chunger

Re: Official C12 Clone - Build and Support Thread
« Reply #2460 on: November 04, 2018, 10:54:18 PM »
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.

DIY photo documentaries consolidated here:  http://studio939.blogspot.com


chunger

Re: Official C12 Clone - Build and Support Thread
« Reply #2461 on: November 04, 2018, 10:59:39 PM »
Here's some specs on the Antek transformer

DIY photo documentaries consolidated here:  http://studio939.blogspot.com

Re: Official C12 Clone - Build and Support Thread
« Reply #2462 on: November 05, 2018, 02:30:59 AM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2463 on: November 05, 2018, 02:22:06 PM »
I covered using a 6.3VAC secondary in reply #2339.

chunger

Re: Official C12 Clone - Build and Support Thread
« Reply #2464 on: November 05, 2018, 06:25:00 PM »
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.
DIY photo documentaries consolidated here:  http://studio939.blogspot.com

Re: Official C12 Clone - Build and Support Thread
« Reply #2465 on: November 06, 2018, 08:10:19 AM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2466 on: November 06, 2018, 04:16:19 PM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2467 on: November 07, 2018, 06:46:09 AM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2468 on: November 07, 2018, 01:36:34 PM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2469 on: November 24, 2018, 10:13:53 AM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2470 on: November 25, 2018, 03:28:33 PM »
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. 

Re: Official C12 Clone - Build and Support Thread
« Reply #2471 on: March 17, 2019, 10:58:50 AM »
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

Re: Official C12 Clone - Build and Support Thread
« Reply #2472 on: May 15, 2019, 03:13:57 PM »
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!


 

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