Class D amps that are superior to all or most?


Recently, I have heard about some Class D amps that may be close to the best there is regardless of class. Certainly, this technology has been in development for decades. The main issue has always been the switching power supply. In this regard, I have taken notice of AGD. They have created a whole new power supply that “switches” at a frequency 100 times the normal silicon based MOSFET. The designer uses a gallium nitride based PS. Interesting, it is enclosed in the KT88 glass envelope that sits on top of his amps. I am aware of two more pricey amps that seem to be also at the top- the Solution and the Merrill. There must be others that compete for the title. After my thread, “Is there a SS amp that can satisfy a SET guy?”, I am still on the quest.
Don’t want to spend $50K!
mglik
Vera Audio P400/1000 or their purifi model. Beats or is equal to my Gryphon Diablo. Dependning on...

But as always you need digital calibration of your system to be sure.


My Benchmark AHB2 does a pretty good job but I don’t get drawn into lengthy listening sessions with it as much as I do with my SET amp. Benchmark seem to be one of the companies leading Class D technology in the US so check them out if you are considering Class D. This amp can either be used in stereo mode or you can use two in mono mode if more power is required 
The PS AUdio Stellar M1200 monoblocks are amazing! 1200 watts into 4 Ohms.They drive my Magnepan 1.7i's beautifully.
D tech and it's hybrids are still in their infancy in terms of development with regards to 'high end' audio.  Since the latter social group is basically small population-wise, the equipment for now will demand a stratospherically lofty price for those adopting it.

There will be a time when a developed D amp will eat A & A/B's lunch, and make reservations for dinner....

...'imho'....
A/AB IS THE WAY TO BE.
If you are talking about solid state, the problem you are up against is linearity of the circuit. Class A is used to help improve linearity, but a very real problem faced by audio designers these days is the semiconductor industry would rather not make linear devices.


So as a result unless one is very careful, feedback has to be implemented in the design to cause linearity. The problem here is twofold: first you have to be careful to not introduce oscillation by exceeding the phase margin of the amplifier circuit. The second problem is a lot trickier- you need to have about 35dB or more of feedback in order to prevent the feedback itself from adding distortion of its own (which tends to be highly audible as its mostly higher ordered harmonics).

To that end you need a lot of something called Gain Bandwidth Product, which to feedback is a lot like gas to a car: When you run out of it there's no more feedback. Put another way, the feedback is gobbling up gain in the amp and this gain has to be sufficient to allow the feedback to do the same job at all frequencies. I'm really oversimplifying this issue but that is because its a very tricky engineering concept.


For decades GBP has been sufficient in the bass region, which is why solid state has a good reputation in that regard. But its not been so good in the mids and highs- most amps made in the last 60 years have less and less feedback as frequency goes up, causing brightness and harshness as that is how the distortion is perceived. Incidentally, this is why distortion is usually measured at 100Hz. If distortion were measured also at 1KHz and 10KHz we'd have a far more accurate picture.


Class D offers a rather elegant way around this by allowing you to impose so much feedback that the amp's phase margin is exceeded, and so it goes into oscillation. The oscillation is then used as the switching frequency, thus killing two birds with one stone. Now you can have in excess of 35dB of feedback so the feedback can clean up after itself. In effect a class D amp is more likely than not to have lower distortion than traditional solid state amps (class A or AB). Its also impervious to weird speaker loads causing it to oscillate because its already oscillating!


Its very natural for a class D amp to make significant lower ordered harmonics due to how dead time and the encoding system make distortion. The result can be that those lower orders can mask any higher orders, resulting in an amplifier that sounds very much like a tube amp but with dramatically lower distortion and therefore more neutral. In addition its output impedance can be far lower than traditional A or AB amplifiers, allowing it to be a better voltage source.

So put another way A or AB isn't always the way to be.
"If that is the case then the designer didn't pay attention to the distortion signature. It can be quite low in a class D amp, but if the higher orders are not masked by the lower ordered harmonics it won't sound right."

Bingo!

Some class D on first impression can make you say wow but once you start to listen you began to realize that something is not quite right.

I was talking to a friend on the east coast he has heard the Mola Mola integrated, top of the line Merrill and AGD amps and according to him he ranks the Mola Mola and AGD amps as not only the best of class D but some of the best amps he has heard period.

I have not heard the Mola Mola amps but i do own the AGD Audion amps and i find them pretty special.
In the under 10K category, clearly the current winners are the AGD Audion monoblocks.

Clearly? How’s that? How many have these or have even heard them or compared them to all the others?



I will give them credit for looking cool, what with the SS components plugged in and looking like a tube and all.



In the under 10K category, clearly the current winners are the AGD Audion monoblocks.

What's coming this year in GaN engineering?  Looking forward to the eventual release of the LSA Voyager (aka "Godot") amp, and to atmasphere's class D circlotron monoblocks.

The other GaN amps currently out that nobody's mentioned are the Orchard Starkrimsons.
there is something to the notion that many class d stages are a little too clean
If that is the case then the designer didn't pay attention to the distortion signature. It can be quite low in a class D amp, but if the higher orders are not masked by the lower ordered harmonics it won't sound right.
ej sarmento at wyred 4 sound was an early mover in employing ice modules in his st series amp, with his nice discrete input stage driving the modules... his amps are as described below... laid back (even a little too smooth) with excellent bass

except for the devialet units whose sound i love (lively, saturated, plenty of body yet transparent), the failing of the others i have heard is on proper decay of notes and ’air’ in sound staging

there is something to the notion that many class d stages are a little too clean ... once again, sympathetic distortions can help our ears hear sounds we perceive as more natural, and in the proper space of a performance venue
@jbhiller I don't know off the top of my head, but the S-500 I own sells for about $2500. The web site has prices.   Arionaudio.com
I have not done a survey, but if you like laid back with plenty of bass, I can recommend ICEpower amps a great deal.
@bondmanp , the HS-500 Arion has a vacuum tube stage linked to the Class D.  I love it!  Never heard of them making amps.  How much is the cost? 
For the 9,999th time:
  • Class D frequency response is determined by the load
  • A particular amp can sound quite fine with one speaker
  • The same amp can sound quite poor with a different speaker
ALL specific recommendations are worthless.

I enjoyed my time with later Nuforce/Nuprime designs. They sounded much more natural and liquid than the several other Class D that I tried. Worked well with Tubed pre amp. You do have to select Power cord and power conditioner carefully so noise is not reintroduced into rest of system.
In my listening room, I started with a NAD M12 pre amp/NAD M22v2 amp combo and Tannoy DC8TI speakers.  It took me a while to get the gain setting right, but once I did the sound was nice. The bass was great, mid range was good, but, depending on recording, it was sometimes too bright and not as musical as I would have liked. 

I replaced the M12 with a Herron pre amp, Herron phono pre, and Audio Mirror Tubdour SE DAC (very nice DAC!).  That combination took the SQ to another level - everything sounded so much better.  Not being satisfied, I sold the Herron and AM gear and bought a PS Audio BHK pre amp, DirectStream DAC, and Stellar phono pre. There was a clear SQ improvement - everything sounded so much better.  Not being satisfied, I bought a PS Audio BHK 250 amp.  Now I'm satisfied. 

I still have the M22v2 as my backup listening room amp, and plan to use it with a PS Audio Stellar Cell Gain DAC in another system.  The M22v2 sounds really nice in my main system, but it is not a musical or smooth as the BHK 250.  I could live with the M22 if I had too, I'm happy that I don't.
I believe MBLs electronics are Class D.  Huge power and ability to drive anything at 4 ohms. They should be mentioned here.  

I personally have 5 Class Ds at the moment.  Three of the five have tube input stages.  Rogue Hydra, Canor AI 2.10 and AVM A5.2.  I have a Marantz CR510 and an NAD M33.

All five sound incredibly good for the price and are all very musical.  Not fatiguing in the slightest.  The tube input stage on the Rogue, Canor and AVM softens the digital sound and it is very musical.  I have had them all driving Vivids and they sound fabulous.  Stock tubes stink in the Rogue and Canor and do need to be changed.  

the M33 needs room correction on.  With room correction, sounds like a completely different amp.  But so does Onkyo.  Without it can be cold and fatiguing.  
I have a customer with the C298 (same amp as in M33) and he has it paired with a VAC preamp and loves it.  
The one that is most shocking is the $500 Marantz network receiver. It sounds good.  Very natural.  No different than one of the class AB integrated language they sell yet is class D.  No tubes yet great sound.  Mar
I own and enjoy an Arion Audio S-500 class D amp. Very affordable, powerful, and very clean sounding, but not bright.  Dead neutral in my system.  Mike Kalellis of Arion knows how to build a class D amplifier.  If you buy without auditioning an Arion amp, you might miss out or spend too much, IMHO.
@rajugsw said
”Those who have a hate on for Class D Switching Amplifiers, are just ignorant to be quite honest.”

Or just experienced..  Sorry.. I had several class D amps starting with the Tripath, ICE and then Hypex ..  Initially, they sound impressive, clean, clear and precise.. Then as time goes on and you realize they are not really musical, but fatiguing , bitter and analyzing..  Something about them is not organic and I found myself not listening to music as much anymore..
Maybe someday they will get Class D right.. but they work great in subwoofers.
Sorry to be so harsh here.. but I tried a FEW times and did not have any musical success..
A friend came over and lent me his KEF R3's. We were listening via my PS Audio DSSr DAC (Windom), BAT VK50-SE Preamp, and Jolida 3502p Tube Amplifier.

Then he asked to swap in my ICEpower 1000ASP Class D Audio Amplifiers fed from the BAT Preamp and PS Audio DAC. Wow ! Why did I but the Jolida again ? Seriously, I'd been using the ICE Amps as Subwoofer Amps for the last eight months. I had no idea how much the Preamp would improve on the Class Dness of the Amplifiers. I used to own PS Audio M700, and this arrangement sounded just as good of not "better".

No harshness whatsover. All the detail retrieval, Soundstage, Phanton Center, and the Treble/upper Midrange did not hurt the ears at all.

Really did make me thin twice about the Jolida but I'm not getting rid of it. Tubes still outdo there Transistorized Counterparts Class A and Class A/B. Class D Amplifiers when fed a nice input stage can sound Phenomenal !

Those who have a hate on for Class D Switching Amplifiers, are just ignorant to be quite honest.
Crown xls series 1502 and up is a good choice for class d and cost less than 700 usd for the highest model.
@georgehifi — Thanks for sharing the Class D Audio link.  Wasn’t aware of them.  Very interesting.  Looks be damned. 


George, those Class D Audio USA amps look nice, but boy are they butt ugly.


 Yes not the best looking, but what’s inside is what counts, they "could" be as good as $5k ones for just $699

Otherwise if all that’s important is the look, then I call those "Glitz Queens" and they are usually the ones that parade their glitzy stuff on glitzy racks in between the speakers.
Not caring they are totally stuffing up the imagine properties by doing that.

But they don’t care as they are hypnotized by the shimmer of their equipment they are gazing at while trying to listen..

Cheers George
I think Class D can be very good but class AAB done right is more natural  overall.My Coda CSIB integrated amp Beats many excellent separates, in class D not one  great Integrated , Merrill Audio  very good but at $20-  $30 k No thanks too many Class A-AB amps That  are better .I have have heard others ,  which are very respectable ,but still a couple steps behind from my experiences.
Btw,  Class G and Class H are really nice sounding.  Typically they are the first X # of watts in Class A and then switching comes in above that.  I've heard a few and owned one (Creek Evolution 100) and they sound really nice.  
George, those Class D Audio USA amps look nice, but boy are they butt ugly. 
I’ve been really impressed with Nuprime’s amps… although they do not claim them as class D, but as a hybrid. Hypex and Purifi based amps range from ok to breathtaking.

My preference is class A or AB for tweeters and maybe mids with D for lows and subs. 
i have not pursued sampling all purported good class d amps, by a long shot

best i have heard in my system is devialet, which is some sort of hybrid
Underwood HiFi was launching a 200Wpc GAN amp for $3000 under the LSA

And don't throw this new one away yet just because it's very inexpensive.
 A US made and designed Class-D using GaN technology, for just $699!!!!!!!!

https://www.classdaudio.com/mini-gan-5-balanced-power-amplifier.html

https://premium-audio.com/

Cheers George
A solid state amp that can compete with any tube amp is the parasound hca3500 but you need to feed it right and buy the best front end you can with the best cables and conditioner and when you do wow you will be hard pressed to find a better amplifier.
Underwood HiFi was launching a 200Wpc GAN amp for $3000 under the LSA brand that was supposed to bow around now so might be worth checking out.  Also, although I haven’t heard them from the few reviews I read the D-Sonic amps supposedly punch way above their price and offer a trial period.  Just a couple other potential options FWIW.  Let us know whatever you find, and best of luck. 



Class D amps that are superior to all or most?


To most Class-D's
Technics SE-R1 https://www.technics.com/us/products/r1/se-r1.html

Technics SU-R1000 (maybe) https://www.technics.com/us/products/reference-class/integrated-amplifier-su-r1000.html

But they probably still don’t quite reach the sound of the very best solid state high bias linear amps.

Cheers George

I have owned the AGD Audion amps for about a month now. They sound great i was a SET guy and the AGD's bring the best of SET and SS without the past flaws of class D.

AGD offers a trial period, i did this and had all intentions of sending them back but they surprised me at how good they were so i bought them and they continue to get better. Take the trial as i did and find for yourself it`s worth it.
Every Class D I have heard is very good.  By that I mean near flawless. Not all created equal however.  Some might prefer  some tubes up front to embellish things a bit.
Are there 50K amps? Only if you pay for it.. My ears couldn't hear the difference because their to darn greedy. Dog gone ears... Will not let my hands reach for anything over 10K, from my back pocket... Ears are to blame... Bad old ears.

One opinion, one man, the only one that counts MINE...

Regards
NO class D can come close to a great A/AB or great tube amp(set etc.).Ill check again in 10 years maybe. 
Although not Class D, the Chord Ultima Line uses a switching power supply and runs cool.  I think technically they are Class G or H but they are phenomenal sounding amps.  I would certainly put them up against other amps in their price tier and they will be quite competitive.  Given the flagship Ultimas are $69K....