Class D = Trash?

randy-11,
     You stated:
"of course, you can measure all sorts of distortion products - inharmonic means non-harmonic."
    Well golly gee, Randy, I would have never thought that 'inharmonic' means the same as 'non-harmonic'.  Of course they mean the same thing, but that doesn't mean that either one is an accepted scientific specification and it definitely doesn't mean either one can be currently measured.
    Despite your claim of certainty, I am going to wait until atmosphere replies before I believe that there's a current specification for 'inharmonic distortion' and whether it's measurable.  I know there's a specification for 'harmonic distortion'  and 'intermodulation distortion' as well as standardized methods of measuring both. 
    But this is the first I've heard of 'inharmonic distortion' and I doubt it's even currently a valid scientific term and, even if it is,  whether there's a standardized method of measuring it.  From atmasphere's earlier post, it seemed to me that the term 'inharmonic distortion' was an informal term used by some amp designers to distinguish it from intermodulation distortion and he made no mention of whether it could be measured.

Erik_ squires,

     I'm in complete agreement with you and I hear absolutely no sonic artifacts/anomalies when listening to my class D amps, either.  I know from personal experience that all of my class D amps outperform my former class A/B amps by a wide margin in every area that I care about, although my A/B amps may not have been as highly biased as yours.
     However, I try to keep an open mind about things and listen to the thoughts and opinions of others, especially from well respected sources such as atmasphere.  Hopefully, he'll impart some more wisdom on this subject soon.

     Ultimately, I realize I'm not concerned at all about whether the theory that current switching frequencies are too low and cause audible artifacts/anomalies is true or not, other than curiosity.  If the theory is proven not true, it will just confirm what I have not been hearing since I began using class D amps in my system.  In the unlikely case that the theory is proven true, I will be admittedly shocked for a few moments but then I'll just continue on enjoying my class D amps as if nothing had changed because nothing will have changed; I will continue to not perceive these sonic artifacts/anomalies that are proven to exist just as I did not perceive these sonic artifacts/anomalies before I even heard of the theory of their existence.      
     Sure, I'll listen to a class D amps in my system that claim, either by employing better passive filtering or higher switching frequencies, to eliminate all  theorized sonic artifacts/anomalies if they ever become affordable just to test if I perceive an improvement in performance. 
    I'm just having a hard time conceiving of how the absence of something (sonic artifacts/anomalies), that I didn't perceive in the first place, is going to improve my system performance.  
     I'm not planning on selling my excellent performing class D amps anytime soon, perhaps ever.

Tim

Hello all,

I only time I can recall listening to "Unharmonic distortions" is when our granddaughter is over and wants to play some of her music,she's 12.

Kenny.

1. Is there a consensus among amp designers that current switching frequencies (what I believe you're calling 'scan frequencies') being too low is the primary cause of 'inharmonic distortion'? If so, is there also a consensus that raising switching frequencies to the 3-5 MHz range would reduce 'inharmonic distortion'?

No.

2. Can you explain why I, and apparently many other class D amp users, do not perceive our class D amps as being cold or sterile? Do you think the ability to perceive the affects of 'inharmonic distortion' differs among individuals or do you think it's more likely the degree of 'inharmonic distortion' varies by amp?

A lot depends on what your reference is and different amps have differing amounts of distortion. Like anything else in this world, you have to try it. As a general rule of thumb though, if you can turn it up loud and it also **sounds** loud, then you know you have a problem. If your system is devoid of higher ordered harmonics and inharmonic artifacts, you won't know how loud the system is until you find that you have to yell at someone sitting right beside you to be heard. 

3. Are there any current methods of measuring 'inharmonic distortion'?

Of course! The best use is with spectrum analysis.

no-bell - instead of wasting time on your verbose post above, you could simply use google to search for "inharmonic distortion"

try it

(and, no, I don't claim that Class D is good or bad -- I DO want to know if it offers any advantages for me)

atmasphere,

      Thank you for replying to my questions.

    Your confirmation that current class D amp switching frequencies are not causing 'inharmonic distortion', along with class D Ice and Hypex NCore power module inventor Bruno Putzeys' statement that current class D switching frequencies in the mid-500kHz range are "completely reasonable", refutes the theory that they need to be raised to the 3-5mHz range (to not affect frequencies in the audible range) as far as I'm concerned.
     These confirmations make sense since they mirror the more subjective perceptions many class D users have, including myself, of the total lack of sonic anomalies and very high quality performance levels of class D amps..

    I'm looking forward to hearing the results of your first class D amp design effort.
   I suspect your class D amp will be transparent, detailed, with a very neutral overall quality while also having the extreme low noise and distortion levels that all seem to be common characteristics of good class D amp designs.  
   I believe you'll also find that an amp with the above traits will be a great match with high quality tube preamps since the amp will operate as the audio ideal of 'a straight wire with gain' which  will allow the sound qualities of your tube preamps to be amplified faithfully without any alterations. 

Tim