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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
dob
577 posts
 
"pls look at the Nuforce site under the award and review menu....the quantity of enthusiastic reviews by TAS, 6moon, Stereotimes etc is embarassing!!!!"

Drooling is embarassing indeed. If you look again into TAS review - it is compilation of three different reviewers. two gave excellent review and one terrible.

Why? Is this one professional reviewer is deaf? No, read again TAS it gave NuForce Editor Choice Award but with the caveat - ineractions with cables (and obvuously speakers).

I know this amp cannot drive electrastatic Martin-Logan speakers (not poorly drive but not at all - coming the the region of difficult impedance and shut itself (v1 for the record).

Without going into engineering as to why let me simply state that despite multiple positive resonse and even drooling ==> BUYER-BEWARE !!!! Good amplifier but not for every speaker!
warrensomebody
8 posts
 
I wanted to believe... but all I can say is my take on class D amps is that their performance must be highly dependent on the system they're plugged into. I had read all the glowing reviews of the Bel Canto Ref 1000s, and sprung for a pair and was sorely disappointed. I tried them on my nearfield towers and they sounded weak and thin -- all treble and no midrange at all. Then I tried them on the subs, and it was the same story -- extremely weak bass response. I A-B'd them with several other amps I had on hand, and they were dramatically worse than all of them (a Classe 10, Proceed HPA-2, and a 300B SET).

A friend with an electronics background offered a theory on why they didn't work for me -- I'm not sure whether it's true or not, but I'll offer it here to see if you guys have any thoughts on it... He said that the performance of switching amps like the Ref 1000s are highly dependent on their ability to draw current from the wall. If the power lines can't deliver the current needed when the amps demand it, they completely fail to deliver the signal. I don't know if that was the case here at my place, but they definitely didn't work for me.

The Bel Cantos taught me a valuable lesson -- you can't just go by reviews. For the forseeable future, I'm sticking with amps with big capacitors.
vicdamone
850 posts
 
Warren, I'm guessing your friend with the electronics background is more than likely correct. I highly recommend you invest a few dollars in a dedicated VAC shielded 20 amp circuit to your audio system. The sonic improvements can be very noticeable regardless of your amplifier choice.

Any future auditioning of class D products should be done after upgrading your VAC, a long run in of the components, using a shielded power cable, and speaker cable suggestions by either the manufacture or by users who have similar amplifier / speaker configurations. These are some simple generalities that can provide a starting point for integrating class D into a system.

Regardless of your efforts in integrating a class D amplifier into your system you may simply not care for the obvious difference in their general presentation. From your description I'll go out on a limb and say, I don't believe you heard the bel Canto's full potential. If your looking for a "tube like" presentation, buy a tube amplifier there are some terrific and affordable choices out there.

Take Care
Vic
eldartford
4,262 posts
 
Warrensomebody...That "power from the wall" theory does not make sense to me. Say what you like about the way they sound, but digital amps make very low demand on input power. They are typically 85 percent efficient in converting wall power to audio power, whereas the typical SS amp runs 30 to 40 percent. Don't ask about tube amps!
getheleadout
144 posts
 
What seems to be constantly overlooked here is the Idea that most digital switching amps sound the same and have the same drive capabilities. This is simply not true.

This is as true as saying all SS amps sound and drive the same all tube amps sound and drive the same.

I think it's just a convenient way for people who obviously don't like switching amps to lob them into one category.

ALL SWITHCHING AMPS ARE NOT CREATED EQUAL.
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