Pavel's "12 cents regarding power amplifiers"

[AudioLapDance]

Felt this deserved its own thread.

From Dec 2017 post:

http://www.diyaudio.com/forums/the-...owtorch-preamplifier-ii-9837.html#post5277959

"
My 12 cents regarding power amplifiers, based on experience:

- stability even with very difficult complex loads, no problems if the load is suddenly disconnected
- high output current capability
- excellent immunity to both air-coupled EMI interferences and supply line interferences
- sophisticated wiring topology immune to grounding scheme of remaining audio chain components
- frequency compensation network that assures high loopgain (feedback factor) even at the upper end of audio band
- very low and as linear as possible output impedance

Reasonably high slew rate and full power bandwidth at least 100kHz as a rule of thumb, no need to emphasize.
"

It would be nice to put some general, basic parameters/numbers to these specs.

1) stability with complex loads: basic impedance description, schematic?
2) high output current:
3) air/line EMI imunity: basic circuits for input/output
4) grounding immunity :
5) high loopgain (@~20kHz), comp network:
6) low/linear output impedance: basic impedance description

Thanks and cheers,
Jeff

 

[stocktrader200]

I also demand unity gain stability. Current feedback amps can provide this

 

[Telstar]

-Flat THD vs frequency in the audio band is mandatory for me.
-flat output impedance in the audio band rather than extremely low (200df is enough).
-decent slew rate (80Vus min), as advocated by JC.

 

[bogdan_borko]

That is 6, not12 ☺

 

[DPH]

I also demand unity gain stability. Current feedback amps can provide this

This is for discrete amplifiers, too. It'd be a total waste to not optimally set your compensation for the desired gain. For opamps, sure, there's a lot of cases where unity gain is needed.

 

[Tromperie]

That is 6, not12 ☺

It is six lots of his two cents worth.