Class D at low volume

Efficiency done well is always a good thing for sound quality I would say, including at lower volumes. Class D amps are the modern way to introduce some efficiency into a system with out the size bulk and other idiosyncrasies that might go with full range high efficiency speakers


Schubert,

Bel Canto has been doing Class D for a number of years so there is significant variability there I would say with newer models capable of outperforming older in general.

The earlier generation Bel Canto Class Ds ref500k, ref1000, not later m models, were stock older generation Icepower modules in a nice box. Prices reflect that.

ref1000m and ref500m added custom power and input sections to improve performance and match better to tube pre-amps.

ref500m uses a newer gen Icepower than 1000m last I checked so there could be some sonic differences there as reported.

latest BEl Canto products probably use newer IcePower mocules and I would assume implement design enhancements learned over time as well. I would expect top notch performance and that is what I read.

So Bel Canto crossed the threshold of top notch performance out of their Class D amps a few years back already I would say based on my experience with the hard to fault ref1000m however I have no doubt the technology is relative new still (compared to the others) and continues to improve technically in regards to bandwidth, noise level controls, etc., to whatever extent it may matter practically. The sky is the limit with this technology over time I believe and may already have crossed the threshold needed for top notch performance in "high end" systems practically. All signs seem to point to that.

I'm considering going to a compact integrated amp on my second system and the BC Class D based integrateds are on my shortlist there currently along with Wyred and Rogue. I am pretty sure I will go Class D only for an integrated as well at this point. It does not make sense to me to do otherwise at this point. Tube amps and monster sized Class A/B amps are becoming increasingly unnecessary to me as a result of the performance and value proposition with Class D.

Although you live in Minnesota right? You might want to go with an amp that wastes power and throws off some heat especially in winter. Kill two birds with one stone. I'm only half joking. Portable heaters are not expensive though I suppose.

Thanks for all the Info map, I'm bone tried of tube amps with their endless problems.

Mentioned Bel Canto amps are the best at any volume level.

My only caveat in recommending Class D amps over others currently might be in regards to the very highest frequencies, tne ones over 12Khz or so that we perceive as "air" in teh sound. I am 50+ and used to hear fine up to 20khz but now I am more limted, as are most people as they age. So I am not a good one to be able to compare how various amps might perform at the highest frwequencies. If one looks at Class D amp measurements, the highest audible frequencies is the final frontier for the technology to conquer on paper. In practice though I do not hear anything to be audibly deficient or missing though I suspect the latest and greatest Class D technology to have the technical edge from a pure bandwidth perspective. Noise control as well as mentioned. To the extent either might matter in practice that is. I have never done a focused A/B comparison on say how well teh best Class D reproduces things like cymbals and air for example compared to others, but I would expect it to be a reasonable competition as best I can tell.

When I was young and heard clearly up to 20khz, I also tended to be very sensitive to anything that was not going on well at teh higher frequencies.

It would be interesting to do a study of amp preferences based on age factor.

It's my understanding that class D power conversion modules typically use high levels of global feedback. The input signal is constantly being compared to the output signal (thousands of times per second) prior to the output signal being amplified. The output signal is only sent to be amplified once it matches the input signal and any necessary adjustments have been made. This high level of global feedback, which designers of more traditional amp topologies typically try to avoid at all costs, is a mainstay of class D amp design. My theory is that this high reliance on high levels of global feedback is responsible for class D amps' astounding neutrality and their performing so close to the ideal of 'a straight wire with gain'. Also, my theory is that this design results in excellent frequency response at all volume levels.

As I've stated I have no technical training on amplifier design or electronics. The above is based on personal reading about class D amplification combined with any small amount of rational thought and common sense I may possess. I may have this entirely wrong, however, and would welcome comments and thoughts on my theory from those with more technical knowledge on class D amps than myself.

while it is true that class-D amps use feedback to make them work & while you are right in stating that without global negative feedback a class-D power would not work, I don't think it is correct to correlate the use of global negative feedback to a class-D power amp's sonic quality.
The way class-D architecture was invented/designed/formulated, global negative feedback is part of its entity. So, just because you read global negative feedback you shouldn't relate it in the same way as you would to GNFB in a class-A, AB power amp. The class-D architecture needs GNFB while class-A, AB architectures have topologies that can do with little or no GNFB.
The class-D power amp is a continuous-time, discrete-voltage pulse width modulated system. The 1st gen of class-D power amps used (& still use) analog/linear power supplies (like the type you see in class-A, AB amps). And, now I'm observing that the next gen of class-D power amps are using switch-mode power supplies (which are themselves class-D power supplies). I think the audio SMPS has finally developed to a point where it is has a low enough noise floor & can handle large currents in a compact size.

Sonic qualities of a class-D power amp have to do with
* power supply design
* noise attenuation at the final output (the amp binding posts) - correct choice of filter
* managing the switching noise in the power output transistors i.e. reducing the switching noise impact on the analog circuits that form the overall class-D power amp
* routing of noisy & quiet signals

just to name a few items.