Nice to hear from you. I don't think that this amp is really suitable for a lower voltage - highly biased application. The output FETs drop around 6-7 volts so this will make it quite inefficient for lower rails. At higher voltages this is less of an issue (in percentage terms).
The other FET amp; Another quasi-complementary design would be better as it drops very little voltage. A few component (resistors mostly) changes would have to be made.
Anyway I have started a new project; A high power complementary design to refit an empty Proton D1200 chassis a friend of mine gave me. I hope to post some details soon.
Some photo's of my very slow progress below.
the question is not related to efficiency or delivered power
the question is will it sound better ?
Quasi, If I don't need 200W output power, can I use only one pair of IRF840 for NMOS 200 amp? Would it be 100W output?
Thanks! I actually need it for a bass amplifier.Hi Rankot,
If you require 100w into 8 ohms then you could run 48v to 50v rails with one pair of IRF840. You must ensure though that it is never connected to a 4 ohm load. Also this amp is strictly for HiFi; use as an instrument or a PA amp will kill it.
If you require 100w into 4 ohms then you will need to drop the supply rails to 36v.
OK, I would do that. I already have ±40V PS, so I will use that one with NMOS200. Is it OK to use only one pair of IRF840 with both 4 and 8 Ohm impedance speakers using that power supply? I don't need full 100W power, just enough to play in my room and be safe with both speakers and to know that I will not damage them or amp.Hi Rankot,
If your bass speaker box has one 8 ohm speaker then I would build the NMOS200 with 4 IRF840 or similar and use 50v rails. If the speaker impedance is 4 ohms then drop the supply rails to 36v. Have a look also at Apex's amp https://www.diyaudio.com/community/threads/150w-mosfet-amplifier-with-irfp250x2.163159/ as well.
If budget permits you could build the Nmos350 for a bullet proof solution and run that on 50-60 volt rails.
I've simulated this (still waiting for PCB to arrive) and I get much better result with 1N4007 than LED on this. What was your final conclusion? The most recent schematic I found still has 100 Ohm resistor there.NMOS200 Scope pictures
My NMOS200 with R21 exchanged with Yellow LED (1.9V)
Much better clipping. Near symetrical
Same module and the 10khz Squarewave. Also less overshoot. Original signal from functiongenerator not shown here but was almost perfect (slightly undercompensated)
Nearly no sign of crossover.