Class-D amps - a different re view


Martin Colloms, the editor of HiFi Critic (ad-free mag from the UK) have recently published the review of several different Class-D amps, together with an in depth technical analysys and measurments.

His conclusions were not favourable, to say at least:

"I regret that not a single model merits unqualified recommendation. Price is not the issue; the poor listening tests speak for themselves. (...)
At present we have to take the prudent view that good sound might be possible from switching amps, but we haven't heard it yet."

BelCanto REF1000 (ICEpower) - score 10.5 pooints
"The ICE power module used has a dependable reputation, and the design is well built and finished as a whole. While I would not suggest that you shouldn't try this amp, on sound quality grounds alone I cannot recommend it for audiophile use."

Channel Islands D100 (UcD) - score 13 pooints
"While I have reservations about a number of aspects of sound quality, and advise personal audition, given the solid lab results (...) the overall performance and the moderate price, these CA Audio monos do make it to the 'worth considering' cathegory."

NuForce 8.5V2 (proprietary technology) - score 9 pooints
"Yes, the price is good for the power output. Yes it's pretty, light, small and runs cool. However, the sound quality simply does not justify recommendation." (on top of that the NuForce amp measured very poorly - Elb)

Pro-Ject Amp Box (Flying Mole) - score 5 points
"I'm sorry to say that Project (...) was a real disappointment in the listening tests, and can't be recommended."

Just as a point of reference, recently reviewed Krell 700CX scored 100 points, CJ Premier 350 - 110 points and ARC Ref 110 - 135 points.

At least someone have had the balls to say it. This is why HiFi Critic is THE mag to subscribe.
128x128elberoth2
Atmasphere,

I take issue, just a bit, with the notion that there is one technology that represents no compromises, based entirely on sonic considerations. I know that all triode, no feedback, and no output transformers have a lot of theoretical advantages, but, some would argue that paralleling multiple tubes to increase output and to decrease source impedance has its drawbacks. I am not arguing that that is the case, but, just pointing out that every technology has its theoretical disadvantages.

That said, I personally like very much what I hear from your amplifiers. There is nothing like a good OTL when it comes to liveliness, energy and sheer fun (something so many designs seem to suck out of music). But, there may be purely subjective reasons to favor another form of amplifier, even if that amplifier is not "objectively" as accurate.

I have only extensively listened to one Class D amp myself. I heard a Rowland (first generation amp which sold for something like $15,000 for the pair) in two systems, in one driving Sonus Faber Anniversarios, and in the other, the same amp driving a custom horn system. I personally did not like the sound, but not because it sounded edgy, as some have commented. To me, that amp, in both systems, sounded shut in on top (lacking "air") and devoid of natural sounding hall cues and realistic decay of notes. The soundfield just sounded artificial and "dry." There was something else "odd" and "unnatural" about the sound that I cannot quite describe, but it was immediately bothersome to me. This was a drop-into-a-system audition with no attempts to find complimentary components and optimize setup, but these same characteristics were evident in both systems which makes me wonder if this was an inherent trait of the particular amp.

I know any one example cannot possibly represent all applications of a particular technology, so I hope to hear other switching amps in good systems.
Larryi, on second reading, the 302 is a stereo amp. You seem to be describing monoblocks. Do you remember their very approximate physical size? JRDG has 3 monoblocks in its 1st gen ICE offerings: 201, 501, 301.
Hi Larryi, I concur with a lot of your findings on the 1st generation Rowland 302 amp. I heard it twice at some length at a dealer, but it was not stirring my imagination at all. . . polite to a fault. Totally different experience with the 2nd generation 312 amp from Rowland. I heard it at RMAF both last year and in 2007 in the fabulous Soundings / Rowland / Sumiko suite, driving a pair of Vienna Mahlers. I have enjoyed the sound of the whole system sooo much. . . I have ordered a pair of Mahlers. . . can't afford a JRDG 312, at least this year [chuckles!]. By the way, the system configuration was identical this year and last. . . but last year the system was set up in a much better suite at least twice as large as this year's. Yet, in spite of their acoustic challanges, this year's two little suites of Soundings (of Denver, Co, 303- 759-5505) still were in my opinion two of NOT TOO MANY RMAF suites where I met music that unconditionally moved my soul . Guido D. Corona
Tubes and Class D. I have heard all solid state systems with class D power amps. Larryi gave a good description of the sound. I have a tube pre and a class d power amp. I think the sound is both highly detailed and warm. Clean, clear, tight, and warm. No solid state "cold". No class D "thin". To get the best out of class D, IMHO, combine old (tubes) with the new(class d). Just as the tube vs. solid state or CD vs. vinyl debates go on and on, so will this new debate in the audiophile world. Muralman, good listening from "Prairie Class T".