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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

Showing 10 responses by elberoth2

elberoth2's avatar
elberoth2 OP
1,223 posts
 
As I said in my initial post - those are just his conclusions. The original review is 14 pages long - full of technical analysys, measurements and his impressions. The amps were very well run in (500h), he tried varoius power cords, varoius inputs, varoius cables, supports and associated equipment. It really is one of the most complete reviews I have read in a long time.

If anyone is interested how he came to those conclusions, I suggest you get the copy of the mag. Sorry, I cannot reprint more of his writing (I prolly already have broken some copyrights), especially that it comes from the current issue.

The mag is expensive (it has to be since it is ad-free), but it is worth every penny IMO.

BTW - I have nothing against Class-D. I have owned BelCanto eVo 4 mk II (Tripath based) and also evaluated for an extended period of time the ICEpower design in my system.

The original title for this post was "Class-D amps - a different (re)view" but somehow the brackets were removed by AudiogoN software. It changes the meaning a bit.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
I've reread Colloms's review and found another interesting point. Martin speculates (since he does not have enough exhamples of different applications of Class-D technology to prove his point), that the above avarage CI Audio resoult may be due to the liniar PS used in this amp. He observed, that switching on the amps with switch mode PS actually degraded the sound of the other system components connected to the same grid ! It may be (or may not) the reason why H2O amps sound superior to other ICEpower based designs that uses SMPS.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
Kijanki - ok, fair enough. I would like to know though, why do you think that:

1. Pushing broad band radio frequency noise into the power supply outlets
2. Pushing broad band radio frequency noise out of the line and ground connections

is considered OK by you. Those are just two first Colloms points. You said they are rubbish.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
Kijanki -> may I ask where are you from ? Are you from Denmark ?

I'm asking since B&O, the maker of ICEpower modules is from Denmark as well, which in my view may influence your opinion (call it a local patriotism).
elberoth2's avatar
elberoth2 OP
1,223 posts
 
Eldartford - the fact is, that some distortions are more easily accepted by human ear than the others. That is where tube designs have their advantage. They may measure as good (or as bad - depending on the point of view) as the SS design, but in the most cases, they will sound much natural to human ear.
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.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
(...) class D marketing is a tendency to hyperbolic generic claims of the type. . . 'X crushes SS/tube sacred cows costing 4 times as much'

You hit the nail o the head, Guido. This is the reason I gave this example.

Class-D ppl are trying to persuade everyone that Class-D amps are SOTA. They are not. They may compare favourably to other SS/tube designs in their price range, but only provided that you like this kind of sound.

As I said before - I have owned and evaluated varoius class-D designs, and they were quite good for the price, but I never considered them to be SOTA or significantly better than competing SS/tube designs.

I just wanted to make it clear.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
Elbroth2, what switching amps besides the already mentioned Nuforce and Bel canto have you evaluated?

I have evluated the following class-d amps:

BelCanto evo 4 mk II (Tripath based) run in both bridged and unbridged mode
NuForce 9v2SE
Two ICE Power based amps (using 250 ASP and 500 ASP modules) - they were local made, so the name will not tell you anything, but since ICEPower only leaves the manufacturer with the choice of a box and the style of speaker terminals/rca sockets, I do belive that they all sound the same. The amp I used was equipped with superior Vampire terminals, and a very solid box.
elberoth2's avatar
elberoth2 OP
1,223 posts
 
The class D amps I have are not cheap. They are expensive to produce.

Muralman1 - could you tell us, what part of your amp is expensive to produce ? The box ? Or the transformer and 2 caps in the PS ?
elberoth2's avatar
elberoth2 OP
1,223 posts
 
Elberoth2 - the H2O is made in America. That should tell you a lot. I have monos. The aluminum plates are made and finished in the USA. There are some 30 or more power caps.

Mularman1 - I asked this question on purpose. The reason is that there are many SS designs that are much more expensive to produce in that price range.

Take $6000 Cary CAD-500MB for example. Also made in the US. Also monos. Thick aluminium front panels. Transformer as big or even bigger than the one one used in the H2O. And so are the PS caps.

On the other hand, H2O uses 150$ ICEpower module and Cary uses full blown Class A/AB output stage which is MUCH more expensive to produce.

My point is, that you cannot uderestimate the cost (and serviceablity) factor in Class-D designs. They are just cheaper to produce (with build-in SMPS power suply the difference is MUCH bigger). That is why so many manufactures are persuing this technology.
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