Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)

[kidvybes]

...website: http://blackspademics.com/

 

[kidvybes]

...and...

 

[stevesteve50]

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

 

[PhatPlanetStudios]

...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!

 

[kidvybes]

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

 

[Lowfreq]

Wow!! Those mic bodies look great.

 

[Tim Campbell]

Hey Steve,
It sounds like you have a short or are missing a connection to your rear backplate or membrane.

 

[chefducuisine]

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

 

[stevesteve50]

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.

 

[Celinara]

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!~

 

[JessJackson]

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?

 

[Celinara]

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!

 

[Bowie]

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).

 

[atticmike]

...and...

How much is the body and basket?

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

Mike

 

[poctop]

...and...

How much is the body and basket?

And to all the others, including Dan 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,

 

[atticmike]

...and...

How much is the body and basket?

And to all the others, including Dan 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

 

[poctop]

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

 

[atticmike]

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.

 

[Banzai]

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.

 

[atticmike]

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?