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Im still looking for published conformation of my belief that is:
  1. Class d rated power limits approximate their dynamic power capacity
  2. Class a and ab can produce dynamic transients far in excess of their rated rms power
Of course if i am right you can still get adequate transient power from class d if you buy one with a high enough power rating so it handles the loudest transients you want to listen to
 

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Discussion Starter #62
Wow, this post really blew up :D

The simplistic way that looked at it was that the biggest issue between A/B and D was cost for me. The second issue was that there was a small, sort of maybe chance that class D is inferior in some ways. So I figured I couldn't go wrong with a reasonably priced A/B from a reputable company. Ended up buying a Rockford Fosgate P1000X2. It was $320 for a class A/B at [email protected] Plenty of headroom for just about any components. I'm happy :)

Enjoying reading all of your insights.
 

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Wow, this post really blew up :D

The simplistic way that looked at it was that the biggest issue between A/B and D was cost for me. The second issue was that there was a small, sort of maybe chance that class D is inferior in some ways. So I figured I couldn't go wrong with a reasonably priced A/B from a reputable company. Ended up buying a Rockford Fosgate P1000X2. It was $320 for a class A/B at [email protected] Plenty of headroom for just about any components. I'm happy :)

Enjoying reading all of your insights.
"Wow, this post really blew up :D"

I think its been pretty civil compared to some 🤣 robust debate is good.
 

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Reading too many datasheets for D-class amplifier ICs, I've noticed that when chips have a THD vs. power output graph there is a baseline range for distortion up to a point, and past that point distortion rapidly starts going up as power output goes up.

The kinda result is that these D-class amps seem to start to distort once they go past their hi-fi power rating(I don't think marketing departments like this number) but keep going and manage to produce output that can be considered music by someone at a multiple of the max hi-fi output. A TAS5630 chip is rated for [email protected] at around 1% THD+n. If you want 0.2%THD+n, you'd want to stop at around [email protected] It's billed as a 300W stereo / 600W mono IC.

A lot of D class products seem to be rated at very high distortion numbers, advertised power being at 10% THD isn't unheard of...
 

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Reading too many datasheets for D-class amplifier ICs, I've noticed that when chips have a THD vs. power output graph there is a baseline range for distortion up to a point, and past that point distortion rapidly starts going up as power output goes up.
Are you saying Class A/B doesn’t behave this way?

What your explaining sounds like a company/marketing problem. Not a Class D problem.
 

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I can say something about how an example A/B class amp will clip once the transistors hit saturation, but the actual behavior of a retail car amp is going to be more complicated than that. If we had an A/B class amp rated at [email protected] 0.2% THD RMS max, driving a 4ohm load, that's 20Vrms and +-28.3Vpeak. If the power rails are only just a bit higher than that, turning up the volume past 100Wrms is just gonna make it hard clip, you won't get much if any more peak voltage out of the amp but RMS power will go up and it'll sound pretty terrible.
 
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