What are the trade offs? PUSH PULL vs. pure SET


Is the triode circuit of a push pull design compromised because of its ability to go to Pentode/Tetrode? Is the triode circuit in a push-pull even considered to be single ended. ?

If not what differentiates the design from pure SET?

Thank you

Groovey Records

Listening to
The Rolling Stones- Rolling Stones Records 10C 06:063616-w/ "Let it Rock" live -Spanish Pressing & Cover-Fowlers Treacle Sticky Fingers in a Can
groovey

Showing 2 responses by atmasphere

Yes, the triode operation of an amplifier that has tetrode or pentodes is compromised. Such tubes in triode mode are not as linear as real triodes.

In triode mode, a push-pull amp still differs from a triode amplifier that is single-ended. Push-pull has greater power and wider bandwidth, but also *more* distortion at low power levels. SETs have vanishingly low distortion at low power levels, on account of the way the output transformer behaves when operating single-ended (no hysteresis loss) as opposed to push-pull (where hysteresis loss causes a loss of low-level detail due to increased distortion).

Of course there is more but that's a good place to start...
Hi Groovey, thanks for the link. In general Eddy is on the money. He does leave out some details that *I* think are important- namely OTL amplifiers.

Take away the output transformer and you remove most of the arguments for SE. So it then becomes possible to have more of the best of both worlds- low harmonic generation along with power and bandwidth. Negative feedback remains optional (in my case I disdain it as it robs the music of soundstage depth and adds and undesirable 'sheen' on top).

All the Best!