Class D

The Levinson amp switches at 2Meg and it sounds bad.  For what reason?........who cares.  You buy it, you lose.  The AGD amp switches at 500K.....it sounds good.   For what reasons?......who cares.  You buy it, you grin.  End of story.....Everything matters.

That's why it's seems only fixable by moving the switching frequency and filters way up higher so there's no effect of phase integrity down into the audio band, and the only way to do this is move the switching frequency up much higher to 1.5mhz and the filter as Technics did with the SE-R1 and hopefully with the SU-R1000 also.

And you can't fix it but throwing "more global feedback" at it, as that is a sound destroyer in itself. The only way is the > 1.5mhz switching frequency, so the filter can do it's job without introducing phase problems down into the audio band.

Rubbish. Bruno Putzey's UcD module, which is quite old at this point (and predates NCore and Hypex), has less than 1 degree of phase shift at 20KHz. It switches at 400KHz and is self-oscillating, with about 40dB of feedback.

Rubbish. Bruno Putzey’s UcD module, which is quite old at this point (and predates NCore and Hypex), has less than 1 degree of phase shift at 20KHz. It switches at 400KHz and is self-oscillating, with about 40dB of feedback.

Serious!!! your rubbish, those things have always sounded crap in the upper-mid/highs, most probably because of all that global feedback, that’s why it’s considered an ok bass/sub amp.

The original UCD module had lots of feedback.....all around the output coil....The Ncore modules added even more feedback and the Purifi adds even more feedback.  Most people feel the Ncore sounds better than UCD and Purifi sound better than Ncore.  Read the reviews of the "super high feedback" Purifi amps.......they like them.  I am not a FAN of feedback....nor am I not a FAN.  There are lots of ways up the mountain.  Again, everything matters.  One amp with 500K switching could sound way better than another at 1meg switching.....or visa versa.....One amp could sound better with more feedback....or with less feedback.....it is not one thing......everything has to be done well.  

that you lie or get hostile about something

Hey sunshine, if you look back just one post, it's Ralph that got hostile calling rubbish on me first, I just reciprocated the same back, get a life, or stop shilling/stalking 

Don't know what he is trying to achieve jumping on all the Class D threads and making a mess

He just told me this was a rumor.  Hahah.

Poor George.

If Class D was as bad as George ever claimed, he wouldn't have to be in every single Class D thread.  He's in every thread because class D is seriously good and it bothers him greatly.

Otherwise, we'd all hear it.  We would all know it.  We'd listen for 30 seconds and shudder. 

Dream on Eric you have no ears, it has problems, and Techincs have gone the distance in the SE-R1 in curing one of them it with 3 x higher switching speed (1.5mhz) and so 3 x higher low order output filter, as not to introduce any phase shift down into the audio band, without the need to increase any global feedback as some do, which we all know, large amount of feedback is not a good thing.
Also Class-D has problems with low impedance loads, that’s why you never see independent tests showing the 2ohm wattage almost doubling the 4ohm wattage. Even the Technics SE-R1 still has this problem. You have no idea!

...that’s why you never see independent tests showing the 2ohm wattage almost doubling the 4ohm wattage. Even the Technics SE-R1 still has this problem...

The H2O does it easily, that is drive 1-ohm Scintillas, not necessarily double down to even 2-ohms as no such spec is given by Henry. It uses a linear power supply, but it can't be as simple as that. It must be of some good quality and design.
And it does it with old ICE modules no less! I would look forward to henry's design of a Purifi version but he's hardly in this business as it is.

that is drive 1-ohm Scintillas

Yes many can "handle" but have pitiful current, because some even have trouble equalling the 4ohm wattage with a 2 ohm load, let alone trying to double. Some even go backwards!!
And as for 1ohm, again they might "handle" it without it dying.

But compare it to a Classic Krell or similar and see which sounds better at 1ohm or 2ohm!

That's why you'll never see independent measurements on Class-D showing it can "almost" double the 4ohm into 2ohm and again into 1ohm from 2 ohm.

Cheers George

Georgy porgy with his ongoing illogical attacks on class D born out of ignorance. You really would look less foolish if you educated yourself Sun"don't"shine.

Your the fool sunshine, for accepting Class-D the way it is, it has a long way to go to equal the likes of Krell, ML, A’gostino, Gryphon ect, as it is it will only ever be mid-fi if the two problems I mentioned above do not get improved on.
Technics has fixed one of those problems in the SE-R1 Class-D, and "maybe" also the cheaper integrated SU-R1000
And it will never be able to drive magnificent yet very hard to drive speakers like Wilson Alexia’s, like a big Krell, ML, A’gostino, Gryphon ect ect ect can.

When you get a chance, check out: Class D Audio.
I have the SDS470C, it uses the TI (Texas Instruments) Class D module.
VERY robust amp. Without the harsh highs. 

Enjoy!

Helllo,  My experience with the Mola Mola Kalugas is far better than others here. They replaced my Classe CA-2300 and the dynamics, bass
and overall resolution improved markedly. They were better with an old Audionet Preamp, and they continue to shine with the Mola Mola Makua preamp with internal DAC.  They drive large and inefficient Revel Salon 2's. and totally control them, with louder, clearer and more dynamic bass than before. This 'LIFESTYLE' system, as it has been described has pros and cons vs a system with large class A/AB monoblocks.  No, it is not as good overall as a great preamp with synergy to matching great A / AB mono amps.  But it does sound great.  And it is small, beautiful, cool to the touch, and fits in very well in an 'upstairs family room'.  My basement system is better. I would like to compare a really nice A/AB integrated upstairs one day, because that is really from the esthetic view a more apples to apples comparison.  But I would still need a DAC, which in the Makua (Tambaqui DAC) is amazing.  I have heard other class D amps, Apollon, Benchmark and NAD, and they were not nearly as nice as the Mola Mola Makuas, both in power, dynamics and resolution. The Mola Mola's used price is similar to that of a new pair of Benchmarks.

Finally, what strikes me as odd is that many describe or compare Class D as a whole, as if all class D amps are the same.  Just like Class A/AB right???  It is the implementation of technology which makes a product shine or not.  Just my thoughts...  Ken

Benchmark AHB2 amp is not Class D. 

Mola Mola Kalugas No, it is not as good overall as a great  A / AB mono amps. But it does sound great. And it is small, beautiful, cool to the touch, and fits in very well in an 'upstairs family room'.  And it is small, beautiful, cool to the touch, and fits in very well in an 'upstairs family room'. My basement system is better.

Correct, they are a compromise, as they stand. They still need "two problems" addressed I mention, one Technics have done with 1.5mhz switching frequency in the SE-R1

1: They have to correct the phase integrity through the upper-mids/highs (up to 70 degrees out of phase) https://ibb.co/vvwzGV5 because of the (switching frequency and it's output filter) WITHOUT resorting to "musicality destroying" gobs of global negative feedback to repair, as some have tried.

2: And the other is "current ability" to "resemble" doubling of wattage as frequency halves from 8 to 4 to 2 and hopefully maybe 1ohm, so they're not "current starved". Unlike the classic larger A A/B models  Krell, ML, A’gostino, Gryphon ect ect are capable of doing all day and yawn at it.
I can't see this happening with Class-D until future output stages/devices are re-design (maybe with even bi-polar dveices).
And then hope the SMP's are up to powering it all, with no current limitations also, if not then back to better big bulky no noise linear power supplies like I use with my Hypex NC400 (BelCanto Ref 600m) monoblocks.

Time will tell, if they can ever match todays "classic hi-end linear amps", that also took ages to get where they are, from the early days of horrible germanium transistors amplifiers that tried to take over from tubes.  

Cheers George    

I wonder if George can tell us how much of the phase-correction in the Technics unit is from hardware, and how much is through software (delay).

I wonder if George understands the math of feedback?

Wasn’t even addressing you, but seeing you butted in yet again, wonder if you understand your own ears, I doubt it very much, as you seem to think all that counts is wattage, and have no idea, just how bad global feedback is for sound quality when not used sparingly, and why some of the best sounding amps ever made have only local feedback.

To me the best sounding amp doesn't have a sound.

Correct, that why I like passive preamps also, if correctly implemented, as they have no sound.

Listen to many Class-D’s they have great bass great lower mids, but "something thins out" and looses it dimensionality in the upper mids and highs, like a separate amps has been grafted in suddenly.
This is what I mean they when I say they (Class-D) don’t sound like the A or A/B classics amps, effortless (invisible) from top to bottom without character change at all.

Cheers George

George,

The difference between me and you is I understand feedback, you do not. One of the amplifiers you previously went gaga about Soulution, uses a ton of feedback. You just don't know what you are talking about.

So back the question, how much of the phase shift in the Technics is from the filters, and how much from intentional correction in software? ... inquiring minds want to know.

I don't know George some of the best sound quality  I've heard came from Class D amps in active speakers. Effortless from top to bottom. 

Well, yes good actives do impress, but I bet my bottom dollar those same active speakers can sound better even again, if they were Class-D on the bottom still, but a nice Class-A or A/B linear on the mids and tops or even the Technics SE-R1 then it won’t be hungry for current "if" the speakers are very demanding with low impedances.

The best I’ve heard Class-D was with BelCanto Ref 600m mono blocks, but into a very easy load 2way speaker with Raven 4ohm benign ribbon tweeter, so much did I like it I bought the same Hypex NC500 modules and use the direct with no buffers and in my second easy loaded system, as you have also.
But they don’t stand a chance in my main ESL based system up against this amp, which BTW has much less wattage!!! .
https://ibb.co/qn6Wnms
https://ibb.co/Qncvkkf

Cheers George

Is that the same NC500 you bypassed the buffer clearly violating the recommendations of the app note that the amplifier stage be driven by a low impedance source to maintain performance?

2.5.1 Audio input


The INH/INC inputs form a differential pair. Note that the input impedance is fairly low meaning that
minimalist discrete circuits or valve input stages won’t work. All op amps commonly used in audio can handle
them though. See section 9 for suggested circuits and connections.


Do not drive the input with fully floating sources, be it electrically floating ones like line driver IC’s intended for driving XLR outputs or transformers. Using a floating source will always result in a common mode
component that will exceed the common mode input range and will manifest itself as gross distortion.

Make sure to set the outputs of your distortion analyser to grounded, not floating.

There is also capacitance in that input which means that a high impedance input will cause phase shift and a non flat frequency response.

Admin, Is there a way for me to ignore a member? I am so tired of trying to read a thread without georgehifi crapping all over it. Thank you

Is that the same NC500 you bypassed the buffer clearly violating the recommendations of the app note that the amplifier stage be driven by a low impedance source to maintain performance?

You buy them without buffers get a life!!
Just yet another furphy of yours, that you can’t remember to see the forest for the trees??
Yes as I told you once before (is your memory shot) because my MSB dac has twice the output voltage needed from it’s very low output 10ohm impedance balance direct coupled outputs to drive the NC500 balanced input direct, so NO!! buffer board is needed!!

Woosh right over your head ....

Over your head that's for sure.

Congratulations George you figured out how to make those Ncore modules sound like bad 1980's tube amps. 

Adding to the list of things george does not understand we must now add this:

While when we hear/transmit audio, 20KHz is enough, that is different from a circuit point that is within a feedback loop. For that point, MHz of bandwidth, if not 10's of MHz may be needed.


Oh well, live and not learn.

Congratulations George you figured out how to make those Ncore modules sound like bad 1980’s tube amps.

Yeah right your dreaming , they have nailed the Belcanto Ref 600m’s in an A/B at our audio society meeting , using the same MSB discrete dac as the source, the extra buffer is not needed, and it sounds much better without it, if the source is up to it’s input stage 2k loading and low 13db gain and my dac is, you guys have a lot to learn.

It’s almost like your shilling here for someone here??

I don’t know George some of the best sound quality I’ve heard came from Class D amps in active speakers. Effortless from top to bottom.

Bet you just love the sterilised, harmonically stripped sound of the $15k Kii THREE active speakers


Cheers George

I probably would like the Kii 3, I like the Dutch and Dutch, Buchardt, Genelec, Adam. I also like Revel and Kef passives. This list isn't all inclusive. 

George you might like the Adam S3V, it has newest ICE amps switching at 1Mhz on the woofer and Mid driver and their own AB amp matched to the tweeter.

@geared4me
+1

newest ICE amps switching at 1Mhz

If you can believe it (please put up a link), that’s a step in the right direction, hope the output switching frequency filtering went up accordingly, like the SE-R1 did, to minimize the phase shift down in the audio band, with resorting to throwing more (music destroying) global feedback at it.

it's Ralph that got hostile calling rubbish on me first

This is not out of hostility. Just calling out obvious misinformation. I see though that you did not refute my comment about phase shift. You might not like the UcD module, but it does not have phase shift. You'll find that the Purify and Hypex don't either, and for the same reason. I've heard the UcD sound quite good; clearly its a matter of execution.


Regarding feedback, you either don't run any or you run really a lot. Its sort of like a bell curve with 0dB on one end and 35dB at the other. The worst place to be is 15-20dB as that's in the middle of the curve. Of course I'm oversimplifying here but to really dive into it is very hard to do on this site since it does not support a lot of mathematical symbols. 

So you calling Rubbish! instead of calmly trying to explain yourself, is not hostile.
Stop your shilling and go back to slowly dying tubes!

Just one word for you and the amount of global feedback you have to use to artificially correct the phase shift down into the audio band introduced by the output switching noise filter, i.e. RUBBISH!!!

Class D is Class D....  Well, in Stereophile and TAS context, Class D.     

And just because an amp uses tubes, doesn't make it good.  And just because an am is pure solid state doesn't make it good.   

Tell me georgehifi, why does Technics have to apply digital filters to correct for phase-shift in their magical Class-D amplifier? Huh?! Huh?!!!

to minimize the phase shift down in the audio band, with resorting to throwing more (music destroying) global feedback at it.

Some people wear their technical ignorance on their sleeve.

And just because an amp uses tubes, doesn’t make it good. And just because an am is pure solid state doesn’t make it good.

To me the purest form of amplification "so far" to date with least colourations, lowest distortions, unrestricted dynamics, unrestricted current ability even into very low impedances, and for hard to drive speakers
Is high biased Class-A push pull direct coupled solid state amplifier, using complimentary bi-polar output devices with appropriate power supply/s and input/driver stage.
Guess what some of them are? Gryphon, Classic/Krells, Dan/Agostino, some Mark Levinsons etc etc etc.

Unfortunately, these are heavy, costly, and expensive to run.

Many say Class-D is there, I say no not yet, unlike the few here will like to have you believe.
And many others say also myself there are problems with it in the upper mids/highs.
Also it definitely can’t compete with the above into hard low impedance loads of many of speakers, no matter how many watts they have.

Cheers George

That's a lot of amplifiers with a lot of feedback there @georgehifi, just like Soulution.

Seems you are talking out both sides of your mouth and trying to eat someone else's cake at the same time.

Does it ever occur to you that there is absolutely no consistency in what you posts?

I have to say georgehifi according to you the only amps anyone should EVER own are Gryphon, “big” Krells, or D’Augostino, maybe a JC1 pair. It’s the same discussion, the same argument, the same bla, bla, bla. Sure you are a fan, those are some great designs, but get off it. They aren’t the end all be all, there are many, many excellent amps out there, a lot of which will drive just about anything. Given the lower sensitivity of speaker designs overall these days, premium designers do pretty well to design amps that do very well. Lots of opinion, not much substance here.

I have to say georgehifi according to you the only amps anyone should EVER own are Gryphon, “big” Krells, or D’Augostino, maybe a JC1 pair.

Lot more big BJT's than just those sunshine

At least your reading about some of them 😉
Must have something that tweaks your fancy 😘

Cheers George

Georgehifi whines about feedback in ClassD while idolizing solid state amps with tons of feedback.

Georgehifi idolizes Technics while ignoring they need to use DSP and variable delay to compensate for phase shift in their output filter.

Ignores circuit design requirements then faults performance.

Just dogmatic rambling at this point. The hole is dug too deep to be willing to admit error.

come on guys, what do you expect, gFi still can manage knowing when you use 'your' and you're Sigh!

So you calling Rubbish! instead of calmly trying to explain yourself, is not hostile.

Correct.

Its simply factual; I have in fact often calmly explained myself. I've often received complements for my patience in dealing with your insults and mis-information, but since I've never met you, its hard to take any of the slings and arrows personally so I've no reason to be angry. I do feel a need to correct misinformation where it occurs, as a rising tide raises all boats.


Regarding feedback. George, do you realize that all the solid state amps of traditional design you've pointed to employ feedback? How do you explain that they are alright and a class D isn't? In common vernacular this is known as 'talking out of both sides of your mouth'. In legal terms its known as 'dirty hands'. 'Dirty Hands' is the legal idea that one cannot reserve for themselves a right that they do not also confer to others.


At this point all the objections you've raised have been debunked, including the one about me being in 'product protection mode'. I think that you do not understand my motivations: right after high school, the very next day, I was employed by Allied Radio Shack as a service technician in their 5-state service facility. I enjoyed working there for years and used that income to put myself thru engineering school at the University of Minnesota MIT. In the late 1970s I started Atma-Sphere. As you know that involved tubes for a very long time, but I missed the troubleshooting I performed in the service industry. So I'm active on this and other sites, often answering questions that have nothing to do with my business. IOW I do it because I enjoy it.


Now I can see that this is hard for some people to understand. But that's how it is. I do this because I enjoy it. Because of my experience as both technician and engineer (which can sometimes be at odds, technicians often find out about engineering errors before the designer does), I do feel a certain compulsion to correct misinformation. For reasons unknown to me (as I've no idea of your motivations) this means that you and I cross swords quite often. I see that as unfortunate. But from an ethical point of view I'm a bit between a rock and hard place when it comes to mis-information; if I sit back and say nothing, people will often flush perfectly good money down the loo. Its a bit like what happens when tyrannical forces come into power:

First they came for the socialists, and I did not speak out—
     Because I was not a socialist.

Then they came for the trade unionists, and I did not speak out—
     Because I was not a trade unionist.

Then they came for the Jews, and I did not speak out—
     Because I was not a Jew.

Then they came for me—and there was no one left to speak for me.

Of course this is about education rather than power. FWIW though, willfully ignorant is almost indistinguishable from just plain stupid.

Georgehifi idolizes Technics

This answer is for others that are interested.
Yes I sure do admire them in Class-D circles for advancing/sorting out (in the SE-R1) one of Class-D’s main problems, switching noise filtering which creates up to 70-degrees phase shift down into the audio frequencies https://ibb.co/MS3xC6M. Without like some do resorting to a band-aid fix of throwing heaps of "musicality destroying global negative feedback at the problem", pity they don’t want to, or maybe just don’t have the design skill to be able to what Technics did, and put it in the too hard bin??.
The other problem is current delivery into very low impedance speakers, like the classic linear high end amps can, that could take some more time, but they can drive the speakers that aren’t such a savage/nasty load like Wilson Alexia etc, so it’s not an overhaul big problem.

Cheers George