Excellent idea for a balanced thread George... I have happily gone back and forth from class A/B to D over the years. In chronological order, here are my amps since 1998....
Rowland M7 -- An uber-currented class A/B mono released around 1987 with a golden sound.
Rowland M312 class D stereo -- My first venture into class D.... Much more nimble and present than M7. Is both more linear, and has greater exposure of harmonics.... Beutiful transparency, and sweeter than M7, although it does not have the euphonic midrange glow of M7. Yes, overall, I much prefered it to M7.
Rowland M625 (V1 (early production actually) class A/B stereo -- Harmonically just a little denser than M312, but did not have the same amazing transparency between notes that M312 had. But the main issue with it was that it was not quite powerful enough for my Vienna Die Muzik... As a result, during fff passages or loud transients, it gave me the impression that it was "working for living". I heard later production units at RMAF, and they were quite superior to my early unit.
Rowland M725 monos class A/B -- These guys had all the power I needed, and had several circuit and materials enhancements that made them really wonderful amps... Yes, I did prefer them over M312.
Rowland M925 monos class D -- My current amps. These are uber amps that use NCore NC1200 modules buried in the output stage. By far the sweetest and most musical amps I have ever owned, as well as the most powerful and resolving ever to be in my system.
What's my future... Not sure yet. I suspect that for my next amp, I might want to simplify a bit.... One option might be to go to the class D Rowland Daemon superintegrated, which will also serve as DAC. The other possibility is to keep my Aeris DAC, and to adopt the new M625 S2 stereo, which instead runs in class A/B. Not sure in which direction to go... I probably will want to listen to the two contenders before making an eventual decision. I have heard from people in the know that the class A/B M625 S2 might be the finest amp that Rowland has designed... But I have also heard that the class D Daemon makes wonderful music in its own right. I am a pragmatist... There is marvellous music and sound possible with any clas of amps. Final decision will be determined by audible satisfaction, and... Budget.
Saluti, G.
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Hi Tim and AIT, I more than sympathize with your shell-shocking experience with class D.... AIT you summarize it best when you describe the NewForce monos as "awful - harsh and screeching "... That was exactly my impression.... Let us not forget cardboard-like bass and completely lifeless treble... That is whenever treble does not screech to high heaven instead. As for Wyred4Sound, Tim you are being kind IMO... I tried to listen to the brand several time at RMAF, and the things were yowling like bobcats with ingrown claws... I typically resist a couple of minutes in the suite... As for Flying Mole... Meh!
It is funny how exactly the same module will make fab music in one amp (Bel Canto REF1000M), and screech in another amp. But after all, we should not be surprised... There is quite more than bare modules in Bel Canto amps... Those little boxes are designed by John Stronczer, an engineer/designer who has a profound understanding of what music sounds like.
Besides, Mapman is 100% correct... No matter how wonderful some class D amps might sound to some of us, their relative neutrality will make them inherently unpalatable to the lovers of much warmer sound... And... Vive la difference, n'est pas?!
Guido |
Hi Phusis, your bring up an excellent point.... The problem of paper listeners who evaluate the musical experience basing themselves on printed graphs and figures... You find these types spread all over the tubed / ss / class D continuum.
Admittedly, I am fond of a neutral sound with a bare smidjin of warmth.... But my only criterion for judging if a particular device is to my liking is.... My own ears.
G. |
Hi Jeffb28451, which Rowland class D amp did you listen to?
G. |
Hi Jeff, I suspected as much... The amp was probably a pair of M501 monos or M201 monos... Unlikely to be the M301 monos, unless each chassis weighed about 95Lbs. Each M501 chassis instead might weigh some 20Lbs, and is about 7.5 inches wide only. is
M501 was a basic implementation using the ICEpower 1000ASP module. Very powerful and clean, but.... Subtlety and high musicality were not its main features. I heard the M501 several times at RMAF.... I deemed its sound not to be involving at all... ANd yes, treble can have a rather cold quality to it, which also means that if complex treble passages go through M501, you might hear more than a bit of harshness.
For the ICePower 1000ASP to sound good, it requires either the fine work done by Stronczer with the REF1000 Mk.2, or the PFC rectifier and custom power supplies that Rowland used in its higher end amps based on the same module, such as the M312 that I had for several years.
Rowland does market an external PFC rectifier called PC-1 which is compatible with M501. People who used PC-1 on M501 report the sound to be completely different, and to have approached M312.
Regardless... All of this is in the past.... M201, M501, M312, M301 are all 3 or four generations old. Class D has made significant strides since these 4 legacy Rowland amps, the only one whose sound I consider excellent for today's standards
is the M312, which shows up very seldom on Audiogon.... Its owners tend to keep it for a long time.
Regards, G. |
Atma, I extend to you the invitation to get out of the house more often. Believe it or not, evolution or not, there is already "Wonderful Life" out there to behold. Oddly enough, it is not even based on tubes, OTL, or classic SS topologies.
To quote the immortal words of our Rodman99999...
"Just
don't fall into the category of those whose minds, like concrete, are
thoroughly mixed up and permanently set"
Regards, G.
G.
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Atma, sadly, I had read your post very carefully... I was hoping to avoid pointing out to you that your logic is painfully flawed.
Essentially you are stating that while class D persists on an evolutionary curve, at any particular point of the curve, it is inherently not good enough to yield a top quality listening experience because a "better" experience is just around the corner. Trez bizarre, n'est pas?!
As for Bel Canto, it is a brand, not an amp... In their history, there are a few dozen models, ranging from their first units several years ago, up to the Black. Did you experience them all? And what about other brands?
From a logic point of view your process is called a false induction. It has the form :
If set X contains at least one element without property A, than the entire set X lacks property A.
Besides, demonstrating a negative remains a futile quest.
Thus I renew my words of encouragement... Do get out of the house more often... Or at least, leave your preconceptions home when you do so... You might be surprised about what you end up discovering!
G. |
Thank you Kuribo, could not have said it better myself!
To be honest gents, most amps leave me cold, regardless of underlying topology... Be it triod, push pull, OTL, SS class A, SS class A/B, analog class D, or digital. On occasion, there are a few amps in almost each class that I love for what they do for music. Some of these happen to be class D.
Eventually, I am pretty sure I will even hear an OTL that does not make my head shake in perplexity. Who knows, may be such ATMA amp already exists today, even though OTL is not on an accellerated evolutionary path per se... I am an optimist, and I know I have heard but a small minority of OTL amps in existence... I have not even had the opportunity of hearing every ATMA amp: until the target set is known to be filled with "NO" on each member, I am hopeful that a "YES" exists somewhere in the extant set.
As for square waves.... Love that clarinet sound, but I do not waste my time confusing paper and an individual graphs with music from a thousand different amps... I much prefer listening to music through my own ears one amp at a time... After all my ears have served my passion quite well since 1957 -- the time I was first mesmerized by music coming from LPs through my Dad's Grundig.
G. |
Thank you George, yes I have heard the screaches you describe, as well as the dark uninvolving sound several times at RMAF.... Quite consistently from some class D brands, and unfortunately equally consistently from some brands that produce otherwise well regarded class A, A/B, and a variety of OTLs and other tubed amps
Luckily none of the amps of any class that I have owned since I sold an Aragon 4004 Mk.2 in the late '90s have had an even remote propensity of creating such audible horrors.
Somehow, my home is blessed by marvellous music... Yes, I hear music that is congruent with the sound of live acoustic instruments that I have experienced since I was six years old.
Can it be enhanced further? ... Of course!
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Hi George, what would you deem to be a sonically safe switching frequency for future class D modules?
Do you know of any such "Upcoming Attractions" with higher switching rates preparing their entry to market?
Meantime, Yesterday I checked the NCore NC1200 switching frequencies... It ranges from 440Khz to 520Khz., which is almost 5 octaves above theoretical human hearing range.
Honestly, I cannot perceive any artifacts or shortcomings from my amps... But there may be some audible artifacts that I am not aware of.
On the other hand, I freely admit that I would be just as happy with a wonderful Solution monoblock, or a major AudioResearch tubed amp... I mean, apart from the heat dissipation, and reliability anxieties from ARC amps.
PS... My class D monos are not light... 160 Lbs per side. They are not furnaces by any means, but are relatively toasty to the touch during Austin summertimes.
Saluti, G.
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George, the answer is... Yes, the current switching frequencies of approximately 500KHz in the power conversion modules are sufficient for some OEMs to implement some marvellous-sounding amps.... Kuribo and several others have already mentioned some example brands and models.
Having said this, and knowing how things proceed in technology, the word "enough" hardly ever applies, no matter where one stands in the evolutionary curve. Whether a switching frequency increase of 5X or 10X yields an audible enhancement or not, such featture will eventually be introduced at some time in the near/medium/long term future by module and SMPS manufacturers.
And with such next gen component parts, some OEMs will create even superior amps... While other ones will persist to develop "Creatures From The Black Lagoon", and all in between.
'Tis all in the handle, George!
G. |
Hi ENIAC, your post could not be timelier. On Friday 11th, Marc Mickelson of The Audiobeat, posted his review of the Rowland M825 stereo amp, which sports those very class D NCore NC1200 modules that you have experienced in your system.
Marc's findings are based on prolonged use of the amp in his system,, which protracted for a number of months... Yes, I estimate the device to have been fully broken in.
He appears to concur with your opinion that appreciation of musical neutrality in high achieving class D amps may require a paradigmatic shift for some audio lovers, away from some much beloved traditional warm sound.
Amongst other things, he expresses the following thoughts in his conclusions...
"Such a peripheral line of reasoning underscores what is very best about the Model 825 -- and potentially any great piece of audio equipment: it makes you forget that you're listening to a complicated and expensive audio system. This is more than the ability to suspend disbelief; it's a disarming of critical faculties, even when you're trying to be critical and unravel what you're hearing. In my experience tubes do this more readily than solid state, and class D almost never does it. The Model 825 does it as a matter of course -- it can't not do it -- and it happens not because of one or two or three of the sonic traits I discuss above, but all of them, in their exact proportions. If the Model 825 were somehow more natural, bordering on romantic, or more round and rosy, especially through the mids, it would be a different amp and perhaps a very good one, but not a great one. And the Model 825 is a great amp -- in numerous ways, greater than any amp I've heard. It speaks not just in its own voice but in a voice I always wanted to hear, such is the pull, at least for me, of the utterly clear yet composed way it reveals all that's on each recording."
http://www.theaudiobeat.com/equipment/jeff_rowland_model_825.htmSaluti,
As for Marc's caveat that "class D almost never does it", I respectfully disagree with him... And suggest that listening to a broad range of current high performing class D amps tends to reveal that class D in general has the same chance of sounding great or horrid as any other topology.
Guido |
Hi Audiolabyrinth, I am absolutely vdelighted to hear that you love your class A amp. I feel exactly the same about my class D Rowland M925, which like your own device, appears to have a propensity for conveying feet shuffling, page turning, and.... Plenty of subvocalizations on old Glenn Gould and Andras Schiff recordings... Did I mention that it is so musical it makes me forget where I am?
Unfortunately, I have no idea how to evaluate amps according to parts count or soldering joints... I just listen to the music from components that I have had the fortune of owning, or at least listening to, with as little prejudice as I can muster in the process.
BTW, In SS class A/B, I truly adore Solution. in high power tubed amplification, ARC and VTL realy strike my fancy. In SS class A.... I am sure I will eventually find an amp that takes my heart away... I am sure it exists out there already *grins!* Y
Regards, G.
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Hi Keith, doing well, and... Wow, I knew I was forgetting something important.... Fact is that Burmester is my other prefered uber-high SS brand, together with Solution and Rowland.
How could I forget, given that I was the one who pointed Matt onto Burmester?!
Only thing is... Seems I had a misconception. I thought Burmester ran in high bias class A/B, hence my original assertion that I had not found a class A amp that took my breath away. Well, seems that I had already found one after all... Burmester 911 and likely 909 at RMAF. Burmies are an interesting case for me. In olden days, think about 15 years ago, they were not my cup of tea at all... I thought them to be both a little dark and a little hard sounding. Yet in the last several years they evolved into what for me are creators of true magic.
So now I know I have already found high magic in class D, Class AB, class A, and hi power tubes.... I am confident that my discovery of magic OTL will come eventually
Saluti, G. |
