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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
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 ?
dazzdax
599 posts
 
One question remains: does a class D amp (in my case the ICEpower amp) sound "bland" and "threadbare" because of lack of harmonic overtones (incapability of reproducing the correct harmonic structure) or does it have to do with lack of distortion? My previous Accuphase A-50V sounded somewhat veiled and opaque in comparison with the ICEpower amp and I've always thought that this is due to "transformer haze", because that's the same type of sound I hear from top of the line Jungson, Marantz and older ML designs.

Chris
branimir
236 posts
 
I agree with Elberoth2.

I personally audition Jeff Rowland Model 302/Concerto Pre combo and it was not up to my liking... To my ears both Krell Evolution One/Evolution Two and ARC HD220/REF3 combos sounded better. Krell was more extended and top and bottom with tighter and more defined bass(it also want deeper), it was also way more musical to my ears. ARC was warmer overall with bigger soundstage(almost Krell size) and more midrange presence(specially on male vocals).

But, honestly Jeff Rowland combo was not that bad either, in fact Model 302 sounded much better then Model 201. Rowland 201 sounded better for me then Nuforce REF9V2 so go figure...

Speakers were Avalon Isis and Escalante Fremont. Both not very demanding to drive...

I guess that for both Elberoth2 and me current Class D(switching) amps are not our "cup of tea"...

What I truly do not understand is how "die hard" are Class D fans...
muralman1
1,527 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.

Branimir, class D is not going to suit everyone. Besides, they are damn hard to coax great sounds from. There is no class D tradition to rely upon.

Some intrepid DIYer wrote a long piece on how to improve the H2O last year. That got me on the tweak binge, and found a great bypass cap choice.

I have already written on the importance of correct wiring, and my thoughts on CDPs.

Preamps have to be compatible with abysmally low impedences of ICE. The Fire preamp is tops in that category.

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