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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.
elberoth2
leisure7
2 posts
 
to anything else I've heard.

There are a lot of switching amps that are poorly designed and that do not manage RF noise. Using a switching power supply saves weight and cost, but places a major noise source next to the amplifier circuitry. It takes a lot of design effort to reduce the effects of this noise, but the effects cannot be made as small as if the power supply is a good linear design.

Colloms commits the error of hasty generalization by blaming the approach for the consequences of inadequate design.
jdillard
5 posts
 
I thought the power supply was built into the circuit boards on these amps. I'm new to this, but aren't most of these products just the B&O board inside a fancy box? For those manufacturers that use the B&O kit, what differentiates their amps?
muralman1
1,527 posts
 
There are module in a box ICE amps, millions. That is why they developed a good digital power supply.

Although some versions of ICE ASP modules do make it into fancy boxes intended for the Hi Fi set, they tend to pass by the wayside. B&O does make a module that requires an add on power supply. How that power supply is designed and applied to the module separates the big boy ICE amps and the pretenders.
bbro
191 posts
 
In answer to Jdillard.

Yes most class D switching amps do use the B&O with the expeption of Spectron, which use their own proprietary module plus a lot of very high speed sampling/feedback plus a very large transformer. I have listened to the B&O based units and the Spectron (Musician III) and the difference is very significant. And I agree with Jw94055 that a tube preamp is definitely advised.
zilla
46 posts
 
My Nuforce 9SE V2's are the best I have ever heard. They blow me away. More reviewers agree then disagree. Just listen to then folks. I hit an endpoint in amps. Different sounding amps yes, better sounding amps perhaps, but these are really very special. The soundstage is simply as good as you will ever want or need. There are no side walls, back walls, or speakers. These are very clean and clear and never run out of steam in my system. Dali MS'5's and Modwright CD player. Move over vinyl. Finally.
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