the Double Diamond VAS

[Stee]

hello collegue
my idea is an original application of diamond buffer
on diamond VAS

[Allen Wright]

Cool, but why "crisscross" the feeds to Q20 & 21. I see no purpose in it.

Regards, Allen

[tiefbassuebertr]

Originally Posted by Stee

hello collegue
my idea is an original application of diamond buffer
on diamond VAS

The other possibility was to connect Q32 and Q33 as folded cascode (Pass Su-Sy) or in such kind, that you get the so called "Lenders circuit" - for more informations and links in this case please visit this thread:
The most linear stage for large voltage swings - Lender's Circuit
and
AD797 discrete clone - comparison of seven variations
and
schematic variation and sim results of Pass "X" series US pat 5376899

Allen Wright: please read in this case the data sheet of the AD-797 and have a look to the internal circuit - I would say, the main reason is the best possible decoupling to the high impedance node of the voltage amplifier stage's output

[Stee]

Originally Posted by Allen Wright

Cool, but why "crisscross" the feeds to Q20 & 21. I see no purpose in it.

Regards, Allen

I think also electrocompaniet use this method:
two rails are separate until OS mixer

[tiefbassuebertr]

Originally Posted by Stee

I think also electrocompaniet use this method:
two rails are separate until OS mixer

basicly yes, to optimizing the switching behavior of the output power devices