Robert Harley: I was impressed overall with the bottom end of the amplifiers I heard, although it did seem a bit exaggerated, as though the amps are more dynamic in the bottom end than in the treble.
Wayne Garcia: That’s what I found, too, Robert, and I found some of the bass almost seemed detached from the rest, as if it were pumped up somehow. These amps didn’t seem to integrate as well in my system—again, except for the Kharma.
Does anybody else hear these almost jittery kinds of things that I was complaining about that I heard from three of these models? Something on the top end that bothered me, that just didn’t sound right?
Robert Harley: I had the impression that acoustic instruments sound a little bit like synthesizers.
Jonathan: If you’re not reproducing the entire harmonic series of any instrument with linearity, particularly any instrument in the midrange or higher, naturally it’s gonna sound strange.
Chris Martens: Well we also have to keep in mind that we’re comparing these things in very high-resolution systems to our reference analog or linear amplifiers.
Jonathan Valin: I was also comparing them to the sound of music—to the absolute sound. And compared to the real thing, not to the expensive thing, I thought most of these Class D amps were just plain weird.
Wayne Garcia: It seems to me that no matter what you’re comparing to, if you hear these problems going on something is wrong.
Neil Gader: I think we are isolating one particular factor (treble response) to the disadvantage of a lot of these amps. I found that a couple, the Spectron for one, created a wonderful black background for the midrange instruments like piano to bounce off of. I actually got a certain kind of focus on individually hammered piano notes that I rarely get from other amplifiers.
Chris Martens: One thing I observed with at least a couple of the Class D amps was that they seemed to be much more sensitive to both interconnect cabling and speaker cabling than most of the Class AB amps. I was able to make that jittery quality in the treble go away by picking cables carefully, and, in particular, in some cases by picking power cables carefully.
Jonathan Valin: Let’s fact it: All amps have limitations. But Class D amps seem to have more than most, and the ones they have seem to be more fundamental than most. No one here is kissing the technology off. It’s way too early in the game to do that. I think what most of us are saying is that Class D amps are still very much works in progress. For me at least, until some of these fundamental problems with bandwidth, linearity, and distortion are fixed, Class D will remain more of a convenience than a legitimate high-end amplification alternative.
What do you think about Class D? Join the discussion with other TAS readers and editors at a special Class D forum.
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