Official C12 Clone - Build and Support Thread

[vinylwall]

Yes, I can do that.  I'll update the schematic bundle (largely unchanged expect for a few component values) and BOM.

Hi Matador.  Will you have a chance to update the docs for v1.4 soon?  I'm ready to roll on this now

Argh - my password appears to have reset which is causing my upload to fail.

If you PM me your email address I'll email the PDF bundle while I fix the account problem on my web site.

I've PM'd my email.  Thanks Matador.  Jimi Ray

 

[vinylwall]

Chung and Matador.  Have you guys built a v1.4 mic with the production boards, or just the prototypes? 

I have some voltage weirdness that I'm not understanding.

R17 - I have exactly the same voltage on each side of R17 100k (112v).  [On my first build I have 112v one side and 65v on the other.]  The resistor itself measures 99.9k on my meter, so it appears correct.  Why would I still have 112v on the other side of it?

R15 - On R15 220m, I have -3.5v on one side and .04v on the other.  [In my first build I had -3.5v and 9.98v.]

I have similar very low readings at C13 (-.05v) and -.05v at the grid connection.

I've double checked all resistor values with my meter and they are placed correctly.

What do you think may be happening here?

Also, the PSU PCB has an extra connector marked "GND" and "HEATER -".  What do I connect here? (see photo)

Thanks.

 

[chunger]

All new boards have changed over to a new revision. . . the heater ground has been floated to allow negative heater supply if desired for U67 application. . . thus the extra screw terminal.  Complete instructions here:

http://groupdiy.com/index.php?topic=58054.0

To your specific question, here is the jumper you need for C12 application (positive heater supply).  Place a wire jumper between "heater -" and "GND".

 

[vinylwall]

Thanks Chunger.  That did the trick!  Works great now.

 

[vinylwall]

I started with MicDaddy's build he was having problems with.  Very nice paint job on the mic body.  I decided to rebuild it with MataChung's v1.4 C12 PCB's.  Type 1 C12 headbasket from Chunger.  A replacement Beesneez CK12 capsule from Ben and Veronica.  AMI T14 transformer.  GE 6072A tube:

 

[vinylwall]

... back inside:

 

[vinylwall]

... assembled mic:

 

[vinylwall]

... PSU inside:

 

[vinylwall]

... front closup:

 

[vinylwall]

... rear closup:

 

[MicDaddy]

Ah looks familiar!  ;D

Glad you got some good use of it, may I ask if that's the same capsule you got from me or did you end up getting Ben and Veronica to swip swap it?

 

[vinylwall]

Hi MicDaddy!  I got a replacement capsule from a different build I was trying (an ELA M 251 - but the backplates weren't isolated for some reason - they let me keep this one so I used it on this build).  They were very good about replacing it.  I still have the capsule you sent with the original kit.  At some point I plan on doing another build and using that capsule to see if I get the same results you were battling.  In the end, with this build, I decided to try the new v1.4 boards from MataChung with your parts.

 

[MicDaddy]

Hey Jimi, probably best, I frankenwerked that board over pretty good.  ;D

I couldn't tell a bit of difference from between the wima and styrene.

Did you redo the psu?

Congrats, glad you will get some good use of it!!

 

[vinylwall]

Yeah, since the PSU PCB came with the mic PCB, I just did that at the same time, but I plan to use your PCB with a different build as well.

 

[geoff004]

Sorry this isn't 100% on topic, but does anyone have a part number for the power switch on the power supply?

I had one go bad (same power supply box but different project) and need to replace it.

Thanks in advance.

 

[Phrazemaster]

Just a small find: cheap cheap Vishay 33M metal glaze resistors...

http://www.mouser.com/ProductDetail/Vishay-BC-Components/VR37000003305JA100/?qs=sGAEpiMZZMtG0KNrPCHnjeX%2fDW687SXcV63D0ozMs0Y%3d

 

[zandru]

Thanks Mata-Chung,

Another AKG “style” C-12 custom mic build that utilizes the original
circuit  design, an accurate reproduction CK-12 type capsule, GE JAN
6072A tube  along with an AMI T-14 transformer. Sounds most true in
all respects. This mic was completed over 8 months ago and since then
has been continually put through the wringer many times with great success. 

 

[Phrazemaster]

Question for Matador... Can I use a 100V cap in place of the Erse output cap? I don't know enough about the circuit to make that judgment. Also, what is the dimension of the capacitor cutout? Or the largest cap that would fit? I have not yet received the kit to measure...

Thanks - what tremendous support you supply here! Much appreciated.

Mike

 

[TLRT]

We prepared a custom PSU case for my projects, I also found a local company who can manufacture custom shielded toriods, I'm curious anybody tried that?  Is there any difference between the stock altron trannies and the toroids? Is it worth the hassle?

 

[TLRT]

I have some if needed from unused alctron psus, however I'm in EU so the shipping costs more that the switch itself...

Sorry this isn't 100% on topic, but does anyone have a part number for the power switch on the power supply?

I had one go bad (same power supply box but different project) and need to replace it.

Thanks in advance.