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.
"Consider that because you have heard some tube amps which have coloration does not mean that all of them are like that."
I agree with you Atma. With any technology there exists stereotypical coloration/distortion, there is also brand-typical coloration/distortion, and then there is simply the atypical kind. I suspect it may be a lot easier to eliminate outright distortions than to tame colorations for everyone. We should remember that one audiophile's poison often is someone else's Nirvana. . . or in other words someone's coloration may be someone else's 'neutrality'. For myself I often do not even attempt to define my preference in terms of warm/lean/neutral. . . I will simply describe what I hear in semi-musical terms as well as I can, and explain what I like and what I do not like, and if I am at all capable, why.
all amplifiers have some consistent sonic characteristic which is detectable after audition, for some period of time by a well-trained listener, given a variety of recordings.
if amplifiers had inaudible levels of coloration it would be almost impossible to distinguish one from another.
what does this mean ? find an amp that you like and the quality and quantity of imperfection should not matter.
What can I say, sadly, I am probably not a member of the species 'Homo sapiens', because 'tubey' distortion do not sound at all priviledged to these poor ears.
You are going to the extreem here. Not all tube amps sound "tubey" and yet, they still have certain distortions characteristics that are more benign to human ear.
To my ears, a good tube amp still sounds much better than current Class-D designs. I have owned BelCanto eVo 4 amp, I have evaluated both ICEpower design (ASP based) and, just recently, the latest NuForce 9V2SE monoblocks IN MY SYSTEM, and all I can tell you, is that the difference between them and my current ARC Reference 110 is so HUGE, that it is almost laughable.
Of course you are correct, Elberoth2. As I said earlier, for any technology there are stereotypical distortions, brand typical distortions, and atypical ones. Where I have problems is characterizing distortions in tube gear as 'benign' as a whole. At RMAF I ran out with 'bleeding ears' of as many tube suites as I did from SS or class D suites. Tube amps sounding classically 'tubey' were definitely a minority.
As for ARC Ref 110, I agree completely that it--and the rest of the current ARC lineup--are darn special amps; I own a Ref 3 and in general I love the new ARC sound; The only reason why I will not even consider a Ref 110 is because. . . tube amps generate too much heat in the ghastly Texas Summer. What switching amps have you evaluated/contrasted against Ref 110 besides Bel Canto Evo 4 and Nuforce? One of the problems I can see with some class D marketing is a tendency to hyperbolic generic claims of the type. . . 'X crushes SS/tube sacred cows costing 4 times as much'. The problem is that such sweeping uncautious claims expose a product to equally uncautious counterargument such as yours, where you contrast a brand new $10K tube design (Ref 110) with a 5 year old $4K switching design (Evo 4) and a current $5K switching design (Nuforce Ref 9 SE) only to apply the old induction step and produce a slightly brave conclusion. Seems to me you are comparing one orange with two clementines. . . and concluding that all oranges are . . . heavier.
(...) class D marketing is a tendency to hyperbolic generic claims of the type. . . 'X crushes SS/tube sacred cows costing 4 times as much'
You hit the nail o the head, Guido. This is the reason I gave this example.
Class-D ppl are trying to persuade everyone that Class-D amps are SOTA. They are not. They may compare favourably to other SS/tube designs in their price range, but only provided that you like this kind of sound.
As I said before - I have owned and evaluated varoius class-D designs, and they were quite good for the price, but I never considered them to be SOTA or significantly better than competing SS/tube designs.
Elberoth, I like the ICEpower amps better than the Mark Levinson 333 or the Accuphase A-50V. Not because I like "sterile" sounding ICEpower. To me the ICEpower amps sound more transparent, dynamic, faster and less colored compared to the artificial ("mechanical") sounding ML or the slow and a bit opaque sounding Accuphase. This is certainly not hyperbole, this is my own experience, which is somewhat comparable to the experience of the fellow audiophile who preferred ICEpower than his ML 33H's! Or is it likely that we are suffering hearing impairment?
Audiofeil and Elberoth2, The class D amps I have surpassed solid state amps costing 3 times as much by a wide margin in my system.
Not only that, these class D amps have uncovered a nest of attending components as the snakes they are.
That is because they have so little personality of their own, and as Dazzdax pointed out they are wicked fast. Minute details get through, both signal, and distortion.
You just don't know the beauty of class D if you match them with tried and true conventional gear.
This is one of the intrigues of class D for me as they often lack some of the more heinous colorations that I associate with transistors and tubes.
Theoretically, since Class-D depends on utlra high speed circuitry it looks like it might be superior in accurately tracking a complex waveform - an extremely linear device that is very cheap and stable.
My concern would be EM/RF noise from the rapid firing of high power MOSFETs in this configuration and how to keep this noise away from power supply rails and everything else. Fundamentally the firing on the MOSFETs is modulated by the audio signal, which suggests thst any noise might highly correlate with the audio signal rather than being random thermal noise...
For a subwoofer this will be less of a problem than for a full range speaker, of course.
I expect Class D will become the norm in future due to progress and the high efficiency.
I haven't thought about it much MRT. . . when did you first realize you were obsessing about class D amplification? . . . Impacting your life? . . . Care talking about it?
Mrtennis. It is no secret why dug in audio companies detest class D. On my own system, Scintillas powered by advanced H2O monos, any listener can easily detect the pollution pressed onto the music by gaudy cables, flu flu preamps, and digitally smeared CDPs.
Some people think I am being sarcastic only have to spend awhile at my home to know I mean every word.
When retailers get four grand for speaker cable hoses, they are none too quick to warm up to the new class D amps that will expose their noisy dielectrics.
Class D amps have imposed rule changes. Wires must be clean. Analog signals must be left untampered by digital slight of hand like up or over sampling. Affordable preamps must improve.
If you ever took part in the passive vs. active preamp wars here and there, class D amps are the passive preamp champion's friend. Most active preamps do mess up the sound.
Not entirely, Tvad. There are cheap solid state amps, and tube amps too. They don't sound so good. The class D amps I have are not cheap. They are expensive to produce.
given all of the observations about class d amps, it seems odd that after all of the relecant points are made, this thread continues.
there can be as many observations about other products as have been generated about this product class. yet, posts continue. this subject has received more posts than most other threads on the forum. i wonder why.
at what point does the light dim and what remains is just heat ? is there more enlightenment regarding this subject yet to be revealed ?
Tvad, you are correct. There is no getting around class D upsetting the audio business cart. ICE modules are everything you say. They are light, inexpensive, powerful, and ready for use in mass market items.
By creating a module, the 500A, that does not fit the above attributes except cost, B&O has thrown down the gauntlet challenging the small, but crowded, hi-end audio.
One question remains: does a class D amp (in my case the ICEpower amp) sound "bland" and "threadbare" because of lack of harmonic overtones (incapability of reproducing the correct harmonic structure) or does it have to do with lack of distortion? My previous Accuphase A-50V sounded somewhat veiled and opaque in comparison with the ICEpower amp and I've always thought that this is due to "transformer haze", because that's the same type of sound I hear from top of the line Jungson, Marantz and older ML designs.
Elbroth2, what switching amps besides the already mentioned Nuforce and Bel canto have you evaluated?
I have evluated the following class-d amps:
BelCanto evo 4 mk II (Tripath based) run in both bridged and unbridged mode NuForce 9v2SE Two ICE Power based amps (using 250 ASP and 500 ASP modules) - they were local made, so the name will not tell you anything, but since ICEPower only leaves the manufacturer with the choice of a box and the style of speaker terminals/rca sockets, I do belive that they all sound the same. The amp I used was equipped with superior Vampire terminals, and a very solid box.
I personally audition Jeff Rowland Model 302/Concerto Pre combo and it was not up to my liking... To my ears both Krell Evolution One/Evolution Two and ARC HD220/REF3 combos sounded better. Krell was more extended and top and bottom with tighter and more defined bass(it also want deeper), it was also way more musical to my ears. ARC was warmer overall with bigger soundstage(almost Krell size) and more midrange presence(specially on male vocals).
But, honestly Jeff Rowland combo was not that bad either, in fact Model 302 sounded much better then Model 201. Rowland 201 sounded better for me then Nuforce REF9V2 so go figure...
Speakers were Avalon Isis and Escalante Fremont. Both not very demanding to drive...
I guess that for both Elberoth2 and me current Class D(switching) amps are not our "cup of tea"...
What I truly do not understand is how "die hard" are Class D fans...
Branimir, it is not a question whether class D fans are die hards or not. I'm not a die hard and I'm not a class D "fan" either. I'm only reporting my personal experience with class D (ICEpower ASP1000) so far. I'm still convinced that some conventional power amps are superior to all the class D offerings.
Please don't paint all Class D owners with a broad brush. Even the H20 can be improved upon. I agree with MrTennis that the questions and issues about Class D can be raised and discussed in far fewer than the 300 posts.
Elberoth2 - the H2O is made in America. That should tell you a lot. I have monos. The aluminum plates are made and finished in the USA. There are some 30 or more power caps.
Branimir, class D is not going to suit everyone. Besides, they are damn hard to coax great sounds from. There is no class D tradition to rely upon.
Some intrepid DIYer wrote a long piece on how to improve the H2O last year. That got me on the tweak binge, and found a great bypass cap choice.
I have already written on the importance of correct wiring, and my thoughts on CDPs.
Preamps have to be compatible with abysmally low impedences of ICE. The Fire preamp is tops in that category.
"Branimir, class D is not going to suit everyone."
Muralman1, that is the truth.
Interesting point that you mentioned in one of your previous posts in this thread is about power supply in Class D amps. All Class D amps that I personally audition features switch power supply(Rowland 302&201, Nuforce REF9V2) so, could this be a reason for sound signature of this amps in your opinion?
Your H20 amps use analogue power supply AFAIK. New Mark Levinson No.53 will also use Class D modul with analogue power supply...
Branimir, I agree with your finding on the Rowland 302. It is worth pointing out though that the 302 was JRDG 1st venture in class D, and was replaced in 2006 by the 312, which sounds quite a bit different, and to these ears is both more musical and much more exciting.
TVAD says:
"Class D amps are getting attention because they are less expensive to manufacture, purchase and operate than SS and tube amps."
Undeniably, one of the major reasons I am interested in class D amplification is its promise to let me listen to music during the sweltering Austin (TX) summers and I won't have to worry about swapping out exhausted tubes. It is also undeniable that Switching amps have largely debuted on the market with rather minimalistic and relatively inexpensive designs that may have created a perceptional stereotype. I should however point out that they are starting to get the attention of major 1st tear manufacturers, and more ambitious devices having significant price tags are now appearing on the market: Rowland has offerings ranging upwards of $30K, Kharma has introduced new monoblocks likely costing over $40K USD, and so is Mark Levinson. I recently heard that more such manufacturers may be preparing to soon enter the race.
I have not heard any all out assault switching models as yet. But -- already in the habit of keeping an open mind on any tube or classic SS device until I have had the opportunity of a personal audition -- I am simply looking forward to giving any such 'statement' switching devices at least the benefit of doubt ahead of any actual audition. After all, if my modest experience serves me, I do end up liking roughly 20% of what I listen to, regardless of underlying technology.
Honestly, I would like to truly love Jeff Rowland sound. New Jeff Rowland Criterion preamp(will be fully introduces on CES2008, double chassis, battery powered!) with Model 301 monos(new version with 600w/8ohms) could be very nice solution despite big price tag...
BUT, is it really better then simillary priced solid state offerings? For example:
Interesting thing is that Hovland and Vitus use UI core power supply transformers, not toroidal one like Krell. Both Hovland and Vitus claim that these UI Core transformers are much, much better(of course, they are costum mode for both manufactures and are really very expensive) then toroidal one...
So, development in "normal" solid state world in still in progress...
Elberoth2 - the H2O is made in America. That should tell you a lot. I have monos. The aluminum plates are made and finished in the USA. There are some 30 or more power caps.
Mularman1 - I asked this question on purpose. The reason is that there are many SS designs that are much more expensive to produce in that price range.
Take $6000 Cary CAD-500MB for example. Also made in the US. Also monos. Thick aluminium front panels. Transformer as big or even bigger than the one one used in the H2O. And so are the PS caps.
On the other hand, H2O uses 150$ ICEpower module and Cary uses full blown Class A/AB output stage which is MUCH more expensive to produce.
My point is, that you cannot uderestimate the cost (and serviceablity) factor in Class-D designs. They are just cheaper to produce (with build-in SMPS power suply the difference is MUCH bigger). That is why so many manufactures are persuing this technology.
Hi Branimir, I have not heard the JRDG 301s so I cannot comment about their sound, and can even less venture tu guess on whether I would prefer them over other comparably priced designs, which I have also not auditioned. On spec only, I am slightly concerned about the 301's low nominal damping factor of 60, which may make their application difficult to some speakers. I do not know if damping has changed in the new version.
I am though even more intrigued about the upcoming JRDG Criterion Pre -- being a completely new reference level design -- and how it may compare to the 'usual suspects' in its price range--tubes hybrids, and SS alike.
Very true TVAD, almost as inexpensive as 6550 tubes or just about any transistor or cap used in traditional designs ranging from a couple of hundred dollars up to stratospheric prices.. . . To tell the truth, I do not really care about the cost of any underlying building block. Nor in fact I care in principle about the cost of a component per se. What matters to me is how all of these chips/modules/tubes are put together to form a component that will in turn contribute to make music in my loft. If it measures up, that's fine and good, if it doesn't, no amount of mil -specced Tantalium-doped machined Aluminium fascias, 0-feedback pangalactic design, 60-year-old-tubes used to decode WW2 German cyphers, 128bit asymptotic hadro-stochastic processors, 3160 transistors, class A/B/D/T, Doppler elimination, poplar or mpingo sidings, or otherwise mouthwatering old or new real or imaginary technology is going to matter to me a single half bit.
Could be, 'nihil sub Sole novi' after all. Marketing rationale may be a factor for determining pricing point of some stereo component. I have seen--or should I better say heard--entire systems at RMAF that sounded terrible. . . and sported price tags of Cosmic proportions. . . then others at similar prices sounded fantastic. . . . then several modestly priced systems sounded awful, while other similarly priced entry systems were pure music to my ears.
I knew you would agree TVAD. . . As a case in point, have a listen to a well broken-in Spectron Musician 3 SE when you have the opportunity. . . I'd be interested in your findings.
I have a question about how long the break in time is for the Spectron Musician 3 is. I am sending my Muscician 2 off for the Hybrid update on Monday. I am really enjoying the Musician 2 in stock form, so I can't wait. Thanks
I have not been following this rambling thread very closely, but perhaps I should clear up some common misconceptions about making Class D amps:
1.) They are cheap to build, and 2.) They are easy to build, because all you have to do is put it in an expensive box.
Well, yes, that can be the case. Indeed, I am sure that there are outfits doing just that. But to say that everyone does that is a gross oversimplification.
Let me give you an example of something similar. I'll let the readers draw their own analogy and conclusion.
About 15 years ago, National Semiconductor came out with a line of parts that has come to be known as "chip amps". We looked into them, to see if they could lead to building a very affordable amp. One that would come close to high-end expectations, without the high-end price.
Well, they sounded good enough to merit consideration, but..............
How much could we knock the price of an amp down by using them?
Depends. Depends on how you want to go about it.
If it has to look nice, you need a decent enclosure. Not cheap. You would need a large power transformer, and decent filter caps. Not cheap, either. Still needs a heat sink, cut down from an extrusion, milled, and anodised. Ok, we can cut down on the size of the PCB somewhat, won't have to buy a boatload of discrete parts and output devices. But how much will that be less than the cost of buying the chip and making a PCB for it?
In reality, not much. You still need the same size power supply. Same amount of heat sink radiating area. After all, it is basically just like any other amp, only with most (if not all) the electronic guts inside one chip.
So, when you get down to it, it is not really all that much cheaper.
In fact, it can cost more.
"Huh? Did he say 'more'? That can't be."
Sure it can. Think about this:
Let's say through "research" that you find that it doesn't work as well as expected with only one chip. There is an awful lot heat to get rid of, and from a small source. Heat sink or not, it is probably going to get hotter than several discrete output devices. And it is all in one chip.
Well, heat is the enemy of ICs. So, you futz around, and through your "research" you find out that for several reasons that it sounds better if you run 4.......or 6........or 8.......in parallel for each channel. Wait......we are back to where we started from: same enclosure, same power transformer and filter caps, same heat sink, and now the same size PCB with the same number of parts. Only 8 ICs cost more than 2 outputs and a handful of discrete components.
Sure, you could cut every corner in the book, and make something inexpensive. Sure, there would be a market for it. Especially if you made a gazillion of them to get the price under $1K.
Or, you could end up with a novelty that cost as much as a traditional amp. Perception being reality for most, how many folks would buy a $3000 amp with a bunch of ICs in it, when you can buy the same thing that actually looks like a real amp for the same price from the same company?
Guess what: we never made any.
OK, fast forward to 2000 and something.........
You can buy a Class D amp module..........cheaply if you buy enough...........and start making amps with them.
But wait! You still need that fancy box. And probably same ol' power supply. Unless you want to go for "novel", and put a switcher in it. You need to market to a different crowd if you go that route.
So, what have you saved? Obviously, no heat sink. And probably not much of a PCB.
You could take those savings and use them for nice touches, like say..........EMI control..........or well, there are lots of tricks that an experienced designer can do at this point. (Sorry, no inside info gets divulged at this point, gang.)
Bottom line is this:
Class D modules are a tool that a designer can use. How they choose to use them is the difference between inexpensive and over-priced. Good sounding, or just good enough. Or something in between.
Yes, you can make an amp without a lot of bother and expense by using them. The opposite is also true.
Apart from all the technicality just like to add one line. I listened to guitar recording by Julian Bream with a Class T the TA 10.1. Music was dynamic and string tones rich. On one track to the very end I heard harmonics of a struck string magnitude of same order with tape hiss then the sound stage subsided to blackness, no hum, noise or rumble and I was using LP. Never beofore I heard in such clarity.
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