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
Guidocorona - Hi-Fi critic is wrong on all 17 points he presents. Class D produces only about 1% of the carrier (usually 0.5MHz) on the speaker and practically no switching noise (zobel network). My Rowland 102 is directly under TV - no problem. At 0.5MHz speaker cable needs to be 150m long to be 1/4 wave antena. Class D Amps cannot be "unstable" (big advantage) because by definition they oscillate (analog modulator). They are in reality high power sigma delta modulators. It is important to realize that most of modern dacs (sigma-delta) are working on principles of class D (PWM) - same with SACD (PWM at 2.8MHz). I read a little bit of Karsten Nielsen doctorate work on Icepower (University of Denmark) - very interesting.
I really wonder if Martin Collums has deliberately written such a controversial overview as a means of getting publicity for Hi Fi Critic.

I am still undecided about Class D amps.I have heard some that certainly lacked vibrancy and image depth but I have also heard a Nuforce 9 V2 that I thought sounded very good.
I would say ,on balance,better than any transistor amp I had heard.But then again I really don't care for the sound of transistor amps.I much prefer tubes and gainclones.

Mr Collums background really needs to be considered.He is obviously a critic who likes the sound of transistor amps.
I think many people who like Class D are also people like myself who do not like this sound and are looking for something with power but with a different type of sound[something more organic?].
When he was writing for Hi Fi News he recommended amplifiers like the Naim Nait 3,Naim NAP 180,Audiolab 8000S and Exposure XX-all amps that sound very coarse and "transistory" by todays standards.

He also has a long association with Musical Fidelity.I believe he designed speakers for them.So when he uses a MF amplifier as a reference and describes its superority to the Class D amps ,questions about bias or cronyism probably need to be considered.
I'll have more impressions in a few days. Meanwhile, does Halcro fit in this discussion, price excepting, of course?

David
Hi Dave, I am not aware that Halcro amps are switching amps. . . but if you have any comparative findings of Halcro with Spectrum, that would be interesting.
While I don't depend on Martin Colloms to make my decisions for me, I've come to respect his views. Mr. Colloms is hardly a reviewer that just likes "transistor amps". In as much as he has historicaly praised classic ss amps like Krell, he's just as often consistently offered kind words for classic tube amps like conrad-johnson. That suggests to me, that he has a fairly open mind and can find the qualities in amplifiers regardless of the technology. I haven't read his reviews re: switching amps, but I applaud the undertaking. My own, very limited (let me stress limited) experience with this new technolgy, suggests that they aren't quite at the forefront of amplifier sound, but, have demonstrated remarkable potential. I believe "digital" amps just might be the choice in the future on sound quality alone, never mind all the other inherent benefits.