EPC (small company) Alex Lidow is the inventor of this new GaN-FET transistor Technics uses, and he happens to be the inventor of the Mosfet/Hexfet all those years ago I believe.
Cheers George
Cheers George
Class D is just Dandy!
I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.
That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.
For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.
Please share your experiences with class D amps!
That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.
For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.
Please share your experiences with class D amps!
Showing 50 responses by georgehifi
The 60’s 70’s 80’s were the change over from germanium transistors to early silicon transistors, and the amps around at that time were ? to say the least. A good tube was better to own still. But the silicon transistor has advanced, so to circuit design. I’m still waiting for the transistor that will take Class-D to where it will eventually get to in the rankings, Technics are using a super transistor (not available for everyone) for their SE-R1 Class-D poweramp (special order only), but it’s a $20k-$30k amp, it shows what’s ahead in the future for Class-D http://www.technics.com/us/products/r1/se-r1.html Stereophile listens. Technics SE-R1 Stereo Power Amplifier "This amplifier delivered some of the best reproduced sound at CES 2017 The broad and deep soundstage, imaging, upper midrange detail, and bass extension were thrilling during the system’s rendition of "Lord, make me an instrument of thy peace" and "Pie Jesu." Digital Trends Listen: Technics SE-R1 Stereo Power Amplifier " Not only are we hearing things we’d never heard before, we’re hearing it in a way we’ve never heard it before. A music system that sounds like a live performance is a tough goal to attain, but Technics’ flagship nails it. This is all due to the higher switching frequency (double of what's around now) of these special transistors. Cheers George |
though i really should try them with a passive pre, just to hear their true nature..Yes that is the way to hear what they are really like, or direct if you don’t start to "bit strip" with a source digital volume control by going below 75% of full volume. I’m also not one for band-aid fixing, by adding a colouration to fix a problem elsewhere, that should be addressed instead. Cheers George |
Gallium Nitride (GaN) and is poised to uproot the high-end audio world. In fact Yes as I posted here, these eGaN fets are what Technics are using in their new $30k class-d and with it are able to double the frequency of the switching noise. And therefore able to remove it with low order filters more effectively from the output of the amp, without coming close to the HF audio band with those low order filters effects (phase shifts) and left over switching noise. https://forum.audiogon.com/posts/1413469 https://forum.audiogon.com/posts/1413463 Why We’ll Soon Be Living In A Class D World Cheers George |
2channel8231 postsAre any other manufacturers using eGaN transistors? No one I know, it's only a small company that makes them, not one of the majors, maybe Technics have taken all supplies. Maybe this is why from what I heard that the $30k Technics SE-R1 poweramp is for privileged few, and pre order, pre pay. Cheers George |
Using feedback to reduce distortion isn't a free lunch though, or is it?From what is understood for years by the guru's of amp design, is that any amp should be designed for as little distortion, low output impedance ect., as possible without the use of feedback. Then to use just a little feedback if necessary to clean it up if need be. Cheers George |
@
whitestix https://forum.audiogon.com/posts/1415192 Cheers George |
phd Odd the opposite of what was heard from the $50K Mark Levinson No.53 Class-D monoblocks Stereophile's Michael Fremer listens to the ML No 53’s. "Through the No.53s Cassidy’s voice was pinpoint sharp but the reverb, instead of being airy and ethereal, sounded like a hard haze that obscured detail at low levels and became fatiguing at higher ones. As seems to be the case with switching amps, no matter how carefully designed, the higher in frequency the music goes, the more problems there are. That also holds true the more you turn up the volume. Generally speaking, the louder I played the No.53s, the more pronounced the haze. The more high-frequency content in the music—women’s voices, cymbals, reverberant backdrops—the more the haze intruded on and obscured the images, forcing me to turn down the volume." Cheers George |
randy-11 +1 many times over Randy, seems like your one of the few that get it here! Just to add to that, the "gentle" filter is on the output speaker terminals, and has to take the full grunt (wattage) of what the amps gives out, it has to be "gentle" (low order), if complex it would soon fry up. Or as Mark Levinson tried with $$$$ the No. 53 monoblocks, a higher order filter and massive to take the grunt, (as you can see by the 4 x chokes on each monoblock), but that has problems also as well as expensive, it wasn’t received very well. http://www.stereophile.com/images/1212levin.side.jpg Cheers George |
I'll lay money on it Eric your the one of the first to change to the higher switching speeds when they come available/affordable, hopefully soon, judging by Technics lead in this area of higher switching speeds. I know I will sell my inefficient, hot, heavy, boat anchors just before it happens, before they become worthless, as will today's Class-D amps. Cheers George |
It’s because a simple low order output filter can take the amps full power, but it’s effects reach down into the audio band and still leave some switching noise left overs, hence the need to take it up much higher as Technics did with far higher switching frequencies, so they can be effectively removed, without effecting the audio band. These days when Stereophile tests a Class-d amp, they put on an external output filter, the Audio Precision’s AP0025 filter, which has a -50db rolloff after the audio band so the 1khz square waves look half decent without the switching noise embedded right across it, (good for sales) 10khz square wave still looks a mangled mess though, trouble is this AP filter can only take very low power, would be real nice to leave it in to listen to, but it would blow up in a micro second. http://www.stereophile.com/content/class%C3%A9-sigma-2200i-integrated-amplifier-measurements#31YFAPfYVDGeowzZ.97 And yes steeper filters as you said do have their own set of problems re sound, as ML found out with their No.53 monoblocks. Cheers George |
and not the usual negatives.Some love them some don’t, and on a forum this is where it should be discussed, not limited to just the "pro sector" usually from owners, but the negatives also from those who’ve listened/owned but don’t like their sound, and then technically the reasons why this maybe the case. and class d does it for me,not looking for class a or tube amps anymore.That’s good, if you believe you’ve reach your holly grail with the Class-D. I’m still waiting for it to mature with future advances in technology that are coming, as Technics have started in very expensive limited supply. Then we’ll all be happy Class-D campers. I see it a bit like the first hard sounding brickwall filtered CD players, which I also didn’t like, took a while but the newer technology especially in filtering and I/V conversion now makes great music, even with using those same old d/a chips, of that era with pcm redbook replay. Cheers George |
+1 kdude66 This equates to an output impedance of 1.25 Ohms at 20kHz and SIGNIFICANT phase shift within the audio band. Just what I’ve been saying all along, would be great if you can post a link to this. This is why it important to increase the switching frequency by hopefully x5, which then takes the filter up higher by the same amount, away from the audio band. And why the above transistor development (in my last post) is so needed to get it up there. Cheers George |
George, They can’t yet, as that technology needs to be taken up by the major semiconductor manufacturers Motorloa, Sanken, Fairchild, Toshiba ect. Then the small Class-d manufacturers will be able to get them as well at a decent price. Remember the guy http://epc-co.com/epc/Applications/ClassDAudio.aspx that invented these special Gallium Nitride transistors that Technics use in that amp, also invented the Mosfet years back, and look where that ended up, every big manufacturer makes them now. So hopefully it won’t be long, then all other Class’s of amps will become defunct, and there’ll just be Class-D. Cheers George |
Class-D that can finally equal or better hi-end linear amplifiers, tube or S/S. It's closer than you think. Why We'll Soon Be Living In A Class D WorldCheers George |
This should be an interesting read for some here. Alex Lidow, Ph.D. CEO and Co-founder of EPC.co. And who happens to be the co-inventer of the Mosfet/Hexfet transistor And now he is leading the way with this higher switching speed GaN-Fet transistor that Technics uses, in their limited SE-R1 Class-D poweramp.
Looks like the GaN Class-D modules have become available, maybe to everyone?
Cheers George |
When I read posts from members like georgehifi and randy-11 about a theoretical issue with class D amps switching frequencies needing to be dramatically raised to avoid affecting frequencies in the human audible hearing range without presenting any semblance of even anecdotal evidence that it’s true, makes me seriously suspicious of their true motives for spreading and trying to validate something that I highly doubt 99%plus of humans could even begin to detectBy saying this, a little better explanation is needed. It’s the output filter to rid that switching frequency completely, that is the problem, not the switching frequency by itself. As that output filter has phase effects down to 5khz, the upper midrange and highs. And by moving it (output filter) and the switching frequency much higher, takes those effects at 5khz upwards by the same amount, hopefully passed 20khz. Why I ask then are these transistors developments happening, if not to do anything good? Forest and trees. Cheers George |
There is no way an Apogee Scintilla will sound anywhere near it's best driven by ANY class-d, and they could just switch off or blow up. Not only is it 1ohm @100hz, but it has a massive -90 degree phase shift at 100hz also, these two together mean almost a dead short as see by the amp. Only the biggest heaviest Refererence Monoblock Krells of yesteryear can drive those sort of loads and sound good. To quote a great Australian movie (The Castle) "Tell'im he's dreaming son." https://www.youtube.com/watch?v=dik_wnOE4dk Cheers George |
George,No don’t own them, but of all the D’s I have heard they were the best, "BUT" only when they drove an expensive Raven ribbon tweeter’ed two way bookshelf. This Raven has a very benign flat 4-6 ohm load and not much -phase angle to contend with, the whole speaker was an easy drive. If so what amps do you like better and what speakers do you use. A pair of these ME1500’s the one for the esl panels in 100w class-A mode the other for the bass in 25w Class-A mode. And highly modified bass Martin Logan Monolith III with the newer aluminium vapour deposited Neolith esl panels. http://www.stereo.net.au/forums/topic/109666-reading-specs/?do=findComment&comment=1689719 I also loved the sound of these on a pair of Quad ESL57's, but you've only got 25watts. http://www.audiocostruzioni.com/r_s/ampli/amplificatori-finali/mark-lvinson-ml2/mark-levinson-ml2.html Cheers George |
George,Should have seen/heard the 90’s system, similar amps but water cooled, doubled stacked Acoustat 2’s with Magnat Plasma MP-02 Tweeters above 10kHz. esl panels crossed over at 80hz to Kef B1814 bass drivers in ported 12cu ft encosures FS at 18hz, tuned by the man himself Neville Thiele (rip), some rich dude from Singapore came to Australia just to buy it all from me, after it was reviewed in Stereophiles sister mag in HK. Cheers George |
Where do you get your data on the Scintillas?Sorry my bad on the phase, looked at the graph wrong. But not on the impedance, still 1ohm in the bass, and again it seems from your measurments at 1.3khz, no place for class-D or tubes or Mosfets, they will behave like tone controls or just give up. "True, you could with some effort, re-wire your Scintillas at home for 4 ohm operation, but with a 6dB loss in voltage-rated sensitivity. At 1 ohm, MC estimated the sensitivity to be 73dB/1W, noting that, ’Consideration also needs to be given to the peak current demand of the Scintilla at 1ohm. Taking an average impedance of 0.9ohms, a Krell KMA-200 on full song will provide up to 60V peak. Assuming minimal cable losses, the Scintillas will draw peak currents of over 60amps. Now you can see why blockbuster amplifiers of Krell current capacity are required for 1ohm working.’" Cheers George |
Just a few of the industry's heavy hitters of hi-end design give their opinion on the merits of Class-D in a round table discussion with Absolute Sounds. http://www.stereo.net.au/forums/topic/110007-switching-noise-in-class-d-amps/?do=findComment&com... Cheers George |
he can’t trust his own ears.I do very much so Eric , maybe it’s you that needs an bi-aural Exostosis operation. As I said before the only one of new breed of Class-D’s that I had any time for, was the latest BelCanto 600 monoblocks to which BC from what I understood by the presenter has done their own switching noise filtering, from what is standard from NCore. But they had to be driving a benign 6ohm load, of a top line Raven tweeter’ed two way bookshelf, to get me to like them, on the other speakers they too didn’t sound very good. Cheers George |
ricred1735 posts05-05-2017 5:43amI’m trying to get a hold of a pair of Bel Canto Ref 600s to compare to my Jeff Rowland 625 S2. May be time for a change. I’m curious to hear if they mate well with the Corus preamp.There a s/h pair for sale here, word is he’s going back to linear amplification. http://www.stereo.net.au/forums/topic/122535-eoifs-bel-canto-premono-blocks/ Cheers George |
This "competes" is not saying anything, as I can "compete" against
Usain Bolt in a 100mt race, I don't think there'd be any money put down on me to win anywhere in the world! This competes http://www.classdaudio.com/sds-series-amplifiers/sds-470c-class-d-audio-power-amplifier/ With this!!!!! http://www.atma-sphere.com/Products/#M-60 Give me a break. Cheers George |
Our Kangaroo some say in plague proportions in Australia is very efficient, a bit like the Class-D, of the distance v speed travelled in the animal world. But is very one dimensional in it's movement and that straight ahead, easily picked off by a Mick Taylor (Wolf Creek) https://www.youtube.com/watch?v=uTUp4IJ_xqQ Cheers George |
randy-11982 posts05-19-2017 9:50amI also saw news on a new Class D amp from Constellation with very high switching freq. - dunno if it uses GaN devices...Very interesting if it does, I thought Technics had a monopoly on them, if so they’d be the first one to start using them, since the Technics SE-R1 started thing off. Have you a link you can post to this? Cheers George |
randy-11982 posts05-19-2017 9:50amI also saw news on a new Class D amp from Constellation with very high switching freq. - dunno if it uses GaN devices... Just checked, just the same as everyone else 600-800khz if they used the new GaN semiconductors it would be 1.5mHz, I wish they did, then that would mean supply to the little folk is available. Technics probably have a monopoly on them for now. " Its Class D amplifiers use a special topology with ultra-high-frequency 600 kHz switching" Cheers George |
autre43 posts05-29-2017 4:52amAs Kenny ( kdude66 ) above mentioned the Red Dragon S-500 would be a good pick, and has come from the same lineage as the Rowland Continuum S2, that many here like, see here. https://forum.audiogon.com/discussions/class-d-trash/post?postid=1428517#1428517 And if your handy you can just get the modules and make it yourself. Cheers George |
Interesting read on two expensive high end mono-blocks from Mark Levinson. The $50K No.53 Class-D mono-blocks where they spent considerable time and effort to address and rid the problems of class-D, but never got the great review (listening or measurement) they hoped for. https://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier Then back to their linear $30K No.536 mono-blocks Class A/B, which by comparison got a great review (listening and measurements). https://www.stereophile.com/content/mark-levinson-no536-monoblock-power-amplifier Goes to show, even a pedigree company, with credentials up the wazoo, can't get Class-D to better their own cheaper linear amps. Cheers George |
erik_squires OP2,223 posts06-24-2017 12:24pmFremer's 2013 review was riddled with bias. He's no neutral observer. Well John Atkinson also backed his "bias" after doing the measurements. " The sound was initially very impressive. It had tremendous dynamic sweep, with superb control of the Wilsons' woofers, tremendous clarity, and nothing identifiably wrong. However, the more I listened, the more the overall sonic picture seemed flat and uninvolving. An enigma.—John Atkinson" Read more at https://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier-measureme... Cheers George |
This is an open forum, I believe that Class-d should be seen from both sides of the camp, not censored to just the pro-camp, this way members can make up their own minds whether or not to get one, because all do not see "Class-D as being just dandy". Maybe soon in the future when the switching frequency can be raised double or tripple with advancement in semi conductor technology, so then it’s output filter can do it’s job properly without negative effect to the upper mids and highs. Cheers George |
Like I said once before, to the ones that have blinkers on, they will be the first to change to the higher switching frequencies when they become available, that's almost a given. As for now maybe just trying to protect their investments, with ignoring that the higher switching frequencies will give them what many hear is a problem with Class-D, which effects the upper mid/highs. Cheers George |
asvjerryWell said, as I've also stated, even I will ditch my boat anchors when the technology allows that dreaded switching frequency (Class-D's Achilles heel) to be 2-3 times higher than what it is. Then it will be an amp to contend with. Cheers George |
No I haven’t yet as the Technics SE-R1 is unobtainium here in Australia, and you need to order them and have deep pockets in counties that do retail them. But from the number of Class-D’s I had here listened to and measured, they (Technics) seem to address to a certain extent the problems that they all have still, which is the filtering that has to get of the switching frequency noise, without it effecting the audio band in any way, and the only way to do this is to raise the switching frequency by at least triple, Technics have done double with the SE-R1 so were on the way. But these are typical of reviews (below) of the sound they give out from those that have heard it, and there are more from others on the web. " Listening to tracks that we’ve heard 100s of times — and on excellent systems at that — is now a revelation of once hidden nuance and detail. Not only are we hearing things we’d never heard before, we’re hearing it in a way we’ve never heard it before. A music system that sounds like a live performance is a tough goal to attain, but Technics’ flagship nails it." Cheers George |
Really? Just because it uses a linear rather than a crap SMP power supply, doesn't mean it's not Class-D From Stereophile: " Although the SE-R1’s huge twin output meters and beautiful anodized-aluminum finish were visually distracting, the marketing of a Class-D amplifier as a separate high-end component was important. This amplifier delivered some of the best reproduced sound at CES 2017. I persuaded Bill Voss to rip the contents of my copy of Rutter’s Requiem to his media server’s solid-state drive. The broad and deep soundstage, imaging, upper midrange detail, and bass extension were thrilling during the system’s rendition of "Lord, make me an instrument of thy peace" and "Pie Jesu." I appreciated the work done by the Technics staff to prepare their exhibit suite with recessed sound-absorbing panels. I left wanting to hear more." From Audioholics: " On the amplifier side, the SU-C700 and SE-R1 are utilizing advanced Class D topologies, featuring a couple new acronyms, JENO and LAPC. JENO (Jitter elimination and noise shaping optimization) provides clock regeneration for low jitter switching in the amplifier stage, sample rate converter, as well as a pulse width modulator that feeds the output stage. LAPC (Load Adaptive Phase Calibration) on the other hand is designed to maintain frequency and phase response regardless of loudspeaker impedance, which is a weakness in some Class D implementations. Finally, the output stage utilizes gallium arsenide FETs (field effect transistors) with a claimed switching speed of 1.5MHz." From Audio Aficionado: " .I read a blip in The Absolute Sound that the Technics SE-R1 power amp ($18,000.00) is Class D. It uses a linear power supply rather than a switch mode power supply to produce 100 watts per channel. That’s a lot of money for a 100 w/p/c Class D amp. Along with the Technics SE-R1 Class D amplifier they also introduced the SU-R1 Network Audio Control Player preamp ($9000.00) and new SB-R1 Reference Speaker ($27,000.00). Technics calls this system the R1 Reference System." Cheers George |
stfoth+1 stfoth, others hear it too, and if they can’t good for them. This is why there are for and against post, from both sides of the camp, so potential purchasers can make up their own minds, and be happy with it or disappointed. These forums are not a marketing exercises to create a push to sell more Class-D. As the opening post says " Please share your experiences with class D amps!" Cheers George |
And stop with the ten-year old stories. Get in the now.The only current crop of D’s I’ve heard that have semi impressed, were the new Belcanto Ref 600M Monoblocks, yes they use the the newest "best" N-force NC500 modules that aren’t available to anyone but to Belcanto and other manufacturers. But Belcanto modifies them from what I’ve we were told by the importer/demonstrator, that was to either cascade/parallel or series a couple of the low order switching noise output filters to give a sharper filtering effect of the switching noise. But any speaker manufacturer worth his salt will tell you that doubling up on low order high power filters at or around the same area has it own set of problems with ringing ect. This is similar to what Mark Levinson tried with their $50k ML No.53 monoblocks, if you look inside at the series/paralleled?? massive red inductors in the pics. https://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier Cheers George |
Just happens a used pair of BelCanto Ref 600 monoblocks have come up, as with smps they work world wide. http://www.ebay.com/itm/Bel-Canto-M600REF-Mono-Blocks-/272735474772?hash=item3f804d1454:g:eu4AAOSwCkZZORA5 Cheers George |
You should get your facts right. It’s not N-Force, it’s NCoreReally!! I stand corrected. And there is no modification to NC-500 module itself.We were told different by the importer/demonstrator, unless he had it wrong. Why should various amps based on circuit boards of the same technology (NCore) and made by the same company (Hypex) sound different?I wonder, could it have to do with what the demonstrator told us??? Cheers George |