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

[trans4funks1]

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...

 

[micaddict]

Jess, the link is not working.
Well, not for me anyway.



Henk

 

[Dylan W]

One too many s's in sesssions

 

[Melodeath00]

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."

 

[Winetree]

Link doesn't work for me.

 

[Melodeath00]

Just take one "s" out: www.JessJackson.com/sessions/251Test.zip

 

[JessJackson]

Sorry fixed the link. it was late. 

 

[JessJackson]

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

 

[micaddict]

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.

 

[micaddict]

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

 

[Dylan W]

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?

 

[bockaudio]

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.

 

[JessJackson]

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

 

[Melodeath00]

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.

 

[JessJackson]

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.

 

[trans4funks1]

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.

 

[Melodeath00]

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

 

[electrisizer]

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...

 

[Dylan W]

Have you tried 5840/will it be a drop-in replacement?

 

[JessJackson]

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