When an amp puts out 90 watts....

Bifwynne, Our amps don't use any feedback at all, yet they can work quite well with speakers that have some pretty wide impedance variation. It all has to do with the intention of the designer of the speaker. ZOBEL networks are one way you can get a zero feedback amp to work with a speaker that is expecting the amp to have a much lower 'output impedance'.

Got it Ralph. But outside of the few exceptions like your OTL type amps, a pure "Power Paradigm" amp that doesn't use NF and that has a somewhat high output impedance will likely choke on speakers that were designed to be driven by low output impedance high current SS amps. Especially if the speakers have wacky impedance and phase angle curves.

You and Al used a jackhammer to get through my thick skull to get me understand the basics of these various interactions. And . . . thanks to the Soundstage and Stereophile bench test reports on the ARC VS-115 and Ref 150, I finally got to see numbers wrapped around the theory.

Folks who are interested in tube amps should keep this stuff mind. Not sure how Zobel networks works, but for folks who are interested in tube amps like yours, or other zero feedback tube amps, it might be worthwhile for those folks to get up to speed on that EE variation.

Regards,

Bruce

Please, instuction for Bias setting, thanks