new Haufe isnt the same like old one,even the T14/1 from Oliver TAB dont sound like original!

So recently I find the real Haufe T14/1 from '60-s on web!The price was funny....

I was solder this Haufe T14/1 in my Elam and I was totaly stunned!Totaly differente sound!

Always my Elam was need lots of gain, now no need for lots of gain! And sound amazing!

I think that is very important what to put in this microphone!

Now I start to  saving for Tim Campbell CT12 capsule,and maybe GE 6072 five star!But I satisified with RCA!


http://groupdiy.com/index.php?topic=47469.msg597086#msg597086

Thats very interesting.

I know this too because in shoot out against vintage elam, my elams have always been lower -3 to -5 db and not due to voltage or capsule or tube.

I know its a pain in ass because you already soldered it in but can you please measure the resistance between the primary and secondary on the old haufe you acquired.

It would bevery interesting to see.

Jesse
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 18, 2015, 04:05:01 AM
Here is a picture of it!

I wont reassemble mic,it is pain in ass...

Wires:red,blue,red,blue-primary and two green-secoundary!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 18, 2015, 04:10:15 AM
And  I get 5-6db more gain!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: lampas on December 19, 2015, 01:50:53 PM
Banzai selling new Haufe T14/1,but I always been sceptic about it cause lots of guru people who knows and heard this mike told that new Haufe isnt the same like old one,even the T14/1 from Oliver TAB dont sound like original!
http://groupdiy.com/index.php?topic=47469.msg597086#msg597086

Did you try  Banzai T14/1 in your mic ?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 20, 2015, 12:00:04 AM
Seems one member had great results in getting better bass response by just changing the tantalum (C3) to 100mf. Enough that he didn't feel he needed to up (C1) the big output coupling cap on the main body. I would start there and see what that sounds like.

I tried the switching of the tantalum to 100mf,  and also switched C2 to a 330pf but I did not feel much change in my case. I am really curious about lowering the voltage on the capsule but not quite sure how to do it. I am still new at this. I am not sure how  to lower the voltage to the capsule or if its the same as the B+ voltage, and then if I do reduce the voltage to 55v if also must switch the 30M resistor to 300M at the same time for it to work correctly. When I look at the schematic  I assume the capsule  voltage is the B+ 120, but I am not for sure!  :-[

I wonder if the low frequency that I am looking for is in the capsule, and if so then if anyone has compared some of the available ones and noticed any to have more low frequency?

Thanks for any suggestions!

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 20, 2015, 10:35:18 AM
Banzai selling new Haufe T14/1,but I always been sceptic about it cause lots of guru people who knows and heard this mike told that new Haufe isnt the same like old one,even the T14/1 from Oliver TAB dont sound like original!
http://groupdiy.com/index.php?topic=47469.msg597086#msg597086

Did you try  Banzai T14/1 in your mic ?


I didnt try Banzai Haufe T14/1 but I read Claus Hayne thread about NEW HAUFE T14/1,and he said that they are not like old ones which was used in Elam250!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on December 20, 2015, 12:05:49 PM
Check out reply #8 in this thread: http://repforums.prosoundweb.com/index.php/topic,36879.0.html

In short, Haufe has always built them the same way, for the same result.  ;)

I didnt try Banzai Haufe T14/1 but I read Claus Hayne thread about NEW HAUFE T14/1,and he said that they are not like old ones which was used in Elam250!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: lampas on December 20, 2015, 12:49:32 PM
The reason I ask is that I did also built two C12 microphones with T14 transfomers from AMI and found that they have a few dB lower output than my other mics. As T14 from AMI is 12:1 ratio and Haufe IS 11.5:1 maybe some expert would know if the ratio is
"guilty" for that few dB loss.... But I am satisfied with end result so the microphone will stay with T14 from AMI.

But I also have a "new" Haufe T14/1 and if you would test it in your microphone I would be glad to send it you as I and probably a few in the forum would like to hear opinion on new and old ones ... And I am not far from you ... (Ljubljana).

I also do not believe that between them are a big difference as on other thread I read that electrically are almost the same...
But I believe that there is a difference between T14 from AMI, CM2480 and Haufe T14/1.  CM 2480 is 10.5:1 ... Does this mean that it should be the "loudest" of the mentioned ones?

Regards.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on December 20, 2015, 02:03:56 PM
The AMI T14's lamination size and winding is definitely different (based on Hiller T14 instead of Haufe T14/1).
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on December 20, 2015, 03:01:19 PM
Where are people getting these elusive 3.2uf 450v wet tantalums that I can't seem to find anywhere? I've been looking for days on the interwebs. :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on December 20, 2015, 05:03:01 PM
I think someone mentioned using these guys:
http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180
 (http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180)
Mouser has brand new wet tants but they're in the $70 ea range.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 20, 2015, 05:04:42 PM
Real Huafe T14/1 was ad still is 1:14 ratio!

And here is schematics of Elam250!

And 1uF is for output capacitor!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: iprovlek on December 20, 2015, 05:07:27 PM
So instaed 3.2uF tantalum you can put 1uF film capacitor, 2.2uF or even 3.3uF to get more low end!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on December 20, 2015, 05:08:24 PM
Where can I buy AMI transformers?

Can they still be purchased through [email protected]?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on December 20, 2015, 07:53:38 PM
I was also looking at the Sprauge 109D's at the ebay link here for my 251. Waiting for a reply from the seller as im in the UK.

http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180

I believe JessJackson used these as explained on page 9 of the thread and it gave the mic the more 3D sound of the original which was why I was interested, he definitely preferred them... There are sound files you can download and compare.

I found a few options  however they seem to be either longer than 51mm or to wide to fit in the body. Other builders have left notes saying its vital to get a good coupling cap but then dont leave details about which one they preferred...

It would be really appreciated if people could provide acutal link of one they used and why it made it better/worse/different! I am working on my build next week so im pretty excited :)

Thanks, Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on December 20, 2015, 07:54:30 PM
I got my T14 from AMI by contacting them direct. Replied same day! Hope that helps.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on December 20, 2015, 09:34:41 PM
I think someone mentioned using these guys:
http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180
 (http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180)
Mouser has brand new wet tants but they're in the $70 ea range.

These are 125v. I don't think they will stand up to the task. Who ever is using these I would be very careful cause the voltage could really damage the cap.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on December 20, 2015, 11:09:36 PM
These are 125v. I don't think they will stand up to the task. Who ever is using these I would be very careful cause the voltage could really damage the cap.

David Bock discussed this earlier in the thread.

I've never seen the wet tant in a 251 short out (I have seen loss of capacitance), though I've seen plenty of tants short out in ATR124 decks taking down the whole machine (smoke optional).
I have also seen original T14/1 xfmrs go open. That wire is mighty fine.
IF your new build mic does not copy the exact footprint of the 251, you should have more room for other cap options. Then you can listen and decide for yourself. But in a vintage 251, space is at a premium so the original cap is a must, unless you are willing to crack the plexiglass body, as some repairs guys are willing to do. FYI there is no electrolytic that will fit in that space that sounds good so don't bother.
Yes you can use a 125v cap, though it's safer with higher tolerances. The occasion of reaching 125v across the cap occurs at power up, when the B+ is there but the tube hasn't fully heated. Reaching full B+ once the tube is heated will likely not happen during normal use, unless you stick it in a kick drum.
I have found NOS went tants (of the value you need for this mic), even recently, so I know they are out there

You're definitely right, higher voltage ratings would be ideal. The problem I see is without having compared wet tantalums to either film type, I don't know what I'm going to prefer. To even buy a 3uF wet tant from mouser rated at 150V you're sinking $100 CAD ($70 for 125V).  I figure $20 for the NOS 125V 3.6uF wet tantalums from Ebay is worth trying and I'll probably get good life out of it. Maybe, I could even delay or switch the B+ and get even more life out of it.

Does anyone know another source for the Polyester film cap? It's no longer stocked at Mouser and there's no others available in singles.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on December 22, 2015, 12:39:26 PM
Finished up a build that was mostly completed by Christopher L. Did a teensy bit of parts stuffing and troubleshooting in the PSU (goo learning opportunity) on the heater supply and picked up the body and PSU from Studio939.

(https://jonpattonmusic.files.wordpress.com/2012/05/d251-tube-mic.jpg?w=800)
(https://jonpattonmusic.files.wordpress.com/2012/05/d251-tube-mic-guts-front.jpg?w=800)
(https://jonpattonmusic.files.wordpress.com/2012/05/d251-tube-mic-guts-back.jpg?w=800)
(https://jonpattonmusic.files.wordpress.com/2012/05/d251-hi-z-bridge.jpg?w=300)(https://jonpattonmusic.files.wordpress.com/2012/05/d251-tube-mic-psu.jpg?w=400)
(https://jonpattonmusic.files.wordpress.com/2012/05/d251-tube-mic-psu-guts.jpg?w=400)

Sounds amazing, and it's exactly what I was looking for: Slightly brighter than a u47 and slightly darker than a C12 (EDIT: apparently the newer C12s are actually more different than I thought, so I guess a regular C12 build would have sounded almost identical to this). The noise floor is super low.

I really like the relay switching. Very cool.

I'm ready to conquer my next mic from scratch I hope :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 28, 2015, 07:09:28 AM
Hi again,

I am having trouble figuring out how to lower my capsule voltage to 55V. I have tried looking at the schematic but just able to know for sure what I am doing! I have read that I need to change a resistor on the voltage divider, but I am not able to understand..

Thanks for any help

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on December 28, 2015, 10:06:44 AM
Hi again,

I am having trouble figuring out how to lower my capsule voltage to 55V. I have tried looking at the schematic but just able to know for sure what I am doing! I have read that I need to change a resistor on the voltage divider, but I am not able to understand..

Thanks for any help

Andy

You're looking for two high-value resistors that cut the voltage in half as a reference voltage before a VERY VERY high value resistor that provides the charging voltage for the capsule on the capsule's side of the input capacitor.  Trace backward through the schematic from the capsule connection and you should find these. Hopefully that's enough of a hint. (There aren't many components in the mic itself.)

Right now the two high-value resistors take a B+ of 120V and make it 60V. If you aren't sure what value to use for the voltage divider, here's a calculator: http://www.raltron.com/cust/tools/voltage_divider.asp
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 28, 2015, 11:37:00 AM
Hi again,

I am having trouble figuring out how to lower my capsule voltage to 55V. I have tried looking at the schematic but just able to know for sure what I am doing! I have read that I need to change a resistor on the voltage divider, but I am not able to understand..

Thanks for any help

Andy

You're looking for two high-value resistors that cut the voltage in half as a reference voltage before a VERY VERY high value resistor that provides the charging voltage for the capsule on the capsule's side of the input capacitor.  Trace backward through the schematic from the capsule connection and you should find these. Hopefully that's enough of a hint. (There aren't many components in the mic itself.)

Right now the two high-value resistors take a B+ of 120V and make it 60V. If you aren't sure what value to use for the voltage divider, here's a calculator: http://www.raltron.com/cust/tools/voltage_divider.asp

Hi there and thanks so much. I tried to follow what you said. I am trying to learn! I am thinking that maybe I could try putting a 13K ohm resistor in place of R5, and a 15K R3? Would that do what I need? I do appreciate it very much!

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on December 28, 2015, 12:14:46 PM
Hi again,

I am having trouble figuring out how to lower my capsule voltage to 55V. I have tried looking at the schematic but just able to know for sure what I am doing! I have read that I need to change a resistor on the voltage divider, but I am not able to understand..

Thanks for any help

Andy

You're looking for two high-value resistors that cut the voltage in half as a reference voltage before a VERY VERY high value resistor that provides the charging voltage for the capsule on the capsule's side of the input capacitor.  Trace backward through the schematic from the capsule connection and you should find these. Hopefully that's enough of a hint. (There aren't many components in the mic itself.)

Right now the two high-value resistors take a B+ of 120V and make it 60V. If you aren't sure what value to use for the voltage divider, here's a calculator: http://www.raltron.com/cust/tools/voltage_divider.asp

Hi there and thanks so much. I tried to follow what you said. I am trying to learn! I am thinking that maybe I could try putting a 13K ohm resistor in place of R5, and a 15K R3? Would that do what I need? I do appreciate it very much!

Andy

Those resistors are presently 500K. 15K and 13K are orders of magnitude smaller. I suppose you could go do some calculations to find out what the demands on the power supply and components would be if you used resistors that small, but I think it's fair to tell you that you should stick to values closer to what's already in the microphone.

EDIT: You can do it with two standard (easy-to-find) values, as well.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on December 28, 2015, 09:29:31 PM
Hi again,

I am having trouble figuring out how to lower my capsule voltage to 55V. I have tried looking at the schematic but just able to know for sure what I am doing! I have read that I need to change a resistor on the voltage divider, but I am not able to understand..

Thanks for any help

Andy

You're looking for two high-value resistors that cut the voltage in half as a reference voltage before a VERY VERY high value resistor that provides the charging voltage for the capsule on the capsule's side of the input capacitor.  Trace backward through the schematic from the capsule connection and you should find these. Hopefully that's enough of a hint. (There aren't many components in the mic itself.)

Right now the two high-value resistors take a B+ of 120V and make it 60V. If you aren't sure what value to use for the voltage divider, here's a calculator: http://www.raltron.com/cust/tools/voltage_divider.asp

Hi there and thanks so much. I tried to follow what you said. I am trying to learn! I am thinking that maybe I could try putting a 13K ohm resistor in place of R5, and a 15K R3? Would that do what I need? I do appreciate it very much!

Andy

Those resistors are presently 500K. 15K and 13K are orders of magnitude smaller. I suppose you could go do some calculations to find out what the demands on the power supply and components would be if you used resistors that small, but I think it's fair to tell you that you should stick to values closer to what's already in the microphone.

EDIT: You can do it with two standard (easy-to-find) values, as well.

Hi and thank you again! I had another look and have attempted again at some common value resistors closer to original. I am a bit confused on how the relationship between the two resistors values work. In the calculator it mentions R1 and R2, if the values of these two are reversed it has a change on the output voltage. In the microphone schematic it appears to my pea brain that on the 251 diagram  R3 would act as R1 on the calculator, and R5  would act as R2 on the calculator. I wonder if that is correct. I do appreciate your help. I am thinking now then that possibly R3 should be a 560K and R5 should be a 470K. This would make my voltage 54.7, I think…

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on January 05, 2016, 11:46:44 AM
Hi and thank you again! I had another look and have attempted again at some common value resistors closer to original. I am a bit confused on how the relationship between the two resistors values work. In the calculator it mentions R1 and R2, if the values of these two are reversed it has a change on the output voltage. In the microphone schematic it appears to my pea brain that on the 251 diagram  R3 would act as R1 on the calculator, and R5  would act as R2 on the calculator. I wonder if that is correct. I do appreciate your help. I am thinking now then that possibly R3 should be a 560K and R5 should be a 470K. This would make my voltage 54.7, I think…

Andy

Hey Andy, did you get that going? How does it sound?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on January 06, 2016, 11:14:41 PM
Hi and thank you again! I had another look and have attempted again at some common value resistors closer to original. I am a bit confused on how the relationship between the two resistors values work. In the calculator it mentions R1 and R2, if the values of these two are reversed it has a change on the output voltage. In the microphone schematic it appears to my pea brain that on the 251 diagram  R3 would act as R1 on the calculator, and R5  would act as R2 on the calculator. I wonder if that is correct. I do appreciate your help. I am thinking now then that possibly R3 should be a 560K and R5 should be a 470K. This would make my voltage 54.7, I think…

Andy

Hey Andy, did you get that going? How does it sound?

Hi there, I actually did buy the resistors but not yet installed them, in the meantime though I did switch the .22 uf Tantalum to a 100uf Tantalum and did not hear a change. Then later switched the 100uf Tantalum to a 100uf gold panasonic electrolytic and man the bottom really came up then. I did not have much time to test it on acoustic guitar yet, but the low on my vocal was much more without being muddy or too much. I will try the resistor change to lower the voltage down to 55V soon, I was sort of wanting to see if what I had calculated was correct first. I guess it won't damage  anything to try! I will keep you posted as I proceed!
Thanks again

Andy

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on January 10, 2016, 09:04:10 PM
Hi and thank you again! I had another look and have attempted again at some common value resistors closer to original. I am a bit confused on how the relationship between the two resistors values work. In the calculator it mentions R1 and R2, if the values of these two are reversed it has a change on the output voltage. In the microphone schematic it appears to my pea brain that on the 251 diagram  R3 would act as R1 on the calculator, and R5  would act as R2 on the calculator. I wonder if that is correct. I do appreciate your help. I am thinking now then that possibly R3 should be a 560K and R5 should be a 470K. This would make my voltage 54.7, I think…

Andy

Hey Andy, did you get that going? How does it sound?

Hi there, I actually did buy the resistors but not yet installed them, in the meantime though I did switch the .22 uf Tantalum to a 100uf Tantalum and did not hear a change. Then later switched the 100uf Tantalum to a 100uf gold panasonic electrolytic and man the bottom really came up then. I did not have much time to test it on acoustic guitar yet, but the low on my vocal was much more without being muddy or too much. I will try the resistor change to lower the voltage down to 55V soon, I was sort of wanting to see if what I had calculated was correct first. I guess it won't damage  anything to try! I will keep you posted as I proceed!
Thanks again

Andy

Andy

Thanks Andy
 for your tweak experiment results ,
I have made a list now on Page 1 of this thread
http://groupdiy.com/index.php?topic=55010.0

 so I will try to compile those tweaks as they go and be interesting
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on January 11, 2016, 01:07:30 AM
is it a wet tant andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on January 11, 2016, 07:32:53 AM
is it a wet tant andy

Hi there, Well it turns out I made a mistake about that cap! I had gotten it from a hifi shop here in Taipei on the store owners recommendation. When I saw it I thought immediately that it was a Panasonic Gold and thought nothing more of it! But today on further examination I realised I was wrong! Sorry for that! It is actually an Elna Silmic ARS. Exactly like this one listed on ebay in the link below. This made a very nice change to the low end of the mic, I can definitely suggest this as one to try! I don't plan to look further than this one for now. It really makes the original recording test I did sound very thin. I have also swapped out a 600K into R3, and a 510K into R5 replacing the original 500Ks  that were in there. That also seemed to add a tiny bit of low to it, not as pronounced as the Silmic. One other cap that I have put in is again on the stores recommendation was a Solen MKP-FC 3.3UF 400V. Also shown below in an ebay link. That one for me did not show much change  from the original one that I had. I have made audio clips, but I doubt they are of much help. I will upload them into a file soon!

http://www.ebay.com/itm/ELNA-SILMIC-ARS-Capacitors-100u-16v-2pcs-/321219958541

http://www.ebay.com/itm/1-pc-Solen-MKP-FC-Capacitor-3-3uf-400v-France-brand-new-/271119840331?hash=item3f2000744b
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on January 11, 2016, 08:11:52 AM
so I will try to compile those tweaks as they go and be interesting
Best,
Dan,
[/quote]

Hi Dan, Thanks for your interest!

I have made a few more changes to the mic now. I posted these changes in another response but I will paste them here as well..
It turns out I made a mistake about that tantalum replacement cap! I had gotten it from a hifi shop here in Taipei on the store owners recommendation. When I saw it I thought immediately that it was a Panasonic Gold and thought nothing more of it! But today on further examination I realised I was wrong! Sorry for that! It is actually an Elna Silmic ARS. This made a very nice change to the low end of the mic, I can definitely suggest this as one to try! I don't plan to look further than this one for now. It really makes the original recording test I did sound very thin. I have also swapped out a 600K into R3, and a 510K into R5 replacing the original 500Ks  that were in there. That also seemed to add a bit more bottom, not as pronounced as the Silmic but still worth it. I also changed out the 100uf filter cap and put in a 330uf. This one I did not notice so much. One other cap that I have put in is again on the stores recommendation was a Solen MKP-FC 3.3UF 400V. That one for me did not show much change  from the original one that I had. I have made audio clips, and uploaded them into a small zipped pro tools session. These are really terrible recordings!  The guitar I have is a real good looker, but man it sounds terrible. Its an old F hole Kay from the 50s that I got for $20, its all I got here in Taiwan. So mainly I just did a guitar to show the differences between part swaps. I tried my best to be in the same location, but still it sounds pretty different before and after the capsule voltage change. I still want to do more testing but I think its a good bit better that it was when I started. I do hear a bit of noise on the mic now though it seems, but not sure its not just the environment here. Seems like the original test I did next to the new telefunken 251 was quieter, but it was across the street in an actual vocal booth instead of my control room which has a console fan running! I think it might be time for capsule and transformer changes next. Anyone have any thoughts of what might be a good choice, please let me know! Thanks

https://www.dropbox.com/s/ilyhotu9tdet6i7/Copy%20of%20251%20mic%20test%202.zip?dl=0
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on January 11, 2016, 09:58:32 AM
Really nice! What capsule do you have on that?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: andybaker28 on January 11, 2016, 10:14:29 AM
Really nice! What capsule do you have on that?

Hi Ding, This is the capsule sent with the full kit sold by Mic&mod. From what they say it is made in France. I am still wanting to try another one to see what is possible.

and BTW, I have been trying my best to get better with understanding the circuits. I still have a long way to go but did want to share with other beginners like me a man that does excellent instructional youtube videos. He puts it as simple as possible and it really is helpful!

https://www.youtube.com/watch?v=x5SSKX74DKg

Btw, does it seem like I made the right choice for the voltage divider resistors?

Thanks!

Andy
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on January 11, 2016, 10:48:20 AM
Looks like it.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on January 17, 2016, 03:45:51 PM
Hey Guys,

I built my PSU this evening for my 251 clone using Chungers Mic PSU from studio 939. Seems to be working as expected.

Some things I noticed that may help other in-experienced builders like me;

On the standard 7 pin XLR connector the white wire which goes to b+ (as in Dany's pictures on page 1) was grounded at the back of the 7-pin XLR from factory. I had to cut this joining wire (looked more like a resistor leg) to remove it from ground.

When using the green blocks and testing for Ground, BIAS, B+ and Heater (H+) voltage ensure the screws are screwed fully down even if there is no cable/wire screwed in. Otherwise you will not be-able to measure voltages as there will be no continuity through the screwhead to the pcb on the block.


Unloaded Voltages; I adjusted the Heater (H+) from 7.92 to 6.30 volts, my BIAS is sitting at -1.201v (with the jumper removed) and B+ was sitting at 189v. I adjusted the trim pot on the B+ and the lowest it seemed to go to was 162v.

Questions;

1) I am going to be using a TC capsule in the final build. Is the B+ going to be low enough when loaded? I seem to remember TC capsule requires 110-120v when loaded and not more.

2) The power supply H+ and bias are constant as soon as power up. The B+ however slowly increases to a voltage and the settles marginally lower. Is this normal. I would say this procress takes around 1-2mins...

3) Should I be using the jumper for the BIAS and what should its measurement be?

4) When soldering the high z point to point section of the microphone, I understand it is neccessary to clean the pcb with ipa or use no clean solder. I am not currently using no clean solder but could switch I guess... I used 99% ipa on the PSU pcb, however clearly I need to keep it away from certain components like the capsule. With regards to the poly caps how gentle do I need to be when cleaning around them as I read they are pretty delicate to heat and alchol i.e. will a toothbrush with alchohol on it be enough to kill them or are we talking spraying them with the stuff? I see some people use cotton buds with ipa on them to cleans these sections but that always seems to leave part of the cotton bud attached in my exerience...

Im excited to continue the build but I thought it would be worth checking out these few points first. I did search the thread but I didnt see any exact responces to the above.

(n.b. prior to installing the tc capsule I will be testing the mic with a cheaper alternative from studio 939)

thanks, Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on January 17, 2016, 07:13:39 PM
I think this PSU doesn't have a bias. Just HT and heater. Please take a look at the schematic one page 1 Or the very helpful diagram where it says things in blue are not used on this circuit.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: jsvalmont on February 05, 2016, 02:13:20 PM
I am interested in this build, particularly with the BeesNeez capsule and frame. I am a complete DIY newbie, and although I took 2 electronics classes in college and did well, I will probably need a major refresher before I get too seriously involved with this.

I have 2 questions that I could really use some help with:

1) I am wondering if anyone knows if it would work for this microphone build to use the Telefunken M 950 or M 950S power supply which Telefunken use to power their $10k ELA M251 remake (but the supply is pretty reasonable at $599 for the solo and $649 for the dual), instead of building the DIY supply. I thought it might look a bit more legit too to have the actual Telefunken supply. Any thoughts?

2) one of the parts in the BOM for the mic shows it has been discontinued, and the manufacturer says it is not being replaced. I also could not find a matching part from another company on Mouser, so does anyone have any thoughts on that? Who knows what could replace that part? Part description is "Film Capacitors 3.3uF 250volts 10% Axial Round" and it's by EPCOS/TDK.  Mouser part number is 871-B32232A3335K.

Thank you.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on February 05, 2016, 05:01:11 PM
The discontinued part is the coupling cap at the output transformer. The BOM already has another coupling cap. I believe the discontinued cap is Polyester and the alternate is Polypropylene.  I would guess the difference is subjective. Ideally you would install one, burn in your tube, record a clip, replace the cap with the other and A-B it with your recording.

Another option is a wet tantalum that is available on Ebay: http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180 (http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180)

Note that the 125V rating is low. You may have to read back a few pages for some thoughts on this.

As far as the power supply goes, if it's not the same pinout or voltage, you can always modify it. It's probably safer to stick with the Chunger PS and poctop board for your first build though.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on February 05, 2016, 05:14:37 PM


1) I am wondering if anyone knows if it would work for this microphone build to use the Telefunken M 950 or M 950S power supply which Telefunken use to power their $10k ELA M251 remake (but the supply is pretty reasonable at $599 for the solo and $649 for the dual), instead of building the DIY supply. I thought it might look a bit more legit too to have the actual Telefunken supply. Any thoughts?

I've seen that question come up before and I don't know why anyone would buy one of those and mod it when they can make their own fairly easily with high quality components at a fraction of the price.  And, it's not more legit.  That company is not the original Telefunken and that's no more the actual 251 supply than one you could make yourself. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 05, 2016, 05:52:21 PM
Quote
The discontinued part is the coupling cap at the output transformer. The BOM already has another coupling cap. I believe the discontinued cap is Polyester and the alternate is Polypropylene.  I would guess the difference is subjective. Ideally you would install one, burn in your tube, record a clip, replace the cap with the other and A-B it with your recording.

Another option is a wet tantalum that is available on Ebay: http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180

Note that the 125V rating is low. You may have to read back a few pages for some thoughts on this.

IIRC the Voltage seen by the bypass Capacitor is around 75V , as know as plate voltage ,
then a 125V rated Capacitor will be fine at about twice the voltage ratings,

Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt Nolan on February 06, 2016, 04:38:33 AM
Quote
Note that the 125V rating is low. You may have to read back a few pages for some thoughts on this.

IIRC the Voltage seen by the bypass Capacitor is around 75V , as know as plate voltage ,
then a 125V rated Capacitor will be fine at about twice the voltage ratings
I should probably go back and read the thread as I may be repeating what has already been said but...

75V is the steady-state voltage seen across the bypass capacitor. When you first turn the thing on, especially with  a solid state PSU, the B+ will come up before the heater warms up - i.e. before the tube starts to conduct and so the plate voltage will be at full B+. Possibly more as, without the tube conducting yet, there is less current draw and so the B+ will be higher than the steady-state value. This may not be for long enough to blow an under-rated capacitor straight away, but it may well shorten its life.

There are mic designs where the output transformer is wired in opposite phase and between the plate and B+, rather than between the plate and ground. I don't know for sure the prime intent of this, but it could be to avoid this start-up problem and allow a physically smaller capacitor. You see it in the C28, for example.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on February 06, 2016, 09:58:15 AM
Note that the 125V rating is low. You may have to read back a few pages for some thoughts on this.

IIRC the Voltage seen by the bypass Capacitor is around 75V , as know as plate voltage ,
then a 125V rated Capacitor will be fine at about twice the voltage ratings
I should probably go back and read the thread as I may be repeating what has already been said but...

75V is the steady-state voltage seen across the bypass capacitor. When you first turn the thing on, especially with  a solid state PSU, the B+ will come up before the heater warms up - i.e. before the tube starts to conduct and so the plate voltage will be at full B+. Possibly more as, without the tube conducting yet, there is less current draw and so the B+ will be higher than the steady-state value. This may not be for long enough to blow an under-rated capacitor straight away, but it may well shorten its life.

There are mic designs where the output transformer is wired in opposite phase and between the plate and B+, rather than between the plate and ground. I don't know for sure the prime intent of this, but it could be to avoid this start-up problem and allow a physically smaller capacitor. You see it in the C28, for example.
[/quote]

Thanks Matt for the precision , I have again succeeded in overlooking this important details of the startup ,
Time to go to bed ;)
yep that's right,
Best,
Dan,

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on February 06, 2016, 11:35:45 AM
I should probably go back and read the thread as I may be repeating what has already been said but...

75V is the steady-state voltage seen across the bypass capacitor. When you first turn the thing on, especially with  a solid state PSU, the B+ will come up before the heater warms up - i.e. before the tube starts to conduct and so the plate voltage will be at full B+. Possibly more as, without the tube conducting yet, there is less current draw and so the B+ will be higher than the steady-state value. This may not be for long enough to blow an under-rated capacitor straight away, but it may well shorten its life.

There are mic designs where the output transformer is wired in opposite phase and between the plate and B+, rather than between the plate and ground. I don't know for sure the prime intent of this, but it could be to avoid this start-up problem and allow a physically smaller capacitor. You see it in the C28, for example.

I think you got it spot on. This is the post I was referring to:
I've never seen the wet tant in a 251 short out (I have seen loss of capacitance), though I've seen plenty of tants short out in ATR124 decks taking down the whole machine (smoke optional).
I have also seen original T14/1 xfmrs go open. That wire is mighty fine.
IF your new build mic does not copy the exact footprint of the 251, you should have more room for other cap options. Then you can listen and decide for yourself. But in a vintage 251, space is at a premium so the original cap is a must, unless you are willing to crack the plexiglass body, as some repairs guys are willing to do. FYI there is no electrolytic that will fit in that space that sounds good so don't bother.
Yes you can use a 125v cap, though it's safer with higher tolerances. The occasion of reaching 125v across the cap occurs at power up, when the B+ is there but the tube hasn't fully heated. Reaching full B+ once the tube is heated will likely not happen during normal use, unless you stick it in a kick drum.
I have found NOS went tants (of the value you need for this mic), even recently, so I know they are out there

I figure I can avoid this problem by intalling a standby switch. I don't want to be drilling holes for another switch yet. I couldn't find a 3 pos that fits the current switch's cutout. Ideally I'd like one electrically like this: http://el34world.com/charts/SwitchDPST.htm (http://el34world.com/charts/SwitchDPST.htm)

My plan is to try the Polypro cap, then the wet tantalum. If I prefer the tant I'll install a standby switch then.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: jsvalmont on February 06, 2016, 07:22:09 PM
The discontinued part is the coupling cap at the output transformer. The BOM already has another coupling cap. I believe the discontinued cap is Polyester and the alternate is Polypropylene.  I would guess the difference is subjective. Ideally you would install one, burn in your tube, record a clip, replace the cap with the other and A-B it with your recording.

Another option is a wet tantalum that is available on Ebay: http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180 (http://www.ebay.com/itm/2-Sprague-109D365X0125C2-3-6uF-125V-20-Wet-Tantalum-Capacitors-/191130283180)

Note that the 125V rating is low. You may have to read back a few pages for some thoughts on this.

As far as the power supply goes, if it's not the same pinout or voltage, you can always modify it. It's probably safer to stick with the Chunger PS and poctop board for your first build though.

Ahh so you are saying the replacement capacitor is already in the BOM even though the old one is obsolete and still shows up on the BOM? Is that replacement cap in the BOM you are referring to the Cornell Dubliner (Mouser Part#: 5984-930C2W3K-F) 3uF 250V Film Capacitor? Also, Is there some benefit of the Tantalum part you referenced or of Tantalum capacitors in general?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on February 06, 2016, 08:39:48 PM
Yes, yes, no. Please use the search and read thru the thread. It's not that long.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: jsvalmont on February 06, 2016, 09:13:17 PM
Yes, yes, no. Please use the search and read thru the thread. It's not that long.
Thanks for the answer.  I did read through the thread but I was still fuzzy on those details as they weren't expressed plainly, at least not from a newbie's perspective (like me) I suppose.  A lot of stuff in this thread is very EE oriented and I am trying to learn/recall this stuff but some of what you are talking about isn't always clear to me, yet, at least.  I read through the David Bock post where he recommended the Tantalum and I am also a little fuzzy on exactly what he was saying.  I highly respect his work, and I even own one of his microphones so his recommendation is pretty much gold in my eyes, but I would like to be clear on the reasoning behind the Tantalum recommendation. It sounded like he recommended it because it is smaller and the replacement Cornell capacitor is larger than the original part and thus a tight or impossible fit? Have people had difficulty using the Cornell because if its size? The Cornell has twice the voltage rating so that seems nice, and I would rather get all these parts just from Mouser (although if there is a compelling reason I will of course reconsider that).  Apologies again if I sound like a newbie; if I do, its because I am.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bowie on February 06, 2016, 10:50:24 PM
I got the impression that he recommended it in ORIGINAL mics due to the space considerations and that one might be best going another route if feasible.  I'm only casually observing this thread though so pardon if I missed something.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on February 06, 2016, 11:09:20 PM
Well hopefully you read Jessjacksons post where he compared the different types of caps including the wet tant. No EE knowledge needed as he has samples and protools session/wave files for comparison. All you need are your ears and your taste. This cap has some relationship with the sound of the mic and it's really up to you what you prefer.  As far as David goes I don't think he was recommending per se just stating that one could use a 125v even though it's rating is a bit low for the circuit seeing as though in his professional opinion he has never seen a wet tant short (bad) in a 251 even though he has seen loss of capacitance (not as bad). He was also commenting on the space restrictions of an original 251 which you don't have with this version. This cap is a matter of taste and a non issue. Buy a few different types, try them, stick with the one you like best, make killer music, profit.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on February 07, 2016, 06:52:08 AM
Yeah i didn't find any other cap that give the richness the original elam 251 gave. The cap still lives in my mic until i can get my hands on an original seimens & halske.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on February 07, 2016, 03:05:14 PM
Hey Guys,

I built my PSU this evening for my 251 clone using Chungers Mic PSU from studio 939. Seems to be working as expected.

Some things I noticed that may help other in-experienced builders like me;

On the standard 7 pin XLR connector the white wire which goes to b+ (as in Dany's pictures on page 1) was grounded at the back of the 7-pin XLR from factory. I had to cut this joining wire (looked more like a resistor leg) to remove it from ground.

When using the green blocks and testing for Ground, BIAS, B+ and Heater (H+) voltage ensure the screws are screwed fully down even if there is no cable/wire screwed in. Otherwise you will not be-able to measure voltages as there will be no continuity through the screwhead to the pcb on the block.


Unloaded Voltages; I adjusted the Heater (H+) from 7.92 to 6.30 volts, my BIAS is sitting at -1.201v (with the jumper removed) and B+ was sitting at 189v. I adjusted the trim pot on the B+ and the lowest it seemed to go to was 162v.

Questions;

1) I am going to be using a TC capsule in the final build. Is the B+ going to be low enough when loaded? I seem to remember TC capsule requires 110-120v when loaded and not more.
       
         A: Yes that is true.

2) The power supply H+ and bias are constant as soon as power up. The B+ however slowly increases to a voltage and the settles marginally lower. Is this normal. I would say this procress takes around 1-2mins...
       
       A: Yes you should wait a good hour and set again. It will fluctuate slightly with line voltage. Only the heater supply is     
             regulated.
3) Should I be using the jumper for the BIAS and what should its measurement be?
       
       A: Re-read build thread for more info but in short the jumper is used for the ELAM build as it is self biasing go to POCTOP
              website and download all schematics there.

4) When soldering the high z point to point section of the microphone, I understand it is neccessary to clean the pcb with ipa or use no clean solder. I am not currently using no clean solder but could switch I guess... I used 99% ipa on the PSU pcb, however clearly I need to keep it away from certain components like the capsule. With regards to the poly caps how gentle do I need to be when cleaning around them as I read they are pretty delicate to heat and alchol i.e. will a toothbrush with alchohol on it be enough to kill them or are we talking spraying them with the stuff? I see some people use cotton buds with ipa on them to cleans these sections but that always seems to leave part of the cotton bud attached in my exerience...

        A: The capsule is the last thing you install. Do not get any cleaning solvent on the Poly caps they hate it, All other parts OK!

Im excited to continue the build but I thought it would be worth checking out these few points first. I did search the thread but I didnt see any exact responces to the above.

(n.b. prior to installing the tc capsule I will be testing the mic with a cheaper alternative from studio 939)

       A: Must be dual backplate!

thanks, Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on February 07, 2016, 03:43:47 PM
Finished build:

CT12 capsule

AMI T14 transformer

Standard component compliment no alterations.

Sounds great works great love this a lot more than my C12 clone.

Had one hiccup. When I first powered up the mic and set all voltages with mic in Omni all voltages set right out of the box and all sounded great. Switch to Cardioid and output of front capsule dropped off the charts switched to Figure of 8 and all worked but front capsule lost highs?! Started doing the visual and then meter check and all seemed OK. But no change when tapping around?!. Started to get depressed about it as I really took my time with the high impedance part of this mic and, if I do say so myself, my work was tight on this one. So after deciding I needed to either rip apart the high impedance stage and start over or maybe it was the relay contacts I had that moment of well maybe, as almost impossible as it might be, there was something wrong with Tim Campbell's capsule.

So I pulled off the headbasket and went about seeing if the backplates were isolated, there where no shorts, no cold solder joints and nothing touching that shouldn't etc... All checked out! That's when it hit me. Tim Campbell ships his capsules with all the screws and solder tabs attached so I just followed this. The backplate tab connections while isolated are shipped right next to each other but yet he offers alternate spots on the capsule "for convenience". Well I have had problems in the past with proximity of connections causing problems in the high impedance circuits of mics, just not enough air between them. So I moved one of the backplate tabs to one of the alternate connection points. Bobs your Uncle all is right with the world the mic and Tim's Capsule are as one with the audio universe! Mic is working like a charm and really sounds like I dreamed it would.

This one is worth the time and effort!!!!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on February 07, 2016, 04:00:27 PM
so I will try to compile those tweaks as they go and be interesting
Best,
Dan,

Hi Dan, Thanks for your interest!

I have made a few more changes to the mic now. I posted these changes in another response but I will paste them here as well..
It turns out I made a mistake about that tantalum replacement cap! I had gotten it from a hifi shop here in Taipei on the store owners recommendation. When I saw it I thought immediately that it was a Panasonic Gold and thought nothing more of it! But today on further examination I realised I was wrong! Sorry for that! It is actually an Elna Silmic ARS. This made a very nice change to the low end of the mic, I can definitely suggest this as one to try! I don't plan to look further than this one for now. It really makes the original recording test I did sound very thin. I have also swapped out a 600K into R3, and a 510K into R5 replacing the original 500Ks  that were in there. That also seemed to add a bit more bottom, not as pronounced as the Silmic but still worth it. I also changed out the 100uf filter cap and put in a 330uf. This one I did not notice so much. One other cap that I have put in is again on the stores recommendation was a Solen MKP-FC 3.3UF 400V. That one for me did not show much change  from the original one that I had. I have made audio clips, and uploaded them into a small zipped pro tools session. These are really terrible recordings!  The guitar I have is a real good looker, but man it sounds terrible. Its an old F hole Kay from the 50s that I got for $20, its all I got here in Taiwan. So mainly I just did a guitar to show the differences between part swaps. I tried my best to be in the same location, but still it sounds pretty different before and after the capsule voltage change. I still want to do more testing but I think its a good bit better that it was when I started. I do hear a bit of noise on the mic now though it seems, but not sure its not just the environment here. Seems like the original test I did next to the new telefunken 251 was quieter, but it was across the street in an actual vocal booth instead of my control room which has a console fan running! I think it might be time for capsule and transformer changes next. Anyone have any thoughts of what might be a good choice, please let me know! Thanks

https://www.dropbox.com/s/ilyhotu9tdet6i7/Copy%20of%20251%20mic%20test%202.zip?dl=0
[/quote]

Noise creeping in after the fact speaks more to tube then anything else IMO! Transformer depends on capsule but I like the AMI. Tim Campbells capsule for my money is the best and he stands behind his product. If you are looking for a warmer voiced capsule then the C12 standard check out Beesneez for both of these capsules I recommend AMI.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 07, 2016, 06:25:51 PM
Hey Pip, coincidentally, when  I was reading through some of the  classic threads today, I saw your first post.
It was posted on April 9th 2013, in the C12 thread. And I happened to be the first to welcome you there.
Time flies, but you've done well! Keep at it.  :)

And now a 251 finished.  :P

Quote
Sounds great works great love this a lot more than my C12 clone.


Could you please elaborate why?



Henk
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on February 08, 2016, 10:14:53 PM
Hey Pip, coincidentally, when  I was reading through some of the  classic threads today, I saw your first post.
It was posted on April 9th 2013, in the C12 thread. And I happened to be the first to welcome you there.
Time flies, but you've done well! Keep at it.  :)

And now a 251 finished.  :P

Quote
Sounds great works great love this a lot more than my C12 clone.




Could you please elaborate why?



Henk

Firstly Thank You!


To my ears it has a more even timbre it is not as bright as the C12 and yet retains a very good top it also is rich and warm sounding. It is less susceptible to sibilance issues. They both have CT12 capsules. I just think this mic to me sounds like I would put it up and not fuss with it as much with EQ. It sounds like an Ela M 251 which I have always personally preferred over the venerable C12.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on February 09, 2016, 04:09:02 AM
Thanks.  :)



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on February 13, 2016, 08:34:18 AM
Actually there is no standard for 7 pin wiring  so you can actually make your own scheme if you will
just make sure it follows the logic from the psu to the mic pcb and you will be fine ,
I just have an habit of following the Neumann scheme for my cable ,  I have wired my cable like this ,
but since this one have 2 pattern control it deviates a little bit from it , but as said if you are using a Gotham cable
reserve the blue wire for Circuit ground and the red wire for the heater as those are the biggest gauge to handle more current
as said you can define your own cable configuration from psu to mic as long as it is following the logic.

here is an example :

1-audio +
2-audio -
3- (Relay control 1) to OMN
cable shield  = up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  ) to Fig 8 on mic pcb ,
7 circuit ground



Couple of questions;

When you say cable shield  = up to xlr tab as well what do you mean exactly, not sure I fully understand?

Is there a preference to the length of cable from the mic to the PSU. Is shorter better or no preference?

Thanks for the Help.

Regards,

  Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on February 13, 2016, 08:49:40 AM
I think he means the cable shield is soldered to the XRL tab. Some XRLs come with 1, 2, 3 and tab.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Matt55 on February 13, 2016, 09:29:04 AM
Yeah thats exactly what he means! I had a blonde moment and though he was refering to something else!

Any notes/thoughts regarding the 7pin XLR cable length? Basically i have two options, place it under the desk or at the base of the mic stand.

One cable would be approx 2-3m the other would be 6-8m?

Thanks, Matt
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Rlucas41 on February 18, 2016, 12:50:25 PM
Hi Dan and fellow DIY folks,

I am completing another build (ElaM-251) the mic sounds great, getting good voltage reading 6.3vdc on H+, and exactly 120vdc on B+

Cardioid is great, Omni is great, but not getting anything when I switch to figure 8… getting continuity from switch to f8 pad on mic pcb, and I think my wiring is correct… Any suggestions?

I think I may have an issue with backplate separation as I am getting continuity between the FB and RB pads with the leads connected.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bbernd on March 02, 2016, 03:11:41 PM
Hi Guys,

at the moment I'm building my first M251 and I'm really looking foward to listen to the result.

Hopefully you can answer me one question: According to the M251 Building Guide I have to use a GND hole on the PSU PCB to ground the signal (marked yellow on attached picture).
Because of my PSU layout, it would be easier to reached the GND Slot on the Terminal Block (marked red on attached picture). Is it possible to use this point instead of the place, which is recommended in the M251 Build Guide?

Thank a lot for your answer.

Bernd

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on March 10, 2016, 12:17:56 PM
I took a look at the schematics cause I'm trying to find out which triode this PCB uses. It looks like the original 251 schematic shows the second triode being used but the D251 is using the first triode. Is this correct?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on March 10, 2016, 01:02:26 PM
It doesn't matter but yes!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on March 10, 2016, 01:36:05 PM
Well when you are selecting a tube with only one mic grade triode it's good to know which triode you will be using.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Pip on March 10, 2016, 04:47:44 PM
Well when you are selecting a tube with only one mic grade triode it's good to know which triode you will be using.

One of the nice things about these 6072/12AY7 based mics is that if one side goes bad its not that hard to rewire to use the other side. IMO if you are selecting tubes or buying selected tubes they are usually best tested in the mic they are going to be used in with the voltages set for the tube in question burned in for a good few days and listened to critically with head phones.

I have found recently after going through several dozen tubes in this manner that while quite good sounding the GE 5 Star tubes I have were not as quiet as the GE JAN tubes. In general these NOS mic grade tubes are getting harder and harder to find. I have recently started looking at New Stock alternatives.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on March 10, 2016, 05:13:23 PM
Rlucas41
Is there continuity between the backplates without any wires connected to them? Then you have shorted backplates.
With the wires connected it could be the circuit.
Who's capsule is it? Please contact the manufacturer to find out about returning it so that it can be cleaned or lapped.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bbernd on March 13, 2016, 02:47:16 PM
Hello,

just finished my M251 Build and I'm really happy with the result. At least the cardioid pattern is awesome!  ;)
Thanks to all the advises and help in this thread!

I recorded an audio sample with the different pattern. If you want, feel free to listen to the files.
There you can also hear a comparison to a Microtech Gefell MT71s.


https://www.dropbox.com/sh/bx4fk73njzxlg8t/AAD9ZV42sdgfS9zQ1f3AKYtsa?dl=0
 (https://www.dropbox.com/sh/bx4fk73njzxlg8t/AAD9ZV42sdgfS9zQ1f3AKYtsa?dl=0)

Unfortunately I guess there is something wrong with the omni and the figure 8 pattern. The  omni is boosting the high-mids and the top end - the figure 8 cuts it. Voltage of B+ is 110V and H+ 6.3 V. I used a vintage microphone CEK12P capsule. I already tried to find a short between the backplates but didn't found any problem. Any other ideas?

Thanks a lot.

Bernd
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on March 13, 2016, 03:17:50 PM
Quote
The  omni is boosting the high-mids and the top end - the figure 8 cuts it.

If it's subtle (!), it's "normal". 
For the top end that is.
The mids tend to shift a bit when changing patterns.
Lows are deepest in omni and most rolled-off in fgure eight. But the latter has maximum proximity effect.

Then again:
http://recordinghacks.com/microphones/Telefunken-USA/ElaM-251E (http://recordinghacks.com/microphones/Telefunken-USA/ElaM-251E)

Hmmm ......
I wonder how representative those plots are. As a rule omni is the brightest and figure eight the darkest.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 17, 2016, 09:34:31 PM
Finished a build with a Beesneez body and capsule. This thing sounds great. I fired it up with an EH 12AY7, replaced that with my 1953 five star from Bowie, then replaced the Polypropelene film cap with a wet tantalum. Not sure I could tell much difference between the two caps but I have a sinus cold and my ears are a little out of sorts.

The Beesneez body is beautiful and fits the board perfectly. I hope there's more projects in the future that the Sneesbys will customize a body for. It ended up being a steal of a deal with the package including the Beesneez CK12.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 17, 2016, 09:38:37 PM
Gutshot.

I did notice that this thing is louder in cardiod than omni and figure 8. I remember someone mentioning that so i'm assuming it's normal for the circuit.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on April 18, 2016, 06:07:42 AM
You've got a quality mic there in every sense of the word.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on April 19, 2016, 08:33:22 AM
Finished a build with a Beesneez body and capsule. This thing sounds great. I fired it up with an EH 12AY7, replaced that with my 1953 five star from Bowie, then replaced the Polypropelene film cap with a wet tantalum. Not sure I could tell much difference between the two caps but I have a sinus cold and my ears are a little out of sorts.

The Beesneez body is beautiful and fits the board perfectly. I hope there's more projects in the future that the Sneesbys will customize a body for. It ended up being a steal of a deal with the package including the Beesneez CK12.

Thanks For taking the time to report you sucess  ;)
Best,
Dan,
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on April 27, 2016, 02:20:49 PM
Hi,

Can anyone point me to how I can calibrate this mic/psu?  I can't seem to find any info anywhere.

Cheers,
DW
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on May 01, 2016, 10:46:57 AM
Hi,

Can anyone point me to how I can calibrate this mic/psu?  I can't seem to find any info anywhere.

Cheers,
DW

So, I'm slowly figuring this out.  I've been able to set B+ with the mic plugged at 110V,  the heater at 6.3V.
There is no voltage change when I switch patterns. 
 
The capsule voltage before the 8Mohms resistors reads about 54 V, is this ok?

Lastly, on the PSU board there is a variable resistor, R4 (250K), what does this adjust?

Thanks in advance!
DW
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on May 01, 2016, 01:13:54 PM
Since you sound new to this, remember that the PS will sting you. It may be fused but treat it like a live electrical panel. Same potential. Make sure you read the silkscreening on the circuit board. It indicates what each pot does. R3 is for adjusting the bias on the C12 (same power supply board). The jumper "CBON" shorts this pot out for an Elam 251. You can ignore it.

R12 adjust the heater voltage, though it sounds like you've got that one. R4 adjusts you B+ which should be 120V.

Getting your heater close is important and overheating is bad. Some people start with dummy loads on their B+ to check their PS. I just put in a 12AY7 from my guitar amp and plugged my mic in. Not a safe option especially if you're new to building. Best to start with a dummy load.

Here is how I calibrated mine:

I fired up my mic with the PS cover off and the mic body all together. I immediately checked the heater and B+ to make sure they were less than spec (B+ will rise as it warms). I checked the mic for audio through my DAW, switched patterns then adjusted B+ to roughly 115, expecting it to rise. I left it for an hour. I made up two mic cables for this guy (make sure you use the larger gauge wires for H+ and GND) and used the longer cable (more voltage drop) for calibration. I removed the mic housing (will be super noisy if you listen to it). I checked B+ at the PS and the B+ check pad on the mic. I also check the heater at the PS and the mic (be careful with leads around the lead termination of the board or the mic socket). Knowing the drops on the cable, I shut everything down, put in my NOS 6072a, put the mic housing back together, fired it up and checked voltage at the power supply. I let the tube burn in for quite a while and occasionally checked voltages at the PS. In the end I removed the mic housing and calibrated one last time using the B+ check pad.

Keep in mind the varying wall voltages in your area (will affect your B+, not your H+) and varying mic cable lengths if you have more than one. You want to keep B+ as close to 120VDC as possible and H+ keep from going over 6.3VDC.

My wall voltage is 121VAC and ranges from 120VAC- 123VAC in my city. Usually; commercial buildings will be different if 3 phase supply. The longer the mic cable the lower your voltage at the mic compared to the supply, especially with the heater.

You don't necessarily have to be that precise but I like to be. Hopefully more experienced builders will chime in if I mispoke.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: muffy1975 on May 16, 2016, 07:35:21 PM
Hi,

if this has been already covered can you point me to the post?

I'm using a Jan 12AT7 and was wondering what the cathode bias voltage should  be? What should it be for a 6072?

Are there any tweaks to be made for this valve to work?

I have removed the pattern switches so there is just the  cardiod pattern and hooked up one side of the capsule.

regards

Michael

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 17, 2016, 05:53:01 AM
In the C12 thread, Matador offers some ideas for tweaking that circuit to the 12AT7.

The Ela M is not the same microphone, but it is based on the C12, of course.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 17, 2016, 06:12:43 AM
Here's the short version.

Quote
Microphone:  Change R17 from 100K down to 47K
PSU:  Drop R1 and R2 down to 33K.  Adjust R3 down to about 900ohms, then tweak with the actual tube.
Test load: decreases from 180K down to (120V/1.35mA) = 88K.  91K would work as a substitute for a real tube for PSU testing.


No doubt Dany can tell us how relevant this is for the Ela M and if he agrees with the tweaks in the first place.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ding on May 17, 2016, 07:36:20 AM
Hi,

if this has been already covered can you point me to the post?

I'm using a Jan 12AT7 and was wondering what the cathode bias voltage should  be? What should it be for a 6072?

Are there any tweaks to be made for this valve to work?

I have removed the pattern switches so there is just the  cardiod pattern and hooked up one side of the capsule.

regards

Michael

The 251 is self biased. No bias voltage from the PSU. Take a look at the schemo.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 17, 2016, 07:44:28 AM
Yup, that is a meaningful difference to begin with.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: muffy1975 on May 18, 2016, 12:10:16 AM
thanks Micaddict,

Ding, I know it's self biased   :o but changing the value of the cathode resistor will effect the bias. In this respect I wondered it it needed to be altered for an AT7. Should it be around 1V+????

Also on the topic of valves and the ELA M250/1 , with a 5840 valve/tube  is the wiring to the circuit ???

grid               pin 1
cathode      pin 2
Ground       pin 3 ( redundant heater )?

plate            pin 5+7 together

heater         pin 6                               =6.3V

Then cut pin 4+8 short. We don't need em.
And what  should the cathode voltage be here??

When i type 5840 into the search there is nothing on it with regards to hooking it up into the ela 251  circuit.

Thanks for any advice here.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 18, 2016, 04:44:09 AM
Quote
When i type 5480 into the search there is nothing on it with regards to hooking it up into the ela 251  circuit.

A 5480 tube does or did exist, but I guess you mean 5840?
That might be the culprit.  ;)

Also, Dany's PCB kit is for the export version of the Ela M251, which has the 6072a tube. Officially, it would be Elam M251E.
The original, European version (non -E) had the subminiature AC701(k) tube.
I once asked Dany if he would make a kit for that one, too, but he hasn't sofar. And I know he's quite busy nowadays.
But perhaps a subminiature tube can be fitted without too many alterations to the existing kit. (?)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on May 18, 2016, 05:35:50 AM
thanks Micaddict,

Ding, I know it's self biased   :o but changing the value of the cathode resistor will effect the bias. In this respect I wondered it it needed to be altered for an AT7. Should it be around 1V+????

Also on the topic of valves and the ELA M250/1 , with a 5840 valve/tube  is the wiring to the circuit ???

grid               pin 1
cathode      pin 2
Ground       pin 3 ( redundant heater )?

plate            pin 5+7 together

heater         pin 6                               =6.3V

Then cut pin 4+8 short. We don't need em.
And what  should the cathode voltage be here??

When i type 5840 into the search there is nothing on it with regards to hooking it up into the ela 251  circuit.

Thanks for any advice here.

better Check this out ,

http://groupdiy.com/index.php?topic=57902.0

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on May 18, 2016, 05:42:25 AM
LOL

Man, I'm getting old!
And I was the first one there to reply, no less.

Thanks, Dany.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 08, 2016, 07:05:59 AM
Hi guys,

Well, after building one of these mics on the PCB kit I managed to get it working but after replacing the tube I broke the tube socket PCB off of the main PCB rendering it useless.  So, I took matters into my own hands and discovered this thread: http://groupdiy.com/index.php?topic=54078.0

Seeing this I decided to "copy" this and make a point-to-point version.  I found some pics online and saw that the relays were mounted on the back of the Plexiglass board so I did the same.  I used the D-251 schematic and managed to get this thing to work.  Yay! 

However, I seem to have the problem that when I have loud-isa vocals going through the mic it seems to have a bit of fuzzy distortion.  I've tried 3 different preamps with the same results.  I've also tried using a Electro Harmonix 6072, a NOS GE 5 Star 6072a and a cheap Chinese no name tube.  Always had the same results.  On quieter or mid loud vocals it sounds fantastic.  Really nice.  A bit bass shy but I haven't tried the tweaks yet.  Anyone have any idea what this could be?

Here's a pic of my build:
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 08, 2016, 07:06:36 AM
Here's another pic (since I can only post 1):
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 08, 2016, 05:55:42 PM
 :o

Responding to my own post:  I've realized that I've put in a wrong value resistor.  8M Carbon.  On the schematic I read 30M 1/2 W and I put in an 8. 

After putting in a 30M it sounded really odd.  Then I put in a 1M 3W.  Sounds a whole lot better now....but still distorts and louder levels.  Wish I understood why....
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on June 08, 2016, 06:11:07 PM
Probably not without  a reason you used 8M. Schematic for AC701K version had this value instead 30M.
Where did you put 1M resistor? Instead 30M?
Did you used other values corresponding to the original schematic?
It's hard to see much here since you did wires spaghetti :D
What for is that 220(pF?) polystyrene capacitor?
Is it in parallel with another polystyrene?
What capsule did you used?
Did you measured any voltages inside microphone?
If not, i would start from plate voltage (before and after 100k), then cathode, heaters and finally polarisation voltage.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 09, 2016, 04:07:03 AM
Probably not without  a reason you used 8M. Schematic for AC701K version had this value instead 30M.
Where did you put 1M resistor? Instead 30M?
I'm using the - vintagemicrophonepcbkit.com d-251 "Walter White" - schematic.  Yes, I put it at R4

Did you used other values corresponding to the original schematic?
 
Very small:  I used 8.2M instead of 8 at R6 and R7.  At R3 and R5 I'm using 499K  instead of 500K.  At C3 I used 22uF instead of 20.  C2 I started with 100uF as suggested but ended up using 2x220.  On C1 I'm using a 1uF and also tried a 3.3uF.  I preferred the 1uF so far but the difference wasn't the world

What for is that 220(pF?) polystyrene capacitor?
C2, see above.

Is it in parallel with another polystyrene?
Yes, see above.

What capsule did you used?
I'm using this:  http://store.studio939.com/product/35mm-k67-style-capsule

Did you measured any voltages inside microphone?
Yes, I did and everything seemed to be within parameters.  I wrote it down somewhere....must look....

If not, i would start from plate voltage (before and after 100k), then cathode, heaters and finally polarisation voltage.
I'll find or re-measure tonight and post my readings.  I just wanted to point out that right now, even with a Generic cheap Chinese tube, the mic is sounding really good.  It's just when I push loud vocals into it that it starts to sound a bit broken up.  Maybe it just can't handle it by design? Thanks for your help!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 09, 2016, 04:09:23 AM
I just wanted to point out that right now, even with a Generic cheap Chinese tube, the mic is sounding really good.  It's just when I push loud vocals into it that it starts to sound a bit broken up. 

I just realized that I currently do not have the "no name" Chinese tube in it but rather the Electro Harmonix 6072.  In any case I have the same issue with both tubes.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on June 09, 2016, 09:38:55 AM
440pF is little bit too much for C2 or your capsule is overbrighted (yes these chinese "ck12" can sound different a little bit).
Desolder these caps, or at least both from one side, and make voice test.
R4 is another posibility and also can causing lack of low end.
1M is really too small, i would think about 100M or 1G but not 1M  :)
30M and 8M are also small values - but if you want to recreate something at least in 20% similar to the original then these are ok.
Rest differences of the parts are ok.
If this wouldn't help - try to change 22uF fine gold to something else (these caps sometimes can be tricky) if this not help, try different output cap, but JB usual works better than fine ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 10, 2016, 10:25:57 AM
440pF is little bit too much for C2 or your capsule is overbrighted (yes these chinese "ck12" can sound different a little bit).
Desolder these caps, or at least both from one side, and make voice test.
R4 is another posibility and also can causing lack of low end.
1M is really too small, i would think about 100M or 1G but not 1M  :)
30M and 8M are also small values - but if you want to recreate something at least in 20% similar to the original then these are ok.
Rest differences of the parts are ok.
If this wouldn't help - try to change 22uF fine gold to something else (these caps sometimes can be tricky) if this not help, try different output cap, but JB usual works better than fine ;)

Interesting. C2 (usually 100pF) is what I started with but it was indeed much too bright.  I worked my way up to 440 and found it to sit well.

Wondering why the 30M would be to low value when this is the value on the Schematic.  I will try a 250M since i have one here.  But 30M really made the mic sound odd.  Also, on the Official 251 point to point on Acrylic build and support thread it would seem that he has put in a 250M at this point.  That being said I have seen a pic online where this was 800K. 
I'll keep trying.  At the moment it sounds pretty darn good.  Just can't handle a loud vocal.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 11, 2016, 05:23:18 AM
Ok, I've tried putting in a 250M in place of the 1M for R4.  Sounded awful.  Fuzzy, had a weird DC offset and it was 10db quieter.  I put back the 1M for now.  Sounds great.  I just can't record loud vocals with it but that seldom happens.  Here's a clip for anyone interested. Mic > BAE 1073 DMP - no comp, no eq, only used a bit of VSS reverb on the vocals:

https://www.dropbox.com/s/jekmx6mqog2mcht/I%20can%27t%20help%20-%20251%20test%201M%20ohm%202W%20resistor..mp3?dl=0
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on June 11, 2016, 01:10:06 PM
Definately you screwed up something if it sound worse with higher resistance.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on June 12, 2016, 06:44:29 AM
Definately you screwed up something if it sound worse with higher resistance.

Apparently I screwed up good. The person I made this mic for is blown away.

Whatever. If th shoe fits.....
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on June 12, 2016, 07:45:41 AM
I would check all, especially if you did this mike for someone else.
It's not about, that you need change resistor, because it should be higher in theory.
Is worth to know, why it distorts and what causing that. Wih the time it can be worse.
I would really checked polystyrene caps - or check mike without it.
Please remember that polystyrene can microphonic also.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Lordward on July 01, 2016, 02:03:17 PM
I would check all, especially if you did this mike for someone else.
It's not about, that you need change resistor, because it should be higher in theory.
Is worth to know, why it distorts and what causing that. Wih the time it can be worse.
I would really checked polystyrene caps - or check mike without it.
Please remember that polystyrene can microphonic also.

Cheers, that's a good point. I will check it when my capsule gets returned from Peluso.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on July 22, 2016, 07:22:13 PM
Here's modified schematic for use single backplate capsule (as from groupbuy for example) to get cardioid and omni patterns in Dan's circuit. It's something like ELA M250E. Utilize less parts and SPDT switch instead SP3T.
Hope that Michael don't mind that i used his drawings ;)
Dan, if you could check is it everything proper according to the PCB connections, it would be great!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Yannic1990 on August 22, 2016, 05:02:52 AM
Hey Guys,

i have the following setup:

Tim Campbell Capsule
Standard Mouser + PCB
Beesneez Body
AMI T14
Neve 1073 Preamp

I have tried many C1 and stuck with
the one in the picture. I also changed C3 to 100 uf
and it gave the Low End a boost around 2-3 DB.

The EQ curve is really really good/close in comparison with
an original ELA M 251 but the Low End (150-200Hz)
needs another boost around 3-4 DB.

- "Reduce 0.5R to Ground" - Do you mean R5 or R3 ?
    -> How do i do this ?

-"Grid Resistor higher" - Do you mean R4 ?

Any other tryouts ?


THANKS GUYS

(http://www2.pic-upload.de/img/31521419/251GDIY.jpg) (http://www.pic-upload.de/view-31521419/251GDIY.jpg.html)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Deepdark on December 09, 2016, 09:18:14 AM
Just completed this microphone. What a fun build. Congratz Dany, this one rock some ass! It sounds freakingly awesome, no noise, no hum, no what so ever else than awesomeness  8) ok seriously, I like it.

(https://scontent-yyz1-1.xx.fbcdn.net/v/t1.0-9/15317796_1163219830429636_2410926642325743705_n.jpg?oh=3391e5946510cee888c878ff913659ad&oe=58B3C185)

(https://scontent-yyz1-1.xx.fbcdn.net/v/t31.0-8/15385385_1163221287096157_4343295828579453198_o.jpg?oh=6edf6cb8cb23c2b47dfc266a351a8ba5&oe=58B40E28)

(https://scontent-yyz1-1.xx.fbcdn.net/v/t31.0-8/15443208_1163221510429468_8529965010689125681_o.jpg?oh=5edf0e6dede91cc0d9de94827e277237&oe=58F2314B)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on December 09, 2016, 10:30:55 AM
 :)

 :D

 :P

And how do you like her body?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Deepdark on December 09, 2016, 10:53:27 AM
:)

 :D

 :P

And how do you like her body?

My girlfriend's body? Like it so much ;) microphone body? Heavy and well made :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Deepdark on December 09, 2016, 10:58:08 AM
Will need to reverse 2 lead. I didn't pay attention to the gage and used 26ga for the heater. Don't think it's really dramatic, but we never know
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 11, 2016, 12:06:03 PM
Sorry for the noob question guys...just trying to finish this build.  Can someone tell me the xlr 7 pin points for the circuit?  It was pretty much paint by numbers for the C12 build but this one not so much :)  Thanks!


Mic PCB=XLR 7 pins
GND = 7?
OMN= ?
F8=?
H+=?
A-=?
A+=?

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Deepdark on December 12, 2016, 11:50:01 AM
It's up to you to decide all these assignement. Just remember them and and stick to them on all 7 pin xlr you'll have to make on this build
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 12, 2016, 10:39:20 PM
Great...Thanks! 

BTW...when calibrating PSU and I am getting 139V and it climbs down to around 120 or then it fluctuates a bit.  Should I be getting a constant value on the  B+ and Bias?  Should I get 120V immediately upon powering?  I am getting a constant on H+ of 6.3V. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on December 13, 2016, 07:00:42 AM
BTW...when calibrating PSU and I am getting 139V and it climbs down to around 120 or then it fluctuates a bit.  Should I be getting a constant value on the  B+ and Bias?  Should I get 120V immediately upon powering?  I am getting a constant on H+ of 6.3V. 

It's unregulated supply for B+ so it will be fluctuating. H+ is regulated so it's constant.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 13, 2016, 06:36:59 PM
So to be clear, its Okay to be at such a high voltage 136V-139V when first making contact and then letting it settle in around 120V?  I just don't want to cause any damage to any components :-\  Please feel free to describe in as much detail what I should be seeing examples etc.  Thanks!!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on December 13, 2016, 06:56:17 PM
If your capacitors are rated for 120V or lower, some may blown. Otherwise nothing should happend, maybe just capsule will suck diaphragm to backplate. That's the deal with unregulated supplies. BTW. you should have potentiometer inside PSU to reduce voltage.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 26, 2016, 02:16:37 PM
Got build complete, just getting a hum on Cardioid and Omni, not Fig 8...any ideas?  Any chance it's the capsule?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on December 27, 2016, 04:45:49 AM
What capsule you are using?
Rather it's problem with grounding than with the capsule.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on December 27, 2016, 04:50:46 PM
It could be a short between the backplates or you've wired the capsule incorrectly.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 29, 2016, 08:36:29 PM
Hi Tim,

I am using one of the two capsules I recently purchased from you.  Perhaps you can tell me if you see any problems here with the wiring?  I used the red wiring for what I believe is the front of capsule and blue for back plate.  There is certainly a chance I misunderstood the diagram that came with the capsules as the solder points appeared different to me than the actual capsule.  I'm new to this so please be gentle :D

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on December 29, 2016, 08:40:27 PM
Other Side...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on December 29, 2016, 11:55:48 PM
Just giving this a quick look I'd say that you removed the wrong tabs on the metal rails holding the pcb. It appears that the remaining tabs might be shorting solder points on the pcb.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 01, 2017, 09:45:58 PM
Problem solved.  I had to ground the ground terminal on the 5 block to pin 1 on the rotary.   I narrowed it down to the PSU as I was getting the ground noise without the mic plugged in.  Next one should be much easier!  Thanks for the support!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 16, 2017, 08:47:51 PM
Anybody have a similar setup?  Using a tab t14, electro harmonix tube and tim campbell capsule.  I feel the 8-12k is overly present.  Is this just my experience or anyone have the same result?  This thing is also ridiculous sensitive as well.  I was picking up the wind blowing outside! (not really) ;)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on January 17, 2017, 02:24:24 AM
The tube can have a lot to do with how bright the mic is. My experience with EH tubes has not been good. You don't mention which EH tube model but I assume their 6072.  The best tube is of course the GE 5 star 6072 but they are expensive and hard to get. RCA 12ay7's are duller but a little lackluster. Many have had good luck substituting brand name 12at7's. You might also tame it a bit with some alternate value capacitors.
The quickest mechanical fix is a nice thick, foam wind hat :)
Where are you located?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on January 17, 2017, 02:47:30 AM
The AMI T14 also doesn't roll off the highs like an original T14/1. It has a noticeably brighter response.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 17, 2017, 10:44:05 AM
I'm in South Florida.  Thanks for the info.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bonnie1 on January 17, 2017, 08:41:45 PM
The AMI T14 also doesn't roll off the highs like an original T14/1. It has a noticeably brighter response.

That's correct the AMI T14 Hi roll off is not at the same freq. as the Haufe T14/1. it's extended a wee bit. 
Nusoundz description "8-12k is overly present" does not sound like the result of a component with a slight freq. extension. 

It is possible AMI T14 is contributing 1-1.5 db, however not the fundamental cause.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on January 18, 2017, 03:13:54 AM
That's correct the AMI T14 Hi roll off is not at the same freq. as the Haufe T14/1. it's extended a wee bit. 
Nusoundz description "8-12k is overly present" does not sound like the result of a component with a slight freq. extension. 

It is possible AMI T14 is contributing 1-1.5 db, however not the fundamental cause.

Not to hijack, (well, not for long anyway), but what about the T67 versus Neumann's BV12 in this regard?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on January 18, 2017, 03:28:47 AM
Bonnie1, since we haven't establish what the frequency response of the mic in question truly is, just that it's "overly present",  it's hard to be sure that any additional  boost at 8-10k wouldn't be contributing to this.  Imagine if the mic has a particularily  bright tube, a smaller value, poorer quality capacitor in the tone circuit and an AMI transformer. I'm sure it would be much brighter than if the reverse were true.

 Here is Telefunken's freq. response for that mic.
(http://recordinghacks.com/graphs.php/0858)

Here's AKG's original freq. response for that mic.
(http://www.foxaudioresearch.ca/AKG-m251-response-graph.jpg)

We haven't really asked how this evaluation was done. Headphones? Recording and playback? Bright compared to what other mic?

Of course if none of these changes bring about the desired reduction in 8-10k NuSoundz is always welcome to send the capsule to me  and I'd be glad to damp down the top end.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bonnie1 on January 18, 2017, 04:48:50 PM
Not to hijack, (well, not for long anyway), but what about the T67 versus Neumann's BV12 in this regard?

Hi Micaddict, are you asking about freq. response T67 vs. Neumann BV12?  AMI/TAb's new website will launch soon and we will provide such comparisons as well as test setup etc... 

So we don't hijack this thread any longer, please PM me or start a new thread for further discussion.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on January 18, 2017, 05:08:23 PM
Roger.   :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Bonnie1 on January 18, 2017, 08:11:06 PM
Hi Tim, the points you make are exactly my points as well.  Presenting a broad statement about a component without specifics will lead to incorrect conclusions. (this is precisely why I commented)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 20, 2017, 08:25:54 AM
I have indeed ordered a GE 5 Star tube to see if I get the desired result or a more favorable one.  I'm sure it could be a couple different things going on.  I'm not blaming any particular component at this time as it's to early to point out the exact cause.  I appreciate the feedback and will update once I have received the tube and perhaps post some clips with each tube.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on January 20, 2017, 11:23:32 AM
I have indeed ordered a GE 5 Star tube to see if I get the desired result or a more favorable one.  I'm sure it could be a couple different things going on.  I'm not blaming any particular component at this time as it's to early to point out the exact cause.  I appreciate the feedback and will update once I have received the tube and perhaps post some clips with each tube.

The main point is that if you don't have all original spec parts, then these original microphone circuits should only be used as a starting point. To make everything fit together and sound right, you can still make adjustments to the capacitor and resistor values.

If it was my mic and the response was too bright, I'd start with the 30M grid resistor.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 21, 2017, 03:31:19 PM
Absolutely.  I'm not expecting an exact replica of the real thing but a loose relative is fine.  However, if the mic is unusuable in many applications (requiring too much eqing etc.) then I have a problem with that. 

Regarding the resistor, what would you suggest as a "not so bright alternative". I'm new to this so please excuse the ignorance on my part.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on January 21, 2017, 05:47:25 PM
Absolutely.  I'm not expecting an exact replica of the real thing but a loose relative is fine.  However, if the mic is unusuable in many applications (requiring too much eqing etc.) then I have a problem with that. 

Regarding the resistor, what would you suggest as a "not so bright alternative". I'm new to this so please excuse the ignorance on my part.

Try a 100MΩ instead. If still too bright, also increase the 22uf cathode capacitor to 47uf.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on January 22, 2017, 09:08:45 AM
Other options

If you are running microphone from 120VDC, then you could try lower polarisation voltage to ca. 55V like in original ELA M250/251. If you are using 500k for divider, then you could replace R5 for 420k/422k/427k.
If you will not hear difference in response, then worth back to the 500k/500k divider.

My standard suggestion is to use MP capacitor as the output C1, range from 0.5uF-1uF.

Other thing is headbasket, some can bump frequency response, especially in hi-mid and hi range.
If you are using standard apex/alctron donor for C12, what kind of headbasket it use?
Original or Chunger optional headbaskets with single mesh layer or two layers?
Or some different donor body?

Last option is to try Haufe T14/1, guys here want to make groupbuy, so you have opportunity, to buy it cheaper.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: NuSoundz on January 22, 2017, 10:39:26 AM
Excellent, I will consider all those changes. 

I am using Chungers Elam style 3 dual layer basket.

What's the procedure to order the Haufe T14/1?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ln76d on January 22, 2017, 07:05:01 PM
First i would try to make voice test with headbasket and without it.
Here's pasted my advice from another topic:

--------------------------------------------------------------------------------------------------------------------------------------------------------------
Do voice test - grab microphone (with whole body metal parts attached and option to take off headbasket) with one hand for the metal base, and with another hand keep headbasket (rather don't cover front of the capsule ;) ). Compare between headbasket installed and without it. Without headbasket you can have problem with hum, so find the place in your listening room where there's lowest problem with hum (it's strongly dependent from your listening gear, amps preamps, psu, wall AC voltage etc.)
You can also try to cover a little the backside of the diaphragm (don't touch capsule) with a hand (second hand always keep metal pipe of the mic body). If you have variable HPF in your preamp, you can use it.
Difference which you should notice is mostly in the upper midrange and high frequency area.
Weak headbasket will usual overbright or make more nasal sounding microphone.
If you find that difference then after removing internal mesh should be better response, more neutral.
--------------------------------------------------------------------------------------------------------------------------------------------------------------

If you will find difference in the range which you don't like then i would consider change of headbasket for single layer or removing internal layer in type 3.

Here's the link for T14/1:
https://groupdiy.com/index.php?topic=64243.0
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Phrazemaster on January 27, 2017, 03:29:27 AM
Ok, here we go folks with the C12/ELAM shootout.  My CT12 equipped Chunger C12 vs CT12 equipped poctop ELAM.  Both mics were run into a vintage 1099 (1073 with fixed line gain) with no EQ or compression and straight to my SSL madi converters.  First is the C12, second is the ELAM.  I purposely mixed the backing track low fyi.  Results were what I expected...   

https://soundcloud.com/paradyne-studios/i-love-you-c12-then-elam-mic
Hey I just loved your sample! So much, where can I buy the whole song? I looked online but couldn't find it. Fab production, singing, playing. Great song! Thx!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on March 20, 2017, 10:52:05 PM
Hey y'all!

Just finished building my D-Elam251. So excited to have it all put together now!!! Its been a journey for sure... I am also now trying to bring up the bass response. I've upped the output cap to 3.3uf and looking into resistor changes and other tweaks as per these forum posts...

Im using the Beeskneez Body (beautiful job Ben and Veronica!), AMI t14, GE 5 star 6072a, TC12 capsule.

Anyway, I am wondering if I will have an issue (other than space) to use a higher voltage rated cathode bypass cap. I tried to find a 6.3v gold 100uf cap to replace the 22uf tantalum... I could only find the 10v rated ones. Could this cause me any issues granted I can fit it on the little tube PCB?

Also, I've seen mixed information of weather to set B+ to 110v or 120v... is there a definitive consensus on this? 

Further, if the voltage is set to 110v does this also mean that the 500k resistors are dividing the voltage for the capsule to be 55v? If I want more bass response would I lower the capsule voltage even more?? Tim Campbell recommended me to set only to 55v for optimum results.

Anyway, still experimenting with capacitor composition and values... But overall I am pleased... just need to get more bass!! :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on March 21, 2017, 12:08:51 PM
Also, I've seen mixed information of weather to set B+ to 110v or 120v... is there a definitive consensus on this? 

I just asked Tim about the polarization voltage and his reply was that "120V [is the maximum] but 110V sounds better." To my ears, he was right. However, the right answer is always "what sounds best to you (as long as you aren't damaging the parts)."

If you've increased the cathode capacitor AND the output capacitor to the values described, your circuit is already full range. At this point if there isn't enough low-end, it's probably not because you're losing it somewhere in the microphone's circuitry. Other factores you maybe can't easily do much about ... see some discussion in a recent thread about trying to get more bass from a figure 8 (which is fighting physics), maybe also something to do with the transformer output (I am murky on xfo resonance, so I won't speculate here), maybe something to do with the headbasket (though my understanding of this is that it mostly affects high end, and a really open headbasket like you're using should be more balanced).

This is what I personally would do if I knew a microphone was full range and I needed more bass. I am of course assuming that you aren't hearing something actually WRONG -- like a really thin sound, or something like that.

1) Easiest: put the mic in card and move it closer to the source to increase the proximity effect.
2) Next easiest: Add bass OR remove not-bass in post.

Neither of these involve altering a working microphone that otherwise sounds good, and if you have to do them every time you pull out the mic for heavy low-end stuff, then that's just part of learning your gear ... and maybe accepting that not every microphone is equally suited for every task.

You could also be hearing the high-end lift that's going to be normal for this type of microphone.

Someone else smarter than me might be along shortly to recommend more drastic measures. :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stribor1 on March 21, 2017, 01:27:53 PM
The Link to the schematics on the first page is not working anymore. Can someone please repost the docs?
Thanks,
J.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on March 21, 2017, 03:03:24 PM
The Link to the schematics on the first page is not working anymore. Can someone please repost the docs?
Thanks,
J.

Hey J,

I had the same problem and used the wayback machine to look for the images with success...

Here are two of the D-Elam251 schematics....

https://web.archive.org/web/20160915002210/https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/Schemtic%20D-E251E.pdf

https://web.archive.org/web/20160915024854/https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

If you want ANY of the broken links just go to:
 https://archive.org/web/

Copy the link from the first page of the forum and paste the URL into the wayback machine and click the date link. I used this to look at some of the photos aswell as all the document files.

Cheers!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Carnesd on March 21, 2017, 03:59:31 PM

If you want ANY of the broken links just go to:
 https://archive.org/web/

Copy the link from the first page of the forum and paste the URL into the wayback machine and click the date link. I used this to look at some of the photos aswell as all the document files.

Cheers!

Wow that is awesome!  How did I never hear about this!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on March 22, 2017, 08:09:12 AM
HarmonyUnited I have PM'ed you.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: stribor1 on March 25, 2017, 02:31:47 PM
Hey J,

I had the same problem and used the wayback machine to look for the images with success...

Here are two of the D-Elam251 schematics....

https://web.archive.org/web/20160915002210/https://dl.dropboxusercontent.com/u/43869772/Elam%20251/Elam%20251/Elam%20251%20Pictorial/Schemtic%20D-E251E.pdf

https://web.archive.org/web/20160915024854/https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

If you want ANY of the broken links just go to:
 https://archive.org/web/

Copy the link from the first page of the forum and paste the URL into the wayback machine and click the date link. I used this to look at some of the photos aswell as all the document files.

Cheers!

Awsome! Thanks,
J.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on March 26, 2017, 05:18:39 AM
Hey everyone,
I am experiencing a higher than normal background white noise in my 251 build.  I put this mic up next to my TAB m49a (with ac701k) through the same pre amps at the same gain and noticed the white noise 251 was so much louder in comparison. The noise level is certainly making the mic unusable for most applications I would choose to use it for (vocals and acoustic finger style guitar). I've redone the whole high-Z circuit trying to clean it up. I bypassed the capsule and discovered the white noise is in the amplifier. I have a noise tested 6072a but swapped it out for other tubes with no change in the white noise. I changed the output cap and still no improvement... I'm thinking that somehow I damaged my styroflex caps while building the circuit.  Could this cause a higher than normal background white noise? I ordered another set of styroflex from Dany's site. Any other ideas from the gallery? Grounding problems don't usually cause white noise so I don't think its something like that... *shrug* Any guidance in the matter would be gratefully appreciated.

Cheers!

-Eric
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on March 26, 2017, 10:50:27 AM
Tube socket? Check that your pins are seating correctly - see if any of the mating pins in the socket are damaged or pushed to one side.

You could always replace the styroflex with any type of cap. Even a different but similar value. It might not sound good but it'll help in troubleshooting.

Don't rule out grounding.

What about your audio pair inside the power supply? Twisted? Short? Avoids filter caps?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gus on March 26, 2017, 11:50:42 AM
I have a noise tested 6072a but swapped it out for other tubes with no change in the white noise.



How are the tubes noise tested? In a microphone circuit or in a lower input resistance audio circuit? This matters a lot.

What tubes NOS  or modern built brands are you using and how many have you tried? Tubes can have noise issues with tube microphone circuits
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on March 26, 2017, 04:09:09 PM
Tube socket? Check that your pins are seating correctly - see if any of the mating pins in the socket are damaged or pushed to one side.

You could always replace the styroflex with any type of cap. Even a different but similar value. It might not sound good but it'll help in troubleshooting.

Don't rule out grounding.

What about your audio pair inside the power supply? Twisted? Short? Avoids filter caps?

I checked the audio pair in the power supply and shortened and twisted them and made sure they were clear of the filter caps. This did not solve the noise but definitely improved the aesthetic.  :P

Looks like the tube socket is doing okay.

How are the tubes noise tested? In a microphone circuit or in a lower input resistance audio circuit? This matters a lot.

What tubes NOS  or modern built brands are you using and how many have you tried? Tubes can have noise issues with tube microphone circuits

I am using a NOS GE 5-star 6072a sourced and tested by Brent Jesse of AudioTubes.com. I also tested a NOS GE 12av7 that David Pearlman sent me. Both offering the same white noise.

I noticed that there is a little melty spot on the C2 styroflex cap. Maybe this is causing the white noise??

Anyway, I am posting some photos of the circuit to maybe shine some light on the subject from y'alls wise eyes.

Thanks so much for the help!

-Eric
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on March 26, 2017, 04:19:21 PM
Did you "bypass" the capsule on the capsule side of the relays or the amp side?

Could be relay wiring. Does the same noise exist in all patterns? White noise louder or quieter in cardiod? Your signal will be louder in cardiod so generally your noise is quieter in cardiod.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on March 26, 2017, 04:23:25 PM
Did you "bypass" the capsule on the capsule side of the relays or the amp side?

Could be relay wiring. Does the same noise exist in all patterns? White noise louder or quieter in cardiod? Your signal will be louder in cardiod so generally your noise is quieter in cardiod.
And here are the photos of the circuit parts...

I bypassed the capsule at the capsule... just put 100pf caps in place of the capsule sides. Not sure how I can bypass the capsule at the amp side. The Noise is pretty much the same in all patterns with the capsule wired in. When i wired the capacitors in place though the noise was quieter in figure 8. which was weird...

Thanks again y'all!!

-Eric
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on April 09, 2017, 12:58:46 AM
And here are the photos of the circuit parts...

I bypassed the capsule at the capsule... just put 100pf caps in place of the capsule sides. Not sure how I can bypass the capsule at the amp side. The Noise is pretty much the same in all patterns with the capsule wired in. When i wired the capacitors in place though the noise was quieter in figure 8. which was weird...

Thanks again y'all!!

-Eric

theres my output cap
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Carnesd on May 27, 2017, 12:27:20 PM
Hello Everyone,  I just got finished up with my D251 and alas my first mic that doesn't work correctly from the get go  >:(  Problem I'm having is only figure 8 pattern is working correctly,  cardoid doesn't work at all, and omni is very very low output. 

B+ and heater voltages are correct,  the capsule appears to be wired correctly and I feel like if it was the capsule wiring it wouldn't work in figure 8 as well.

I have relay voltage 6.2v to the omni and figure 8 pads on the mic when switching and no voltage in cardoid.  I can hear the relays clicking when switching between patterns.

I feel like I have an issue in my relay High Z ptp wiring but everything looks good,
Mainly wanted some confirmation that this sounds like an issue with the Hi z portion before I tear it apart and redoe it.

Thanks All!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on May 27, 2017, 12:36:01 PM
Carnesd it sounds like you reversed your backplate connections , have a short between your backplates most likely within the capsule or your backplate connections are shorting against each other.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Carnesd on May 27, 2017, 01:12:43 PM
Thank you Tim,  I will go over the capsule and wiring again.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Carnesd on May 27, 2017, 10:03:33 PM
Carnesd it sounds like you reversed your backplate connections , have a short between your backplates most likely within the capsule or your backplate connections are shorting against each other.

You are the man Tim,  I swapped the backplate wires and now its working correctly.  I guess I'm a little confused on why the backplates are hooked up the way they are, you would think the front BP would be closest to the front membrane.  I guess I'm a little confused on whats going on inside the capsule and I couldn't seem to find a good diagram of how to hook up the c12 type capsule. 
Thank you for your help. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: jbassino on June 14, 2017, 02:04:01 PM
I built this Clone some time ago with Campbell's capsule. Overall the mic sounds excellent but I only find it too silibant in the 8-12k area, almost with any singer.

I'm wondering if anyone had this similar issue and what tweaks worked best!

Thanks :)

 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: LeFinbongo on June 28, 2017, 04:48:56 PM

What about your audio pair inside the power supply? Twisted? Short? Avoids filter caps?

Wow. thank u for that comment! I gave up on my ELA nearly a year ago when I just couldn't figure out why it was so noisy and turns out all it needed was some twisting. Now its perfect!  :´D
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: micaddict on June 28, 2017, 05:43:07 PM
Welcome and congrats.  :)


BTW why didn't you ask for help a year ago?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: LeFinbongo on June 29, 2017, 05:51:31 PM
Read through replies to people with similar problems. After troubleshooting for a long time I guess I just assumed it would be no quick fix and that I'd need hands on assistance. Something I never got around to...
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: HarmonyUnited on September 11, 2017, 04:33:43 PM
(Probably should have just posted this here in the microphone thread, apologies)

Greetings All,

I've been on and off trying to track down the white noise in my D-251 build for about a year now. I have noise tested the 6072a and its super quiet, Replaced the CT12 capsule, de-soldered the whole thing, cleaned it, re-soldered it up again, changed the output caps, twisted the audio wires in the power supply and kept them from the filter caps, tried filtering the B+.... all to no avail. The white noise makes it pretty un-usable for any voiceover/vocal or acoustic guitar application as the hiss is too noticeable.  I am going to post a few sample recordings, perhaps anyone has any ideas. Listen to the lead in before the guitar comes in... I am posting a recording with my D251 and next with my MK Audio U67. The 67 is dead quiet in the lead in...

251 link: https://www.dropbox.com/s/doga2sonunml4u6/Will%20She%20Be%20Gone%20%28251%29.mp3?dl=0

u67 link: https://www.dropbox.com/s/1dmqcloash2avqx/Will%20She%20Be%20Gone%20%28u67%20no%20filters%29.mp3?dl=0

Ideas Anyone?

I am out of them... Perhaps there is a qualified technician who may be able to troubleshoot this on their bench for a fee? Anyone out there servicing DIY microphones? Any help is so appreciated.

Thanks a ton!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ShaneSBG on September 11, 2017, 08:02:52 PM
(Probably should have just posted this here in the microphone thread, apologies)

Greetings All,

I've been on and off trying to track down the white noise in my D-251 build for about a year now. I have noise tested the 6072a and its super quiet, Replaced the CT12 capsule, de-soldered the whole thing, cleaned it, re-soldered it up again, changed the output caps, twisted the audio wires in the power supply and kept them from the filter caps, tried filtering the B+.... all to no avail. The white noise makes it pretty un-usable for any voiceover/vocal or acoustic guitar application as the hiss is too noticeable.  I am going to post a few sample recordings, perhaps anyone has any ideas. Listen to the lead in before the guitar comes in... I am posting a recording with my D251 and next with my MK Audio U67. The 67 is dead quiet in the lead in...

251 link: https://www.dropbox.com/s/doga2sonunml4u6/Will%20She%20Be%20Gone%20%28251%29.mp3?dl=0

u67 link: https://www.dropbox.com/s/1dmqcloash2avqx/Will%20She%20Be%20Gone%20%28u67%20no%20filters%29.mp3?dl=0

Ideas Anyone?

I am out of them... Perhaps there is a qualified technician who may be able to troubleshoot this on their bench for a fee? Anyone out there servicing DIY microphones? Any help is so appreciated.

Thanks a ton!

I have no idea if this will help you or not, but I was talking with a few people a few months ago about noisy 408a tubes and it seems the noise was from a binder connector...again, no clue if this will help, but check this out and maybe. I don't know what type of connector you have...hope it helps

https://groupdiy.com/index.php?topic=66062.40
we were talking about it here and specifically reply/post 42
http://prorecordingworkshop.lefora.com/topic/19405924/EF800-as-a-microphone-tube-issues?page=1#.WWPwAulpyM8
read until post 43
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: ComplicationFetish on October 20, 2017, 04:17:30 PM
So, I finished this build and I love it (my first successful mic build)! 

Now, I'm looking into implementing some of the suggestions to modify the low end response.   I am a noob when it comes to electronics, but if I wanted to slightly increase the cap value of C1 (or any cap), but still wanted to maintain the use of my original cap, can I simply add an additional cap, wired in parallel with the first cap, or am I thinking of this wrong, or would there be unwanted consequences to the sound that I am not aware of?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: snaredrum on April 07, 2018, 11:52:22 AM
Hi i try to built this elam,  first i had built a c12 copy and it work well,  but i dont understand all the indication on mic pcb.  S+ s-  p+ p-  a+ a- i have a small idea but i am not sûre.  Can i get more info for plug right from the t14 and xlr 7 pin thanks
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 07, 2018, 01:27:24 PM
See Trans4funks1's diagram: P = primary, S = secondary; +/- for polarity.

https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf)

A+ and A- must be audio out to your mic cable. Check with ohmmeter. A+ and S+ (also A- and S-) should have continuity.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: a.payne on April 23, 2018, 05:34:56 AM
I'm currently building an ELA M 251 and had a beginner question regarding the point to point between the pattern switch, 7 pin xlr and 3 pin xlr.

I have added the link to a really sketchy diagram of how i think it should look based on the wiring i saw on Dans PSU. I just got confused because it seemed a little different to the PSU diagram uploaded with the original post.

https://drive.google.com/open?id=15UNCnW2NtRvbosZPzj_aF0fmjHR9aDbl

It would be great if someone could let me know if it's going to work or not :)
Best,
ali
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Zebra_PD on May 23, 2018, 04:56:45 AM
What tubes would u guys recommend/prefer for this build if you tried some different ones?

What sonic difference have you experience with different tubes?

For example NOS Telefunken or NOS GE 12au7/ecc82/6072? Perhaps even some other brand/model?

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tonycamp on May 26, 2018, 11:50:12 AM
What tubes would u guys recommend/prefer for this build if you tried some different ones?

What sonic difference have you experience with different tubes?

For example NOS Telefunken or NOS GE 12au7/ecc82/6072? Perhaps even some other brand/model?

1950’s Nos GE 6072 5-star tested for low noise/microphonics, the red/orange ink if u can get it.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gus on May 27, 2018, 11:41:22 AM
(Probably should have just posted this here in the microphone thread, apologies)

Greetings All,

I've been on and off trying to track down the white noise in my D-251 build for about a year now. I have noise tested the 6072a and its super quiet, Replaced the CT12 capsule, de-soldered the whole thing, cleaned it, re-soldered it up again, changed the output caps, twisted the audio wires in the power supply and kept them from the filter caps, tried filtering the B+.... all to no avail. The white noise makes it pretty un-usable for any voiceover/vocal or acoustic guitar application as the hiss is too noticeable.  I am going to post a few sample recordings, perhaps anyone has any ideas. Listen to the lead in before the guitar comes in... I am posting a recording with my D251 and next with my MK Audio U67. The 67 is dead quiet in the lead in...

251 link: https://www.dropbox.com/s/doga2sonunml4u6/Will%20She%20Be%20Gone%20%28251%29.mp3?dl=0

u67 link: https://www.dropbox.com/s/1dmqcloash2avqx/Will%20She%20Be%20Gone%20%28u67%20no%20filters%29.mp3?dl=0

Ideas Anyone?

I am out of them... Perhaps there is a qualified technician who may be able to troubleshoot this on their bench for a fee? Anyone out there servicing DIY microphones? Any help is so appreciated.

Thanks a ton!

Have you substituted a fixed cap for the capsule and checked for the noise?
Something else to think about is the tube socket, how clean is it? I have ultrasonic cleaned tube sockets.

How did you noise test the 6072a? Did you build a microphone circuit fragment using the same value grid resistor and place it in a metal shielding box and listen to it?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: bancho on June 01, 2018, 04:54:54 AM
I want to use toroidal tx for the PSU. What are the required current values for the secondaries? Are these correct / would these be ok?
200V - 0.1A 
9.5V - 0.5A
I searched the forum "million" times but couldn't find the answer (there are just few posts by kosi which were never answered)
Thanks!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: poctop on June 03, 2018, 09:15:22 PM
I want to use toroidal tx for the PSU. What are the required current values for the secondaries? Are these correct / would these be ok?
200V - 0.1A 
9.5V - 0.5A
I searched the forum "million" times but couldn't find the answer (there are just few posts by kosi which were never answered)
Thanks!

Secondary: 200VAC @ 10mA (~2VA)
Secondary: 9.5VAC @ 500mA (~5VA)

yes they would ,
best ,
D.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: rmburrow on June 04, 2018, 12:35:35 AM
Have you substituted a fixed cap for the capsule and checked for the noise?
Something else to think about is the tube socket, how clean is it? I have ultrasonic cleaned tube sockets.

How did you noise test the 6072a? Did you build a microphone circuit fragment using the same value grid resistor and place it in a metal shielding box and listen to it?

Good suggestions.  Is the noise still present immediately after the AC is turned off to the P/S yet the capacitors still hold charge?  Have you tried a battery supply (4 D cells in series for heater,  twenty 9 volt batteries in series for the HT?

Is this mic being used near (3 km or so) any known FM radio or TV transmitter locations?   One would hear the audio if RF interference (" RFI")  was from an AM station.   Over the air FM radio and digital television use different modulation techniques, but the microphone circuits can rectify the offending signal and create noise in the microphone.  Some mic manufacturers put a small ferrite bead between the capsule and the grid of the tube for RF suppression.    In any event, it is imperative that all metal work of the mic case including the head basket, screens, shields, etc. be thoroughly and electrically bonded together to minimize RFI problems.    The next problem area can be the mic to P/S cable.  Poor solder joints or unintentional ground loops result in hum or other noise.

Last but not least:  Is the output transformer correctly wired?  Does the primary or the secondary of the output transformer contain "split" windings that require interconnecting jumpers in addition to the usual input and output connections?  Forgetting the jumpers (if required) can rack up hours of troubleshooting time...  Do not give up; troubleshooting noise can be a "tough dog" problem.

Be careful when working around dangerous voltages associated with vacuum tube microphones.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: snaredrum on June 06, 2018, 04:51:16 AM
Secondary: 200VAC @ 10mA (~2VA)
Secondary: 9.5VAC @ 500mA (~5VA)

yes they would ,
best ,
D.
i try to find a new transfo for my apex PSU and it's very difficult ,  i look for  tips and make my own transformer :))
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Zebra_PD on June 10, 2018, 04:16:30 AM
1950’s Nos GE 6072 5-star tested for low noise/microphonics, the red/orange ink if u can get it.

The 6072 seems like the most logic choice since it was the original ones for the export version. But I haven't been able to located a good source for them in Europe. Any tips of a european store/source that not is extremely over priced and/reliable?

Otherwise has anyone used a high quality telefunken/phillips  tube like a ECC802 in there mic builds? They seem to be easier to find here in Europe?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: snaredrum on June 11, 2018, 02:30:39 PM
i try to find a new transfo for my apex PSU and it's very difficult ,  i look for  tips and make my own transformer :))

i have found in france for 17 euros a hand made transfo , i order 2 :))))
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: axlreddy on July 03, 2018, 02:52:59 PM
Hi,
I just finished my D251E, but all patterns sounded like cardioid.
I follow the schematic which made by Trans4funks1 on page1.
Here's my connection:
--------------------------------
7-XLR to Mic PCB
1- audio +
2- audio -
3- omni
4- heater
5- B+
6-  F8
7- GND
---------------------------------
AMI T14 to Mic PCB
1st pair
red - S+
Blue - P+
2nd pair
red - S-
blue - P-
----------------------------------
PSU 7pin-XLR connection
1 - pin2 on XLR3
2 - pin3 on XLR3
3 - pin1 on pattern switch
4 - heater on PCB
5 - B+ on PCB
6 - pin3 on pattern switch
7- GND to XLR3

The capsule is Tim's CT12.

I really need recommend.

Thanks.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on July 04, 2018, 09:29:57 PM
axlreddy check that you have a good connection to the rear membrane and backplate. Sometimes soldering can loosen the connection. Your capsule has 2 sets of connections to the backplates.  Perhaps try changing the connection to the rear backplate to the other side.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: axlreddy on July 04, 2018, 11:10:30 PM
axlreddy check that you have a good connection to the rear membrane and backplate. Sometimes soldering can loosen the connection. Your capsule has 2 sets of connections to the backplates.  Perhaps try changing the connection to the rear backplate to the other side.
Thanks for reply, I've checked the connection and changed the rear backplate to the other side, but the problem still there.

BTW, I got the sound on rear membrane only on omni after changing the backplate.(FB to RB, RB to FB)
Did it mean something?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on July 05, 2018, 07:02:34 AM
That just means that the capsule is working and the problem is with your connection to the rear backplate. Trace that cable back to the power supply.  Perhaps the relays?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: axlreddy on July 05, 2018, 09:33:57 AM
That just means that the capsule is working and the problem is somewhere else. Perhaps the relays?
Hi, Tim

Which one did you mean?
Relay on mic or relay on PSU?

I've some scratch on relay on mic.
(K1&K3, see the pic below with red circle)
Did it matter?
Sorry about that sounds a stupid question.
I'm new here.

Best
Axlreddy.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on July 05, 2018, 09:49:44 AM
check from the backplate all the way to the power supply. The fault is on that connection. A reversed component or a bad connection.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tommymariot on October 26, 2018, 06:30:07 PM
Hi Guys, I'm building a D-ela M 251E. I'm using poctop's pcb and chunger HT-11A body but I found my mic doesn't close.
Photos in attachments.
Can you help me to solve the problem?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tommymariot on October 26, 2018, 06:35:26 PM
other photo
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: duantro on October 26, 2018, 06:39:57 PM
Might need to file edge of relay slightly, if it is soldered and flush to pcb.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tommymariot on November 23, 2018, 09:15:53 PM
I just finished the mic and now I'd like to test the PSU with a dummy load. Can you suggest me some good values for a dummy load for this mic?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: tommymariot on November 25, 2018, 05:52:53 PM
Are these values correct for this mic?

B+ 120V/0.5A=240K 1/4W


H+ 6V/0.175A=33R 2W
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on November 25, 2018, 07:08:12 PM
Heater current of 6072 is 350mA

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: buckethead on November 26, 2018, 02:50:44 AM
Heater current of 6072 is 350mA

There's only one system in use -> only one to heat -> 175mA
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on November 26, 2018, 07:48:53 AM
There's only one system in use -> only one to heat -> 175mA

Fair enough. I always wire voltage to 9, and both 4+5 grounded.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: buckethead on November 26, 2018, 08:08:48 PM
Is there any reason why you're doing that? Sorry for the off topic talk - but would be interesting to know

As far as I remember, C12s only heat one half too. And some DIY clones use different systems each for stereo pairs, so you can swap tubes between mics, get more life out of those things...not a good idea to poison cathodes there
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on November 27, 2018, 09:17:58 AM
Just a habit of always tying off everything unused and open to ground – everywhere, not only the tube. Gives me quiet builds, so guess I just stuck with it.

I'll give it a try on the next one, and leave one heater open.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: JessJackson on December 02, 2018, 04:08:29 PM
wasup guys I've been using my 251 more and realized that the waveform it creates is lop sided, asymmetrical (heavier towards the bottom)

what do you think could be causing this? the tx?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 25, 2019, 12:52:42 PM
Hi guys,

Out of interest what have people using as bridging wire?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on January 25, 2019, 01:43:37 PM
PG_Sax: by bridging wire, are you referring to the hi-z wiring? Chunger sells a nice little package of small gauge Teflon (PTFE) coated stranded wire. I've also purchased some from Apex Jr but if you're not building a lot of gear, buying rolls of of different colours is way too expensive making Chunger's store your best bet.

Wherever you get it, get something small (26AWG or so), Teflon coated (not only heat resistant for soldering but also very hi-z) and stranded (less microphonic).
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on January 25, 2019, 01:47:59 PM
wasup guys I've been using my 251 more and realized that the waveform it creates is lop sided, asymmetrical (heavier towards the bottom)

what do you think could be causing this? the tx?

Jess, any progress on this? Does the mic sound OK? Did you view a waveform with a scope? Is your DC on (is the waveform asymmetrical or is it riding DC)? What is your quiescent current (measure VDC across R2 at idle)? Do you have another tube to try? Any hum?

I'm not the best around here for support like this but I noticed no one else replied.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 25, 2019, 02:22:48 PM
PG_Sax: by bridging wire, are you referring to the hi-z wiring? Chunger sells a nice little package of small gauge Teflon (PTFE) coated stranded wire. I've also purchased some from Apex Jr but if you're not building a lot of gear, buying rolls of of different colours is way too expensive making Chunger's store your best bet.

Wherever you get it, get something small (26AWG or so), Teflon coated (not only heat resistant for soldering but also very hi-z) and stranded (less microphonic).

Cheers Delta!

Yeah the bridge wiring in HiZ section. I have some teflon coated wire but from Dan's pictures he seems to be using some non coated stuff?

I assume that there is no advantage to using coated or non coated?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 25, 2019, 04:11:30 PM
Also can anyone clarify does the Relay 1 need to be grounded (to shield on 7 pin)?

I guess what I'm asking is does any other pin need to be linked to ground other than pin 7? It looks like Relay 1 should be grounded also?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on January 25, 2019, 04:30:24 PM
I getcha now. Looks like Dany used component leads to make the little "bridges" in his photo. This allows some structure when building the floating sections. Use your stranded Teflon to connect to the hi-z section (like the capsule leads).

Are you using Trans4funks1's schematic? You'll find it much easier to follow.

https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

Voltage applied to the coil of a relay will "energize" it, causing the contacts to change state. The above schematic shows the relays in a non-energized state. When a pattern selection is made on the power supply it either adds or removes 6VDC to the one side of the coil (1) so for it to energize, the other side of the coil (16) is tied to 0V. IIRC this is done via PCB.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 25, 2019, 04:42:56 PM
I getcha now. Looks like Dany used component leads to make the little "bridges" in his photo. This allows some structure when building the floating sections. Use your stranded Teflon to connect to the hi-z section (like the capsule leads).

Are you using Trans4funks1's schematic? You'll find it much easier to follow.

https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a06461.pdf

Voltage applied to the coil of a relay will "energize" it, causing the contacts to change state. The above schematic shows the relays in a non-energized state. When a pattern selection is made on the power supply it either adds or removes 6VDC to the one side of the coil (1) so for it to energize, the other side of the coil (16) is tied to 0V. IIRC this is done via PCB.

Cheers Delta! Appreciate your help. I was looking at that Schematic, Dan just mentioned in one of the posts that Relay 1 (which to him was on Pin 3 on the PSU was tied to XLR shield)? But that isn't the case on the schematic?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 25, 2019, 04:47:44 PM
I always run my cable the same way on the xlr cable pinout,
1-audio +
2-audio -
3 shield up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay voltage )
7 circuit ground

For AMI T14 it will be :

Blue , Blue    will be primary + and Primary -
red , red       will be secondary + and secondary -

hope this helps ,
Dan,


I actually made a little mistake here as there is 2 wire for the relay control , i will be making a drawing in a short moment ,
to make this all clear , for the mean time i will dit this post to add the proper xlr config for this particular build,
 
edit:

1-audio +
2-audio -
3- (Relay control 1)
cable shield up to xlr tab as well
4-heater
5 B+
6 Pattern control ( relay control 2  )
7 circuit ground

I have highlighted in bold the one I am wondering whether it is tied to the shield of xlr?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on January 29, 2019, 01:13:18 PM
Pin 3 is not tied to 0V or the shield! Pin three supplies voltage to pin 1 of K2 when supply is switched to omni.

I see the confusion. Dany uses the same pinout for his builds where pin 6 is pattern control, pin 7 is 0v and pin 3 is tied to the shield. He must've posted this in error as this build needs two pins for pattern control relays where others only needed one pattern pin. He then corrected it in the post you quoted.

Think of a variable pattern mic like the M49 or C12; changing of patterns in continuously variable pattern mics comes from a separate variable supply from the power supply. That variable supply is tied to the back membrane and when it reaches the same voltage as the front membrane you get omni, when it reaches the backplate voltage you get cardioid and when it becomes opposite of the front membrane you get figure 8.

In the 251, there is no separate pattern supply. The variable patterns are achieved by relay contacts changing how the membranes/backplate are tied to B+ and 0V. To achieve figure 8, pin 6 supplies voltage to K1 and K3 changing their states. To achieve omni, pin 3 supplies voltage to K2. With all three relays de-energized (as drawn in Trans4funks1's schematic) the mic will be in cardioid.

Review the schematic even if it is a lot to absorb - it's probably as clear as it can be in Trans4funks1's schematic - and try to get a grasp on the switching. Consider diodes as open. They reverse polarity so no current flows. They are there to protect the relays (flyback diodes).
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on January 30, 2019, 07:32:08 AM
Thanks for your help Delta.

Thats what I took from looking at the Schematic was just confused by the post as he left in ('cable shield up to xlr tab in both posts'). Couldn't understand why you would ground that  pin. I have the pins organised slightly differently on this build. Was just trying to be super vigilant as am waiting on some valves to fire the mic up.

Hopefully will get it working later on today. Will post up some sweeps when its working as I have a couple of transformers/coupling capacitors/valves to try. Be interesting to see what the differences will be.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: rockinrob86 on February 21, 2019, 12:36:45 PM
I am also having the dreaded "white noise" issue.  It is at about a -50db level with the gain on my UAD 1073 at 45.

I tried 4 different 12ay7s with no appreciable difference in the noise.  I guess next step is ruling out the capsule?

The mic was perfect after I built it a year ago, first noticed the problem a couple months back, but just assumed it was a noisy tube and hadn't had a chance to check.

Will the backplates show continuity in circuit?  Visual inspection of the hi-z section does not show anything.  I sprayed contact cleaner on one of the tubes I switched out with no difference. 
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on February 21, 2019, 06:32:53 PM
Well there are still quite a few  things you could check before the capsule, especially if it has been quieter before.
Clean everything, the pcb, around the relays, etc.
How have you been storing it? It should be kept in a plastic bag with a desiccant pouch.
Does it make noise after switching?
Capsule noise usually sounds like an uneven paper rustling sound not a constant hiss but so does any dirt.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: rockinrob86 on February 22, 2019, 09:10:11 AM
Thanks Tim

I found Matador's useful test here:
Try to narrow down where the noise is coming from.  I posted this several times in the thread, but the basic steps are:

1) First make sure you have a low impedance ground:  with everything powered off, check the resistance between ground on the PSU PCB and all ground points in the mike body, including all parts of the outside shell.  You should have less than 0.1 ohms everywhere in the mike
2)  Make a small length of wire with two small alligator clips, one on each end
3) Clip one end to ground on the PCB
4) Starting at the 'output' hard ground different points in the circuit:  then measure noise
a) the output of the coupling cap (where it enters the transformer) - it should be dead silent
b) the grid of the tube - this should only output the self noise of the tube
c) the capsule connection - this should only be the noise of the tube + HiZ components

You should be able to see the noise contribution of each stage this way.
--------------------------------------------------------------------------------------------------------------

After running this (I went through a 500uf Electrolytic capacitor because I was under the impression dead shorting stuff to ground wasn't the best way to do this) and I get near silence with headphones on and the gain turned up at every step. 

It would describe this sound as a "SSSSSSSSSSSSSSHHHHHHHHHH" white noise

I have been storing the mic in the "fancy" box with the velvet lining in an air conditioned room, but no dessicant pouches.  I ordered some of those, but also scrounged around and found one.  Put the mic back in the box with the pouch in there. 

The noise is steady regardless of switch setting, other than the quick pop/freakout thing all mics do when you switch patterns for a second.

The circuit was very clean, but I cleaned it again with isopropyl just to be sure, and confirmed all ptp connections were truly floating.  Solder joints look good.

If the capsule has taken on moisture or something, can it be saved with the pouches, or is it toast?  I would be very surprised, as I have taken good care of this mic.  It has maybe been left out for a few days here and there on the stand, but it has not been subject to temperature changes, humidity, etc.  I don't even really use it on vocals, it is more a go to room mic for drums, acoustic guitar, guitar cabs, etc.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on February 22, 2019, 03:30:01 PM
How are the connections at the capsule? Are they tight?
Do you have another capsule you could try? Or perhaps another mic to try the capsule in?
If it is the capsule and it's one of mine please contact me about how to ship it to me and I'll get it back to you asap.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: rockinrob86 on February 22, 2019, 03:34:45 PM
It's not one of yours, but thanks!  I am hoping to get one of yours in the near future for a different mic build, and appreciate the service on display here
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: rockinrob86 on February 23, 2019, 10:51:55 AM
It works!  Desiccant packs saved the day!

Will this cause any recurring issues, or if I keep it stored with the packs going forward it should be good?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gustav on March 18, 2019, 02:02:23 PM
Just finished a build for a friend who has been sitting on one of these for years, and dropped it off with me.

It has a pretty insistent, extremely loud hum going on.

No hum from the PSU with the mic unconnected.
Voltages seem fine.
Hum comes on with the heater, stays on as long as the PSU caps are charged.
I can wave a finger around the capsule/relay area, and it gets worse.
I can touch the base or the basket, and it lessens (still very loud, though).
I tried reversing the pins to the backplates, same same.
I haven't hooked up the relay switching yet, so just checking in cardioid (unless I am reading that incorrectly).
Can hear sound coming through when I scratch the head basket, so something is right.

Tim's capsule

(finished a C12 as well, seems the PSU is the same, except for  jumper added, using Tim's capsule as well, no problemo on that one).

Any pointers?

Gustav
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on March 18, 2019, 02:25:22 PM
Shielding? Ground loop?

I had grounding issues in an M49 build that caused a loud hum. I ended up changing my grounding scheme and that corrected the problem.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Erik2345 on March 18, 2019, 02:39:17 PM
This may be a delicate operation: switch capsules and see if the problem moves to the C12
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on March 18, 2019, 03:13:20 PM
Capsules don't hum. If you're getting a hum it's either a bad sheilding problem or if it concerns the capsule it is a broken connection.
Make sure all the connections are good to the capsule. How does it behave when switching patterns?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gustav on March 18, 2019, 03:44:04 PM
Thanks!

I wired up the selector.

I dont have an analyser to put on it, but I would describe it like I have two octaves of hum in cardioid, only the lower octave in omni, and only the higher octave in fig 8.

So, the switching is working, at least.

 :o

(Id rather not swap the capsule, since the C12 is working perfectly)

Ill go over the p2p assembly, give it a cleaning, and trace the ground through it - just wondering if there were any obvious caveats.


Gustav
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: RuudNL on March 18, 2019, 04:22:21 PM
Are you using a single layer headbasket?
Sometimes the openings in the mesh are big enough for a less than perfect Faraday cage effect. (Screening.)
I have heard from a lot of people who had hum problems with single layer headbaskets.
(It is not without reason that Neumann uses 3 layers of mesh in a lot of their microphones!)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gustav on March 19, 2019, 06:41:33 AM
Are you using a single layer headbasket?
Sometimes the openings in the mesh are big enough for a less than perfect Faraday cage effect. (Screening.)
I have heard from a lot of people who had hum problems with single layer headbaskets.
(It is not without reason that Neumann uses 3 layers of mesh in a lot of their microphones!)

I doubt its anything that esoteric - Getting very loud hum, completely drowning out signal.

Just going over all the soldering, components placement and the p2p section.

C3 is oriented incorrectly on the pictures in the first post, right?

Gustav

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: gyraf on March 19, 2019, 07:54:50 AM
from the description, I am pretty sure that you have a ground missing to the chassis/shield/mesh of the mic. Try beeping from ground (XLR3Pin1) to all parts of the mic to find what is not electrically connected to the rest..

Jakob E.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on March 19, 2019, 09:08:13 AM
A loose bottom bell can also cause shielding problems. Just tighten a bit more to make sure.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gustav on March 19, 2019, 10:25:49 AM
Went through all the ground point nodes on the mic PCB, -P had some gunk on it (had already cleaned up on the p2p section).

All good now, thanks for the help! :)

Just building these as a favour for friend who has had the parts for ages, so it would have sucked to give him back one not working :)

edit:this was fun, by the way!!!

Gustav
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Gustav on March 19, 2019, 10:50:09 AM
The pair...

Noting left but tidying up the cabling on the PSUs.

Gustav
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Banzai on March 20, 2019, 08:33:45 AM
If you haven't already, make sure to remove all paint from the top circle of the body sleeve where it connects with the headbasket. Same for the little cutout where the capsule plate tab sits in the body sleeve. These areas need clean contact for the body to shield properly.

It's why the bell can cause problems. When loose, the sleeve and capsule plate tab/headbasket might no longer be properly connected.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on March 27, 2019, 09:57:03 AM
Has anyone experimented with changing the plate voltage up and down? Thinking 55v-75v?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: axlreddy on March 30, 2019, 11:26:44 AM
Just finished mine!
The problem was sloved!
There are one jumper that I miss between R4(T2) and relay.

Thanks GroupDIY
(https://i.imgur.com/KuEZTgm.jpg)
(https://i.imgur.com/2LzOviW.jpg)
(https://i.imgur.com/iw1ZgaO.jpg)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on April 02, 2019, 06:56:37 AM
Just wondering whether anyone has any insight to this scenario I'm in,

Was having trouble getting the capsule polarisation to 55v even with the B+ trim pot set to minimum resistance.

When B+ was 120v polarisation voltage was 44v-45v.

So I increased the resistor to the plate from 100k to 125k. This allowed me to get 55v at capsule and the plate voltage was close to 62v.

Would it be better to change the voltage divider (to capsule) at R3 and R5 dropping R3 to increase voltage to capsule?

Any help much appreciated.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 02, 2019, 06:56:45 PM
How are you measuring your capsule voltage? Where exactly are you putting your VM?

You should be able to read your capsule votage at the R3/R5/R6 junction. To be sure your VM isn't loading the circuit, measure across R3 then subtract that from your measured B+. Result should be the same as what you measured across R5. Don't measure to the grid (R4). That should be 0V as virtually no current flows so assume it is and only reference ground.

The front backplate (plus rear backplate in omni & rear diaphragm in fig-8) sees 0V from the junction of the R4 & the grid. The front diaphragm (plus rear diaphragm in omni & rear backplate in fig-8) sees half of your B+ from the junction of R3 & R5. No current flows through R6 so if R3 & R5 are the same value, you get half of your B+. If you want to change the capsule voltage while keeping your B+ at 120V, change the R3/R5 voltage divider.

If you want 60V on your capsule and a B+ of 120, it's probably safe to assume you have 60V on the capsule if you have all the right component values (matching R3/R5). I think you'd hear some audible issues if you had current flowing where it shouldn't in your hi-z section.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on April 03, 2019, 04:28:08 PM
How are you measuring your capsule voltage? Where exactly are you putting your VM?

You should be able to read your capsule votage at the R3/R5/R6 junction. To be sure your VM isn't loading the circuit, measure across R3 then subtract that from your measured B+. Result should be the same as what you measured across R5. Don't measure to the grid (R4). That should be 0V as virtually no current flows so assume it is and only reference ground.

The front backplate (plus rear backplate in omni & rear diaphragm in fig-8) sees 0V from the junction of the R4 & the grid. The front diaphragm (plus rear diaphragm in omni & rear backplate in fig-8) sees half of your B+ from the junction of R3 & R5. No current flows through R6 so if R3 & R5 are the same value, you get half of your B+. If you want to change the capsule voltage while keeping your B+ at 120V, change the R3/R5 voltage divider.

If you want 60V on your capsule and a B+ of 120, it's probably safe to assume you have 60V on the capsule if you have all the right component values (matching R3/R5). I think you'd hear some audible issues if you had current flowing where it shouldn't in your hi-z section.
Thanks for your reply.

Yup thats where I'm measuring from. I can double check across R3 but have measured at R3 and R6.

The meter is loading the circuit slightly but then I would expect to see the same thing at R2 which I don't.

Basically there are 10v going walkabout after the voltage divider between R3 & R5. (ie voltage in 110v voltage out 45v)

Mic works great but just bugging me a little why I'm seeing this drop in voltage for the capsule.

With B+ at 110v I see 55v at plate as I should but 45v at the R3 and R6.

I have checked R3 and R5 and they are the same value. Its a weird anomaly.

Interestingly I'm running the plate voltage higher at the moment and the most I can get at R6 and R3 is 54v. I should say that I have now returned R2 back to its original value of 100k did have it at 125k to balance the voltage differential.

Just measured across R3 and R5 I see 54v across both of them which is the same voltage I see at the capsule. At the moment the B+ is at 134v so that would mean 80v at capsule! Which I think would mean no more capsule surely? As I said mic has been working great just recorded on it all day.

Can't see why my meter would load down 13v each side but maybe I'm wrong? Input impedance is 1Mohm on meter.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Avgatzeblouz on April 03, 2019, 10:29:28 PM
Just finished mine!
The problem was sloved!
There are one jumper that I miss between R4(T2) and relay.

Thanks GroupDIY
(https://i.imgur.com/KuEZTgm.jpg)
(https://i.imgur.com/2LzOviW.jpg)
(https://i.imgur.com/iw1ZgaO.jpg)

Hey, this body looks nice, which one is it ?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on April 04, 2019, 08:05:17 AM
Anyone with deeper knowledge know,

Is there any disadvantage to using the a 1/4w grid to ground to resistor at R4. I see most people including Dany put a 1/4w in there so I'm guessing not as can't see current / voltage being an issue. Also its 1/4w on the BOM, but on all Schematics its 1/2w.

Cheers
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 04, 2019, 08:46:32 AM
Nothing wrong with 1/4W.  Telefunken probably could only source 1/2W high value resistors.

Unless there is something wrong with your mic wiring, half of your B+ is at your capsule. 1M VM input impedance is quite low and will load the 500k resistors. Most modern meters will have an input impedance of 10M or greater in voltage mode.

You may want to find a voltmeter with a 10M input impedance , even for measuring your B+. Set your B+ for 120V if that's what it's supposed to be. If you want 55V at your capsule, change R3 & R5 for the correct voltage divider.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 04, 2019, 08:47:33 AM
Hey, this body looks nice, which one is it ?

I'm curious about this as well. Did you powder coat the mic & PS? Looks very nice!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on April 04, 2019, 09:09:21 AM
Nothing wrong with 1/4W.  Telefunken probably could only source 1/2W high value resistors.

Unless there is something wrong with your mic wiring, half of your B+ is at your capsule. 1M VM input impedance is quite low and will load the 500k resistors. Most modern meters will have an input impedance of 10M or greater in voltage mode.

You may want to find a voltmeter with a 10M input impedance , even for measuring your B+. Set your B+ for 120V if that's what it's supposed to be. If you want 55V at your capsule, change R3 & R5 for the correct voltage divider.

Cheers Delta!

I'm going to test with a different meter tomorrow that has a higher Input impedance (10M). I may build another circuit as well.

The B+ voltage was higher as I was testing the effect of more voltage to the tube. Have had the B+ at a lot of different levels.

I still don't understand why I would see 54v with the meter connected at R3 and ground? It's not in parallel to the 500k resistor then? So meter loading shouldn't be an issue should it?

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on April 04, 2019, 05:17:26 PM
By measuring at the junction of R3 to ground you are in parallel with R5.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: PG_Sax on April 04, 2019, 06:59:04 PM
Sweet! Thats excellent Delta, nice one!

Will confirm tomorrow with the other meter, fingers crossed!

By measuring at the junction of R3 to ground you are in parallel with R5.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: 100WChris on May 14, 2019, 05:48:42 AM
Hi,
i´m planning to build a ELA 251 based von the pcb-set from vintagemicrophonepcbkit.
Can somebody give me a hint, where i could buy a prpoer donor-mic in europa?!
Thanks
Chris
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: TillM on May 14, 2019, 12:18:04 PM
 you can take this
https://www.musicstore.de/de_DE/EUR/Fame-Audio-Pro-Series-VT-12/art-REC0009822-000

or look at Thomann. There is a T-Bone with the same mic body, you just had to drill the holes in the mic PSU for the capsule orientation switch.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: 100WChris on May 14, 2019, 05:34:32 PM
Thanks TillM,
i tried the tbone SCT-800, but both pcbs (mic, psu) do not fit!
I searched all over the www, but i could not find any of those Alctron HT-11-Mics in Europa :(
The Fame-Mic seems to be the only one, but it´s expensive… i could probably order a donor mic from Studio393 for less…
  :(
Is there no source for a HT-11-Style-Mic in Europa (below 200€…) ?!?
kind regards
Chris
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: cornell9 on September 13, 2019, 08:07:34 PM
Low Sensitivity Issue?

I was wondering if this 251 behavior was considered normal:

I have to add 45db of electronic gain in my audio editing program (on top of the 13db gain from my Lavry AD10 ADC) for spoken voice recordings within 6-12 inches of the microphone.  Same issue with my other ADC with built in gain.  This has been the case since building the mic about two years ago - it did not worsen over time.  Otherwise the audio quality is pretty good - a bit noisy due to the low signal but not too bad.

For those who built a 251 and are not using additional gain stages in between their mic power supply and ADC , how much total gain are you adding to reach good recording levels?

Transformer seems to be correctly wired.  Resistance at the end of the blue wire (primary resistance) and ground is 965 ohms - close to the 1k needed there.  S+ from the transformer goes to pin 1 of the microphone which goes to XLR pin 2 and S- goes to 2 of the mic which goes to pin 3 (bottom pin) of the XLR connector, per the wiring diagram.
Secondary (between two red transformer wires) measures 21 ohms - close to 25 needed.

Components measure within tolerance for all the ones I tested, except one:  137pf for c2 should be 100pf - this is a 2.5% tolerance cap - would this be worth replacing for the 251 circuit?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on September 16, 2019, 09:48:22 AM
What are you using for a preamp? 13dB from your ADC isn't enough to bring mic level signals up for recording on its own. If you've already added gain before your ADC and still requite 13dB from your ADC and 45 digitally then there is something wrong with your mic.

C2 @ 137pF will not cause your level to be low, it'll just take slightly more high end off - but probably not noticeable. Are you measuring components with a component tester or a DMM? Your DMM probably won't be accurate in the 100pF range.

Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: e.oelberg on September 16, 2019, 10:14:11 AM
Hi cornell

I suspect you are not using a mic pre. Although a tube mic has a PSU, which looks similar, you will need a preamp with Phantom power switched off. With something between 30 and 40 dB gain on the mic pre you feed the adc. Than you should have a nice spoken word amplification with still maybe 10dB headroom on the digital side and this is what you are aiming for.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: cornell9 on September 20, 2019, 09:57:38 AM
Thanks e.oelberg and Delta Sigma; I will order a mic pre. 

Am using the DER EE DE-5000 LCR meter for testing.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dapolk on October 19, 2019, 05:16:38 PM
Hi guys,

I built this mic about 3 years ago, it always sounded great and quiet, no issues of any kind across many sessions. Haven't used it much in the last year and just noticed a lingering noise issue that occurs when I make certain low vowel sounds and/or plosives. Here's  a short recording where you can hear it :

https://drive.google.com/file/d/1Lbm5J1s50biGCBkLHFdw3MCJZSk4OEjb/view?usp=sharing

(I was monitoring through speakers thus the slight feedback/ringing)

It's a CT12 capsule, NOS GE 6072, AMI T14. I went for a couple of the LF mods discussed earlier in the thread, though I can't remember exactly which ones. The output cap is a Sprague 3.6 uF, 125V wet tant.

Has always been stored in a zipped pouch with a dessicant pack.

Any help would be much appreciated!
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on October 20, 2019, 07:10:53 AM
does this happen only when speaking or singing into the mic at close range?  How about if you just move the mic through the air or play an instrument into it?

Try making sure all switches are clean by mechanically manipulating them and make sure the connections to the capsule are tight. examine to make sure there are no cracked or cold solder joints.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: dapolk on October 20, 2019, 04:45:51 PM
Thanks Tim - I worked the 3-way switch with contact cleaner, and touched up the solder joint going to ground in the mic's output section that looked a little suspicious. The joints w/ leads coming from the capsule all looked good.

It's dead quiet again now, even if I give it some strong plosives with my mouth touching the grill. Much appreciated!



Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on November 01, 2019, 10:04:43 PM
I've got a weird problem that just started today with my 251 build. In cardiod and fig8 only, there's an occasional squeaky sound like someone letting air out of a balloon slowly. It lasts for a couple seconds then goes away for a minute or so, then it comes back.

My capsule voltage is 110 (it's one of Tim's). I cycled the power a couple times, double checked the cable, etc. It went away for about an hour and then it came back again.

I'm going through the diagram and schematic and I'm not really seeing a cap that's only involved when the mic's in cardiod or figure 8, even though the behavior seems like something capacitor-y. Any ideas?
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on November 02, 2019, 05:08:49 AM
I'd say to try all the advice I gave dapolk. Is it after speaking/singing into it?  Sounds like it could be dirt or moisture.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: midwayfair on November 02, 2019, 09:58:54 PM
I'd say to try all the advice I gave dapolk. Is it after speaking/singing into it?  Sounds like it could be dirt or moisture.

I'll clean it. It was really moist yesterday since we had a tornado and a ton of rain, so maybe it was just humidity. Hasn't made the noise today.

I'm about 12 inches from the mic, off axis with a popguard, so I wasn't really considering any human-produced moisture. :)
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Tim Campbell on November 03, 2019, 05:46:10 AM
Storing mics with a dessicant pack in a plastic bag is always a good idea.
Title: Re: Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)
Post by: Delta Sigma on November 03, 2019, 06:34:19 PM
Storing mics with a dessicant pack in a plastic bag is always a good idea.

I like these guys because you can tell when they need to be recharged in the oven.
https://www.amazon.ca/Dry-Packs-Indicating-Silica-Aluminum-Canister/dp/B00967JZY0/