Can one reliably hear any difference between this amplifier and a lower THD amplifier. A really good amplifier. As you can see no capacitor is used for stability compensation
https://www.pcbway.com/project/shareproject/mosfet_amplifier_f17685a0.html
https://www.pcbway.com/project/shareproject/mosfet_amplifier_f17685a0.html
It is not necessary a good thing.
I can see the input stage is heavily degenerated to keep the gain low enough to maintain stable.
The sound should be OK. Anything below 0.5% THD, you probably won't notice. (At least for me)
I don’t know.
Are you the designer? Probably you can share some philosophy behind this design.
Comparative performance although experiences may vary. The LM3886 is a chip amp so its graph should still hold for near field easy speakers. Our focus is on the blue curve, you can see that this amp gets in there easy
Looks similar to a Blameless design. Any reason you’re not going with a current mirror on the LTP? That usually decreases the THD dramatically. But it also increases your OLG, so you’ll probably need to fit a Miller capacitor.
An amplifier that doesn't need capacitor compensation for stability is always attractive and can act as a reference amplifier or standard
I think this design is relying on the inter-electrode capacitances of the output devices for stability. At best I think the amp is only conditionally stable. Has a prototype been tested with adverse loads?
I’m not sure I understand what makes that a reference amplifier. Have you measured/simulated the phase margin?
No Cdom, and no tubes, either. In the end we get a solid state oscillator.
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Your worries are quite justified and you started thinking about how it works, the board measures 100mmx100mm , the mosfets arent offboard nor are they connected by long leads. Any fix with alternate devices is also surprisingly simple, a low pass filter at say 1Mhz at the VAS section, for the mate using EF3 we cannot omit this filter https://www.pcbway.com/project/shareproject/Pot_luck_amplifier_09c74fc8.html. The mosfets and bias used give us the characteristic we want. , this amplifier configuration is quite simple and robust and surprising for its good performance.
You still haven't explained why the lack of Miller compensation makes in better and in what way. Better bandwidth? Here's my very simple go-to design. No-frills, just basic common sense, totally not fancy in any way. But I get 700kHz bandwidth and 0.0005% THD @ 150W (in simulations, lower than I can measure in the physical version) and LOADS of phase margin. Why teether on the edge of oscillation and self destruction? Why increase the THD by degrading the OLG? I'm a bit new to this, but I don't get it.
If you claim your amplifier is "up there with the best" as you do on PCBWAY, you need to back it up.
If you claim your amplifier is "up there with the best" as you do on PCBWAY, you need to back it up.