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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.
128x128elberoth2
atmasphere's avatar
atmasphere
11,966 posts
 
Guidocorona, you may not believe this but I agree with you- I don't like 'tube' colorations either. I think many of those colorations have to do with design considerations rather than the tubes themselves.

Consider that because you have heard some tube amps which have coloration does not mean that all of them are like that.

I don't really like *any* colorations (tube or solid state). Spending a lot of time in the studio, hearing the live feed as opposed to the recording, how different mixers, speakers and amps behave will do that to you.

This is one of the intrigues of class D for me as they often lack some of the more heinous colorations that I associate with transistors and tubes. For all that, my experience is that class D amps often have their own unique sonic fingerprint that varies from brand to brand as it does in the scale of execution. Its getting control of those variables that seems to be at the cutting edge of this art.
guidocorona
4,298 posts
 
"Consider that because you have heard some tube amps which have coloration does not mean that all of them are like that."

I agree with you Atma. With any technology there exists stereotypical coloration/distortion, there is also brand-typical coloration/distortion, and then there is simply the atypical kind. I suspect it may be a lot easier to eliminate outright distortions than to tame colorations for everyone. We should remember that one audiophile's poison often is someone else's Nirvana. . . or in other words someone's coloration may be someone else's 'neutrality'. For myself I often do not even attempt to define my preference in terms of warm/lean/neutral. . . I will simply describe what I hear in semi-musical terms as well as I can, and explain what I like and what I do not like, and if I am at all capable, why.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
What can I say, sadly, I am probably not a member of the species 'Homo sapiens', because 'tubey' distortion do not sound at all priviledged to these poor ears.

You are going to the extreem here. Not all tube amps sound "tubey" and yet, they still have certain distortions characteristics that are more benign to human ear.

To my ears, a good tube amp still sounds much better than current Class-D designs. I have owned BelCanto eVo 4 amp, I have evaluated both ICEpower design (ASP based) and, just recently, the latest NuForce 9V2SE monoblocks IN MY SYSTEM, and all I can tell you, is that the difference between them and my current ARC Reference 110 is so HUGE, that it is almost laughable.
mrtennis
3,295 posts
 
all amplifiers have some consistent sonic characteristic which is detectable after audition, for some period of time by a well-trained listener, given a variety of recordings.

if amplifiers had inaudible levels of coloration it would be almost impossible to distinguish one from another.

what does this mean ? find an amp that you like and the quality and quantity of imperfection should not matter.
guidocorona
4,298 posts
 
Of course you are correct, Elberoth2. As I said earlier, for any technology there are stereotypical distortions, brand typical distortions, and atypical ones. Where I have problems is characterizing distortions in tube gear as 'benign' as a whole. At RMAF I ran out with 'bleeding ears' of as many tube suites as I did from SS or class D suites. Tube amps sounding classically 'tubey' were definitely a minority.

As for ARC Ref 110, I agree completely that it--and the rest of the current ARC lineup--are darn special amps; I own a Ref 3 and in general I love the new ARC sound; The only reason why I will not even consider a Ref 110 is because. . . tube amps generate too much heat in the ghastly Texas Summer. What switching amps have you evaluated/contrasted against Ref 110 besides Bel Canto Evo 4 and Nuforce? One of the problems I can see with some class D marketing is a tendency to hyperbolic generic claims of the type. . . 'X crushes SS/tube sacred cows costing 4 times as much'. The problem is that such sweeping uncautious claims expose a product to equally uncautious counterargument such as yours, where you contrast a brand new $10K tube design (Ref 110) with a 5 year old $4K switching design (Evo 4) and a current $5K switching design (Nuforce Ref 9 SE) only to apply the old induction step and produce a slightly brave conclusion. Seems to me you are comparing one orange with two clementines. . . and concluding that all oranges are . . . heavier.
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