Who tried Class D only to return to S/S or Tube

11-28-15: Kijanki
My Rowland 102 sounded the best after about 400 hours. Class D amps are very revealing and often don't work well with some "bright" components. [...]

The exposure goes both ways; what's at the end of the signal chain (i.e.: speakers) can also be ruthlessly revealing as well as, conversely, reveal their limitations. When people describe SET's as possessing "lush, warm [i.e.: meant as warmer than strictly "neutral"] midrange" and generally "loose bass," it could be descriptive of speakers lacking mids resolution/speed and of (bass-)ported designs with poor damping and overhang. Connect well-implemented horn speakers instead (themselves far more revealing than most direct radiating designs) with non-ported bass of higher damping and the "math" can suddenly reverse into match-bliss: here the mids are no longer warmish warm, but attain a "bloom" and naturalness that's ultimately freeing of any containment resembling "hifi" in the usual sense, and a bass enriched with an organic imprinting more about texture, immersion and cohesion (traits of true horn bass as well) than oomph, attention-seeking and depth.

If one were to insert a Class-D amp here instead (many iterations though they are), and the sound suddenly became slightly bleached, bass-thin and lacking fullness (that's a guess), my take would be to assess the amp lacking harmonic richness and being over-damped in this particular setup rather than aiming the search light towards other components - not least the speakers. Though speakers (and their acoustic environment) are by far the most coloring and limiting factors, their potential to put into perspective on what to use earlier in the chain is significant.

One cannot simply swap out an AB amp for a D. The system must be coherent and matched.

This seems to be in response to my post so I will bite...and ask what do you mean by "coherent and matched?"

I didn't mention that I tried the amps with three different preamp options, two of which were made specifically for the amplifiers, by the same manufacturer that made the amplifiers. Because two of the preamps have low impedance outputs, those two matched well with either amplifier wrt impedance. The highest gain preamp was +6dB and the other two have zero gain, while the source is 4V. These numbers work well with either of the two amplifiers. Are there other parameters that need matched? Regarding coherence, what attribute or parameter would make one preamp more "coherent" than another when used with a Class AB or Class D amp, and couldn't the same preamp be "matched and coherent" with both of those amplifiers?

The Rowland was, I believe, a 500 series. (301"s?) It went from Atlanta in my car to my home after audition where the previous owner claimed he had owned it and it had been in his system for 2 years. Definitely broken in. It had the same sonic signature as the Bel Canto 500 References that I had such high hopes for.

The highs on all of these amps did have the "unbroken in" sound of limited extension, chunky mids. It was the upper mid distortion that drove me crazy, sort of like original cd players had. 4-12 khz was just a mess. Resolution, yes, due to a really good noise floor, but a harsh and not so musical sound. Maybe I'm not being fair, since I did not own any of them long enough to "tune" cables to their particular needs, but I didn't hear anything promising me that it would be worth the time and money.

It's for sure that technology has progressed way beyond the days when everyone used ICE stuff (and it all sounded the same). I remain curious and it still amazes me that SS amps of any sort work as well as they do (and I've owned a lot of them).

However, I just turned 60 and settled into a Mac 275. I have owned so many amps, etc. that I'm just going to listen to music for a change.

Yes ,the class D amps from a few years ago were unlistenable to me as well. I do
not think many of us are touting past class D designs as being musical and
competing with other class amps .Only in the latest implementations are they
competing with other classes these days .

Hi Jeff, I suspected as much... The amp was probably a pair of M501 monos or M201 monos... Unlikely to be the M301 monos, unless each chassis weighed about 95Lbs. Each M501 chassis instead might weigh some 20Lbs, and is about 7.5 inches wide only. is

M501 was a basic implementation using the ICEpower 1000ASP module. Very powerful and clean, but.... Subtlety and high musicality were not its main features. I heard the M501 several times at RMAF.... I deemed its sound not to be involving at all... ANd yes, treble can have a rather cold quality to it, which also means that if complex treble passages go through M501, you might hear more than a bit of harshness.

For the ICePower 1000ASP to sound good, it requires either the fine work done by Stronczer with the REF1000 Mk.2, or the PFC rectifier and custom power supplies that Rowland used in its higher end amps based on the same module, such as the M312 that I had for several years.

Rowland does market an external PFC rectifier called PC-1 which is compatible with M501. People who used PC-1 on M501 report the sound to be completely different, and to have approached M312.

Regardless... All of this is in the past.... M201, M501, M312, M301 are all 3 or four generations old. Class D has made significant strides since these 4 legacy Rowland amps, the only one whose sound I consider excellent for today's standards
is the M312, which shows up very seldom on Audiogon.... Its owners tend to keep it for a long time.

Regards, G.