" Here is a quote from Bruno Putzey, creator of Hypex modules and Mola Mola in an interview with Sound & Vision.
S&V: Generally speaking, what are the key benefits of Class D versus the traditional Class AB and Class A designs that have long been favored by audiophiles?
BP: Efficiency and therefore the ability to construct amps that are powerful for their size. Only that. Modern Class D amps, in particular mine—ahem—sound good not because they’re Class D, but in spite of it. I can’t repeat that often enough. Left to its own devices, a switching power stage tries to do just about anything except amplify audio. You choose Class D to save energy but it’s all elbow grease after that. People don’t realize how much more challenging Class D is compared to Class AB. It’s truly an order of magnitude."
Hello seanheis1.
I read that full Sound & Vision Bruno Putzeys interview years ago. I noticed you selectively cited only the above quote from BP from the interview because it, apparently, supported your own opinion on class D but failed to cite other quotes that do not. I believe it’s useful for anyone on this thread or anyone interested in class D in general to read the entire interview, less your selective censorship and cherry picking of quotes, to obtain a better understanding of class D and BP’s unrestricted thoughts on the subject. To promote the honest, full and accurate edification of thread readers and continue this free and open discussion of the pros and cons of class D amplification, here’s a link to the complete Sound & Vision interview:
https://www.soundandvision.com/content/bruno-putzeys-head-class-d-page-2
For those readers lacking the time to read the entire interview, here are a few other interesting and relevant BP quotes from the interview seanheis1 conveniently felt the need to omit:
"S&V: Conventional wisdom says a great amplifier has no sonic character of its own and, beyond boosting the signal level, is transparent in the audio chain. But does the nature of high-quality Class D amplification—perhaps through the absence of distortions found in other circuit topologies—produce a particular sonic signature or specific attributes you could describe?
BP: Well, if the amplifier is truly great that’s absolutely right. Sonic signatures are what you get when you approach the same ideal from different angles. There are a few distortion mechanisms conspicuously missing in Class D, mostly those related to the input stage of a Class A(B) solid-state amplifier and nonlinear capacitances. Those are also missing in valve [tube] amplifiers so it’s quite common for people to notice that a Class D amplifier is somehow reminiscent of valve amplification in terms of “sweetness” for want of a better word.
I’ve heard several reports of valve aficionados ditching their glassware and switching to Ncore. All I can conclude from that is that those people clearly weren’t actively seeking the distortion of valves as many believe, but instead had a legitimate beef with certain sonic aspects common to most solid-state designs. That’s one thing I have to explain again and again to my fellow doubters: when audiophiles report a particular listening experience, that experience is real. Trust that. Just don’t trust the explanation they proffer.
S&V: The new generation of Class D amps are obviously good enough to herald audiophile kudos, as we saw most recently with David Vaughn’s review of ATI’s AT527NC and AT524NC amplifiers, but what lingering issues might still need to be resolved to move performance to an even higher level?
BP: I’d say that basically the cat has been skinned. Further refinements will surely happen but the same can be said of the other amplifier classes. In terms of things affecting sound, I don’t see any fundamental outstanding issues that merit much attention—it’s mostly down to lesser implementation details, ordinary technological progress, and perhaps some more adjustments in the math department. I would like to see magnetic materials with less hysteresis though."
The complete interview contains a lot of other interesting and relevant information about class D, I encourage anyone wanting more unadulterated information on class D to read the full interview.
Tim