Low microphonics preamp tubes

[mashaffer]

In my experience 12AX7 has a tendency to microphonics and the 12AY7 is pretty resistant to it. What I would like to see is a listing of tubes that tend to be resistant to microphonics. It seems to be a a hard thing to quantify but important in some applications.

 

[turk 182]

is it the tube or the circuit? the 12ax7 as a preamp tube is driven at ridiculous high gain levels and max heater voltages in an effort to squeeze more out of it, which shortens life (especially in instrument pre-amps) the 12ay7 is lower in gain to begin with.
i say look at how it's being used before you jump to a conclusion the tube type has a "tendancy" to microphonics.

 

[Merlinb]

12AX7 is not generally a microphonic tube. Sometimes you get an unlucky sample, but that is true for anything.

Frame grid tubes like the ECC88, and tubes where the getter is supported by a single wire, tend to be more sensitive to microphonics.

 

[Lingwendil]

Most of the Russian "EV" types are pretty nice tubes that aren't very microphonic. The best 12AX7 you can get is actually the 6N2P

 

[piano3]

My experience is that it is often the very high gm pentodes which are microphonic. Try 6s17k for zero microphonics.

 

[Wavebourn]

My experience is that it is often the very high gm pentodes which are microphonic. Try 6s17k for zero microphonics.

6S17K is zero microphonic, but it can't substitute 12AX7 because it's grid is too close to cathode, it's grid current is much higher. I use them with grounded cathode, and bias by 47k and it's own grid current. Excellent for new design in phono and microphone preamps, but can't replace 12AX7.

 

[hego]

Most of the Russian "EV" types are pretty nice tubes that aren't very microphonic. The best 12AX7 you can get is actually the 6N2P

I agree !!!

The 6n2p-eb is very quiet. I use them in my phono-pre.

Others I tried, in especial new chinesse (MkII) with frame-grid tech, are like a bells.Horribles!!!

Cheers