Tube substitute for 6SQ7?

[johnhenry]

Is there such a thing? Possibly a 6SL7? I believe they're similar to a 12AX7(?). Thanks.

[wyatt]

Nope.

The 6SL7 is a dual triode (as are the 12A*7 tubes).

The 6SQ7 is one triode and dual diodes. Except for British equivalents (CV1990?), you need to stick with a 6SQ7. Now some amps don't seem to use the diodes, just the triode, I believe the GA-40 is this way, but the triode's pinout is different than either a 6SL7 or 6SC7.

[johnhenry]

thanks, wyatt. this site is indispensable for this type of info.

[Slunderfungus]

Glad I dropped in here because I am working on a conversion that uses 6SC7, 6SL7, and 6SN7. Is there an 8 pin triode that has and amplification factor of 100 like the 12AX7???

[wyatt]

Originally Posted by Slunderfungus

Glad I dropped in here because I am working on a conversion that uses 6SC7, 6SL7, and 6SN7. Is there an 8 pin triode that has and amplification factor of 100 like the 12AX7???

No, the 6SL7 is tops at 70 mu. But it has a lower plate resistance so you can bias it a little on the hot side.

Octal preamp tubes tend to be very full sounding, but also noisy, you introduce too much compression to the preamp design and you may end up boosting a lot of noise. They are usually best in vintage designs, though at least one build I think makes a cascading octal preamp.

[Slunderfungus]

Thanks, thats good to know, I got one in a glass tube that is branded as RCA but is actually a Tung Sol from the 50s NOS that I got for 5.95 shipped. I'll find a use for it somewhere. No telling how many projects I'm goingto be taking on between now and death.

[johnhenry]

the amp in question is my 1962 Gibson Ranger. it sounds fabulous, but the tremolo has gotten a bit weak, and i thought that's all this tube was used for in this circuit. do i have that wrong?