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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Wow! We all know our own equipment is a matter of our own taste and personality. Most of the time when we give our opinion when asked on this site what is better or sounds best we add the IMHO. We all have opinions most of us just don't get paid for them. For some reason if we are paid and published it seems to matter more. I value members of the Audiogon community opinions much more then one single minded reviewers opinion.

Just like mentioned above, "new technology gets it hard like when solid state was new". Remember when CD players were still developing in the late eighties? Philips came out with their TDA1545A 16 bit dac chip. People liked it, but wanted better. Now many designs are being designed that sound better then anything else using this chip. Zanden comes to mind here, if you want a TDA1545A-S2 chip it will cost you $200.00 for just the chip.

My point is in 15 years we will be trying to find these current class D amps because they sound so good and the new technology will be the argument.

I changed from $8K Melos separates to an $8K integrated to a class D amp and tube preamp because it like it.
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.
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?
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.
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.