Poweramp 10 Watt IRFP240/9240 Symmetric Class A

[lineup]

Simple Symmetric Class A with IRFP240/9240 MOSFET.
Moderate THD.
Power supply 30V single.

 

[lineup]

U1 and U3 should be matched.
U2 and U4 should be matched.

J113 and the other should be close match, U5 and U6.
Should be ~2 mA each.

 

[WhiteDragon]

You loose 6 volts to each rail and it is 2 amps of current at idle.

Maybe BJT with less idle?
Was slightly inspired by the simple amp thread as well.
Is kinda fun to try out low parts count amps though.

 

[WhiteDragon]

Never mind just noticed the feedback

 

[chermann]

Q1:
is it better if you use a other JFET for CCS instead of J113?
other members mentioned at different threads that J113 has a bigger current noise .

Q2:
does a snubber with 220pF and 47R at the power MOSFETs reduce something? connected between Drain to gate.
at the VSQA amp thread its an idea to avoide oscillation - i did this on a real FX8 amp with LatFET and it give me better sonical improvement at higher frequencies, e.g. flute, singers, high hats...etc....feels more open.

kr
chris

 

[lineup]

There is no need for compensation!

 

[mr_zener]

Seems very sensitive to set up bias, maybe some resistors on the source pins of IRFP's might be desirable?

 

[mr_zener]

@lineup - Why not try a 'diamond' input buffer? I am simulating with very similar results ditching the J113's with just emitter resistors. Thermal stability should be the same.