saving?
I've mentioned this on and off for over a year, here and other forums.
Cheers George
I've mentioned this on and off for over a year, here and other forums.
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
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 |
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 |
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 |
with In my experiences with good quality class D ampsThey just faithfully amplify the inputted signaout adding or subtracting anything. They’re like the audio amp ideal of a "straight wire with gain". which I have proved couldn’t be further from the truth In https://www.stereophile.com/images/archivesart/999A565fig2.jpg Out https://cdn.stereophile.com/images/1212AM1fig02.jpg I have a feeling there’s another new Class-D coming. |
Sorry you started it all with this little misquoted rant. "The idea that anyone would run one without the filter is ludicrous."And I said in reply " No one said run or listen to class-D without the output filter, it said to "look" at it with a scope. Your in product protection mode, and that says it all. |
Actually Georgehifi, YOU made the claim the the output of Class-D is not recognizable, and then you compared the switching residue internal or external,Go back and read a bit more carefully, please🤦♂️. If the Class-D output filter is removed, then "input test signal" (not switching noise as you say) is not recognizable at the output terminals because of the switching noise monsters it. With the filter in place, it still sad with residual switching noise, but recognizable, as to what’s going into the input. |
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 |
I do though see some advantages regarding heat generated (if that is a concern.. for me it isn’t) and size/weight. They offer a ton of power in a small mass versus trying to heft around a 90 pound Class A/B amp or an even heavier (with less power) tube amp. I see my system as something I want to get the very best from, and if I have to compromise and pay for it in less efficiency so be it. I wouldn’t buy a Ferrari put low octane fuel in it, stick cross-ply tires on it and drive it like a granny just so I could say I’m being kinder to the environment. But Class-D amps with the promises of higher switching frequencies technology in the future, may become all they need for me to jump camp, then my current amps will become door stops or boat anchors. Cheers George |
But again that’s preference. I was mislead by dealer and the internet that led me to believe that Maggie’s required brut power it wasn’t until I decided to let my ears be the judge and bought a class A amp that puts out a whopping 95wpc. I’m not saying class D is bad I’m just saying that for my system and listening preference I went class A.What was this 95w linear Class-A amp?? Cheers George |
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 |
@
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 |
,l with In my experiences with good quality class D ampsThey just faithfully amplify the inputted signaout adding or subtracting anything. They’re like the audio amp ideal of a "straight wire with gain".Sorry they don’t look the same, just look at any 1-10khz test shot of input v output wave form. And then without their output filter, the input wave form will be unrecognizable from the output, because of the HF garbage, and melt your tweeters silently in a nano second. It’s like a customers preamp I had to work on, the owner said it sounded little bit hard, a quick look on the scope showed the output wave form looked just like the input wave form, all looked fine?. Then I looked with the scope in the center of the preamps circuit, and found the wave form unrecognizable from the input with the amount of hf garbage on it. That center amplification stage was oscillating its brains out!!! And all they (manufacturer) did was to filter it out at the end stage, instead of fixing the source of the problem. I compensated the center stage so it didn’t oscillate anymore and removed the end stage output filter, and the customer was happy. But you can’t do this with Class-D, so the only thing to do is to raise the sw noise in it even higher (1.5mhz) so then the output filter then can do it’s job fully without any phase effects down into the audible frequencies. Then a Class-D’s input wave form will be much closer to matching it’s output wave form. "straight wire with gain" 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 |
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 |
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 |
JA used his high order special testing output filters because he didn't yet have the Audio Precision's auxiliary AUX-0025That's right, what I said and why you can't see much switching noise on the square waves Without those "special testing filters" the square wave will look like this https://cdn.stereophile.com/images/1212AM1fig02.jpg Sorry it's is you that needs to get some tutoring on this, as I said the output filter limits bandwidth and also because it's a low order creates phase shift down into the audible frequencies. |
heaudioIncorrect, it is you that is saying something false, if it was completely filtered out as you say, then they wouldn’t still look like this, with much residual switching noise still riding on the audio test waves 1-10khz, and with severe phase shift indicated by the inward slope of the sides https://www.stereophile.com/images/1212AM1fig02.jpg Instead of looking nearly perfect like this, and with hardly any phase shift indicated by the almost vertical sides. https://www.stereophile.com/images/811532fig2.jpg Cheers George |
jollygreenaudiophile2Yes it was the very first Class-D I listened to and tested back in around 2004, sorry wasn’t pretty, in sound or test against my Threshold Stasis S500 Optical at the time on the ML Monoliths. Then I got a Channel Islands Class-D with linear supply, better but still not near hiend. Since then the only Class-D that has piqued my interest was the BelCanto 600M monoblocks but only on a 2 way speaker with a very benign 6ohm load, with Raal ribbon Cheers George |
coffee-jerkYes you should, as they to me and others sounded better than the Belcanto Black mono’s and Ref 1000 mono’s, still wouldn’t put them in with linear hi-end territory driving hard loads especially Cheers George |
the idea that anyone would run one without the filter is ludicrous. Your scare mongering. No one said run or listen to class-D without the output filter, it said to "look" at it. Whichimplied to see it on a scope as that’s what was being discussed, comparing input wave form to output wave form, far from the same or what your implying. For those that wish to see what goes in and what comes out between Class-D v Linear amplification which is closer to the original input, or closer to "straight wire with gain" as what was the start of this Test input:1khz perfect square wave http://www.tronola.com/moorepage/Sine/1kHzsquare.jpg Output: Class-D: https://www.stereophile.com/images/archivesart/406Halfig01.jpg Output:Linear Amp: https://www.stereophile.com/images/archivesart/999A565fig2.jpg |
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 |
dutch12 Sorry to burst your bubble there Dutch old mate. But the Belles 150A V2 is a 150w Class-A/B linear amp, nothing to do with Class-D. https://ibb.co/yn8f6FJ https://www.stereophile.com/axpona2010/advanced_transduction_belles/index.html http://www.soundstagenetwork.com/noisy13.htm And your right the Belles 150A have a great sonic reputation, probably better than most Class-D, except for maybe the Technics SE-R1. Stick with it you’ll be happy for a long while, till Class-D rids itself of it’s Achilles Heel. Like what Technics did to combat it with SE-R1, but yet to remain affordable as well, instead of being $20K. 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 |