Studio Project TB1 mic, mod in a C12 with 6S6B-V Tube

[Papa Tango Charly]

Hello, I have a Microphone Studio Project TB1
apparently the transformer is a 12:1
I think it would be a good candidate for a C12 cardioid mod with a 6S6B-V tube.
Could someone give me some advices to make this mod? I have posted the schematic

Thanks to you all.

 

[LevinGuitar]

You would need a good capsule and can leave the rest almost as it is. Change R4 to 470K to have a ~60v polarization on the capsule (the original is near 74v, can be dangerous for a good CK12).

For a cheaper version, use a Rode capsule

 

[kingkorg]

Hello, I have a Microphone Studio Project TB1
apparently the transformer is a 12:1
I think it would be a good candidate for a C12 cardioid mod with a 6S6B-V tube.
Could someone give me some advices to make this mod? I have posted the schematic

Thanks to you all.

If the tube is 6072, it doesn't make much sense to replace it with 6s6b, unless you prefer one over the other for some particular reason.

Otherwise, remove c7, c4, replace c3 with 47uF. Adjust r6 value to get 1/2 (approximately) of the voltage at r1 and r2 junction compared to voltage at r2 and c2 junction.

Edit:
Let me rephrase that. Voltage at r2 c2 junction should be circa half of the r1 r2 junction. Adjust r6 to get that.

 

[Papa Tango Charly]

Thank you. can you tell me where i can control the bias? Between the top of R4 and the ground? Is that it?

 

[Papa Tango Charly]

On this blog the guy has moved R7 to an other place... Micro statique à tube à large membrane Studio Projects TB1 mod RK47 should i let it where it on R7?

If the tube is 6072, it doesn't make much sense to replace it with 6s6b, unless you prefer one over the other for some particular reason.

Otherwise, remove c7, c4, replace c3 with 47uF. Adjust r6 value to get 1/2 (approximately) of the voltage at r1 and r2 junction compared to voltage at r2 and c2 junction.

Edit:
Let me rephrase that. Voltage at r2 c2 junction should be circa half of the r1 r2 junction. Adjust r6 to get that.

I just have find out about this this 6S6B tube. But if you think it's does make much sens to change one for the other i will keep the 6072. If i keep a 6072 tube do i have to correct the bias? could you advise me for a good 6072 tube for a C12 capsule? Thank you.

 

[kingkorg]

I just explained how to adjust bias by adjusting r6. The schematic says there should be 6072 in it stock. That's the tube used in c12, so why change it? Unless there's an issue with it.

Levin and me pretty much explained all you need to do to get what you wanted.

The only CK12 i can recommend is Tim Campbell's. Using any of the cheaper alternatives is just fooling your self you have anything resembling C12. It doesn't mean you'll get a bad sounding mic though. There are other true CK12 manufacturers, but my experience with those is limited, and at least one of those, which i won't name, is way off.

Rode's capsule Levin named is great. But keep in mind it's not true CK12.

 

[LevinGuitar]

I doubt the original chinese tube is a real 6072, but is very low noise, so would leave it unless you find a low noise (hard to find and expensive!) 6072 GE tube. Theese sound the best but the difference will be small.
Spending money on the capsule is the key!

 

[Papa Tango Charly]

Ok thank you very much. Guosheng from 3U audio makes nice capsules clearer or darker as you which he loves what he does. Do you know these capsules. I hope he is not the one you don’t want to mention…what about this tube 12AY7 or ECC83?

 

[LevinGuitar]

A true multichamber ck12 usually is no less than 400€/$. Don't expect a 100-150€ capsule to sound the same.
Rode capsules at least are very transparent, but again, far from real ck12.

 

[Papa Tango Charly]

Thank you