Class D is just Dandy!

Thank you Erik for starting this thread. Since I am a manufacturer and of Class D at that. Therefore, I am obviously biased. So I think my comments isn’t worth much and rightly so I suppose. Anyway, I won’t get into endless debate on the technical mumbo jumbo, rather to say that class D CAN (and this is the key word) sound extraordinary. Then again, the same can be said for tube, conventional class A and class AB design. 

Henry

George,

It seems no matter how factual I am you complain about me being abusive to you.

You have made dozens of posting on this thread, and ignored the request in the OP and myself and others to start an anti-Class D thread if you are so inclined.

You've also made the same arguments dozens of times.

Would you please be a gentleman and go start your own Class D bashing thread?

Thank you,


Erik

HI @noble100 ,
GaN is has been around for awhile. Several manufacturers are using it. It is an interesting material, not only is it fast it is also more energy efficient. I have heard it in Class A and Class A/B products. So you can find amps using this material and they may have no heat sinks or small heat sinks.

Best regards,

heaudio
class D amplifier, with fairly well defined harmonics hence why they can be filtered.

Incorrect, 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

I just finished reading this thread from the start. I have to say that of all the areas of audio, I find the class D debate to be the most diehard and in some ways hardheaded; its almost like politics.

I think, like a lot of things in life, the danger or pitfall comes with the broad generalizations - e.g. all class D is (crap, lacking, great, musical, whatever); or the best class D can already compete with anything (or no chance against good class A at other end of spectrum), and with having intractable positions. But to each their own. I’m not here to change minds, and I don’t have strong opinions on the class in general, just making an observation.

I think it’s much more fruitful to focus on specific models and thoughts on them, rather than trying to paint whole class with a broad brush. I’ll give an example.

Two of my three systems use class D amps, the other class AB. My main system uses class D Audio Research DSI200, and paired with my Spendor D7 and Teac NT505 to my ears sounds absolutely amazing. I don’t foresee changing anything for 10 yrs. My third system uses class D Bluesound Powernode 2, and paired with my Spendor SA1’s to my ears really leaves me wanting, to the point of hopefully I’ll soon be replacing it with similarly priced class AB Marantz pm7000n.

So fwiw I personally love one of my class D’s and can’t wait to replace the other. So I’ll stake out a new position in this thread: some modern class D is really good to my ears and some is really not so good to my ears. It’s okay to admit both : )

Good thread tho, twas a fun read

I'm afraid I haven't had time to go out and listen to a lot since the last show here in ... Long Beach? Newport Beach?

I've also gotten to a poin where I'm very happy with the sound quality at home but not the remotes. :) Seems bad for me to find a dealer to listen to gear I'm not going to buy.

Maybe I should ask manufacturers to send me gear to review instead??

Erik, three years later, and still going strong, excellent thread.  Class D is the bomb, and your thread would seem to amplify that message.  I purchased a D.A.C. older amp for my first try at Class D, A/Bs left something wanting.  My Signature Technology is a very nice tube amp, the cymbals never sounded right.  The DAC4800a was my first thousand dollar amp.  It has been a delight ever since, so much so, I purchased a used Maraschino 60 volt model.  Absolutely delighted with each.  The 4800a uses a toroidal transformer, the Maraschino a linear power supply.  Currently saving my money for another 60v Maraschino, will have to be new as these amps seldom come up in the used market.  In another class compared to my Acurus or MTX Soundcraftsman.  Use any adjective in the audio lexicon and these fit and fulfill those descriptors.  I would really like to hear a review about the DAC amps from you.  With respect, Jerry.

There is no such thing as straight wire with gain.  Every single inch of wire sounds different from every other kind of wire and even the directionality of the wire makes an audible difference.  Every single thing inside a power amp (class A, B, C, D or whatever) changes the sound.  This is why every class D amp sounds different from every other one.  They don't all have no sound or the same sound.  I did 14 mods to the IceEdge modules to make them sound more dynamic, musical, extended and transparent.  There is no end to infinity.  We have not reached any sort of final class D sound orgasm..  If class D sounded perfect with mosfets, then why would we be looking at GaNs?  Nothing is perfect on this plane....all is perfect in spirit......all is suppose to be this way....perfect in its imperfection.....and always we strive for more perfection.....hey, its fun!

,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

     I also have high expectations for the use of faster switching GaN  output transistors in class D amps since they have the potential to eliminate dead-time, which even further reduces distortion, which in turn,  typically results in improved sound quality. 
     I've been using good quality class D amps in my combo music and HT system for almost 6 years now.  In my opinion, they're the best option for attaining hi-end amp performance quality at an affordable price.  
     In my experiences with good quality class D amps, I've discovered their most unique quality is that they have no sound qualities of their own.  They just faithfully amplify the inputted signal without adding or subtracting anything.  They're like the audio amp ideal of a "straight wire with gain".
     Due to this extreme neutrality of class D amps, I've come to the conclusion that the most important factor determining the overall sound quality level of a system utilizing a good quality class D amp is the sound qualities of the preamp  chosen to pair with it. This neutrality also means the overall system sound quality contributions made by source components, and even interconnect and power cables,  will be readily apparent and need to be chosen carefully, too.
     I've not yet listened to a class D amp utilizing the much faster switching GaN transistors but am looking forward to doing so, hopefully, at an affordable price.  Based on my experiences with good quality class D amps, however, I suspect the use of GaN transistors will result in these amps being among the most neutral ever produced.  Choose your preamp, source components, interconnect and power cables appropriately.

Tim

Would require more technical ability and energy than I have and my health could be better (I will leave the amp making to the younger guns) .....but mostly I am writing a book that hopefully will make more difference in the happiness of people than a better inexpensive power amp.  I want everyone to be happy!

@ricevs why don’t you do it? (No sarcasm)

Check out this review:

http://www.enjoythemusic.com/magazine/equipment/0220/AGD_The_Audion_GaNTube_Monoblocks_Review.htm

He loves them...bought them...replaced his tube amp.

AGD says they are using the IRS20957S PWM driver chip ($2.01@100).....and probably then a pair of $1.05@ GaNs on the output.  You can see most of the circuit inside the tube in the above review.  This means anyone can do this for practically nothing.  Putting the circuit in a tube is just a gimmick.  If they put that board inside the box and it was made in China with all the very same parts it would sell for around $1000 for the pair of mono blocks....no kidding   AGD are using LM4562 op amps ($1.00 each) on the input. There are no expensive parts in this amp.  You can see the very good sounding inexpensive Wima caps and Nichicon caps.  

But we don't want to wait for the Chinese version that sounds as good for $1000......no, let's buy the one with the board in a tube for $7000......heck, we have money to burn.....he he.  You see, fun times for cheap are right around the corner.  Of course, anyone can make an amp similar to this....if someone else here is the US made it and sold it direct....probably $2500 the pair.....still...way less than $7K.

*G*....and I've yet to see or hear a Class A amp'd cell phone....

Not that I expect 'serious response' from the speakers in one....that's what Bluetooth is for....;)

(Back to the serious discussion....)

@erik_squires 

It seems that many folks hear one or two examples of a particular technology and if they like them then they equate that like across that platform. And vice versa some do not like the one or two examples of a tech they've heard and so they think that all examples in that tech sound bad.

Erik, you and I, Guido, and Ralph (and I'm many others) know that Class D can sound good. Obviously Ralph thinks so since he is working on bringing a Class D amp to the market. We also know Ralph made his mark in tubes and so working to offer a Class D amp he is basically stating that Class D can sound good, maybe not like tubes, but good in an of itself.

For those who've heard Class D and don't like it, I challenge you to go listen to Mbl or TAD. They both have Class D offerings that are very very good. You can't judge a book by its cover or its categorization. Don't listen for the Class, just listen for music. You may be very surprised and preconceptions may just be shattered.

Really, after having had this same exact discussion for a year or two we need to rehash it a millionth time?  

Yes..... but this time it's a lot quieter somehow.

Really, after having had this same exact discussion for a year or two we need to rehash it a millionth time?  

It’s one of the first, commercial Class-D that came after the original Class-T (Google these also as they only used N channel fets which allowed in some cases a higher switching frequency)

I wonder if this is the reason why I only like Tripath amps under Class D category. Class D amps other than Tripath, give me kind of fatigue after 30 minutes of music. When I put my Tripath amp back, I can listen to my Harbeths for hours.

but replace my simple little single ended tube amp?

First, @wolf_garcia , I applaud you for being willing to expose your audio quirks without fear. I wish I had that kind of personal courage. ;-)

But that’s just it. If you love the LP sound, only the LP sound will be good enough. If you have a particular niche of amp, no other amp will sound as good. It’s not proof Class D is behind the best solid state amps. If you have a love for 30 watt Class A, same thing. It's a bit like comparing all restaurants to mom or dad's home cooking.  Kind of unfair to rate them that way, unless of course your mom (or dad) was an absolutely terrible cook.

As I always say, buy and enjoy what you like, even if it’s’ some quirky SET or full-range with a giganormous bass horn. That’s fine.

But I think it’s unfair to diss Class D because it doesn’t sound like a SET. Among large solid state amps, I don’t know anyone who can listen and say "Oh, that’s a Class D amp, I can tell because....."

Best,

E

The technological backflips and design hurdles inherent in making Class D viable seem challenging to every designer who bothers with it, and clearly some are more successful than others. I think cheap Ice modules in a box or whatever Atmasphere Ralph is designing may work for many (I have one in an Ampeg 350 watt bass amp a friend traded to me...matches a vintage looking speaker box I already had), but replace my simple little single ended tube amp? Why? Less heat maybe, less distortion perhaps, more power that I don't need...and the biggest thing by far, an amp that likely doesn't sound as good to my ears as the harmonically rich and musically profound tube amp and preamp I'm using now. The "sounds like tubes" argument for some items, including the Schiit Aegir (not Class D but I'm tossing it in anyway) I recently auditioned and sent back, never really sounds  like tubes (Nelson Pass tries, and the things of his design I've actually heard do sound real nice...but...)..."drives like a sports car"...right...until you drive a sports car.

'nuff said

Class D is just Dead!

Like Tube amps, or Pass (who makes it clear this is his goal) the distortion profile may have more to do with euphonic capability than merely lower distortion.

He is certainly right in that regard IMO. But we can hear that difference provided the distortion profile is also correct. The problem is that in most cases the difference between 0.05% and 0.005% isn't the issue- the fact that the distortion that is there is mostly higher ordered stuff that is highly audible even in those trace amounts. The correct distortion profile can mask those higher orders making the amplifier easier to listen to. But a class D amp tends to have a different distortion profile than a traditional solid state amp. Many of them using PWM encoding tend to have lower ordered harmonics too- which is the profile you're looking for.

Whether a designer takes advantage of this fact is another matter but generally speaking GaNFET amps should sound better as they have less distortion on that account.

@atmasphere

As you are well aware, I’m kind of touching on an issue of specmanship that that affects us with all amps. Can we hear "better" when you go from 0.01% distortion to 0.001%? I know distortion can be reduced, which technically means more fidelity to the input signal. What I don’t know is that this alone is audibility, let alone desirable.

Like Tube amps, or Pass (who makes it clear this is his goal) the distortion profile may have more to do with euphonic capability than merely lower distortion.

If there are actually audible benefits to GaN based amplifiers I look forward to hearing them.

There should be. GaNFETs are generally faster than MOSFETs (although MOSFETs aren't done by any means) and so the use of GaNFETs means you can run the amp with less dead time. Whether a designer takes advantage of this fact is another matter but generally speaking GaNFET amps should sound better as they have less distortion on that account.

Personally, I think it's a horrible thing to price out a product based on component costs.

I think everyone would be horrified if we did this consistently across audio.

There's more to a high frequency design than the cost of the transistors. PCB layout must be done meticulously, and test failures common, so R&D matters.

Still, having said that, Class-D amplifiers are quite good already. Better than some Class A amps, worse than some Class A/B.

If there are actually audible benefits to GaN based amplifiers I look forward to hearing them.

GaN transisitors don’t cost any more than mosfets. People are charging more for GaN amps because it is the latest buzzword and they are first out so they gouge you. The EPC GaN fet recommended by EPC for audio use costs $1.05 each at 100 quantity. Hardly expensive. At the most 4 per channel....so that is $9.

GaN amps will be available from China for a few hundred dollars.....I have no doubt. However, they have to design the circuit from the ground up.....so will take a little while to come. The big manufacturers are slow and conservative (Hypex, IcePower, Pascal, etc.). It takes a sledgehammer to get these guys to try something new and then it takes years for them to develop it. It will be just small companies for awhile with GaN amps.....but hopefully, the big guys will get on board. TI and Infineon, etc. make class D amp chips as well. Maybe they will be first to come out with a GaN version......then you will see things like this:

https://www.alibaba.com/product-detail/IRS2092S-Mono-Channel-Digital-Amplifier-Class_62169638554.html?spm=a2700.pc_countrysearch.main07.99.3d202a3c3TR7hg

The above is an Infineon class d driver and some IRF mosfets.....cheap enough for you? Maybe the 2092 can drive GaNs? Fun stuff ahead.

Hello All, I was long hoping to evaluate the Rowland Daemon 1500W Superintegrated amp. Could a class D integrated fulfill my yearning for sonic nirvana, or would Daemon leave me pining for the wonderful music of my separates: Rowland Aeris DAC fed by the ultra-capacitor-based PSU external power supply, driving my beloved M925 monoblocks? Eventually, a Daemon review unit was delivered on February 28th. I Started break-in the following day, and have been scribbling my listening notes since… The writing project will continue for at least a few months, until the device has stabilized, and I have exercised several of its many input and output features. I have been waiting for a long time for this 99Lbs single box critter. It is Jeff Rowland’s integrated statement. The DAC + Preamp + 1500W/8 (2500W/4) dual-mono power amp in a single chassis measuring 17.5” x 15.25” x 9.5” is sounding amazing after just a little more than a couple  hundred hours of break-in.

  

Discovering the phenomenal musical beauty that Daemon produces is being a fascinating experience… Already I am stunned by Daemon's power reserve and unreal tonal grace. Join me to chat about my adventure with this integrated flagship around its new Audiogon watering-hole:

 

https://forum.audiogon.com/discussions/jeff-rowland-daemon-reviewing-the-jrdg-superintegrated-flagsh...

 

And, feel free to PM me with any questions about it.

 

Saluti, Guido

Hi @eddiet

I never heard one.  Ended up with the NAD equivalent and very happy.  They use a hybrid , almost like a Class H, Class D and Class A in one, designed by Hypex. No, the new transistors won't make anything obsolete, but sure will make things more expensive.

Erik

im thinking of the Peachtree Nova 150

I remember the Peachtree importer a friend of mine here in Australia demo’ing me a pair of midrange floor standing Focals to be our Audio Clubs "house" speaker, which he also imports, as well as Krell amps.

He was using the Peachtree at the time because he had no Krell’s handy, and quietly said to me the Peachtree isn’t very good, you should hear these Focal’s with the small integrated Krell feeding them.

Cheers George

Hi guys
is this thread redundant?  
im thinking of the Peachtree Nova 150.
Any owners?
im wondering why they’ve gone back to Ice for this line. Didn’t they use Hypex previously?
Also won’t eGaN make all these redundant quite soon?
Cheers

Anyone can recommend me where to order one NCA525 at a good price?

celander:  " I suspect some type of class A-class D hybrid will likely be the future for all class D topologies."

    There are currently class D amps using the topology of both transistor and tube analog class A input stages combined with analog class D switching power amplifier stages. 
      I've never auditioned any of these amps but did read a very good professional review on 6Moons about the French DeVailet solid state hybrid integrated class A-class D hybrid.amp.  The reviewer loved it but it was uber-expensve like most of the best traditional amps are and always have been. during the past century and possibly for another century.
     Perhaps the most significant  aspect of the many good class D amps is their affordability.  From my perspective, the egalitarian nature of class D technology is a beautiful thing, bringing extraordinarily high sound quality to an increasing number of individuals' systems that otherwise would not be able to afford and experience it.
     I'm hoping the future of class D topologies is a bit more interesting than just relatively expensive hybrids.  The inventor/designer of both Ice and Hypex NCore  class D amp module technology, Bruno Putzeys, has stated he's able to design class D amps that sound like any traditional class A, tube or hybrid amp topology desired.
     I wonder if he could design an affordable class D amp that could mimic the sound characteristics of the best current and past examples of traditional amps, along with the best example of independent class D amp sota efforts, that is user selectable. 
     A guy or gal can still day dream, right?

Tim

We've not put a lot of thought into what embodiments the amps will take, although an integrated seems likely. Probably some sort of power amp too.

I think the amp is likely to be less than $4k.

@atmasphere can you give us any information on when your Class D (not digital) amps might be ready for prime time? Will they be stereo or mono-blocks? Estimated price?

+1, atmasphere. 

I don't find good digital amps bright or fatiguing today.

What's a 'digital amp'??
Surely not a class D- I thought this thread was class D only ;)

maplegrovemusic
  They are active with class d amps inside . These are in no way bright or fatiguing , things I have associated with older class d amps . Looking to find out how and why this could be ?

This may help, but the reviewer found it  a bit dry and lacking in harmonic complexity and bloom in the upper midrange, a bit dry in the mids, and maybe even somewhat aggressive on top.
It's one of the first, commercial Class-D that came after the original Class-T (Google these also as they only used N channel fets which allowed in some cases a higher switching frequency) 
The 18 year old Sharp  SM-SX100 Class-D, if you look at the 4 ohm frequency response it's already starting to roll off the high frequencies at 2khz, and the simulated speaker load is not much better.
https://www.stereophile.com/content/sharp-sm-sx100-digital-integrated-amplifier-measurements

Cheers George

@maplegrovemusic 

I don't find good digital amps bright or fatiguing today. 

In the late 1980's I was listening to some digital amps that sure were though! 

I don't know how old the B&O/ICEpower designs are, but that's what I listen to every day now. :)  It's quite possible the speakers, designed as integrated wholes, eliminated issues with the rest of the Class D crop. 

I will say that the Class D amps I was listening to wwas through entirely different speakers, TAD pro studio monitors from the time, so that could have been a horrible match overall.