Replacing 6N7 with 6SL7?

[Shark_Sandwich]

I have a very old PA amp that I'm using as a guitar amp. I'm planning on replacing a 6N7 in the preamp with a 6SL7. The max plate voltage ratings are the same and I know the pinouts are different. Is there anything else I need to watch out for or do?

Also, what would be a higher amplification replacement for a 6SJ7? If I can find a suitable replacement, I'll switch that one out too.

Thanks,

Don

[Alexander]

I heartily recommend trying a 6AU6-A pentode; all the gain & slam of an SJ7 but better shielding and lots available cheap NOS!! here's one I built with one:

http://www.retrodyne1.com/29Wamp.html

shielded NEW ceramic sockets available at Triode Electronics, Chicago IL. Plus they have some inexpensive iron worthy of trying too.

HTH,
Alexander

[Rob Mercure]

Hey SS.

Do you have a schematic or have you diagrammed out your amp? The 6N7 was designed as a driver and not a voltage amplifier - possibly as the phase inverter. The 6SL7 has a much greater mu but no where near the power dissipation. I don't know squat about your particular amp but if it in anyway approaches class AB2 with the N7 driver then the SL7 won't work. While I seem to remember a few amps that used the N7 as a preamp this would put your design either at the late 30s/early 40s or one that used the N7 due to WWII materials restrictions - does it have metal 6L6 outputs?

Rob

[Shark_Sandwich]

Yep, here's the schematic (I eliminated the shaded area). I'm a newbie at this, but I believe that the 6N7 is used as a voltage amplifier. The circuit uses a transformer as a phase inverter. This circuit is indeed from the early 40's. The 6N7 is set up in a grounded cathode configuration (class A stage, correct?). The amp likely came with metal 6L6's (push-pull class A), but they were glass when I got the amp.

[Shark_Sandwich]

I heartily recommend trying a 6AU6-A pentode; all the gain & slam of an SJ7 but better shielding and lots available cheap NOS!! here's one I built with one:

http://www.retrodyne1.com/29Wamp.html

shielded NEW ceramic sockets available at Triode Electronics, Chicago IL. Plus they have some inexpensive iron worthy of trying too.

HTH,
Alexander

Nice looking amp! I'd rather not change to a 9-pin tube, though. I'd prefer to stay with the octals in this amp - keep it as "period" as possible.

Don