Current design of amplifier VAS

[OldMercuryTube]

I am confused as to how to calculate the VAS current source output required to feed the output transistors. Do you start by assuming power out at the 8ohm speaker load to get the output current and then divide this by the beta of the output transistors to get the current required by the VAS current source? Or is it more complicated than this?

 

[bertus]

Hello,

Read the following article:
https://www.edn.com/distortion-in-power-amplifiers-part-iii-the-voltage-amplifier-stage/

Bertus

 

[OldMercuryTube]

Thanks . . I will go through that primer on VAS.

 

[bertus]

Hello,

I noticed that the article is written by Douglas Self.
He also wrote a book, that is now available at the Internet Archive:
https://archive.org/details/fe_Audio_Electronics_Transistor_Amplifiers_Design_Handbook_D._Self

Bertus

 

[WHONOES]

Depends on whether you are planning to use bjt's or fets for the output stage.