Maker Pro
Maker Pro

Mosfet amplifier noise update

Whilst wating for some ferrite beads to arrive, I decided to dig a
little deeper into my circuit, disconnecting the outputs of the phase
splitter from the two output devices, and output noise virtually
disappears - just bit of mains hum creeping in due to the loss of the
relatively low impedance drive to the gates.

The prototype uses a pair of VN10LMs, hand selected for reasonable
matching of the gate threshold voltages. These devices were chosen for
no other reason than they have an adequate Vds rating and are readily
avalable.

I think I will get much better results if I replace the mosfets with
jfets. I will however be fitting the ferrite beads as a precaution.

(Sorry to have to use Google to post on here, but it's the only
newsgroup reader I've found that works with TalkTalk).

Regards

Ted Wilson
 
Whilst wating for some ferrite beads to arrive, I decided to dig a
little deeper into my circuit, disconnecting the outputs of the phase
splitter from the two output devices, and output noise virtually
disappears - just bit of mains hum creeping in due to the loss of the
relatively low impedance drive to the gates.

I should point out here that the output mosfets are still biased on,
( for the elimination of crossover distortion), in the absence of
drive from the phase-splitter.
 
Top