My mosFET amplifier

My 1st mosfet amplifier i built in ltspice.
 

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It is very tweakable 🙂

Just doodling. Try this:

Emitter degeneration added to LTP. Driver current reduced (it was way to high). Input cap scaled down to give a more controlled LF response. Bias preset should really be the lower resistor to prevent damage if the wiper ever went open circuit.

Screenshot 2023-11-29 144644.png


Screenshot 2023-11-29 144335.png


Screenshot 2023-11-29 144949.png
 
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It is very tweakable 🙂

Just doodling. Try this:

Emitter degeneration added to LTP. Driver current reduced (it was way to high). Input cap scaled down to give a more controlled LF response. Bias preset should really be the lower resistor to prevent damage if the wiper ever went open circuit
Thanks again mooly sir my 1st mosfet amplifier could not have been completed without your help.
 
Remember Zohaib was Quasi fan.
So all N channel outputs.

Cool to see your having fun playing with software
and learning more about amps.

Mooly got yah covered pretty good I think.

stability little tricky with mosfet.
So I thought too, adding little degen might help.
Seems he added R26 / R27
Good Idea.
So hopefully helps and since C7 was high to keep stable.
100p. Hopefully that can be smaller now around 47 to 68p
help improve slew rate at higher frequency.

can tweak with it a little, degen could probably be anywhere
from 56 ohms as shown up to 180 ohms to try and bring
down C7 value.

R23/24 gate resistor seem high value, maybe for lateral type.
Probably not needed with enhancement type.
I would assume 100 ohm all is needed for gate.
 
In absolute terms its pretty good. Remember a real build can introduce all sort of other issues that the simulation doesn't show (unless you model them) such as the power supply being modulated and wiring resistances and so on.

Many highly regarded designs have much higher distortion (and can sound great) and there are many designs with much lower THD that don't always sound quite so good.
 
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In absolute terms its pretty good. Remember a real build can introduce all sort of other issues that the simulation doesn't show (unless you model them) such as the power supply being modulated and wiring resistances and so on.

Many highly regarded designs have much higher distortion (and can sound great) and there are many designs with much lower THD that don't always sound quite so good.
Thank you mooly sir for fast reply you are really very nice humble and helpfull person on diyaudio.
 
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Dear mooly sir what is this dc component in ltspice log error? Or what should be the value for it? Or is this matter or not?
Kindly guide me.
See in the red circle in the picture given below.
 

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It is the DC present at the location the FFT is taken. The results are not always consistent and seem to depend on whether the signal modifies the static DC value.

The true static DC offset here is 28mv and that is also the DC component shown in the FFT analysis.

Screenshot 2023-12-05 112034.png
 
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