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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
jtgofish's avatar
jtgofish
515 posts
 
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.
deshapiro
177 posts
 
I'll have more impressions in a few days. Meanwhile, does Halcro fit in this discussion, price excepting, of course?

David
guidocorona
4,298 posts
 
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.
unsound
7,329 posts
 
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.
kijanki's avatar
kijanki
4,428 posts
 
If Martin Collums does not like the sound of switching amps that's his right, but his 17 points are garbage. He thinks that switching amps are digital and have limited resolution (like in 60's). He claims that switching amps have "fragile output devices" where in reality they are more robust than class A/AB amps. For instance output of Icepower contains H-Bridge of 4 very strong Mosfets with all sorts of protection. He writes nonsense about power supply folbacks and heat dissipated in output devices. He appears to have no education in electronics and his statements are pure demagogy. His points about usage of negative feedback, high output impedance or "clipping" are all nonsense. He is right about soft clipping - B&O added it to protect tweerters from possible high energy during overdriving (Class D has a lot od power). He makes it sound bad but it is a virtue. Many traditional amps have soft clipping (NADs for instance). He mentions high intermodulation distortions where in reality it is just opposite - having no nonlinear output devices does not suffer from IM (Icepower 200ASC has 0.0005% IM at 10W 4Ohm 14kHz/15kHz). I could discuss every single point he makes - all of them are garbage. It is much better to say "I don't like the sound" instead of making uneducated false claims.
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