WAMP: 1W class A mosfet amplifier

[tca]

> whats negative (pun) about negative feedback?

I can not explain it better than Nelson Pass so here's the text: Audio distortion and feedback

P.S. (edit)
Although is about hi-fi the physics is the same.

[knutolai]

nice. thanks!

[bool]

Gus said it like it is. Biasing resistors ARE the NFB. These are "Schaded" circuits. The biasing arrangement makes them IRF's to sound more "triode-like" ... if you appreciate such buzzwords.

But ... if you desperately crave "a little more" of NFB it's so easy to stick a small .1 - 1 Ohm wirewound into the output IRF's source ... and up the volume knob a notch ... or proportionally increase the biasing/NFB resistor to compensate ...

[tca]

> Gus said it like it is. Biasing resistors ARE the NFB.

Agreed.

> These are "Schaded" circuits. The biasing arrangement makes them IRF's to sound more "triode-like" ... if you appreciate such buzzwords.

Sounds better that way comparing with the fixed bias arrangement.

> But ... if you desperately crave "a little more" of NFB it's so easy to stick a small .1 - 1 Ohm wirewound into the output IRF's source ... and up the volume knob a notch ... or proportionally increase the biasing/NFB resistor to compensate ...

I know what you mean, but I'm getting more and more the feeling that when it comes to these simple circuits the decision to include  of an extra component should be taken after a long period of listens tests.

Because I'm running this with a 18V laptop powersource and limited to 1A max (heatsink restrictions) that 100k drain to gate resistor is on the verge of its acceptable value due to the drain-gate capacitance. Drastically increasing, or only for a small amount, that resistor will require to alter the input and output caps values and, at least for my ears, the pre and pos filtering will change dramatically the sonic character of the stage.

Obviously one can fine tune all the components values for a hand chosen device.

Cheers.

[bool]

IRF's are fun