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
Increased ownership of class D amps. As little as a year ago, there may have been maybe a dozen posts. Some few of us were championing class D four years ago. We were laughed at then. Now there is strength in numbers. This is great!
I am elated to see in this thread manufacturers discussing merits -- or perceived issues -- with switching amplification. We consumers can only learn from these exchanges. I am however much less comfortable with veiled potshots about one's competition of the type:

"So into what impedance does this spec occur or is it 'marketing'?"

I appreciate a designer being proud of his own products, but there are more effective ways to demonstrate it. . . . than resorting to the 'lower' ground, which is not necessarily deemed a highly regarded marketing technique. Regards, Guido
Imho Martin Colloms should make apologies because he tried to disqualified class D amps by using pseudo scientific arguments that underlie his lack of knowledge. This is funny: What would Mr. Colloms do if class D was the only type of amplification? Kill himself? :)

Chris
Guidocorona, I was merely commenting on a spec that clearly was not possible as it was represented. I also demonstrated that with the math.

If you think I was taking a pot shot, I apologize. However, let me point you to a paper:

http://www.atma-sphere.com/papers/myth.html

The paper is about 5-6 years old, written long before class D was commonplace. The fact of the matter is that amplifier manufacturers have been placing specs like this before the public for years. I would prefer that the spec be placed in its meaningful context: that it is not speaker current but something else.

I've been watching the class D technology for some years as you must know if you've been reading through this thread (which has grown quite quickly!). Is it a threat to what we do? I don't think so, not because it might be better or worse, but for the simple reason that I am not going to be so close-minded as to think that nothing can beat what we do: there is no integrity in that.

We've been dabbling with class D for about 4 years and I plan to continue. As I've mentioned before, its a newer technology, and obeys price/performance curves that all new technologies follow. Right now we are in the middle of the curve. What that tells me is that we don't know yet where the technology levels off as it matures: it could go a long way yet! I apologize for my pragmatic outlook, but it is what has kept me in business for the last 30 years...
Atmasphere, Thank you for your contributions to this thread. I was discussing this thread with a friend a few days ago. We both agreed how much we appreciate your contributions and how you participate with a constant high level of courtesy and professionalism. You set a standard we should all strive for.