Do ClassDAudio Amps Have Proper Decay Of Notes?
The ClassDAudio goes out to 35khz, do you think this is far enough to avoid the ringing issues that switching amps have?Its generally agreed that you need more bandwidth than that. Even the AES which tends to be overly conservative recommends 2 octaves above 20KHz (80KHz). I can't comment about ringing- that seems to have more to do with the individual design rather than an overall characteristic. |
The trouble with Class D is the frequency of the switching noise, (the saw tooth you seen on the top of this bandwith limited 10khz square wave) http://www.facstaff.bucknell.edu/esantane/movies/10kHz10v4ohmsquare.JPG In the future when the components are faster and the switching noise is much much higher then this noise can then be filtered out effectively and then not effect the audio band. At the moment it will always influence the sound quality of Class D as it’s too close to the audio band not to effect it after being filtered out. Manufacturers either filter it out low so it’s not there but the trouble with that is it’s filtering way down to 5-10khz, into the audio band, which ruins any decay/harmonics of the music signal. Or they filter it up high,, and let through the switch noise to the speakers, this then sound hard and etched, some go for the middle ground with a bit of both. Cheers George |
BTW: that "future" much higher switching frequency I talked about above, is closer than we think. Technics with their SE-R1 are showing vision by developing their own much fast switching frequency transistors, double the norm that’s around now. It would still be better if it were 5 to 10 times faster, but it’s small steps to a good end for Class D. Then you’ll see me sell my big hot power hungry boat anchors. But the amp is expensive at around $22,000.00usd I believe. http://www.technics.com/us/products/r1/se-r1.html#overview And you can bet they’re not going to sell those transistors to just anybody. Just one reviewers words of what he heard: "Listening to tracks that we’ve heard 100s of times — and on excellent systems at that — is now a revelation of once hidden nuance and detail. Not only are we hearing things we’d never heard before, we’re hearing it in a way we’ve never heard it before. A music system that sounds like a live performance is a tough goal to attain, but Technics’ flagship nails it." Cheers George |
Class D has evolved into many different iterations. Since my first switching amplifier, the PS Audio HCA-2, I've owned four other brands and auditioned in house six others. During this time I had an Ayre V-1xe, MFA D75, and Carver VTA 180s on hand. Nothing personal but I guess I'm just skeptical when I read about generalizations regarding switching amplifiers. While I've seen graphs that dramatize a digital waveform I honestly can't hear anything that would suggest a stair stepped waveform or "digital noise" from any of the switching amplifiers I've listened to. Early on I would admit to there being a difference in presentation but I've been fooled by the NuForce SE's and the nCores in short term listening in my own system. The only commonality that I've found in most class D designs is their sensitivity to the quality of AC power and poor synergy with silver cabling. If memory serves me the Hypex nCore kits were $1300 direct. The nCores are in my studio system driving a pair of Avalon Acoustics Monitors. The combination is stunningly transparent which is amazing for monitoring my recording but not exactly ideal for casual listening. Over the long term I prefer my VTA 180s driving the Eidolons in the main system, but thats me. |
