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
I paired the MBL 101Bs with the Spectron Musician III signature. It was great. So good in fact. that a friend purchased both items from me and is thrilled. I moved on to the MBL 101Es and MBL 9008 mono amps. But, for the money, the Spectron/111 combo is tough to beat. If you get 2 and run them balanced in mono you ought to really have something special.

David
Hmm...
I had a chance to audtiton Jeff Rowland Model 302 with Synergy IIi preamp and did not like it.

It sounds like comparison between LCD and Plasma displays. Rowland is average LCD and very good solid state or tube amp is Pioneer Kuro HD Plasma IMO.

BTW, here a a link to Italian Audio Review Jeff Rowland Model 312 review with full measurements:

http://www.audiogamma.it/upload/prove_pdf/AR274%20-%20Jeff%20Rowland.pdf

Just check out 10kHz damping factor...
Maybe I shoud stay out of this one, especially as I do not have time to read all of the posts, but.......

The critcism that not all of the vendors disclosed all of their specs is no reason to find fault in them. Most here have been around high-end long enough to know that specs, i.e. measurements, are just design tools for the guy who design the stuff. (We have been making and selling amps, conventional and switching, for over 20 years. Without once "disclosing" all of the specs. Is there any reason to?)

Yes, a lot of guys like to look at the numbers, but since when could anyone say how something will sound based solely on numbers? If we could, tubes wouldn't be as popular as they are.

Several have already said so, but let me reiterate as a manufacturer of switching amps:

Synergy.

Not every amp will sound good in every system. If they did, we would all own Carver amps driving Bose speakers. But obviously, that is not the case.

Yes, these amps are not for everybody. I do not know of anyone making them that claims such.

Likewise for fine companies like AtmaSphere. I don't see Ralph telling anyone that tube amps are the only way to go. (I only point out Ralph as I have friends that own his products, and they sound good in the right system.)

Martin Collums and his friends may not like them, and I can accept that. To each his own. To dismiss them all, based on his perceptions would not be an enlightened positition. Listen first, then make up your own mind.

To be perfectly honest, I have heard listeners say that our (switching) amps sound "very tube-like".

In the right system.

I have personally heard them sound like crap.

In the wrong system.

Synergy. Simple as that. Need I say more?
Hello Kijanki.
Excellent review of the review. I would point out only that

"Have thermal dissipation limitations due to the small power module size which means that thermal dynamic variations are present in the performance with time"

has a lot of sense and if designers did not so proper and extensive thermodynamic analyses then this is exactly what is occuring...with time.

Don't measure tmeperature outside the amp - measure it inside the small power module size and at not in one point... Nobody cheated physics yet

Simon
Hello Art_t,

"To be perfectly honest, I have heard listeners say that our (switching) amps sound "very tube-like".

... and it is because in all probability they do. Most published measurments of switching amplifiers distortion patterns are very similar to....that of the tubes. Strong 2nd harmonics and strong even harmonics.

I personally love to read in Stereophile comments of reviewers on most of class D amps they review: "tube-like", warm, musical etc...and then glance to John Atkinson measurments with huuuuge 2nd harmonic distortion etc

I love expression "life-like" be it tubes, snakes or whatever...

All The best
Simon