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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.
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muralman1
1,527 posts
 
Atmasphere, you are entitled to your opinion. I did not know you are an amp producer. I have never heard a tube system, regardless of cost that can bring on the real performance better than my own class D system. Can you tell me what areas you think class D does not match your amp's performance? I have heard unspeakably expensive tube systems.
audioperv
18 posts
 
"and luck only determines the sound of the system- no doubt why so many want to know which class D sounds the best!"

Good point Ralph, perhaps that's also why I would really like to know what solid state and what tubed amp sound the best, . . . because with all those technological constraints, compromises, and underlying limitations out there, regardless the underlying technologies, it is my own ever-so-limited experience that results are more often than I would like less than stellar. . . but then, I am admittedly a little hard to please. . . regardless of technology.
atmasphere's avatar
atmasphere
11,784 posts
 
Muralman1 and Audioperv, I think the thing to look at is intention. If you start out with a given compromise, and then try to do the best you can, you wind up with something that is very good but with a compromise.

In the case of tube amps, compromise might start by choosing pentodes over triodes, as they make more power for their size. In fact if you look at transistors and the succeeding art, class D, that particular compromise of sound vs cost/size/weight/heat is one that as an industry we've been trying to beat for years.

So- what happens if you chose to do away with compromise? The intention is entirely different and so are the results. I agree that if you've heard a compromised (tube) amplifier, it might not best the class D amp that you have now, but the world of compromise has no meaning in the face of state of the art.

There is a common myth in audio that there is no 'best'. However, the English language tells us that it does exist- else the word 'best' would be meaningless. Usually we *believe* there is no 'best', since we have only heard that which is based in compromise. So we again come back to intention.
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simontju
257 posts
 
Hello,
I would respectfully disagree with Atmasphere words, if not all then vast majority. Class D designers and manufacturers are not for iPod and such alhgough I will admit that Spectron, for example, is designing, now, amplifier with 50 watts rms power with size less then postal stamp - as one of the project in professional audio. On other end of the spectrum Spectron is developing (compact!) 8000 rms amp for Inter-M, where Spectron won the contact against Bang and Olufsen (ICE), Philips (Hupex) and others.

No, class D was not design to work against heat. Spectron chief designer John Ulrick designed it in 1974 (so its not so young technology either!) to drive bass modules in his (and Nudell's) Infinity speakers - which I believe were accepted rather well ay that time.

I am AND engineer (digital signal processing) AND professional musician (graduated conservatory class piano centruries ago) and I can't imagine any audio designer who build amplifiers that cannot handle speakers with huge phase shifts and yet cause the chill down my spine when I hear the real piano sound in my listening room ( not heavenly piano glorified by 2nd and other even harmonic distortions nor one made out of steel or other metal with all non -existing details).

All The Best in Your search of perfection
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