Official C12 Clone - Build and Support Thread

[HellfireStudios]

I used Loctite Go2 Glue on my single layer headbasket from Chunger, and it did the trick. Check out my earlier posts on the subject for more details about the glue and how where to apply it. I noticed one person had a hard time finding it. I found it in both Target and Wal-Mart chains (usually in their "hardware" sections).
I realize after reviewing this post that it may look like I own loctite. I am in no way affiliated with them. I just like most of their adhesives.

-James-

BTW, here is the finished mic. Sorry it took so long to get a pic up here.

 

[Melodeath00]

Thanks for posting. The ring is completely gone?

 

[HellfireStudios]

Yeah. I just get a dull thud like tapping the other metal parts of the mic. Just make sure you only do one side of the support ring at a time.
I recommend laying the head basket on its side with supports to keep it from moving, and applying the glue to back of the rail that is facing down. Use a toothpick to push the glue between the holes in the mesh making sure the glue makes contact with the rail. In 30 minutes, rotate the headbasket, and repeat. Next, comes the base ring. Add plenty of glue here to really dampen things. BTW, painter's tape will save you a lot of cleanup later. Let the glue fully cure before reattaching to the mic. If it still rings, add more glue.

-James-

 

[Spencerleehorton]

HI All,

having some bubble ans swooshing noises on my build:

voltages on tube are: 1=53.5v, pin 4=6.24v all others are 0v

voltages on r16 = 38v, 1000j/630v = 1.855v

for both 250m resistors i have used a 200mb + 68M is this ok to get away with?

1uf = 54.1v
r17 100k = 93.4v left leg 53.5v right leg
the lower 250m (268m) 1.929v right leg 45.7v

im not quite sure i have the capsule wired in correctly?

fb =  side
rb = side
fc = front edge
rc = rear edge

and i have connected both side connection together, hope thats right?

any help would be great.

regards

Spence.

 

[Matador]

Looks pretty close.  B+ is low:  should be 120V, but with 93 that's about 45V polarization voltage which means you'll loose 6-10dB off sensitivity.  Would cause what you are describing though.

Pops are fizzy sounds sound like leakage currents to me:  how well did you scrub the area around the telfon standoff's with IPA before you finished everything?

 

[Spencerleehorton]

hi,

i will clean thoroughly and put back together and was gonna put a different connector on there as well.

regards

Spence.

 

[chrispsound]

I would like to build Matadors C12 power supply PCB into another enclosure and have a power transformer whose secondary HT winding is rated at 200V@10mA and 12V 1A on the 2ndd secondary winding.  I know the microphone draws around 1mA (Not including the heaters) so the 10mA spec on the transformers HT winding should not be a problem.  My question is, does having 4 R-C filtering stages effect the power transformers VA limit?  Should one consider getting a transformer that has a higher VA rating if there are a large number of passive filtering stages, or does it not matter?  Thanks, ChrisP

 

[Matador]

In short, it doesn't matter.

The 1mA current flows through the filters.  There is no DC path to ground through the filter caps.

 

[scott_humphrey]

I finished one of these with a Cinemag CM-2480 xformer and Tim Campbell capsule. It sounds GREAT! Worked without a hitch on first power up!

Here's a tip for anyone who might want to improve the build. You can purchase a staking tool to attach the turrets to the board here:

http://www.turretboards.com

Click on the "turret tools" link, and choose the "desktop staking tools kit."

OK, now it's time to build a second one….

THANK YOU, MATADOR!

 

[Spencerleehorton]

Hi All,

pardon my ignorance but what are the teflon stand offs?

Pops are fizzy sounds sound like leakage currents to me:  how well did you scrub the area around the telfon standoff's with IPA before you finished everything?

regards

Spence.

 

[Spencerleehorton]

Hi,

to say im a little confused is a small understatement!! maybe having a bad day but here goes!

the labelling im finding very confusing and cant get my head around how to wire up the psu to the mic:

on the psu i have the following to the 7 pin XLR

pin 1 = p5
pin 2 = p8
pin 3 = p3
pin 4 = p4
pin 5 = to pin 3 on XLR output
pin 6 = to pin 2 on XLR output
pin 7 = p6

on the mic pcb i have the following:

pin 1 = p5
pin 2 = p8
pin 3 = p3
pin 4 = p4
pin 5 = transformer +
pin 6 = transformer -
pin 7 = p6

is this correct?

regards

Spence.

 

[Pip]

Hi,

to say im a little confused is a small understatement!! maybe having a bad day but here goes!

the labelling im finding very confusing and cant get my head around how to wire up the psu to the mic:

on the psu i have the following to the 7 pin XLR

pin 1 = p5
pin 2 = p8
pin 3 = p3
pin 4 = p4
pin 5 = to pin 3 on XLR output
pin 6 = to pin 2 on XLR output
pin 7 = p6

on the mic pcb i have the following:

pin 1 = p5
pin 2 = p8
pin 3 = p3
pin 4 = p4
pin 5 = transformer +
pin 6 = transformer -
pin 7 = p6

is this correct?

regards

Spence.

Yes except for audio outs pin 3 should be audio (-) pin 2 audio (+) as per 3 pin XLR audio standard. So just reverse your connections on PSU 3 pin XLR. It is mis-stated in Chungers wonderful build thread.

 

[Pip]

Hi All,

pardon my ignorance but what are the teflon stand offs?

Pops are fizzy sounds sound like leakage currents to me:  how well did you scrub the area around the telfon standoff's with IPA before you finished everything?

regards

Spence.

The teflon covered pins you should use for the capsule connections see Chungers build thread.

 

[Pip]

So today I changed the Phillips JAN 6072 Tube that I used for the build to a GE 5 star 6072. Big difference. The output went down a bit but so did the annoying sibilant high end.

I am using Mr. Campbells capsule and it was sounding good but now I think it sounds better. A friend of mine is using it in his studio which is very busy right now. It was getting good reviews with the original tube on everything except vocals. It was to sibilant. Stay tuned I will report back.

 

[Spencerleehorton]

hi pip,

so just to be 100% clear, this is the correct way to wire the psu 7 pin connector and the mic 7 pin connector:

pin 1 = p5
pin 2 = p3
pin 3 = p8
pin 4 = p4
pin 5 = to pin 3 on XLR output
pin 6 = to pin 2 on XLR output
pin 7 = p6

is this ok?


regards

Spence.

 

[Matador]

Just to be clear, you are free to assign your own mapping from signals to wires on the XLR.  What matters most is that you are consistent between the mike PCB and the PSU.

The mapping shown will work fine.

 

[Spencerleehorton]

hi matador,

ok thats great thanks, one other thing was that i didnt use teflon stand offs, i used the same bits i used for mounting the resistors and caps, will this be problem?
they are soldered in on the bottom of the board on chungers thread, but are they not ment to be soldered in on the top side?

regards

SPence.

 

[Spencerleehorton]

hi all,

have wired back up and seem to be getting much better S/N now, all crackles and bubbles gone, first turned on and got them but they went after about 2 minutes (tube burning in maybe?)
only getting 90v on B+?  and adjusting B+ doesnt do anything? getting correct voltages everywhere else.
Also i suspect i have the wrong ratio transformer in there as i tested the ohms and it was 68ohm and 1428ohm pri/sec on my turns calculator this puts it at 5:1 ratio?
have plugged in and get a very trebly low signal?

getting there now but still a few hurdles!!!

regards

Spence.

 

[Matador]

It should be a step down - the higher impedance side should be the primary.

You should have 40-50v adjustment on B+.  I suspect you have the low ohms pot in the incorrect place (the B+ trimmer should be 100K, or read 104 on top).

 

[Toure14]

I used Loctite Go2 Glue on my single layer headbasket from Chunger, and it did the trick. Check out my earlier posts on the subject for more details about the glue and how where to apply it. I noticed one person had a hard time finding it. I found it in both Target and Wal-Mart chains (usually in their "hardware" sections).
I realize after reviewing this post that it may look like I own loctite. I am in no way affiliated with them. I just like most of their adhesives.

-James-

BTW, here is the finished mic. Sorry it took so long to get a pic up here.

Where did you get the nice badge made for the mic?