I've heard some people get a good sound out of mixing pre-amp valve types.

I'm tempted to try this in my Peavey XXX 120w

V1 - Tungsol 12AX7
V2 - JJ ECC83s
V3 - JJ ECC83s
V4/PI - EH 5751

Has anyone tried a mixture like this? I'm sure 12AX7s and ECC83s are fine because they're pretty much the same.. but the 5751 should reduce the gain. Especially in the PI position.

If anyone has had experience with this I'd like to hear your thoughts! Cheers.
Id use a 12at7 in the PI. Keep the 5751 for V1 for nice cleans.

Just try em and experiment, see what sounds best.

12ax7 is the same as the ecc83, just different codes for it depending on where you are in the world.
5751 is a lower gain 12ax7
12at7 i think is lower gain than the 5751, generally theyre used for the PI in fenders, i stuck a NOS sylvennia 12at7 in my orange and i quite like it.
12au7 is realllly low gain

if you want to reduce the gain of your amp then try a 5751 in v3 as well, should make things a bit smoother.
Just try stuff out, see what you like. There's no right and wrong.
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Unless its electronic drums.

Thanks for the advice! lots of good info there

I'm hoping to get more headroom and improve my cleans. So you're suggestion of a 12AT7 in PI and 5751 in V1 sounds like a good idea.

My Peavey XXX has tons of gain so losing some won't be a bad thing.
Last edited by Leanland at Sep 29, 2011,
in terms of gain, a 12AX7 (ECC83) amplifies the incoming signal 100 times, a 5751 amlifies 70x, 12AT7 or ECC81) 60x, 12AY7 45x, 12AV7 41x and 12AU7 (ECC82) 20x.

other than this, I can only acknowledge what others have said before
Quote by tubetime86
Most people don't give a shit about tone... We are the exception, not the rule.

I probably am a bit more rule than exception though
I use the JAN phillips 5751 is every position. Its gain factor is not much lower at all than a 12ax7 so it won't lower the gain much but it does make the gain much more usable and dynamic. I used them in my 3120 and still never maxed out the gain.

^actually the JAN 5751 has a gain factor of 90
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