Do the tubes in the phase inverter effect the tone?

[zonta]

I mean, does changing the cheap chinese tubes in the phase inverter to let's say mullards effect the tone of the amplifier or phase inverter tubes are totally inassociated with the tone?

Thanks.

[Jim Jones]

The PI tube (or a tube in any position) has an influence on tone - but not as much as a tube "earlier" in the circuit.  You'll likely notice a big difference when swapping tubes in your amps first preamp stages.

Jim

[bwanasonic]

The most important trait in a phase inverter is that that both sides of the tube's triodes are balanced. Many tube dealer's offer a "balanced" tube for phase inverters. Both the gain and balance of the PI tube will affect your tone. OTH- If it ain't broke, don't fix it. Get to know how your amp sounds with the tubes already in it before you get too happy with tube swapping. Then try one tube slot at a time to see what really makes a difference.  Start with the first preamp tube and work from there.

Kerry M

[puretube]

"balanced tube" is only interesting for 2-triode PI`s.
for the simple "equal anode & cathode resistor" PI:
not important.

[idlefaction]

heh.  so many opinions.

it depends on your amp's topology man - are you wanting clean tone, or is this a design where you get loads of distortion in your PI?

i tend to disagree in context with bwanasonic here - you might not be wanting the lowest possible distortion from your PI!!!  it's a great idea for hifi, but a lot of amp guys unbalance their PIs on purpose - gives you some extra second order harmonics.

in general, if your distortion is all in the preamp, then the first tube is the one that will make the most difference to your sound.  if however your pre is low-gain you might find the PI is the one doing the distorting, and that's the best place for your 'good' tube...

what's your amp?    i wanna know!  i love tinkering with valve amps hehe

[zonta]

ok.

a marshall el84 20/20 stereo pa.

:wink: