'It's tubes stupid'.
Or as Vladimir of Lamm said in an interview - You can get killer bass out of transistors but that's not how it sounds in reality. He himself makes hybrid power amps, though, in addition to tube amps. Oops..
The Truth about Modern Class D
Bought the Rowland 501 monos when they first came out and have had absolutely no regrets. Class D is just a technology which can be used or misused. Really unfair to relegate it to some inferior status or to make generalizations. Tubes versus solid state is another example of either one sounding superior to the other being subject to the quality of design and the price range. Like they say 'it all just depends'. |
Straight from the horse's mouth: 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? |
Opinions vary. I power my studios Avalon Acoustic Monitors with Hypex nCore 400s and my listening rooms Avalon Acoustics Eidolons with Bob Carver Tubes. When using the switching amps to drive the Eidolons the subtle difference in presentation becomes obvious to us. We find we listen for much longer periods of time with the tubes. Relaxing is the word that best describs the difference. The switching amps slightly more forward and plate glass transparency that many may describe as brightness has become religiously indispensable in the acoustically treated studio. Pitting Class D against linear solid state or tube amplifiers is silly. They're simply another class of amplifier to choose from, that's a truth. I'm not going to drive my subwoofers with tubes nor am I going to use the studio for my listening room. |
helomechStraight from the horse’s mouth: We had better quote some noted designers as well. Bob Carver In a little update of my classic "Valve Analogue Stages for DAC’s #" I wrote: "Perhaps more crucially, so called Class D Amplifiers, which have in recent times sprouted up like mushrooms after a warm rain, continue to use the straight two or three level modulation scheme described above. And thus they still require the use of heavy handed noise shaping to attain anything like acceptable 16 Bit Audio performance. The clock frequencies for these amplifiers are usually at 300 KHz to 1MHz in the best cases. That is 3,000 to 10,000 times lower than what is required to attain 16 Bit / 44.1 KHz performance without noise shaping and other forms of signal manipulation! And again, one is baffled and perplexed by the rave reviews many Class D amplifiers receive, as baffled as one was about the late 90’s reviews of timeslicing dac’s. The best of breed I have auditioned were certainly not bad; however in direct comparison to the best available valve and solid state amplifiers they do not produce a very good sound. Well, at least they offer novelty and the reviewers something to write about other than another (however good sounding) 8 Watt valve amp. Incidentally, the best sounding Class D amps tend to be really low power single chip devices (putting out little more than the 8 watt valve amps), presumably because they are faster AND because they always work near what one might call “full scaleâ€, if they would be dac’s. On second thought, they of COURSE are DA Converters and where a Class D amplifier accepts analogue input directly it is an A2D converter followed by a power D2A converter! What an insight!?" Mark Levinsons interleaving of multiple Class D Amplifiers is potentially a step in the right direction, but does not go far enough. Personally I think that the best option would be something that combines a Class D Amplifier for the heavy lifting with something Class A for fine detail. Probably implemented in the style I did for AMR’s AM-77 "Jikoda$" Style. In this case both of the circuits involved can operate fully open loop. In many ways the problems in Class D Amplifiers are analogous (but not identical to) those in Class B Amplifiers (but without an option to implement Class AB or Class A) so similar solutions apply. Thorsten Loesch All Class D amplifiers are essentially delta-sigma DAC’s. If the input is not digital PWM signals (aka "DSD") but analogue audio then it is also a Delta Sigma Analogue to digital converter... Now DSD (aka SACD) which to my ears fails to come close, never mind equal true PCM CD Replay in most aspects of sound quality, operates at 2.8MHz switching, or around 10 times as fast as common Class D Amplifiers... Why anyone would want to listen through an A2D followed by an D2A Converter that are around 10 times worse than single speed DSD is beyond me. But with enough hype and snazzy naming it cannot help but sell high and wide. Cheers George |