Circuit question regarding a higher gain preamp tube

My Sanos call for a 12AX7 and a 12AU7 in the preamp section. Is there any circuit danger if I put a 5751 or 12AX7 in that 12AU7 socket?

I know putting lower gain tubes than designed for may not hurt components but what about if I upped the gain when the schematic calls for a 12AU7?

Thanks!

 

That would likely be the 300R, Mike.

I have two 160R's and a BA-1 which is in the flavor of a Bassman 20 but with EL84's.

IMHO, the best Sanos are the EL84 driven amps and all three of these amps are EL84 driven but the curcuit design makes them thick and big sounding almost like a low powered 6L6GC amp. All three of these amps are amazing. I'm dropping some different 5751's in that socket to see what happens

Thanks for you reply too.

I had a 300R but sold it and I still have the matched Bogen Sylvania 8417's you sold me for it. The original Sylvanias were ok when I didn't think they were.

 

Todd,

I've used those "hybrids" before and had great results with them but I did install a USA made black plate Hewlitt Packard "selected" 5751 (looks like a Sylvania to me but what do I know!) in that socket last night and played it with my Agile AL-3000 with the alnico humbuckers and the tone is fabulaous with not too much gain so I'm going to leave it there for the time being I'm plugging the Suhr into it today to see how that sounds. With the 12AU7, I didn;t have enough gain to get the tonal overlfows I wanted even at 3/4. But then I had those lower output GE oval plate EL84's in ther then too.

Thanks for the heads up though. Now that you say one of the 12AU7 stages is the split load PI, I'm going to go read the schematic so I can learn. Knowing this tidbit will give me reference to what I'm looking at