Class D is just Dandy!


I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.

That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.

For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.

Please share your experiences with class D amps!
erik_squires
I think we'll all live long enough to see the day when Class D is the only amp used in subwoofs. The little 350-watt plate amps in my Tylers allow for a higher-frequency roll-off that spares the tubes some real heavy-lifting and allows them to concentrate on critical mid-bass, mids and highs where (don't want to start a flame-throwing contest here) tubes still reign supreme.  I also have one of those little cigarette-pack-sized 20 WPC Class D Lepais (which always seem to be on close-out for $20 from Parts Express ) that is on 24/7 hooked up to a pair of small $60 Dayton speaks for the TV: net result being an $80 "sound bar" that sounds pretty good and beats anything from Wal-Mart for $<200. (I mean, who wants to waste tubes listening to Judy Woodruff or some ancient B&W movie with a crappy sound-track anyway?)

Subject for another thread, perhaps, but why do the makers of of $2,000 flat-screen TVs include sound that is worst than a 1950s transistor radio?
Class D amps seem to be very much more speaker impedance sensitive than traditional A/B types. Knowing that an 8-ohm (nominal) speaker can wander down to 2 ohms depending on the music, I wonder about the effect on Class Ds at high levels with fussy electrostats, for example.

So much in future will depend on execution just as it does now: pwr supplies, the outputs' electrical behaviours, good ol' quality control, the quirkiness of the specific technology and the like. I can just see a snobbery develop amongst transistor types towards Class D amps the way some of my tube-loving brethren hold against s/s/ amps. The ultimate arbiter will be the ear, and we each have a different pair ...

I love my little Benchmark AHB2 amps. They are A/B with class H rails but minimize the distortion to pre-amp levels using feed forward error correction. Ultra small and fast switching power supplies that move the switching out of the range of human hearing. There are a lot of exciting innovations on these. They whip around my Maggies like nobody's business, are crystal clear and are dead quiet even at concert volumes. I don't have to turn them off like my Pass amp. . . 

https://benchmarkmedia.com/blogs/application_notes/14680625-the-ahb2-a-radical-approach-to-audio-pow...

https://benchmarkmedia.com/blogs/application_notes/131424519-amplifier-crossover-distortion

They have some good videos and articles speaking to their designs if anyone is interested. 

- Steve
I have 2 PS Audio D amps,they are good enough for me and I have no problems with better or newer technologies...after all it is the sound that counts...
@hgeifman I'm in a similar situation. I just purchased the Bel Canto Ref600m monos and will be driving them directly with the PS Audio DirectStream Junior. The DSJ isn't quite the M1 DAC, but I hear they are both similar in the way they present more of an analog sense of ease and lack of digital glare. I'm excited to get my new setup running.  

This setup is an upgrade to my previous pair of Cambridge Azur 851N DAC driving an Audio Research DSi200 which is a class D integrated using a linear analogue power supply. I was actually very happy with the ARC, but it had a passive pre section that couldn't be bypassed to use just the power section. I need a power amp that will allow me to control volume digitally elsewhere in the chain (and perhaps do some DSP/crossover stuff with a DEQX in the future). The ARC amp had awesome drive and really wide soundstage. Everything I read about it online was very positive from 6 Moons, Absolute Sound, etc., but ARC stopped making their class D line. I always wondered why. I can only speculate. It certainly wasn't from poor reviews.



@noble100 @neil_squiresNiel

@neil_squires@neil_squiresand Tim, harmonic distortions lower than 0.005% have already been achieved in class D for a few years. One example is the Mola Mola Kaluga designed by Bruno Putseys using an enhanced NC1200 Ncore modules. THe amp is rated at less than 0.003% across the audible frequency band. The big Rowlands M825 and M925 amps also exceed the 0.005% target, but their price tag makes them somewhat more exotic.


The interesting thing in Gallium Nitride transistors is not so much whether they can in principle enable a high priced class D amp like the panasonic to achieve distortions lower than 0.005%, but if the technology could bring such performance in designs that serve the sub_$10K market, and perhaps one fine day, even below the $5K market.


On the other hand, the audible performance of an amplifier is not created by one particular measurement, nor by a slew of measurements, but by the effect -- iuntellectual and emotional alike -- that the device is capable of having on a listener... Plenty of amps of any class can mesmerize a listener, with a somewhat weaker link to their total declared distortion.  


G.

  


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@neil_squires@neil_squires