ILoveHiFi wrote:
I actually tried out a new type of emitter and collector resistorless output stage biasing method, but didn't work out well.
Distortion figures were pretty much same, zero gains were observed.
I ran out of time so I skipped the capacitve testing.
Yeah I think emitter and collector resistiorless amplifiers aren't good in anyway other than being unique and that I like the sound of it.
Distortion I think is higher than standard output stages however I have not built any for a long time to do comparison with emitter resistorless.
Emitter and collector resistorless output stage, you mean like Q5 and Q6 in this:
Attachment:
CE CC output stage.jpg
This is not a good topology, I never seen people using this since the early 70s.
This and common emitter output stage is not good. Output impedance is too high. You can only lower the output impedance by GNFB, that is a really bad way to do that. You need as low output impedance without feedback, never depend on closed loop feedback to do the job. Like any closed loop feed back, loop gain is low at 20KHz, no loop gain at frequency of oscillation. Amp like this cannot drive capacitive load as output impedance and load capacitance form another pole.Output impedance of my design is 0.03ohm without feedback,