phase inverters tone??

[swt]

can someone explain to me the different tone from phase inverters...i know the principles on how each works...but what's the defference tonally between long tail, cathodyne...etc, and also direct couple followers as in sss.

[David Root]

Cathodyne predates longtail and is great if you don't push it too hard, then it can get real nasty tonewise. Impedance issues as impedance is unbalanced. Very old school tone with cathode or fixed bias.

Longtail is versatile and more tolerant of being overdriven. Most folks think of it as having good harmonic content, which it does, and in a Dumble type circuit where you balance the PI and then knock it off perfect slightly with the plate trimmer you can optimize that.

DC followers, or PI for that matter, DC coupling involves no phase shift because it does not use a coupling capacitor, which is good for stability with global NFB, but it has other potential problems and in guitar amps phase related instability is not usually a problem because of the limited bandwidth we typically use. Superclean tone.

IIRC, www.aikenamps.com has some good analysis on this in his technical sections.

[swt]

ok thanks, that's what i need to know...been curious as oranges had cathodyne, and princetons reverbs. So traditional long tails from now on...

[FYL]

Cathodyne predates longtail and is great if you don't push it too hard, then it can get real nasty tonewise.

You can follow Merlin's excellent advice and add a large grid stopper. No more nasty disto when overdriven.

http://www.freewebs.com/valvewizard/cathodyne.html

Impedance issues as impedance is unbalanced.

Not significant for MI applications. You may add a driver stage if needed, a single Mosfet and it's glue or a paraphase diff driver are fine here.

Oh, and don't forget the paraphase, which can sound really nice when properly used.

http://www.freewebs.com/valvewizard/paraphase.html

[swt]

well thanks again guys for the kind and informative replies. guess i will have to try them, to decide which one i like best.