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It is the notion that Class D switching speeds are the cause, and that someday they'll be fixed that irritates me. It's a type of prejudice not born in evidence. It's the equivalent of "all feedback is bad" sales pitch for some amplifier designs."
Hi Erik,
'A type of prejudice not born in evidence' is a very accurate and succinct way of describing how some class D detractors have a knee-jerk response, whenever class D is mentioned, of proclaiming a completely unproven theory that current class D switching frequencies are too low and negatively affect frequencies in the audible range.
Nevermind that the current leading expert on class D, UcD and Hypex NCore inventor Bruno Putzeys, has stated the current switching frequencies are not too low. Nevermind that there is absolutely no scientific evidence supporting the claim that current switching frequencies are too low and cause audible sonic anomalies. Regardless, there seems to be a small group of class D detractors that still claim that current switching frequencies are too low and negatively affect sonics that they're able to detect.
I've spent more time contemplating this subject than it likely deserves as well as why there are so many class D amp listeners and owners, just like you and I, who perceive no sonic anomalies at all while an apparently smaller group claims to hear some and dismiss class D technology as a result.
My current thinking, based on multiple threads discussing the amps and technology over the past 5 years, is that class D detractors and naysayers are best not considered as a single group but as a collection of smaller groups such as these:
1. Those that have never actually listened to a good D amp in their system but simply parrot other critical comments they've read previously. This group can typically be identified by their comments being more biased toward whatever amp type they own and use than biased against class D.
2. Those that acknowledge the strong points of class D but consistently mention the same perceived flaw of switching frequencies being too low This group can usually be identified by a lack of scientific support and a lack of even an anecdotal description of the claimed flaw's sonic affects.
3. Those that actually do try out class D amps in their system but claim that 'something is missing from the sound' and decide to just continue using their existing amps. This group can usually be identified by statements containing sentiments about how they really wanted to like class D but liked the sound of their existing amps better.
Their existing amps are often high quality and expensive tube and class A amps that are very large, electrically very inefficient, emit copious amounts of heat into their rooms and color or flavor the inputted signals in some preferred manner. This group is typically and understandably seeking a more electrically efficient amp that doesn't raise the temperature of their rooms but still performs at a high level.
The 'something missing in the sound' they have difficulty pinpointing is predictably the coloring and flavoring of the inputted signals that is avoided by design by most good class D amps in favor of a much more neutral approach that emphasises faithfully amplifying inputted signals more attuned to the audio ideal of an amp as 'a straight wire with gain'. I have no issue with this group preferring their more colored amps.
Of my 3 general groups above, I agree that group#3 is definitely the most frustrating since they offer no scientific evidence of support because none exists, are very vague about the sonic manifestations they theorize exist in the audible band due to the switching frequencies being too low and I'm not aware of a single experienced class D user/owner, including myself, who has ever heard any sonic anomalies that they claim exist.
I think it's safe to state that any logical person would consider their theory as being thoroughly and completely debunked.
Just for fun, however, let's assume they're correct and all the thousands (millions?) of very satisfied class D amp owners/users are wrong. Let's assume these sonic anomalies actually do exist in the audible range due to switching frequencies being too low.
If this was actually the case and the truth, I would expect medical experts, neurologists and hearing care specialists to inevitably classify the ability to hear sonic anomalies in class D amps as an auditory/cerebral affliction, malady or syndrome. Just the fact that the majority of humans are incapable of perceiving these sonic anomalies but a small minority of the population can indicates an allergic reaction to class D by this minority.
I agree that individuals in group#3 can be extremely frustrating and annoying. But perhaps we should be more sympathetic to these poor afflicted souls. Just as being lactose intolerant prevents those afflicted from enjoying a delicious glass of cold milk, being class D intolerant prevents those afflicted from enjoying the delicious sound of a good class D amp.
Love,
Tim
