To say class D is bright means you are not very well versed in quality class D.
This is correct as they can be either too bright (hard) or to opaque (soft) or a milder mix of both, and it nearly always comes down to how savage the output filter is that attenuates the switching frequency. As it's phase shift effects can be measure within the audio bands upper frequencies right down to 5khz, especially, the "opaque sounding one". You never hear of anyone criticizing the bass, that's because it good!
There are those that for the life of them can't hear anything wrong, good luck to them I say.
Cheers George |
helomechStraight from the horse’s mouth: We had better quote some noted designers as well. Bob Carver
"I built many of them right here in my own laboratory with the thought they could and would fulfill that final promise.... I was never able to build a Class D amplifier that sounded as good as a linear one."
John Curl (Parasound, CTC, Vendetta Research, Constellation)
"Some version of hybrid Class A/D looks like the future in optimum audio design."
Cyrill Hammer (Souloution)
"if you want to have your product performing at the cutting edge it is not possible with today’s known switching technologies. In order to come close to the performance of the best linear design we would need high-current semiconductors that provide switching frequencies of several MHz or even GHz."
Lew Johnson (Conrad Johnson)
"I tend to think that Class D circuit design is an approach best relegated to producing low-cost, physically manageable multichannel amplifiers where one might accept some compromise in sound quality for the sake of squeezing five, six, or seven 100 watt channels into one moderate-sized package for a budget home-theater installation."
Vladimir Shushurin (Lamm)
"No, it is not. And I would like to respond to the second part of this question with an allegory. Any field of human activity defines a number of requirements which, when properly implemented, guarantee a positive outcome.
For example, the basic requirement in the army and sports is an able-bodied individual. So, it would be quite natural to concentrate on searching for such an individual (especially as we know where to find him).
However, out of the blue we decide to choose a feeble-bodied person who, on top of that, is encumbered by various diseases. Having made this decision (which is a priori improper) we start justifying it to ourselves and others by citing the great state of our medicine, which is capable of curing many ailments."
Fumio Ohashi (BAlabo)
"No. Class D can’t really be considered for super-high-end performance in its present stage of development, although it can be fine for mid-market products."
Nelson Pass (Threshold, Passlabs)
"Does a $10 bottle of wine compete with a $100 bottle? Of course it does, and it often wins based on price. Right at the moment Class D designers seem to be still focusing on the objectively measured performance of their amplifiers. I expect that at some point the economics of the marketplace will encourage them to pay more attention to the subjective qualities, and then they will probably play a greater role in the high end."
JÃrgen Reiss (MBL)
"I have worked a lot lately with Class D. Ninety-nine percent of Class D circuits are not competitive with linear circuits.
Most Class D sounds sterile. Its tricky to figure out what to do to compensate for that."
Jeff Rowland
"I consider Class D to be highly competitive in the present, and to offer an evolutionary pathway of audio design that may produce even more astonishing results in the future."
Thorsten Loesch
I have yet to hear a pure class D Amp I’d rate above "below average for solid state" (which is not very high performance). In a little update of my classic "Valve Analogue Stages for DAC’s #" I wrote: "Perhaps more crucially, so called Class D Amplifiers, which have in recent times sprouted up like mushrooms after a warm rain, continue to use the straight two or three level modulation scheme described above. And thus they still require the use of heavy handed noise shaping to attain anything like acceptable 16 Bit Audio performance. The clock frequencies for these amplifiers are usually at 300 KHz to 1MHz in the best cases. That is 3,000 to 10,000 times lower than what is required to attain 16 Bit / 44.1 KHz performance without noise shaping and other forms of signal manipulation! And again, one is baffled and perplexed by the rave reviews many Class D amplifiers receive, as baffled as one was about the late 90’s reviews of timeslicing dac’s. The best of breed I have auditioned were certainly not bad; however in direct comparison to the best available valve and solid state amplifiers they do not produce a very good sound. Well, at least they offer novelty and the reviewers something to write about other than another (however good sounding) 8 Watt valve amp. Incidentally, the best sounding Class D amps tend to be really low power single chip devices (putting out little more than the 8 watt valve amps), presumably because they are faster AND because they always work near what one might call “full scaleâ€, if they would be dac’s. On second thought, they of COURSE are DA Converters and where a Class D amplifier accepts analogue input directly it is an A2D converter followed by a power D2A converter! What an insight!?" Mark Levinsons interleaving of multiple Class D Amplifiers is potentially a step in the right direction, but does not go far enough. Personally I think that the best option would be something that combines a Class D Amplifier for the heavy lifting with something Class A for fine detail. Probably implemented in the style I did for AMR’s AM-77 "Jikoda$" Style. In this case both of the circuits involved can operate fully open loop. In many ways the problems in Class D Amplifiers are analogous (but not identical to) those in Class B Amplifiers (but without an option to implement Class AB or Class A) so similar solutions apply. Thorsten Loesch All Class D amplifiers are essentially delta-sigma DAC’s. If the input is not digital PWM signals (aka "DSD") but analogue audio then it is also a Delta Sigma Analogue to digital converter... Now DSD (aka SACD) which to my ears fails to come close, never mind equal true PCM CD Replay in most aspects of sound quality, operates at 2.8MHz switching, or around 10 times as fast as common Class D Amplifiers... Why anyone would want to listen through an A2D followed by an D2A Converter that are around 10 times worse than single speed DSD is beyond me. But with enough hype and snazzy naming it cannot help but sell high and wide. Cheers George |
Cyrill Hammer (Souloution)
"if you want to have your product performing at the cutting edge it is not possible with today’s known switching technologies. In order to come close to the performance of the best linear design we would need high-current semiconductors that provide switching frequencies of several MHz or even GHz." This is the one, that I believe hits the nail on the head, and why to some that hear it Class-D sound in the upper ranges hasn’t come of age yet. Only Technics with their unobtainable $30k SE-R1 comes close with a 1.5mHz switching frequency instead of what all the other are using today 400-600kHz. But as Cyrill Hammer states it should be even higher. Cheers George |
because even though you don’t like Class D you are in every single discussion about it. Sorry didn’t know it was a closed shop, and only one sided opinions were allowed! "Why I can’t move past 30 year old arguments." Because they still apply today, but there’s light on the horizon. Just because you can’t hear the problems, doesn’t mean others can’t. As posted here already by others to your chagrin. |
helomech608 posts09-02-2018 9:00amVladimir Shushurin (Lamm)
"No, it is not. And I would like to respond to the second part of this question with an allegory. Any field of human activity defines a number of requirements which, when properly implemented, guarantee a positive outcome.
For example, the basic requirement in the army and sports is an able-bodied individual. So, it would be quite natural to concentrate on searching for such an individual (especially as we know where to find him).
However, out of the blue we decide to choose a feeble-bodied person who, on top of that, is encumbered by various diseases. Having made this decision (which is a priori improper) we start justifying it to ourselves and others by citing the great state of our medicine, which is capable of curing many ailments."
helomech
Bingo We better put up the question again to what this answer above relates to, which is: " Is Class D competitive with linear designs in sound quality, and if not, will it ever be?" Cheers George |
There is no reason an active speaker cannot be an audiophile grade product. We are at the beginning of this technology. There is Dynaudio, Genelec, Kii, KEF and very few others. I sat in the same seat as the presenter used to tune the $14k Kii system from, and listened to 2 known songs that I had with me, and I was outter there. To my senses it was like a surgical knife dissecting the music, that’s the only way I can describe it. The same happened at the Uno ZERO 1 XD demo. Maybe the future, but not yet. Cheers George |
I mean, we can’t even get George to accept Class D even at its simplest face value! :) I do accept it, but not in competition to hiend audio yet, they make great bass/upper bass amps so far. And I’ve said it all along I’ll be the first to dump my stinking hot, heavy, inefficient, boat anchors. When they’ve got rid of their problem/s, that Technics with the $30k SE-R1 have semi addressed with their 1.5mHz switching speed power amp, 3 x times higher than what’s around at present, then the (switching noise) output filter can do it’s job properly without effecting the audio bands upper mids and highs that so many hear, and owners can't!. I see threads like this "looking for the truth" started as a "reach out for confirmation" from owners who know their Class-D’s are not quite right, but can’t bring himself to go back to linear, almost like begging for forgiveness, for what they have done and everything will hopefully be fine. Cheers George |
guidocorona
I remember no more than one year ago you advocating that the day of class D would come once designers adopted Gallium Nitrite transistors switching at 1.5Mhz.... 1graber2
E.g., “even”George has said he finds Class D acceptable at the 1.5 MHz switching speed. How much are those SE-1s? What I said was G, they can’t yet because the mainstream manufacturers (Motorola, Hitachi, Fairchild STMicroelectronics Texas Instruments ect ect) haven’t started manufacturing them yet for maybe $2 each, because GAN is invented and made by a small (relative to the above) development company (EPC-Co) , they on sell the licence to major manufacturers to make them. (EPC-Co) also invented the power Mosfet in the 60’s which the major manufacturers use under licence from them to make. Yes Technics has the GAN probably direct from EPC in limited supply, and you can bet they’re not $2 each, hence the $30k price tag on the SE-R1, anlong with limited tooling costs. I’ve always stated that the 1.5gHz switching frequency used in $30k Technics SE-R1 was a massive stepping stone in the right direction, instead of the 400-600mHz used today by others. Because at 1.5gHz the low order output filter can remove "almost" all the switching noise without any effects down to around 5khz into the audio band which happens with all other Class-D’s now. As Cyril Hammer of Soulution amps also says, we need to get even higher, he’s at 5gHz I’ve always thought 3gHz is fine, and when I see that on the way with future technology, it’s time for me to start advertising my boat anchors. Cheer George |
ricevs
they are not mosfets as Mouser has no category for them at present.....
You need to read and comprehend better. Go back and read my post again. I never said they were, your going off half cocked again. What I said, the inventors of these new GAN devices (EPC. Group) YET TO BE TAKEN UP BY THE MAJOR MANUFACTURERS (just in-case you have bad eyes). Were also responsible for inventing the power Mosfet years ago. "
Alex Lidow, Ph.D. CEO and Co-founder Alex joined International Rectifier (NYSE:IRF) as an R&D engineer and is the co-inventor of the HEXFET power MOSFET, a power transistor that displaced the bipolar transistor and launched modern power conversion."
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guidocorona3,975 posts09-04-2018 8:50amYou might have a point George.... I just did a quick Google search and came up with this article....
https://phys.org/news/2018-07-path-high-performance-transistors.html If indeed Gallium Nitrite transistors may be applied to push into the Ghz switching frequencies for 5G transmitters, they will need to be eventually supplied by mainstream/major fabs... Perhaps we will see more high speed GaN transistors before long.
Thank you for digging this up G, maybe now the doubters will "back off" It’s frustrating when posters like last one I had to address, skip read something get it all ****** up, before their mouths spew forth. BTW, I did not know that Soulution is already using GaN technology. That’s is interesting they have applied it to linear amplifiers, maybe used in their power supplies for full rail regulation? The only power amp I knew of that did that was the old Naim 250, nice sounding but didn't like Quad 57's, it oscillated and blew up, in the first second of turn on. Cheers George |
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ieales
Stating that 1.5GHz will solve all the problems is as silly as saying a 10MHz Class AB bandwidth has to sound better than 100KHz. Not "all" but the major one, that point to listeners having issues with the upper/mids and highs. Cheers George |
ricevs
you might think they are mosfets. Please point to where it says I think they are Mosfets?? I said the GAN device was invented by the same guys (directors of EPC) that invented the Power Mosfet!!! All those years ago. They (EPC) are into inventing/developing and selling their patented inventions to the major semiconductor manufactures, just like they did with the Power Mosfet. Also the ones used in the Techincs SE-R1 may not even be the same ones that are on Mouser that are non existent not in stock anyway. BTW "G" here is the difference in switching noise ringing on a square wave between Mosfet and GAN, https://www.technics.com/content/products/r1/images/se-r1-img2-2-uk.pngthere is still a little ringing but it’s far better than what all the other Class-D’s do. https://www.stereo.net.au/forums/uploads/monthly_2016_12/583f6e91157f6_Class-Dsquarewaveringing..jpg... And this is at 1.5gHz at 3gHz it could be all but gone, without effecting down to 5kHz into the audio band. |
I just wanted to make sure you read the data sheet to see that these are indeed GAN devices.
I saw all these when the SE-R1 was released, a year ago and posted them up here. Thanks anyway. |
The quote from Mr. Hammer is false. Here’s why:
As @merrilaudio states, the problem is dead time. And the rest seems like an ad. It’s not false as Ralph would have you believe. It is "also" a problem, but isn’t the "major problem", and the cause is of what many dislike what they hear in the upper/mids and highs which is a product of the switching noise and it’s associated filter. It is believed that the dead time will also be vastly improved with a 3mHz switching speeds. This analogy from Nelson Pass will help: "Imagine that the two transistors are runners in a relay race and that the signal is the baton they carry. In a real relay race, the runner receiving the baton begins running before the hand-off, which is made with the runners at speed. The runners who hand over the baton at a dead stop will operate at a severe disadvantage". (if that runner can stop on a dime from full speed, then take off like a nitro drag car, you have higher switching speed) And an interview with the great man (Nelson Pass) just a couple of months ago;
JS:There has been an explosion in high-end Class D amps in recent years. Some companies now market some fairly sophisticated – and expensive – Class D models. Pass currently manufactures Class A and AB lines only. What are your thoughts on Class D? NP: Personally I think it’s a miracle that they work at all, but then I think that about my phone, too. I have great respect for people who can make Class D amplifiers sound pretty good, and for delivering low cost, high power, and efficiency. They have earned their place in the industry. That said, I am not tempted to go in that direction.
Cheers George |
You might dislike the whole lot instead *Grins!* Why? ... "BECAUSE!"
G.
It's simple G As it stands now the switching frequency noise output filter, has phase shift effects that reach right down to 5khz, that doubled for the worse at 10khz and doubled worse again 20khz. That's what many listeners find objectionable, in the upper mids and highs. If the switching frequency is moved much higher from the present 400-600khz to 2 or 3mHz, then the filter can be moved up accordingly. So it has no phase shift effects down to 5khz, but only then at over 20khz instead where it really doesn't matter. And the dead time will magically improve as well, it's a win win, for higher switching speeds that's why Technics with the SE-R1 persevered to get it, at a cost rrp $30k aud. Cheers George |
But you are reverting instead to your single track paper-bound comments
Only because of those "looking for confirmation" to what they think that Class-D is finally Hiend. It hasn't changed that much since it's inception, many you will find are buying Chinese modules some modded via Pascal EU, just more and more trying to make "big bucks" out of what is essentially very cheap to make, if you take away the "glitzy chassis" they have.
NP: Personally I think it’s a miracle that they work at all.
I am not tempted to go in that direction.
Cheers George |
Here is an interesting read for those at odds with what’s being presented here. Not just with the filtering of the switching noise, which I primarily "bat" on about, but also what is a secondary problem of Class-D advantages in the "dead time". From the makers of the GAN transistors that Technics use in the SE-R1. " EPC’s enhancement-mode GaN (eGaN®) transistors switch up to ten times faster than silicon MOSFETs, with ‘zero’ stored charge. The increased switching speed of eGaN FETs allows amplifier designers to increase PWM switching frequencies, reduce dead-time, and drastically reduce feedback; producing a sound quality previously limited to large, complex, heavy Class-A amplifier systems." Also there could be a module for sale using these eGan transistors from Austin Texas. Elegant Audio Solutions of Austin, Texas, has produced an amplifier capable of a continuous power output of 200 Watts into an 8Ω, or 400 Watts into a 4Ω speaker load, with THD+N as low as 0.005% and very low feedback. Moreover, this is done without the need for a heat sink and eGaN-based amplifier can plug directly into the standard amplifier implementation of many existing systems. https://epc-co.com/epc/Portals/0/epc/blogs/elegant-audio-solutions-eGaNAMP2016.pngCheers George |
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We have George repeating over and over and over and over and over and over.....he he..... about phase shift due to filter effects....trouble is, he is guessing about its sonic effect. He knows nothing because he has not heard anything......he is just talking. Ok, were stooping down to that level. Many of us know your comments are biased and maybe in it for the monitory gain, and you’ll say anything because of this, and your protection of it. http://tweakaudio.com/EVS-2/EVS_1200_amplifier.html I have no financial interest in Class-D at all, just what I hear and others report.. |
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Which approach is best: modding a Prius to be almost as quick as a Lambo (with better MPG), and charging Lambo prices, or just starting from the ground up with a real gas-guzzling Lambo?
Personally, I'd take the latter though I can understand the argument for the former.
+1 That's about it alright, for now anyway. I think we maybe in for a shock in the not too distant future, re all the stuff EPC is doing with the GaN. Then all the Class-D's being raved about at present, will become as popular as solid state was when they were made with Germanium transistors when Silicon transistors hit the market. You couldn't sell them to save yourself, they made excellent door stops and that was it. Cheers George |
Musically speaking ... well I am very happy were I landed with a 625s2...
Yours and the 725 mono seem to be the last linear Class-A/B amps JR make, and seem to be a worthy choice. Cheers George |
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1extreme Excellent way of utilizing them as that’s where they shine at the moment, with their output impedance down in the milliohms region (damping factor massive), so long as the speakers load impedance doesn’t get real nasty, as most that I’ve seen don’t seem to like <3ohms too much. Cheers George |
At $699 it’s got what it takes under the hood, Mike Moffat is no fool, he made Theta digital what it is when it was on top. What he’s done with Schiit is hiend at lowend pricing, using volume to make his profit.
He’s giving Italian V12 quadcam horsepower but with US V8 supercharged iron and no glitz and glamour.
$50 more for front switch, a $100 for a smarter chassis, $50 for a more expensive remote, all of a sudden your over a grand and it sounds the same.
Cheers George |
