Little Class A ?

[Stee]

USE an OPA !

see this circuit
from cut and paste of an italian KIT
never tested

better have to connect twice CAR loudspeakers
because power is little

 

[nikwal]

oh man, that looks old, are thoose really silicon transistors? hmm well I guess it's possible.
I have two lm12's deep in the cellar, I'd like to do something like that with them some day just for the hell of it.. 80watt driving something hmm, that gives some weird thoughts in my head :-D

 

[Stee]

discrete op-amp --> the solution

Working voltage: +/-25v DC

http://www.bursonaudio.com/Burson_HDAM_Module.htm
http://www.audio-gd.com/enweb/pro/diy/OPA.htm

that is good to have an accurate VAS
with a domestic power

need just design a current stage in class A
easy with LED's polarization
you have to select numbers and color!

...the problem is thermal drift control
maybe a very big dissipator it's a way

or see this current stage with IGBT
http://www.diyaudio.com/forums/showthread.php?s=&threadid=128784

 

[Stee]

again without drift correction

a variation of Elliot

 

[Stee]

IGBT version

hello

this can be famous until a season...

(copy from esp - australia)

 

[Nico Ras]

Re: IGBT version

Not quite sure why it is class A. The output stage is classA, what about the OPAMP, its crossover distortion will simply be amplified, what is the point?

 

[Stee]

Hi

i think the OP-Amp works in class A also final stage

see version two
maybe 5A biasing is too much?
(5A x 30V = 150W for one device on dissipator)