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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
11,894 posts
 
Unfortunately companies are racing for best specifications. I would advise to take specifications, promtly discart[sic] them and just listen.

Still the best advice anyone can give.
simontju
257 posts
 
"Unfortunately companies are racing for best specifications. I would advise to take specifications, promtly discart[sic] them and just listen."

Hmmmmm.. these stupid people from Spectron wrote on their silly web site:

" BLA BLA BLA
BLA BLA BLA
YADDA, YADDA, YADDA,
BLA, BLA, BLA
BLA BLA BLA
YADDA, YADDA, YADDA,
BLA, BLA, BLA
BLA BLA BLA
Conclusion: We hear time and time again that the numbers on the data sheet do not predict an amplifier's sound quality. While largely true in the past, today more and more parameters, measured correctly and even more importantly - truthfully reported - do reflect well some very important amplifier sonic characteristics. When you are considering buying any amplifier, the first question must be if it can drive your speakers at all. If it can drive your speakers, then can it drive them well. Can it drive them, at the very least, without euphonic coloration, muted treble and veil etc? The right approach is to check the amplifier's distortion level and output impedance at high frequencies(* - for class D specifically - my comment here) . Also look for peak current and its duration, flatness of frequency response, noise level, bandwidth etc. Of course, Spectron also considers the speed of the feedback loop and inclusion of the output filter in the feedback loop to be of great importance, even if an audiophile cannot really check on this. Each and every one of these measurements contributes to a gorgeous musical experience, and each deficiency will be readily apparent to the critical listener."
muralman1
1,527 posts
 
We have concentrated on the Rowland 201 because the most vociferous defender of class D happens to own that Rowland. I have not heard any of the Rowlands, and have no opinion of their sound.

The builder of my amps, the H2O (a 500A module amp), also makes the digital power supply amps. He makes no bones about it, he feels the 500A module, mated to his massive power supply, sounds better.

The point of this is there are a large number of class D amps. One cannot draw a general opinion through these amps, unless that opinion is derived from a built in love for tubes or solid state sound.

For my ears, Class D amp builders are not trying to achieve a sound like tubes or solid state. They are trying to amplify the truest signal to their ability. If it were the mimicry of tubes they were striving for, they would not have employed a passive filter to peel away the manufactured even and 2nd order harmonics, the very distortion that endears some tube defenders.

Recently I auditioned a higher order DAC. It introduced a lot more tubes into the mix. While the huge DAC did spit shine shine separation, and power, it's three more tubes obviously lent a good deal of color.

My preference, and I must insist it is my preference, is for less coloring, and more raw truth. My amps and preamp (class A) are doing that for me.
larryi
4,077 posts
 
I wonder if Class D tends to shine more in certain applications than others. I note that some of the big supporters here have notoriously difficult speakers that would tax most amps. For example the Apogee Scintilla has an impedance curve that drops well under 1 ohm at certain frequencies; the MBLs, while not as brutal, are also tough.

I find it interesting that B&O (maker of ICE module) itself, in some of their active speakers, uses the ICE module for the bass unit, but conventional solid state amplification for the mid and treble amplifiers. Any reason for that?
coffeey's avatar
coffeey
363 posts
 
Lets see if we get a answer for that last ?
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