A great article on Class D/switching amps

TJ, what is in your opinion the biggest flaws regarding the sound of class-D amps? Lack of harmonic structure? Do they sound too "artificial"? And why? In my opinion the sound of class-D amps (and in my case, the ICEpower based Acoustic Reality Figaro's) is very clean and smooth, very "neutral" and accurate with awesome bass. I hear none of the typical signatures of solid state (some kind of "haze" and coloration).
PS: I'm only trying to find out what distracts people in case of class-D amplification.

Chris

Teajay, Henry has class A amps that will give your XA-100 amps tough competition. He isn't producing them because class A is a far cry from what his class D amps sound like. His first ICE amps were very much like the best of Class A amps. Now he has moved on towards making them sound just real.

Like many threads, this one has evolved, one idea building on another. There is no doubt simple class D amps are not the equivalent to first rate class A amps in some respects. What was brought out was a linear power supply steps up both the sound and the cost of a class D amp.

Right on, Dazzdax

Chris, you asked a great question, so let me answer it in three ways:

1) As a reference point I'm not a fan of amps like Krell or Halcro or speakers like Wilson because I find them to have certain qualities (details, dynamics, transparency) but for me I found them "sterile/cold" sounding which I do believe has much to do with their way of presenting timbres and harmonics in their overall sonic presentation.

2) Another example would be the Pass Labs X series, that I found quite dynamic, detailed, with great extension, but not very "musical" to my ears. However, when Nelson Pass came out with the XA and X.5 series, it kept the dynamics but also returned the timbres/harmonics of his Aleph design.

3) So, when I have listened to a few of the switching/D amps they offer great clarity, dynamics, and a silky presentation, but not the realistic timbres I hear in the best of class A linear amps.

I believe that many of the class D amps are very good bargains for their price range, but do not yet compete with the reference class a/b amps quite yet in their development. I'm quite aware that at this level of gear we are really talking about personnal taste and system synergy, so there is no "right" or "wrong" answer to what are the best amps or designs in the world.

Teajay,
Usually I agree with you, but not this time...
You apparently did not audition any new Krell amp(Evolution One, Evolution 402, 600 or 900) because they simply do not have anything similar to Halcro's(DM88,DM78 or DM38). If fact if Halcro is flavor #1 then new Krell's are definitely #2! New Krell amps use zero global feedback with just 8db of local nested feedback. Of course I am biased since I own one of them, but your description is section 1) is IMHO not accurate. Even A.H.Cordesman liked them in his review(BTW, he is known Pass fan!)...

Now back to original subject, class D are still not at the best level IMHO. I audition only two of them in my home(Jeff Rowland Model 501 and Audio Research 150.2) and both were nearly not as good as current SOTA tube or solid state amps IMO. Jeff Rowland Model 501/Concerto Pre combo were better then ARC 150.2 is every way, but they could not stand against my reference amps in any way. As I said before bass was very good and tight in Model 501. Midrange is pretty good, but somehow artificial to my ears and highs... High Frequency needs little bit more in-depth description, low highs are very open and almost bright sounding, but upper highs are closed-in or non existant! Exactely as J.Valin described in his review, they are cut off. Soundstage size is just decent and depth is a big problem in both Model 501 and specially in 150.2, depth impression is pretty limited with both of them to my ears.
To be absolutely fair I must say that Model 501 needs to be compared to tube or solid state amps up to $10k IMO. So, my comparison is not very valid to most people...
Also, when you buy Pass, Krell, Boulder, ARC, CJ, CAT, Lamm etc. you get the design and long time work of N.Pass, Dan D'Agostino, Jeff Nelson, Ken Stevens, Bill Conrad/Lew Johnson, Vladimir Lamm etc. In class D amps you get B&0, Tripath etc. modules implemented by some "desingers" in different metal(or not) boxes. These days great name like Jeff Rowland is simply putting somebody else designes in his excellent metal boxes. Also 99% of class D amps use switch power suplly. Good or not? Only time will tell...
Limited bandwith(mostly 5hz-60khz)... Since class D natur is limited bandwith, is it also a limiting factor soundwise in class D amps? Big damping factor(usually above 500)... It also impact pretty much on class D amps sound IMO.
Do all class D amps sound the same? Based on my limited experience(only two models) I think not, but they all share some things(strange timbar IMHO and soundstage depth shortage).
"I believe that many of the class D amps are very good bargains for their price range, but do not yet compete with the reference class a/b amps quite yet in their development. I'm quite aware that at this level of gear we are really talking about personnal taste and system synergy, so there is no "right" or "wrong" answer to what are the best amps or designs in the world."
Here Teajay I full agree with you!

Down here where I live, the question of whether or not a Class D design is superior to $40,000 Class A amps is utterly academic. My RWA Signature 30 is the best sounding amplifier I can afford and it outperforms anything I'm aware of at less than 3 times its price.
The mere fact that we are discussing subtle areas of comparison between the newcomer, dirt cheap digital amps and the finest, most expensive conventional designs speaks very well of the future of Class D.
In photography, we might find a parallel. I'm told by some hobbyists that film provides a certain character that digital doesn't quite convey but that digital has a clarity and precision that film was never able to capture.

I think the latest issue of TAS has a good summary of prevalent opinions on class D amps and why they differ.

Thus far I have heard some class D amps that I find sound good and some that I don't. I have had no opportunity to compare these with other linear amps. I owned some class D amps in the past and not been very impressed. The ICE modules, however, seem to be a substantial improvement.

And in doing such a comparison as the Ab. Sound did,most of the amps probably did ok to very good compared to how they set everything up.There is no haze or colorization to what i listen to.

Also I think part of it might be ,do you really need 40,000 to build a reference,seriously 30,40, 50,000 thousand,pretty ridiculous when it gets right down to actually.

Copy that, Coffeey. Why should a pair of speakers or an amplifier or a turntable cost as much to produce as a luxury car? Or twice as much? The prices of modern high end equipment are downright scandalous. We audiophiles seem to be goose stepping along in mass hypnosis nodding our heads in agreement about what a bargain a $600 power cord represents.
I think the reason behind the endless proliferation of new high end manufacturers relative to the nearly static growth in the number of audio buyers can be explained by the preposterous margins enjoyed when a sale is occassionally made. I never really fed this beast in any big way in the past but I'm going to try to starve it from now on by seeking products which do very well for little money. Class D seems to provide that option.

Teajay, there have been two pairs of H2O amps for sale recently. One was sold along with speakers for financial reasons. The other sale was speaker driven IMHO. In any event, that seller is a die hard tube lover. There is no telling for preferences.

I would love Nelson to drive down the hill to hear what I have. My bet is he would change his design priorities straight away.

Who says there must be one design? Henry makes ICE ASP amps at a substantially lower price for those who want them. He sells the Signature monos direct, and makes only a decent return. It takes some dough to make these amps in America.

Branimir, you are quite correct. I have never auditioned the present Krell Evolution generation of amps. I was refering to past experiences with prior generations of Krell gear, that was not my cup of sonic tea.

Muralman1, it sure would be fun to have Nelson come to your house and see what his opinion of the H2O amps would be! I just don't understand your statement, " Who says there must be one design", I did not say that or even imply that there is only one design or type of amp that is surperior sonicly to all others. I also firmly believe that D/switching amps will get better and better as more talented designers get involved with this type of amp design.

Its harder to build something with a limited budget and get good results then unlimited.There is just as many designers who cant build on a 30,000 ,as there is on 3,000 design,money doesnt matter,i dont have any Nuforce never heard it,but look at all the people voting with their money on that one,to say something like they cant hear or this isnt right compared to other products is simple wrong,ice or whatever platform can free up the designer to do his magic,like somebody above said good job B and O,Ucd,good job and well done to each and every platform.

As far as for sale items go,did we forget this a Agon,everything stereo is for sale sooner or later.

Teajay, you got me, Reading back on what you say, I don't know what I was replying to. BTW Henry's amps are just a bit less expensive than the Kharma.

There is one big drawback for all highly resolving amps. A persons attending fair is likely to betray itself as not up to snuff. My Pass preamp was the first to go, then the wires, and after that I revamped my front end. Visitors have brought over their CDPs, and they all were non-listenable. I am now a super believer in non oversampling rigs. I did not spend a lot of money fixing things. Henry took care of the preamp issue. I did not have to look elsewhere.

For a lot of audiophiles, changing out stuff may seem normal. I am a conservative audio enthusiast.