Official C12 Clone - Build and Support Thread

[chunger]

Hi everybody !

I'm about to step up and build myself a c12 !
I have one question regarding the power supply.. In every build guide, you're using the one already in place in the mic psu !
I'd like to build my own power supply in an other case.. But I can't find any toroidal transformer with 200v & 9V..
Do you know where I can find one?
Thanks in advance for your answer

Hi Sinkia,

You may want to take a look at this Antek AS-05T200-50VA 200V transformer http://www.antekinc.com/as-05t200-50va-200v-transformer/ .

It has 200V, 180V, and 6.3V outputs.  The heater circuit should be able to run from 6.3V .  I would however wait for Matador to confirm.

 

[chunger]

Here's some specs on the Antek transformer

 

[Sinkia]

Hi Sinkia,

You may want to take a look at this Antek AS-05T200-50VA 200V transformer http://www.antekinc.com/as-05t200-50va-200v-transformer/ .

It has 200V, 180V, and 6.3V outputs.  The heater circuit should be able to run from 6.3V .  I would however wait for Matador to confirm.

Yeah !! Thx Chunger !
I’ll make an order from you anytime soon

 

[Matador]

I covered using a 6.3VAC secondary in reply #2339.

 

[chunger]

I covered using a 6.3VAC secondary in reply #2339.

Ah!  So not enough voltage to work in spec. . . Can you run the 6.3V coils in series and do 12.6V input?

I guess the other obvious solution that's sure to work would be to use two separate smaller toroids.  One 200V and one 9V.

 

[Sinkia]

Ah!  So not enough voltage to work in spec. . . Can you run the 6.3V coils in series and do 12.6V input?

I guess the other obvious solution that's sure to work would be to use two separate smaller toroids.  One 200V and one 9V.

I think I'll just order the full kit with power box and make it easier...  :-X
But thanks for your help both of you !

 

[Matador]

Ah!  So not enough voltage to work in spec. . . Can you run the 6.3V coils in series and do 12.6V input?

I guess the other obvious solution that's sure to work would be to use two separate smaller toroids.  One 200V and one 9V.

Actually someone did those mods (swapping in the TLV part and reducing the series resistors) and wrote back that it trims to 6.3V just fine. and the microphone worked just fine as well.

Also keep in mind that 50VA is about 48VA more than is needed for this design.

 

[Neutrino]

Actually someone did those mods (swapping in the TLV part and reducing the series resistors) and wrote back that it trims to 6.3V just fine. and the microphone worked just fine as well.

Also keep in mind that 50VA is about 48VA more than is needed for this design.

I confirm this. I used a toroidal transformer from tube-town with a 6.3 V secondary. With the mod as described by Matador, I was able to trim the voltage to 6.3 V at the microphone.

 

[Neutrino]

Since I'm here, another question on a slightly different the topic 

I'm currently fine-tuning my 251 to adjust the sound more to my liking: In the current configuration (Tim Campbell CT12 capsule, GE 6072A 5-Star tube and Haufe transformer) I like the high-end very much, but I'm missing some warmth in the lower midrange on vocals.

So I ordered two 14-1-like transformer from Sowter to see how it would affect the sound. The Sowter however is somewhat larger and won't fit into the bottom bell so well. There is however a place on the PCB closer to the high-impedance section, where it would fit (see position in attached picture). Are there any reasons against putting it there, like induced noise due to proximity of the transformer?

Thanks in advance, guys! 

 

[Neutrino]

I'm currently trying to tweak my 251s in order to achieve somewhat more warmth in the lower midrange which I find lacking. My original configuration is:

- Chunger kit
- Tim Campbell CT12 Capsule
- GE 6072A 5-Star tube from Christian Whitmore
- Haufe 14-1 transformer

So far I have tried to exchange the transformer by a similar model from Sowter and the output cap by a 2.2 uF Metal-Paper cap. However, in a blind test comparing with the original configuration (I have built 2 mics) I can hardly tell the two apart.

Which modification would you recommend to achieve a more pronounced lower midrange?

 

[Matador]

Hmm, the balanced frequency response is kind of the signature trait of the C12.  8)

You might try simultaneously rolling off the low end and the high end to make the overall response more midrange focused.  Try reducing the output cap down to 0.47uF, and increasing the size of the plate shunt capacitor to 1nF. 

 

[creation]

I have looked for the answer to this question, but damned if I can find it. Using 100M resistors in place of 250M and 30M? Since the BOM has 8 of them, I am assuming they are used two in series for the 250Ms and two in parallel for the 30Ms. Correct me if I am wrong about this. Also, if anyone is interested, I found an alternative to the MOX-30002506FE. It is not thick film, but it is 1%, 200ppm, 0.5w, 250M.  They cost $0.29 and overnight shipping is free.  I used it in my C12 build, seems to work.
https://www.arrow.com/en/products/hva05fa250m/stackpole-electronics?gclid=Cj0KCQiAg_HhBRDNARIsAGHLV51Ysx2uWuX_lvb2ORk7NqCZ7nxL2-2oKDZUPT-iRD4cVt6t9S1tGqkaAg_TEALw_wcB

 

[doggy6812]

Hey guys, my mic sounds pretty good but it is stuck n figure 8.  I’ve only seen  one connection point for backplate. Should there be 2? If so can you instruct me as to where front backplate and rear backplate points are? Thank you guys!

 

[justinheronmusic]

Does anyone have a part number for the Lorlin switch that is displayed in Chunger's build guide?

 

[Matador]

The Mouser part # is 10WA364 (Lorlin 1 pole, 12 position).  The Lorlin part # is CK1454.

 

[MPCNYC]

I don't think it's in the BOM?? What's the part number for the 0 ohm SMD resistor?

Thanks....

 

[kcatthedog]

C12 to 251, I built mine a while back and the build thread contained a reference to switching 3 parts for 251 performance.

That seems not in current thread, csn you tell me where to find it or remind if the parts and their placement?’

Thanks.

 

[plugged1]

First(second?) post, having problems posting. C12 build done, it’s stuck in omni polar pattern. Loren switch not doing anything. Any ideas? I tested the switch after I assembled it and it tested the same as noted in this thread, it just seems to have one setting-omni. I disconnected the rear capsule for now and it sounds great, it’s just strictly cardiod until I can figure out why it’s not changing.

 

[plugged1]

Hey guys, my mic sounds pretty good but it is stuck n figure 8.  I’ve only seen  one connection point for backplate. Should there be 2? If so can you instruct me as to where front backplate and rear backplate points are? Thank you guys!

Sounds very similar to my problem. If I figure it out before someone responds I will post how I fixed it. I’m thinking it may be a ground issue. I have one of the RK12 type capsules that only has 1 backplate wire and mine is doing the same thing I think it is something else. But yeah same problem, sounds great but stuck on omni/figure 8.

I fixed it the wires on #1 and #9 on the Lorin switch were swapped. I had to install it upside down or the knob would have pointed downward away from the polar labels. But now it’s totally backwards. Doesn’t matter still works.

 

[doggy6812]

Hey guys!! I am build a PS and I’m having a little trouble. This is my 2nd mic. My first one went smooth.  The transformer on the power supply is not right, I think. One side reads 120 on both blue wires. The 9.5 side reads 13.5 on one yellow wire and 8.2 on the other. I can’t get the voltages to a good spot. What sgould I do?