Hi,

I'm playing around the simulation of a single-stage class A mosfet amp with triode curves, an efficiency close to 50% and a Zout around 0.38 Ohm.

I've used the same concept in two stage tube amps doing what @Tubelab_com did on pentodes, but here I would like to apply to a simpler low voltage circuit.

On LTSPICE (file attached) results are very good:

I would like to have suggestions from you more experienced people concerning the feasibility of the circuit and the choice of the best components for it.

Most critical parts seems to me the choke (is the Hammond 193U a good choice?) and the mosfets: the p-mosfet should be able to dissipate 10 W and each of the two n-mosfets 20 W each.

Thanks in advance for your help.

Roberto

I'm playing around the simulation of a single-stage class A mosfet amp with triode curves, an efficiency close to 50% and a Zout around 0.38 Ohm.

I've used the same concept in two stage tube amps doing what @Tubelab_com did on pentodes, but here I would like to apply to a simpler low voltage circuit.

On LTSPICE (file attached) results are very good:

- a Zout of 0.38 Ohm (so a DF of 21)
- 0,09% THD at 1 Wrms with 180 mVrms at its input (all harmonics fall 20 dB below the previous one)
- 0.47% THD at 10 Wrms (all harmonics fall 8 dB below the previous one)
- 5% THD at 20 Wrms. This is due to the error only feedback that scales down the output and subtracts the input signal to in, in order to have only the error to inject as feedback: no loss of sensitivity for the amp while increasing the DF and reducing the THD.

I would like to have suggestions from you more experienced people concerning the feasibility of the circuit and the choice of the best components for it.

Most critical parts seems to me the choke (is the Hammond 193U a good choice?) and the mosfets: the p-mosfet should be able to dissipate 10 W and each of the two n-mosfets 20 W each.

Thanks in advance for your help.

Roberto