Class D is just Dandy!

Welcome @whitestix  !

I am glad you are finding it informative, I'm learning a lot more about the marketplace, and happy to find so many sharing my appreciation for the latest amps!

Best,

E

Erik,
What a most informative thread you have going here!   Thanks to the fellows above who share their take on the progression of the design of amplifiers.  I won't be parting with my delightful Dennis Had Inspire EL84 SET anytime soon, but this Class D amplification has come of age and will only get better in the future.  

Several of the Class D amps mentioned above are uber-expensive and clearly out of my budget, but likely not for others.   This technology will emerge in more modestly-priced gear in time, such as with the Wyred4Sound gear that can be had for a song.  BTW, a pal sent me a note recently telling me that he had acquired a pair of Nu-Force mono's and they bested his high-end Pass Labs amp by a fair margin.  

I read elsewhere that RF interference can be a problem with these amps, as well as the need for power conditioners and better power cords, so this may be an issue to be aware of.  Cheers, Mark  

Curious if any of you have tried the Pioneer Elite AVRs and taken a serious listen to the D3 Amplifiers.  I am pretty sure Onkyo now owns them all.    I use them for 2-channel, it is musical, fatigue free, harmonically accurate to my ears.   I does lack the warmth and SLAM if my good Sim Audio separates on my main rig for audio.   But I have to say that in many respects it is more accurate in coherent at about 1/20th the price :).    I can listen to it all day long without issue.   Any other receiver I have owned doesn't come close.         It maybe just me, since I dont hear much about AVRs taken seriously for audio.

Hi George,

Feed forward in a linear amplifier is very different. :)

In this case, I’m using it more as an analogy or principle rather than a specific circuit design.

While most amplifiers have feedback at the output stage, the Technics does the correction mathematically at the input, pushing the error compensation from the front instead of the back.

For this reason, I think of this as a feed-forward idea, being the opposite of feed-backwards.

Best,

E

feed-forward loop

Feed forward was used in the old days, and it was resurrected again by Rogue in their M120 and I believe in their M150/180's.

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 

It may not be, but it works totally differently.

In a digital amp the feedback affects the width of the "on" period.

First, I’m not sure that anyone has proven in a linear amplifier why moderate feedback is a bad thing. Second, in class D it is a couple of stages away from the output signal, so whatever arguments you might have made for a linear amp’s feedback I don’t know that they would work at all.

As I understand it, Technics is using more of a feed-forward loop. They analyze the errors with the output stage, and then digitally correct it ahead of time, before the actual power amplifier stage. Talk about a huge amount of processing and signal meddling though. :)

The Technics approach is VERY similar to digital EQ and phase correction if you were to limit the correction to purely electrical, it is identical in theory.

If you go that far, might as well include the acoustic output of the speakers as well and finish the job. :)



Best,

E

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

Using feedback to reduce distortion isn't a free lunch though, or is it? 

Nord One SE  uses the same components as the Nord One UP,  Hypex NCore NC500, twin SMPS1200A700 PSU’s in our beautiful sleek Japanese Mono Block or Stereo Chassis.  SE comes with Nord Class A Discrete Input Buffer board with choice of discrete Op Amps, Sparkos SS3602 or Sonic Imagery 994 +£30 and Sparkos discrete Voltage Regulators. Choice of Dual Mono Stereo or Mono Block chassis
these are what i use in the UK driving my soundlabs they sound amazing prices start around  600gbp up to 1700gbp for the top reference monos which are what i use 
i have heard nothing like them , very detailed , dynamic , powerful but so musical and natural sounding , i have tried half a dozen class D before these , no amp i have heard betters the nord 
they ship all over the world 

Thanks for starting the thread. Two of my three home setups are now Class D, the third being a much-loved Marantz 2230. My listening room is the newest, a Rogue Sphinx driving Magnepan .7s, with a Musical Fidelity V90 DAC, Marantz 5004 CD player and Pro-Ject Debut Carbon with Ortofon 2M Red. I just think it all plays together very nicely. Auditioning the Sphinx I also listened to an NAD C368, but thought it had just a bit more sibilance and an amplified character with solo voice, which I'll assume is the effect of the Sphinx's tube preamp section. I listen to mostly classical, jazz and acoustic. 

My other Class D is -- please don't laugh -- a Teac A-H01 driving Magnepan MMGWs. It's in the living room, and I wanted to keep the music system as small as possible. When I was shopping a few years ago for this setup, the Teac was one of the few small integrated amps that had a good mix of digital and analog inputs and a subwoofer out. It's got ICE amp modules and a Burr-Brown DAC (I didn't need a phono, which it lacks), so I was willing to give it a go for $330. It puts 43 watts into 4 ohms, which isn't supposed to be enough for Maggies, but they sound great. They seem to love being spread far apart - about 15 feet on opposite walls. They don't go very loud, but they don't need to in this location.

Here's the deal: Like I'm sure a lot of people here, I listen to a lot of live music, meaning symphonic or chamber or opera/musical -- unamplified sound, in other words.As far as I'm concerned, if an amp makes a violin sound like a live violin, and a piano sound like a live piano, etc., it's doing it's job - Class A, A/B, D or whatever. That's what both these Class D amps do, and what the Marantz still does as well. I first heard the MMGWs at a friend's home with a very nice, all-tube amp/pre combo with quite a bit more juice than the Teac. But I've never been disappointed in how they sound with my setup.

Cheers.

Bought the latest class D ATI and am loving it. The amp just disappears 

saving?
I've mentioned this on and off for over a year, here and other forums.
Cheers George

" 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."


     Yes georgehifi, you were definitely the 1st to post here and link info on the eGaN FETS that are used in the new Technics amp.  I recently happened upon an article about the eGaN FETS while on Audiophilereview.com and didn't recall your earlier posts about them. 

My mistake and apologies.  I forgot you've been saving up for this $30,000 class D amp.
          Tim    

Todd,

If you like tubes, stay with tubes. :) No matter how good the Mytek is, it won’t be a tube pre. :)

Best,

E

Erik - those mytek DAC/PREs look lovely. I don't need a lot of inputs, but I also listen primarily to vinyl and don't have lots of high res files, so it would seem to me that I'd be paying good money for something that has features I'd hardly use. My other concern is buying a DAC bundled with anything when the tech seems to change rather quickly. Then again, maybe that's less of an issue than I worry it is...

Thoughts? 

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   

I like it, a line of electronics named after great cheeses of the world.

Mmmm...

No. Gorgonzola. 

Does it have Graphene in it?

Are any other manufacturers using eGaN transistors?

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
By Skip Taylor | September 17, 2016 4:27 AM

"A high-definition eGaN FET-based system with higher PWM switching frequency"

Cheers George

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

     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

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

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.

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!

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

@dougsat 

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

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.

@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

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.

@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

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. 

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.

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

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

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

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

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!

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

Thanks for the thread, Erik!

I'll be following closely and trying to keep quiet until my Primare breaks in a bit.