Official C12 Clone - Build and Support Thread

[ln76d]

Just wanted to thank-you and kudos to you LN76 because you always provide such interesting and well-thought out ideas! Thanks for being such a great asset to this community.

Mike

Thank you Mike
:-[

 

[DDay]

The build thread is careful to denote that tubes should be trimmed before the capsule is connected, as some capsules say to never exceed 130V or somewhere similar.

So, for the purpose of setting the B+ correctly, it's acceptable to plug the microphone into the PSU without a capsule connected to the PCB?

 

[Matador]

So, for the purpose of setting the B+ correctly, it's acceptable to plug the microphone into the PSU without a capsule connected to the PCB?

Absolutely.  If you want to evaluate the self-noise of the tube and high-impedance sections without a capsule, you can replace the capsule with a small 50pF cap.  But it's fine to just leave it disconnected. 

Just remember that before evaluating noise, make sure the outer brass body tube is installed, or else all you will hear is 60Hz hum.

 

[micaddict]

50 Hz probably. 

But he wouldn't want that, either.

 

[Diegel]

Everytime I check the microphone parts kit for the c12 is always sold out on studio939's website.  Is there any other place to get it or any ideas how often they have it in stock?

http://store.studio939.com/product/c12-microphone-parts-kit

 

[Matador]

Everytime I check the microphone parts kit for the c12 is always sold out on studio939's website.  Is there any other place to get it or any ideas how often they have it in stock?

http://store.studio939.com/product/c12-microphone-parts-kit

You could try sending Chunger a PM and asking him directly.

 

[wowi]

Hi, i have a little miracle here. I build a stereo set and one is working correct and one has only minimal output.
I swapped everything (capsule, transformer, tube, all capacitors) and the problem remains on the second mic.
I checked every single resistor: nothing.
I checked all voltages and the difference is at  R15/C13. The working mic has -1 V and the non working 0,04V at this point.

Somebody got an idea ?

 

[chefducuisine]

Check the backplate connections of the capsule. Also check if the backplate halves are connected to each other (typically this is done via the capsule holder if you are using Tim's).

 

[wowi]

Hi Christian. I checked the backplate connections and they are connected directly at Tims capsule.
When i split them, i get full output !!!!  My stomach says, the tube pcb is suspect, but i can't find anything.
The non working mic was build with TG2, TP2 and TK2. And yes, i realized, they are in the opposite order. Like i said: a miracle

 

[Matador]

I checked all voltages and the difference is at  R15/C13. The working mic has -1 V and the non working 0,04V at this point.

Somebody got an idea ?

R15/C13 is the tube grid.  You can't measure there.

What is the P4 node right where it enters the mike PCB at the bottom for the working and non-working cases?

 

[wowi]

Hi Matador, on P4 i measure -1V on both mics. I can change the psu and the problem remains in the same mic.

 

[Matador]

Can you take a picture of your capsule connections in both cases, as well as where the capsule leads attach to the PCB (again, in both cases).

Can you turn your non-working mike into a working mike by *just* swapping the capsule (nothing else)?

 

[wowi]

No, i can't make the non working mic working by changing the capsule , transformer or tube. I tried everything. I can make a picture of the capsule connections tomorrow if you want, but i am pretty shure, the are ok. I changed the capsule two times and in this case i must made the same error for three times. 

 

[wowi]

I double checked the capsule connections again. These are identical between the working and the non working mic. I have only these two hints:
1. The great different measures at the grid
2. Getting full output when cutting the connection between the backplates. (Which is very confusing for me)

By the way: The working mic sounds fantastic. Thanks for your work. ;D

 

[Tim Campbell]

Since you have already proved to yourself that it isn't the capsule at fault I would recommend  not soldering/desoldering  the capsule connections further. The risk of damage is too great to such a delicate part. Even the heat used is destructive. I tin all my solder tags with old fashion lead solder to minimize the heat necessary to make good connections.

The scenario you describe would lead me to believe you have a short to ground in your rear capsule connection. Perhaps a solder bridge or dirty pcb.

 

[Green Slime]

Has anyone or any manufacturer ever made a C12 style body (skinny/tall) as opposed to the more popular 251?

 

[micaddict]

Flea makes a pricey but excellent copy of the original.
Ami TAB has a good one, too.

Alctron HT-11 (Apex 460) with C12-style headbasket comes sort of close, but is a little wider.
Also, the quality, albeit good enough for microphone use, is not in the Flea league.
It's a lot less expensive, though.

 

[micaddict]

Oh, and welcome to this place BTW. 

 

[chunger]

Has anyone or any manufacturer ever made a C12 style body (skinny/tall) as opposed to the more popular 251?

I may have located a solution, but it would be many months before anything materializes for a more budget friendly skinny body.

 

[tonzauber]

Has anyone or any manufacturer ever made a C12 style body (skinny/tall) as opposed to the more popular 251?

I may have located a solution, but it would be many months before anything materializes for a more budget friendly skinny body.

I'd be in for three....