Official C12 Clone - Build and Support Thread

[dmp]

The capsule in any configuration is significantly louder in figure of 8 than in cardioid mode. Whatever side is wired as the rear, in omni mode the rear is about 6 dB louder than in cardioid.

This sounds like a circuit problem. You have both 5000pf caps out of the circuit? Why?
You didn't remove the 1000pf did you?
And verify that the capsule back is connected to ground, and the center plate is connected to the 250 M

Maybe you removed the 1000pf and you are only getting capsule sound through the polarization resistors?

 

[Matador]

Hmm, very interesting problems.  In any of the 5 or 6 prototypes we built, non I would consider anywhere near "dark".

So dmnieto, I'm assuming you removed C10 and C11.  This is good for troubleshooting, as these are noise filters and won't effect the operation of the mike (other than noise wise, as you've already discovered).

Let's eliminate cap problems: with C10 and C11 removed, remove C13 and replace with a ceramic or mica cap.  These can tolerate a ton of soldering without damage (unlike styrene's).

...Sorry for the profanity, but if you guys could get this build to be EASY for people who can read and and solder...

This build thread has hundreds of detailed pictures about this build:  including the capsule itself.  What exactly isn't clear?

There are 4 connections on the PCB, and 4 connections on the capsule.

FC = front capsule
FB = front backplate
RB = rear backplate
RC = rear capsule

The only rub here is that FB and RB need to be tied together (either at the capsule or the PCB), as the C12 design is intended for use with 3-terminal capsules.  Bridging FB and RB turns a 4-terminal capsule into a 3-terminal one.

As for all of the specific capsule connections:  I don't have thousands of extra dollars to buy all of the possible capsules and take pictures / build prototypes of each of them.  I think the connection guide above should satisfy most cases.

 

[dmnieto]

So dmnieto, I'm assuming you removed C10 and C11.  This is good for troubleshooting, as these are noise filters and won't effect the operation of the mike (other than noise wise, as you've already discovered).
Let's eliminate cap problems: with C10 and C11 removed, remove C13 and replace with a ceramic or mica cap.  These can tolerate a ton of soldering without damage (unlike styrene's).

Yes, I removed C10 and C11, but they were fine...

Umm I already mailed the capsule back to Ben so he can try it, but I can try subbing C13 and check with the RK12 and see if gets a bit brighter. I doubt it is the problem as I could inject signal in C13 with the capsule disconnected and the circuit was flat up to 70KHz almost...

I can also drop the headless microphone to you if you want to chase the poltergeist; )

 

[Matador]

So dmnieto, I'm assuming you removed C10 and C11.  This is good for troubleshooting, as these are noise filters and won't effect the operation of the mike (other than noise wise, as you've already discovered).
Let's eliminate cap problems: with C10 and C11 removed, remove C13 and replace with a ceramic or mica cap.  These can tolerate a ton of soldering without damage (unlike styrene's).

Yes, I removed C10 and C11, but they were fine...

Umm I already mailed the capsule back to Ben so he can try it, but I can try subbing C13 and check with the RK12 and see if gets a bit brighter. I doubt it is the problem as I could inject signal in C13 with the capsule disconnected and the circuit was flat up to 70KHz almost...

I can also drop the headless microphone to you if you want to chase the poltergeist; )

Yes it sounds like you have your bases covered.

The C12 circuit does not add any high-frequency emphasis:  it's essentially "wire with gain", modulo the effects of the transformer at very low frequencies.

One trick I've used in the past is to pass in a constant amplitude signal from my DAW injected directly into the grid of the microphone, while monitoring the output.  Fletcher-Munson aside you should be able to monitor a sweep and see if the bare circuit becomes subjectively "quieter" as the frequency increases.

 

[dmnieto]

So dmnieto, I'm assuming you removed C10 and C11.  This is good for troubleshooting, as these are noise filters and won't effect the operation of the mike (other than noise wise, as you've already discovered).
Let's eliminate cap problems: with C10 and C11 removed, remove C13 and replace with a ceramic or mica cap.  These can tolerate a ton of soldering without damage (unlike styrene's).

Yes, I removed C10 and C11, but they were fine...

Umm I already mailed the capsule back to Ben so he can try it, but I can try subbing C13 and check with the RK12 and see if gets a bit brighter. I doubt it is the problem as I could inject signal in C13 with the capsule disconnected and the circuit was flat up to 70KHz almost...

I can also drop the headless microphone to you if you want to chase the poltergeist; )

Yes it sounds like you have your bases covered.

The C12 circuit does not add any high-frequency emphasis:  it's essentially "wire with gain", modulo the effects of the transformer at very low frequencies.

One trick I've used in the past is to pass in a constant amplitude signal from my DAW injected directly into the grid of the microphone, while monitoring the output.  Fletcher-Munson aside you should be able to monitor a sweep and see if the bare circuit becomes subjectively "quieter" as the frequency increases.

I have a HP 3562A, a HP8903a and a Keithley 2015P to do the freq analysis... wonderful instruments... My probes s***k unfortunatelly

 

[mica]

Thanks for bringing this to everyone's attention about the Beez Neez capsule. Im gonna be waiting to hear from Beez Neez about this "dark sound" problem before changing my capsule. How about TSKGUY's capsule.. Anyone tried that out yet in this build?

/M

 

[dmnieto]

Thanks for bringing this to everyone's attention about the Beez Neez capsule. Im gonna be waiting to hear from Beez Neez about this "dark sound" problem before changing my capsule. How about TSKGUY's capsule.. Anyone tried that out yes in this build?

/M

Hey Mica,

My capsule was dark, but it was muffled as well, and after talking with Veronica and Ben they believe it is defective. I sent it back and they are going check it out. Building these capsule is not for the faint-hearted as they need to be tuned properly. Look at the comments from Tim in this thread and Tskguy on his thread, there is variability to an extent that is not normally present in the chinese copies because of the manufacturing process.
My own RK12 has almost indistinguishable membranes, but if I compare to the sound samples from Tim's capsule, or Tskguy's capsule you can see that it is missing lots of detail. Same when comparing with a vintage C24.

The issue is that my particular CK12 capsule didnt work properly when installed with the mic. I had the opportunity to do a face to face with a C24 and we actually didnt even try as both the engineers thought there was a problem on the signal path because of the muffled sound coming from it.

I have not heard a lot of comments concerning the CK12 by fellow members, other than one in Beesneez's white thread raising praise for the one he received. I won't take my words as gospel as my particular case is still being tested. I would recommend that you engage directly with Ben about your concerns, if any, before you buy. This is what I am doing as well. For starters I have sent it back as I said and specifically asked them to hold on a new one till they check this one as I want to be sure that whatever is going on with this one does not reproduce on the one that I will eventually receive.

 

[micaddict]

Could still be something else.
But no worries; Ben will take care of you.

 

[dmnieto]

Could still be something else.
But no worries; Ben will take care of you.

Of course he will, I have full trust on him. I would have not bought it from him if I had any doubts.

 

[Pip]

Aren't C12s desirable because of their brightness? Anyway, I've got a Peluso capsule. Peluso told me that the red wires (front capsule and back capsule) should be in the according places. The two blue wires, they said should be hooked up to the "tube grid". I would really appreciate it if I could get clear directions as to how to solder these wires. On the PCB there are four spots

FC - Front capsule?
BC - Back capsule?
Two others that I can't remember offhand. I am a touring musician and I have to leave the project,so...I'm at a disadvantage. I'm not an electrician, but I can solder. It would be great if there were clear instructions on where to send/solder the wires for the few different C12 clone capsules that are available. Peluso, Beesneez, Advanced Audio, as well as Tim Campbell(which no one can get).
I want to believe that this is going to work, but I'm thinking that it's a wash. I don't want to just throw this mic in the trash. If it were to work, and, sound like a vintage C12 or at least sound good, I would use this mic on my next album, or, take it to a major studio to see how it stacks up. I took my Peluso P-47 to a studio and the engineer freaked out it sounded so good.
I WANT this mic. So, how the hell do I hook this f**cker up and get it to work?
Sorry for the profanity, but if you guys could get this build to be EASY for people who can read and and solder, like me, this mic would get used on big albums and tons of people would buy your product. Microphoneparts.com have great, easy to understand and execute instructions. If this C12 clone build is for electronic snobs, then you should state that in the beginning. I feel like Matador and Chunger are not snobs, and are really on to something here. But if you look at the final segments of the instructions, there is really no clear directions on how to solder the wires coming from the capsule. Do you guys want to be successful? Directions like "learn how to use a multi-meter" are not only insulting to musicians like me, but it's going to cost you the success that you've worked hard to achieve. I suggest you cater to the people who DON'T know how to even turn on a multi-meter.
So, in closing,how the fff do I hook up a Peluso capsule to your damn PCB that had gfing ground problems?

Its all in the build thread Rev. Yes FC = front capsule BC = back capsule FB = Front Backplate RB = Rear Backplate. The back plates should be tied together anyway at the capsule or the PC board. I have to say that it does not get any better than Chungers pictorial step by step build thread. So patience my brother and read the thread.

As to the comment about this mic ending up on hit records. What makes you think it hasn't already?! ;D

 

[mica]

Could still be something else.
But no worries; Ben will take care of you.

Yeah i really hope its just that one capsule. Would very much like to try the Beez Neez capsule in my build. Let us know what Ben says abount your capsule dmnieto..

Thx

/M

 

[Reverend]

Aren't C12s desirable because of their brightness? Anyway, I've got a Peluso capsule. Peluso told me that the red wires (front capsule and back capsule) should be in the according places. The two blue wires, they said should be hooked up to the "tube grid". I would really appreciate it if I could get clear directions as to how to solder these wires. On the PCB there are four spots

FC - Front capsule?
BC - Back capsule?
Two others that I can't remember offhand. I am a touring musician and I have to leave the project,so...I'm at a disadvantage. I'm not an electrician, but I can solder. It would be great if there were clear instructions on where to send/solder the wires for the few different C12 clone capsules that are available. Peluso, Beesneez, Advanced Audio, as well as Tim Campbell(which no one can get).
I want to believe that this is going to work, but I'm thinking that it's a wash. I don't want to just throw this mic in the trash. If it were to work, and, sound like a vintage C12 or at least sound good, I would use this mic on my next album, or, take it to a major studio to see how it stacks up. I took my Peluso P-47 to a studio and the engineer freaked out it sounded so good.
I WANT this mic. So, how the hell do I hook this f**cker up and get it to work?
Sorry for the profanity, but if you guys could get this build to be EASY for people who can read and and solder, like me, this mic would get used on big albums and tons of people would buy your product. Microphoneparts.com have great, easy to understand and execute instructions. If this C12 clone build is for electronic snobs, then you should state that in the beginning. I feel like Matador and Chunger are not snobs, and are really on to something here. But if you look at the final segments of the instructions, there is really no clear directions on how to solder the wires coming from the capsule. Do you guys want to be successful? Directions like "learn how to use a multi-meter" are not only insulting to musicians like me, but it's going to cost you the success that you've worked hard to achieve. I suggest you cater to the people who DON'T know how to even turn on a multi-meter.
So, in closing,how the fff do I hook up a Peluso capsule to your damn PCB that had gfing ground problems?

Its all in the build thread Rev. Yes FC = front capsule BC = back capsule FB = Front Backplate RB = Rear Backplate. The back plates should be tied together anyway at the capsule or the PC board. I have to say that it does not get any better than Chungers pictorial step by step build thread. So patience my brother and read the thread.

As to the comment about this mic ending up on hit records. What makes you think it hasn't already?! ;D

First off - Pip, thank you so much for this reply. I'm grateful for your comments. Second, your right about the fact that I don't know that this C12 Clone hasn't been used on big records. Your also right to point out that the pictures and instructions on this thread are beautiful. My frustrated rant should have been more measured. Matador and Chunger have got me through some bone headed mistakes like putting the three trimmer pots in the wrong place even though the thread clearly warns about that potential problem. But...
After looking at the thread about how to hook up the capsule again and again, I've come to the conclusion that this vital part of the build is somewhat hazy. I now see that the pictured Tim Campbell capsule seems to have a wire soldered, at the capsule, between the front back plate and rear back plate. Of course, I saw the part about hooking up two wires together on the original Alcatron test capsule, but how would I know to do that on the new, Tim Campbell, Peluso, or other Bees Kneez or whatever?  I will once again go look at this thread, but I didn't really get it and I think that if you guys go back and look at the part of the thread that describes the crucial instructions on wiring the new capsule to the PCB, you'll see how a noob like me would not know.  It just seems to me that, where you've got a few options on how to solder the leads from the capsule to the PCB, more in depth instruction was warranted. I'm seeing now what I think I've got wrong on my CK12 hook up, but I won't be off tour until April 16, when I'll have the chance to re-do and check. I want this mic really bad. So I'm going to be back on this thread with those results in April. Thanks for replying, Pip.

 

[dmnieto]

Just in case needs to debug, I am attaching the simulation of the frequency response of Matador's C12 and ELAM251 preamp using a 12ay7EH model... It is amusingly, quite accurate. Power supply is also simulated.

Please take into account that this is using my own realization of Matador's power supply, I had to modify the values of the resistors to accommodate my power supply (160V/12V)

ELAM 251:
plate: 62.24V grid: ~0V cathode: 1.04V Polarization: 60.112V
C12:
plate: 61.139V grid: -1.04V cathode: GND. Polarization: 59.99V

 

[Matador]

Just in case needs to debug, I am attaching the simulation of the frequency response of Matador's C12 and ELAM251 preamp using a 12ay7EH model...

This is with transformer and all of the filter caps in place?  Which transformer?

If you ever have chance to run it again, could you run it up to 100kHz?  I'm curious at what point the winding capacitance starts to dominate the response (I would guess in the 40-50kHz range).

I've also found another dirty little secret:  once can use a K67 type capsule in this circuit by adding a plate shunt cap (ELA M251 has a 100pF one, from plate to ground):  however size it at 470pF.  This moves the rolloff down to about 7kHz and lowers the piercing highs of this capsule type.

 

[dmnieto]

Just in case needs to debug, I am attaching the simulation of the frequency response of Matador's C12 and ELAM251 preamp using a 12ay7EH model...

This is with transformer and all of the filter caps in place?  Which transformer?

If you ever have chance to run it again, could you run it up to 100kHz?  I'm curious at what point the winding capacitance starts to dominate the response (I would guess in the 40-50kHz range).

I've also found another dirty little secret:  once can use a K67 type capsule in this circuit by adding a plate shunt cap (ELA M251 has a 100pF one, from plate to ground):  however size it at 470pF.  This moves the rolloff down to about 7kHz and lowers the piercing highs of this capsule type.

Yes, everything simulated.

I have simulated leakage, but not capacitance in the T14 as I don't have the values yet. Empirically, I have found that it is about 70KHz

 

[omribgr]

hey there
i have a problem with the apex 460 stock power supply transformer,
where can i buy a new one? something good

thanks a lot !

 

[dmnieto]

A bit more of the simulation...

It seems that the circuit has indeed resonance with the AMI T14 transformer at ~75KHz due to the winding capacitance. This issue may not appear (it does not in simulation) with the Cinemag transformer as the higher winding capacitance and different phasing seems to make the circuit flatter.

Those are the plots for the C12 circuit

 

[Dennyp]

Hey Guys,
A question.  I finished the build and I'm happy with the way the mic sounds.  to be honest, Ive never heard a real c12 or a u47 so my interest in finishing this build was purely one of getting more quality for less money.  since this mic is to be for personal use I decided to go with a k47 type capsule from AA mic's Dave Thomas but this kinda has me wondering? besides historical inaccuracy, are there any other reasons why a k47 type capsule does not make sense in the c12 circuit?  Like I said, I like the way the mic sounds but since i don't know any better is there something I'm missing?

Denny

 

[Matador]

Hey Guys,
A question.  I finished the build and I'm happy with the way the mic sounds.  to be honest, Ive never heard a real c12 or a u47 so my interest in finishing this build was purely one of getting more quality for less money.  since this mic is to be for personal use I decided to go with a k47 type capsule from AA mic's Dave Thomas but this kinda has me wondering? besides historical inaccuracy, are there any other reasons why a k47 type capsule does not make sense in the c12 circuit?  Like I said, I like the way the mic sounds but since i don't know any better is there something I'm missing?

Denny

No reason not to use a K47-type capsule.  The tube doesn't care.

 

[chunger]

It's DIY  This is a nice flat response tube mic circuit.  That can use "still available" tubes of various kinds.  If you like the more mid-forward Neumann style voicing of the center terminated capsule, go for the k47, m7, or whatever other flat response capsule suits your application!  The pedigree of the sound should not be compromised in a hybrid configuration.