12ay7 or 12au7 or 12at7

[youngshu]

In a tube microphone are there expected differences in changing these out. Lower gain more noise etc? I built a micparts tube mic and changed the capsule, transformer and tube. I noticed it needs a lot more gain now. Still sounds great and the noise floor is equivalent to my Lauren Eden but it was lower before I swapped the parts out. Just wondering as I am still new to microphone diy.

Capsule is beesneez c12
Transformer Ami t14
Tube RCA 12au7 (old idk what year)

Same noise floor increase with
Sylvana 1950s 12at7
New electroharmonix 12ay7

Also changed the transformer between
Beesneez toriodal transformer
Ami t14
Micparts stock
Same noise floor increase.

Is it the capsule? Do capsules change gain and noise floor?

Trying to learn sorry if these are stupid questions.

 

[soliloqueen]

it's the capsule. the micparts capsules are absurdly hot. they have a capacitance of ~90pf, almost 100 under charge. That's like 5dB hotter than a regular capsule from any other supplier. almost twice as loud. they will literally clip mic circuits with lesser headroom. i get a few emails about this a month haha. i'm sure ben and the others do too, since we all run about the same sensitivity.

 

[kingkorg]

In a tube microphone are there expected differences in changing these out. Lower gain more noise etc? I built a micparts tube mic and changed the capsule, transformer and tube. I noticed it needs a lot more gain now. Still sounds great and the noise floor is equivalent to my Lauren Eden but it was lower before I swapped the parts out. Just wondering as I am still new to microphone diy.

Capsule is beesneez c12
Transformer Ami t14
Tube RCA 12au7 (old idk what year)

Same noise floor increase with
Sylvana 1950s 12at7
New electroharmonix 12ay7

Also changed the transformer between
Beesneez toriodal transformer
Ami t14
Micparts stock
Same noise floor increase.

Is it the capsule? Do capsules change gain and noise floor?

Trying to learn sorry if these are stupid questions.

Depending on the circuit, diferent tube types can make weird interactions with rest of the parts like transformer, coupling caps, etc...

Nothing magical going on, you can see it as diferent EQ curves. Some THD diference as well. I'd stick with tube that is intended to be used with that particular circuit. But you can experiment and go by ear.

I wouldn't go crazy chasing low noise, it's a tube mic after all, they are not first choice if absolute low noise performance is necessary. Unless it's obviously noisy.

What matters is signal to noise ratio, if it needs more gain, just use more gain.

 

[youngshu]

it's the capsule. the micparts capsules are absurdly hot. they have a capacitance of ~90pf, almost 100 under charge. That's like 5dB hotter than a regular capsule from any other supplier. almost twice as loud. they will literally clip mic circuits with lesser headroom. i get a few emails about this a month haha. i'm sure ben and the others do too, since we all run about the same sensitivity.

Thank you yeah I had that thought as I was writing the post. Is there any way to get a better signal to noise ratio by changing something in the mic circuit? Is that even something I should worry about. The mic sounds great but I am interested in improving it within reason and my ability of course.

 

[youngshu]

Depending on the circuit, diferent tube types can make weird interactions with rest of the parts like transformer, coupling caps, etc...

Nothing magical going on, you can see it as diferent EQ curves. Some THD diference as well. I'd stick with tube that is intended to be used with that particular circuit. But you can experiment and go by ear.

I wouldn't go crazy chasing low noise, it's a tube mic after all, they are not first choice if absolute low noise performance is necessary. Unless it's obviously noisy.

What matters is signal to noise ratio, if it needs more gain, just use more gain.

Thank you. that is a good point i do tend to chase things sometimes ending up fruitless lol

 

[youngshu]

Thank you yeah I had that thought as I was writing the post. Is there any way to get a better signal to noise ratio by changing something in the mic circuit? Is that even something I should worry about. The mic sounds great but I am interested in improving it within reason and my ability of course.

I saw a post talking about polarization voltage having an effect on signal to noise. Is it possible the polarization voltage is to low for the beesneez capsule i put in? and if so is that relatively easy to fix?

 

[kingkorg]

I saw a post talking about polarization voltage having an effect on signal to noise. Is it possible the polarization voltage is to low for the beesneez capsule i put in? and if so is that relatively easy to fix?

CK12 is not a capsule you want to experiment with when it comes to rising pol.voltage. It can collapse easily.

 

[youngshu]

CK12 is not a capsule you want to experiment with when it comes to rising pol.voltage. It can collapse easily.

Perfect thats all I needed to hear not touching that then! lol Thank you!