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!
erik_squires

erik,

Do you use class d amps in a professional setting? I've read many of your threads, but if you mentioned your profession, I missed it. 

Hy Roxy,

I never did. My experience in the pro world was in motion picture auditoriums. At the time my employer bought Hafler amplifier modules, attached their own supplies, and their own surround processing. We probably kept Hafler in business a lot longer than they would have been otherwise. I understand they have come back though.

My day job is esoteric related to IT.

My current set-up uses custom loudspeakers driven by ICEPower 250ASP modules. I did a lot of listening and comparing them to Parasound Halo A23 amplifiers, which while small, are fabulous performers. I rate the two as equivalent in sound quality.

Best,

E
I should say that in the mid-80’s I did get to listen to early Class D amplifier from one of our vendors. It was not then up to snuff, especially not with metal dome compression drivers. :)

Best,

E
  I am on my second amp from the digital amp company.  They don't get much fanfare here on audiogon but the cherry plus amp is awesome.  Very clear and just a tad bit warm and laid back, plus it is very powerful.  Very happy with mine
I'm running one of the original IcePower-based seven channel amps from D-Sonic.  They run two Bowers & Wilkins Nautilus 800s each driven with two 1000ASP modules (biamped) and a pair of Nautilus 803's plus a center.

The amp absolutely dominates the 800s in this configuration and sound better than with any other amplification that I've heard them through.  Of course I've not heard them through $45,000 monos :)

Greg

Greg,

Good to hear. TBH I've only heard B&W speakers with Krell amps, and that combination never made me reach for my wallet.

Interesting you find the ICEPower modules working so well for you. :)

Best,


E

erik,

Thanks for the context. They must be pretty good if they stand up to the Halo amp. I know that a lot of people like the Parasounds. I have no experience with them. I s there anything you don't like about your class D?

Purchased a Rogue Sphinx from Audio Connection a few monthes back to use with my Green Mountain Europa's. Very happy with the sound

I use Class D Audio amps I built from kits. My old Adcom 5 channel bit the dust, and I needed a low cost replacement. I made a three channel amp using two modules, sharing a common power supply. One module is in stereo mode for the surround speakers. The other is bridged to mono, for 500 Watts to the center.

I like this arrangement so much, I built another amp, using two modules bridged to mono, for 500 Wpc for my main speakers. Sounds ridiculously good, especially for the cost. I use this amp for 90% of my listening, an SET 300B for the remainder. They both sound good in my situation, though the modules that are bridged tend to be a bit noisy. They sound so good, I really don't mind.

Regards,
Dan
I always liked your handle, islandmandan.  Maybe the noise you are hearing is the tropical breeze blowing though the palm trees.  Please don't spoil it for me if you are on Long or Staten Island.
George
Happy to see a thread "celebrating" this technology.  I have a Taranis Class D power amp from Merrill Audio.   Apart from the sheer power this thing supplies, I'm very impressed with the quality of bass from Totem Forests when driven by it. I think outstanding bass quality might well be a hallmark of Class D design.  The Totems' bass is impressive to begin with - especially considering their driver size, but the Taranis takes them to another level.  Bass is deeper and fuller than with either the solid state integrated I was using (Hegel H-200) or my EL-34/78WPC tube mono blocks.  The Taranis makes using a subwoofer with the Forests truly unnecessary for most (most) recorded material.  I also like the fact Merrill has produced a balanced design.  Having recently brought a Schiit Freya pre-amp into the system, I can now run balanced outputs from CDP & DAC into the Freya and from Freya into the Taranis.  Balanced, to my ear, is associated with a less fatiguing and cleaner sound.  The Taranis certainly allows long listening sessions; I don't experience listener fatigue using it.  Add to that cool running and no reliability issues, so far.  I did attempt a review of it here on A'gon. shortly after buying it.  Thanks very much to Audiogon member D. Patterson for getting me started thinking about Class D (he's been something of an audio mentor - intentionally or not!).  Thanks also to Guidocorona for pointing me towards the Taranis and Merrill Audio.  
I have a Class D Ampeg bass amp. It's tiny for 350 watts. Thought I'd toss that one in there, and I'm hoping it counts.
the nads look interesting
Gents,
I had a pal construct a Class D amp in a nice wood cabinet that set me back the princely sum for $125.  It won a blind comparison against a pricey Class A ss amp at a gathering of the Bay Area Audio Society.  I initially felt the sound of the amp was rather dry sounding compared to my tube amps, but upon further listening, I conclude that it has a very neutral sonic signature.  However, this 125 wpc amp, paired with a Don Sachs 6SN7-based tube preamp, is a wonderful combination.  It drives my Dali Zensor 3 speakers with ease with great detail and extension.

I believe Class D amps are clearly the wave of the future.  They run so cool and efficiently and the new wave of designs I suspect will be able to mimic attributes of the sound of tube gear that so many of us like.  
Hi @roxy54

You know, I probably heard the same Class A amps @whitestix heard in the Bay Area and I have to concur. I re-iterate, blindfolded and level matched I don’t think I could tell them apart from the Parasound A23’s. Both are excellent, modern sounding amps via my reference speakers.

Negatives?
The ICEPower 250 ASP modules are in no way euphonic. They lack the utter calmness and dark backgrounds of the very best Ayre or Arcam systems. They lack the juiciness if not excessive boldness of the best big Conrad Johnson tube amps.

Despite all of this, they are very very engaging and when the music and sources are right just as compelling to listen to as the best amplifiers I have heard.

Unlike the worst SS amps, they also don’t sound thin, compressed, underpowered or grainy at all. I just listened to Trombone Shorty’s latest tracks via Jazz FM 91 and man, freaking awesome playback. Absolutely nothing was missing nor called attention to itself in terms of the amplifier.

Best,


E
Hi randy-11,

If you mean the multi-channel amps with Hypex/nCore modules, YES THEY DO! 

I would just be sure to listen first. I have heard a couple of modern NAD gear and I didn't like it. This is a brand I really encourage you to listen / try out before committing.

Best,


E
Erik,
Great informative post, with accurate descriptions of the objective differences of the sound of Class D vs. other fine amps.   You nailed it.  Class D amps do not presently have the euphonic sound of the best Class A solid state or tube amps, but I think they are exceeding accurate, so one must pick their poison, so to speak.  I dig "green" gear that needs minute amounts of electricity to make my speakers sing and doesn't heat up my listening room in the blistering hot CA summers which was always the curse of my many tube amps, running a half dozen KT88's hard.  To my ears, a tube preamp and solid state amp, including Class D amps, is a match made in audio heaven.  Cheers.     

Thank you Eric, nice to see an Audiogon watering hole for fans of good class D amplification. Over the years, I have had a variety of very fine amps.... Among class D designs I enjoyed for several years the Rowland 312 stereo based on ICEpower ASP1000, and the Bel Canto REF1000 MK.2 -- also based on ASP1000. I agree with Ghosthouse that Merrill makes wonderful amps based on NCore NC1200 and NC500... Worth not only listening, but also owning. Read my super-favorable review of Merrill's Veritas monos at on Positive Feedback No.68:


http://positive-feedback.com/Issue68/merrill_audio.htm


 My reference amplifier is the Rowland M925 mono, also based on NCore NC1200 modules, amongst its many component parts... It is an absolutely enchanting amp, which I have discussed elsewhere on this forum:


https://forum.audiogon.com/discussions/experiencing-rowland-m925-4-chassis-reference-amps      


Yep, 4 years have elapsed since M925 has arrived at my doorsteps, and I am still in love with it.


Here is where you can find information on M925 design and architecture:


http://jeffrowlandgroup.com/kb/categories.php?categoryid=212


Saluti, Guido





I have had Nuforce Reference 9 V2, the V3Se and Now Nuforce/Nuprime Reference 20 monos. They have bested in my opinion all Class A and A/B designs that I have heard with high end Pass Labs coming closest to reflecting the beauty of music. Also Nuforce best of the 5 Class D amps that I have heard which were all great in the bass but not as liquid and natural in mids and highs. Plus I do love the size, weight (which allows me to easily take them to other's homes and compare to their amps or ship for mods) and continuous on because of low power use. Have found class D to be sensitive to power cords, electronic and mechanical isolation, long break in and warm up. I agree with many that they are especially nice paired with a tubed preamp, in my case Ayon.
Guys,

You know I was just thinking about something. If the current crop of digital amps had appeared in the 1980's I think they would have pretty much ended the solid state / linear amplifier market.

The SS amps at the time were, by and large, full of compromises, and consumers were hungry for all things digital.

This did not happen however, the digital amps of the 1990's weren't nearly as good as they are now, and solid state amplifiers also continued to advance to where they are today.

Still fun to think about. :)

Best,


E
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
Interesting, @georgehifi re garding transistor manufacturing.

In 1976 Dr. Leach introduced his paper, Build a low TIM amplifier which transformed, if not codified, what would be linear amplifier design for the next 3 decades.

Also 80's were flirting with MOSFETs that promised to behave more like tubes. High input impedance, more linearity, blah blah blah. and some worked out, some worked out some of the time. :) I think James Bonjiorno (spelling?) and Sumo in general were among the early names that were associated with this. But we digress.

Well, there is always some technology around the corner, some new way of winding a transformer that promises never-before heard of improvements. 99% of the time, these changes don't pass the test of time, and are forgotten by their own inventors, or fail to make enough of an impression to be adopted by others. There are also a number of amplifiers who end up being door stops once the manufacturer of the super-special magic transistor stops making them.  << sigh >>

Remember Halcro with their super low distortion, universal accolades? It went under, came back... and now who knows.

I guess my point is, we can always look forward to new things, but we can't let that stop us from enjoying what we can get now. :)

Best,

E

@georgehifi

Your link just reminded me of something. One thing I really like the Japanese manufacturers for is power meters. Yamaha (professional), Hitachi, Technics, early Onkyo. Gorgeous analog meters in the 1980’s. I’m very happy to see some of this coming back, even if it is in gear I can’t afford. :)
Interesting info on the Technics SE-R1 amplifier from @georgehifi

One thing I thought was particularly interesting (and a lot of work) was the Load Adaptive Phase Calibration.

All digital amps must go through a low pass filter at the output. This may cause some variability in the high end response based on many things. Modern digital amps with easy to drive speakers should not suffer this very much (especially if they use feedback at the output, shhhhh!)

The SE-R1 takes on the approach of measuring and directly compensating for this at the input instead of using feedback.

This is a LOT of number crunching to put into an amp. Cool ideas for sure.
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

@georgehifi

Very interesting! :)

Hexfets..... I seem to remember ... was it Toshiba that invested heavily in them for a while?

Best,

E
Thanks for the thread, Erik!

I'll be following closely and trying to keep quiet until my Primare breaks in a bit.
I really really like the idea of putting a tube pre in front of these amps, especially with the high-input impedance varieties I've read about.

I often suggested tube pre/ss amp before, so this idea appeals to me a great deal.

If I wasn't 50/50 HT and music I would consider it more seriously for myself.

Best,

E
i love my tube preamp with my class D monoblocks.  i haven't heard loads of gear, but the tube pre seems to add that bit of warmth and a sense of the sound being tangible that may be missing with straight class D amps.  though i really should try them with a passive pre, just to hear their true nature..

i'm running ghent audio monoblocks, which apparently use 2 ICEpower ASP modules in each amp putting out 500w/channel into my 4ohm floorstanders.  the preamp is a modest dared mc7-p.  

the build quality of the amps is very solid.  excellent cmc binding posts and rca jacks, solid housing.. and the sound!  my speakers have side firing 12" woofers and these amps control those drivers like it's their job.  because it is.  but they do it well and with authority.  the separation of sounds is equally incredible and i'm constantly amazed at the raw power my ghents deliver along with delicate detail effortlessly floating on top.

good stuff!
Todd,

Remind me please your preamp?

I was a big fan of the old-school CJ preamps. I had thought about getting a modern Cary instead, but man, the press they get about service quality.

I've not listened to CJ pre's since they came out with the ART line.

Best,

E

@toddverron


There are not too many speakers with large side-firing woofers... Might you be using VIenna Acoustics Mahler speakers? I hav owned those, and they are amazing with class D amps.


Guido

 

Been on the class d amp seen since Wyred 4 sound early stereo ones, got interested so I built a ClassD Audio dual mono bridged one with the SDS 254 boards and was hooked best sound for the money bar none. Went to D Sonic monos and now have The Nords like the OP (they use the NC500 boards). Can confirm that a passive is a good match I had the Wyred 4 Sound Pre and that sounded great should of kept it. Then got a Audio Research LS17SE and that sounded good but wanted a little more warmth so now I have the PS Audio BHK Pre another great pre with the sound I have been working for, also you can turn off the tube section when not listening
You know, one digital-ish amp technology we haven't talked about is Yamaha's EEEngine. It is a hybrid approach, which reminds me of Carver's Magnetic Field and NAD's voltage switching technology.

It uses a digital amplifier to provide the + and - voltage rails, but a linear amplifier at the output.

http://www.yamahaproaudio.com/global/en/training_support/selftraining/technology/eeengine.jsp

I've never knowingly heard them, but if anyone is using one let me know. :)

Best,

E
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
Guido, my speakers are barely even on the audiophile radar. I have a pair of rbh sound 1266 se/r. Up top there’s a mtm arrangement with a scanspeak tweeter and proprietary mids. They sound lovely with big, tight bass. I’ve always been a fan of narrow, tall floor standers with side firing woofers. Before these I had a pair of JBL L7s.

Erik, my preamp is a dared mc7-p. I’m considering trying the new schiit pre, but then I’d need a phono pre and I don’t know if I even want to open that door.
Todd,

Have you heard the Mytek DAC/preamp combo? They're pretty good if you have liminted number of sources. :)
Eric, reading your post about the old amps with meters got me thinking about buying a doa for the chassis and gutting it to install a class d module. Could be a fun project. 
@chrshanl37

I think that's an excellent idea. :) Some modules provide supplementary 12V power, so with a little tinkering you may indeed be able to revive them without very much work! :)

You may also want to think about replacing any lights with modern LED equivalents. May help with the power supply situation.

Best,


E
I had thought about the lights and agree that is a good way to go. I had a class d sds 470c and enjoyed it as much or better than any amps I've owned (especially when paired with both a Modwright tube pre and a Tad 150) so I may start there.
I recently picked up a Peachtree Nova 150 that uses the latest ICE power modules. I'm loving the sound which is in part to the D amp technology. This unit is a Swiss Army knife integrated that I'm really enjoying for several reasons. 
@dougsat 

Congrats. The Peachtree was on my shortlist. It is a great amp. I just received a NuPrime IDA-16. It's only been a few hours and I'm really liking what I'm hearing. Let the break-in begin. I'm sure with a DAC and an amp inside I'm in for a ride.

How many hours do you have in your Peachtree?

Cheers,

Scott
As several have noted the "Class D Audio" brand amps are superb.  I have the SDS-470C and think it may sound as good as my PHalo JC-1's and Atma MA-60's.  Amazing... actually.  And... I think I'm going to try a couple of his 4 channel amps to drive my Linkwitz Orion's.  

Not only do they sound great... but... the price is right - a true bargain for quality sound.

I buy them assembled, but you can buy the kits, if you're into that - as others have noted.
I've had the Peachtree 150 for about 3 to 4 months. I was breaking in a new pair of Dynaudio Emit M20 speakers at the same time. 
Both have broken in nicely together and seem to be a good fit. When I settle in to listen to some tunes I'm hearing a good blend of detail, warmth and punch. 

@dougsat 

Very cool. Peachtree and Dynaudio, well played. You have some great gear. Enjoy!

Cheers,

Scott
It's really interesting to me what great participation one gets when you start the thread off right. :) Thanks to everyone for chiming in.

Best,

E
As I had mentioned on another thread, I had for some time been considering purchase of the Bel Canto Ref 600M Class D mono blocks. After a second long listening session yesterday, I bought them, and just finished installing them a few hours ago.

The dealer ran them for several days for a little break in, but I recognize they will need a lot more to sound their best.

That said, they already sound great--lots of clarity and detail (with incredibly low noise floor), but more natural and musical than I previously heard from my Tripath Class D.

I will be doing a lot more break in over the next while, but for me these are already really dandy!
My Hypex NCore NC400 Bridged Mono block class D power amplifiers resulted in my sound quality being more natural, clearer, having more bass, a lack of noise, excellent dynamics and details. I am running my Bricasti M1 DAC direct into the Hypex NCore power amplifers and am not using a pr-amplfier.

It is my opinion that another layer of sound is presented WITHOUT the pre-amplifier in the system (I also know some people disagree on this topic so we will agree to disagree). The Hypex NCore NC400 bridged mono block class D power amplifier is highly recommended.

Other excellent Class D amplifiers are (random order):

1) The Acoustic Imagery Atsah 1200 mono block Amplifier uses the NC1200 module and the NC1200 power supply. List price is $9,995 and the delivery time is 12 weeks (yes, I confirmed this and each unit is custom built). Acoustic Imagery reports "The ATSAH NC1200 is the NC 1200 OEM module with the SMPS 1200A700 power supply. We do not modify it in any way, it is simply as Bruno designed it. To be honest, there is no comparison, the NC1200 module is a far better amp in all departments".

2) The Bel Canto REF600 amplifier uses a the single NCore NC500 per side and is not much of an improvement over the bridged NC400 mono blocks (my opinion). Bel Canto reports "The critical issue is more how one implements any power supply. We have done extensive collaborative research with Hypex and have developed product that is as unique as the Hypex is to others in terms of their context but that ours actually sound better and are labeled Bel Canto power supplies in most cases. The Ref600M's are a recent introduction of what we have learned with the whole Black Series project”. The Bel Canto Ref600 amplifier has been in production for almost a year.   The build quality of the Ref600 looks terrific (IMHO).

3) The Merrill Veritas class D amplifier look very interesting and costs $12,000. In addition, each box is 17”wide and the two boxes are too large for my single shelf space. The Veritas amplifier is a fully Balanced design. The Veritas mono-blocks have been in production since 2011. There is an upgrade planned as well as a price increase for the new mono-blocks. It will be about 1+ year before that is released (estimated).  The reviews for the Veritas have been excellent.

4) The Mola-Mola Kaluga power amplifier also use the NC1200 module and NC1200 power supply. I was told the "Mola-Mola Kaluga amplifier is Bruno’s very best efforts and he kept a few secrets behind for himself. Every single thing has been looked at in the Kaluga’s and he is even using Kubala Sosna cabling internally. Special damping, a discrete switching power supply (which you can’t buy) and a proprietary input stage". I am sure the Kuluga sounds terrific but it is very expensive.

5)  The Jeff Rowland 525 mono block class D amplifier uses the Pascal module.  

I am sure there are other excellent Class D amplifiers on the market that I have not looked at (or discovered).  Please add additional Class D amplifiers to this list.  Thanks. 

I am considering replacing my Hypex NCore NC400 Bridged Mono Block class D Power Amplifiers with another Class D amplifier that uses the NC1200 module and NC1200 power supply. Research to date is my bridged Hypex NCore NC400 mono block amplifier (2 NC400 amps per side) sounds excellent and an upgrade to the NC1200 is expensive and maybe might only offer slightly improved sound (this is to be confirmed, some people feel the NC1200 module is the best sound).  My research continues and I am in no hurry.
Northernfox,

      Congrats on your new Bel Canto Ref600M class D mono-blocks!

      From the reviews I've been reading, good amp designs based on the newer Hypex NCore 500 module are very close to the good amp designs based on the NCore 1200 module for about half the price.  I haven't heard them yet but will make a point of auditioning them asap.  
      You're obviously already very pleased likely without complete break-in, which means they're only going to sound similar or even better going forward.

  Enjoy,
    Tim

     Class D's current state is very good and its future is looking even better.  I recently read an article about new faster switching MOSFET transistors.  

      This transistor technology is called Gallium Nitride (GaN) and is poised to uproot the high-end audio world. In fact, GaN-based Class D is much more power-efficient than traditional, MOSFET-based Class D and offers orders of magnitude better performance. Performance that to many listeners, even surpasses the quality of Class A.   At any given product price point, these new Class D solutions can meet, or surpass the quality of today's linear amplifier solutions. As an example, the eGaN FET-based Class D amplifiers can easily achieve a mid-band THD performance of 0.005%, where a comparable linear amplifier Class would achieve around 0.05%. Here's a link:

. http://audiophilereview.com/cd-dac-digital/why-well-soon-be-living-in-a-class-d-world.html

     Just to make sure everyone was aware of this important new class D development, I also posted this link on the "class D=Trash?" thread.

Later,
 Tim
Great info @noble100

I don't usually agree with the theme that "Class D is about to get as good as Class A" as I think it has been there for a while.

Linear amplifier distortion can be reduced by feedback, something digital amps may use in buckets.

Where I think the new Technics amps using this transistor will be most interesting is in amp/speaker matching, as the average Class D module is not the current delivering brute that say a giant Boulder or Krell is across the frequency spectrum. Technics has an interesting way of handling it. I handle it by making easy to drive speakers. :)


Best,

E