Re: All power amps “good ones” sound the same.
« Reply #120 on: December 20, 2020, 05:08:08 PM »
You used your ears to tweak it to sound better? Perish the thought.


Errr...  Well, ummm...  Yeah.  That's about it really.    :D

I think I got away with it too.   ;)





 
D. J. H.


Re: All power amps “good ones” sound the same.
« Reply #121 on: December 29, 2020, 03:45:52 PM »
G'day chaps,
attached is the open loop plot of the amplifier I mentioned earlier, illustrating the difference between standard miller compensation (blue line) and two pole compensation (red line).  (The green line is also 2 pole comp but has a slight overshoot which was smoothed out with the addition of a small bridging cap - it then became the red line).

Assuming a closed loop gain in the vicinity of 25dB:  with single pole miller comp -  @ 100Hz we have a gain of about 105dB but by 10kHz the gain is down to a hair under 65dB.
So closed loop, we have only 40dB of feedback at 10kHz.   

Compare this with 2 pole compensation where we still have most of the 105dB open loop gain available up to 10kHz so, the full 80dB of feedback is still available right up into the top end.

Note that the individual amplifier stages are linearized as best as possible before the loop is closed, in other words, the feedback isn't being used to try and hide multitudinous sins within the amp.

Anyway, only you can decide if you'll hear this change and if its for the better but it was a no brainer as far as I was concerned.   
 

 

 
 
D. J. H.


 

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