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My NAD 3020 D proves your Class D tropes are wrong

I have a desktop integrated, the NAD 3020D which I use with custom near field monitors. It is being fed by Roon via a Squeezebox Touch and coaxial digital.

It is 5 years old and it sounds great. None of the standard myths of bad Class D sound exist here. It may lack the tube like liquid midrange of my Luxman, or the warmth of my prior Parasound but no one in this forum could hear it and go "aha, Class D!!" by itself, except maybe by the absolute lack of noise even when 3’ away from the speakers.

I’m not going to argue that this is the greatest amp ever, or that it is even a standout desktop integrated. All I am saying is that the stories about how bad Class D is compared to linear amps have been outdated for ages.

Great to see new development with GaN based Class D amps, great to see Technics using DSP feed-forward designs to overcome minor limitations in impedance matching and Atmasphere’s work on reducing measurable distortion as well but OMG stop with the "Class D was awful until just now" threads as it ignores about 30 years of steady research and innovation.
erik_squires
atmasphere's avatar
atmasphere
11,991 posts
 
I do not believe you can hear any difference in normal home listening from equivelant models with A/B power.  
The class of operation isn't important. How much feedback the amp uses *is*. This can have an enormous effect on how much and what kind of distortion is present. Distortion is a good deal of the reason we hear differences between amplifiers- that old trope about 'distortion is negligible and therefore inaudible' so often seen in reviews of the last 50 years is false.



twoleftears's avatar
twoleftears
5,320 posts
 
All musical instruments can be defined by their unique spectrum of harmonic overtones.  Harmonics are what enable you to distinguish between a viola and a clarinet playing the same note, e.g. A at 440hz.

Amplifiers running in any class, e.g. AB, will not have the same amounts and combination of second, third, fourth, etc. harmonic distortion.
dletch2
455 posts
 
And that is the difference between a technician and a scientist. With the exception of Floyd Toole who hangs out there and I have the deepest admiration for, they are technicians pretending they know a thing about science when they don't.

Nelson Pass, Revel, Bose, JBL, Meyer Sound. That's where t he actual scientists are. I don't necessarily like the result of all of them, but their science and business practices are rock solid as a result.


Na, you just have to know who exactly you are dealing with. There are a ton of tire kickers there, but also some people really strong, especially on amplifiers and electronics, and digital.  Acoustics is pretty weak, but that is pretty true for most forums.


I don't see Nelson at all as a scientist. Tinkerer and artist perhaps, but not scientist. Bruno Putzey is far more of scientist, as is Dr. Bose, and not just because of the Doctor, but the company overall. Certainly some scientists at Harmon (Samsung) and I would put Meyer far ahead of Pass too.


erik_squires OP
16,429 posts
 
The class of operation isn't important. How much feedback the amp uses *is*. This can have an enormous effect on how much and what kind of distortion is present.



Class D feedback works so differently than linear amps that I have trouble believing the amount of feedback behaves the same way, but what do I know?


deadhead1000's avatar
deadhead1000
720 posts
 
I've had many Class D amps over the years, Hafler, NAD, Mcintosh, B&K. They all sounded good. I actually miss the B&K. I also had some Pioneer, Marantz, Denon and Sony amps/receivers which all sounded horrible. I even had a Hitachi Class G which actually sounded quite good.
But I finally did try a Class A (590AXII Luxman) and I can never go back to Class D. I'm not bashing D, just saying that A has been a big improvement over every D I've ever had.
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