Unipolar vs complementary input stage

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Hi LineSource
Interesting that this thread should reach this point ...
A question I have is ... can an Input Stage be made to produce sufficient Gain , Current/Voltage drive and a low output impedance to remove the need for a VAS?

ciao
 
Level shifting in this one is interesting. What is Q6-7, Q10-11, Q8-9? Are they current mirrors?
 

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KLe said:

A question I have is ... can an Input Stage be made to produce sufficient Gain , Current/Voltage drive and a low output impedance to remove the need for a VAS?

ciao


Nelson Pass has several 1 and 2 stage amplifiers from Aleph through Zen. His Super-Symm topology can bridge two stage gain paths together to get higher power. The Pass DIY website has great info, as do the Pass product service manuals.
 
KLe said:

A question I have is ... can an Input Stage be made to produce sufficient Gain , Current/Voltage drive and a low output impedance to remove the need for a VAS?

95dB OLG
As per low Zout, there is no need for that if you use an T output stage
 

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forr said:
Said otherwise, what happens internally when an input pair has more transconductance than the input pair of the other polarity ?

The complementary drive to the symetrical VAS will be a bit imbalanced and you’ll get a little more even harmonic distortion.

Cheers,
Glen
 
PMA said:
You can start playing with structures like this. The only question is if it makes any sense for audio.
Pavel, please take a look at post no.66 in this thread.
It make sense, that topology sound very good and is unconditional stable. The output stage has CFP drivers plus three pears of ThermalTrack devices (NJL0302/0281)
 
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