DoZ Single ended or push pull ?

[vizion]

Hi Guys, is the death of Zen single ended or pp ?

thanks

 

[JeffYoung]

Single-ended.

Q2 and Q3 form a constant current source.

Cheers,
Jeff.

 

[sgrossklass]

Rod Elliott himself writes

After some more testing, I found that the optimum quiescent current was 0.75 times the peak speaker current. At lower currents, third harmonic distortion predominates, while at higher current distortion seems to remain stable (but device dissipation is increased).

This couldn't be if the circuit were truly single-ended - quiescent current would have to be at least as big as peak output current.

The supposedly "constant" current source is being modulated by the output signal via capacitor C4, too.

Ultimately, it has a lot in common with the trusty JLH.

 

[JeffYoung]

The Pass Alephs also use modulated current-sources, and most people consider them single-ended.

But you're right that the DoZ does look a bit more like the JLH (with Q4 acting as sort of a phase splitter) -- and people have been arguing for ages whether it's single-ended, push-pull, or neither.