Class D Technology

Seanheis 1,

If you're only interested in sound quality and nothing else, you're likely missing the finer points of a good class D amp.  IMHO, the ONLY good point of a class A amp is its sound quality.  If you would list all the pros and cons of a class A amp, the only pro would be sound quality. ALL the other factors  you could think of when buying an amp would be on the con side, and I mean EVERY SINGLE factor you can think of:
Most expensive to buy
Most electricity consumed to operate
Most of the electricity inputted is converted to heat and wasted.
Nuclear reactor type heat  produced in your listening room
Huge due to huge heat sinks required to try and prevent nuclear fusion from occurring.
Constant high heat reduces reliability and life span.

Put it this way: would you only pick a life partner based on looks? Would you ignore the fact that she required a very large payment to even consider you? Required expensive gifts to keep dating? Raised the temperature 20 degrees every time you were near her? Occasionally pooped in your bed blaming the high heat that she was the cause of and requiring expensive 'repairs'? Grew to enormous size and weight in an attempt to dissipate her excess heat through an increase in surface volume like a hippo?  Okay that's enough, I can't think of many more analogies or are they metaphors? I think you get the picture.

Sure, looks/sound quality is important but I suggest you might be happier with a woman/amp that is only one of the most beautiful in the world but not quite THE most beautiful but is your best friend,  low rather than high maintenance, a toned and healthy size and weight rather than extra large and heavy, generally has many more pros than cons. Besides, the higher quality class D amps currently sound strikingly similar to the higher quality class A amps.  I think you'd be pleasantly surprised if you gave a good one a try, I know I was.

Okay, that's the gist of it but I wrote more specifically about my experiences with class D in the book below:  

  
I've become  a big fan of class D amps for several reasons:

1. They are extremely quiet, having THE HIGHEST S/N Ratio and THE WIDEST DYNAMIC RANGE of any amp type, with almost no audible background noise and highly detailed.  I can turn my volume control to maximum without any source playing, put my ear an inch from the tweeter panel of either speaker, and there is absolutely no sound. Is this possible with a class A amp?  This is very important because it enables sound to emerge from a dead silent background which enables very fine details to be distinguished, including the all important spatial cues required for good sound staging. I believe the quietness of these amps is the root cause of their excellent detailed nature; this is my theory but it has been proven to me repeatedly through my actual listening experiences.  I know my music well and I can easily discern a redbook CD from a hi-resolution 96/24 digital recording mainly based on the low level of background noise, high level of detail, lack of the 'loudness wars effect' and the very life-like attribute of having THE greatest dynamic range of any amp type. 
I also found it is now much easier to discern audible differences between different speaker, interconnect and power cables and other upstream issues with these class D amps than with any of my previous class A/B amps I've used.
Contrary to comments by previous posters, I have never heard any 'switching noises', they are the quietest amps I've ever heard (not heard?).     

2. They are very powerful and good ones are very stable into very low impedance speaker loads.
My main speakers are relatively inefficient (87 db at 1 watt)  Magnepan 2.7qrs. that can dip a bit below 4 ohms.  I'm currently driving them with a pair of D-Sonic M3-600 monoblock class D amps rated at 1,200 watts @ 4 ohms.  These amps are rated as stable down to 1 ohm.  All tube amps, and many class A and A/B amps, are not capable of driving speaker loads that dip to a dangerously low 1 ohm (almost a complete short) as some more exotic speakers do at specific frequencies.

3.  They are very neutral in their overall tonal characteristic, not adding or subtracting anything audibly that I can perceive.

I had previously always paired decent class A/B amps (McCormack and Aragon) with a good tube preamp (VTL 2.5 with NOS Mullards) to achieve the slightly warmer sonic characteristics I favored.  Initially, I paired my class D monos with the VTL and it sounded very good.  But, after extensively comparing my system's sound with and without the VTL, I decided my music sounded just as rich, sweet and dimensional  without the added tube coloring so I sold my beloved VTL to a friend.  I don't want to portray the sound of these amps as 'tube-like', but the natural sweetness and richness of good music and instruments played well is definitely conveyed if the recording is well done and the recording captured it. 

I think it's important to note that most of the newer class D amps rely heavily on feedback circuitry that constantly compares the signal accuracy at the input stage to the signal accuracy at the output stage going to the speakers, making adjustments as needed to ensure the accuracy prior to releasing the signal to the speakers. This is likely a major factor in the generally neutral nature of the best class D amps.  Those using tube preamps need to choose carefully since the tube preamp's sound will be passed through faithfully without any alteration and the differences in sound qualities between preamps and tube swaps will be readily apparent and distinct.  

In my listening experiences, tube and class A amps tend to have a sound more to the warm side of neutral, which I previously thought I preferred to neutral.  Class D amps are closer to the classic audio amp ideal of a 'straight wire with gain' than any amp type I've listened to.

4.  They excel at dynamic range so much I feel the need to mention it again.


My system is a combination 2-channel and 5.1 HT surround system used about equally between both.   I use an Oppo BDP-105 as a 2-ch preamp, 5.1 surround processor and as a wireless DAC.  I run JRiver on a laptop that wirelessly streams music files from a Synology 20 TB NAS to the Oppo DAC. My entire CD collection, along with numerous 96/24 hi-res digital WAV files are stored on the NAS.  All amplification is class D:

D-Sonic M3-600M monos power my front Magnepan 2.7 mains
A bridged Emerald Physics 100.2SE powers my Magnepan CC-3 center
A stereo ClassDAudio CS440 powers the Infinity in-ceiling rears.
A Dayton Audio class A/B amp powers 4 Audio Kinesis subs configured in a distributed array bass system. I'm currently searching for a good class D amp that can handle 4 subs @ 4 ohms to replace the Dayton that came with the distributed array sub system.

The video connections from the cable box to the Oppo to the tv are all HDMI. The audio cabling is all run directly from the Oppo to the amps, XLR for the D-Sonics and RCA for all others. All of the class D amps have the same neutral, ultra quiet, detailed and highly dynamic sound quality that seems to be charactaristic of good class D amps. The ability of these amps to go from quiet to loud for both music and HT audio is very good and can be even startling on well recorded content, an obvious improvement over my previous class A/B amps.

5.  They are space and energy efficient.

My previous main amp was an older class A/B Aragon 4004  that was very big (19"W x 14.75"D x 6.75"H), weighed 76 lbs, got warm-hot to the touch, was inefficient and put out 400 watts @ 4 ohms. This amp had to be replaced due to leaking caps in the power supply section.  My current D-Sonic monos are small (7.25"W x15"D x4"H), weigh about 10 lbs. each, never get more than mildly warm, are very efficient and put out 1,200 watts @  4 ohms which has had a very positive effect on the performance of my inefficient panel speakers.
After switching my previous 3 class A/B amps for class D amps, I would estimate my monthly average monthly electric bill decreased between $30-$40 varying by the season.  I've always left my amps on 24/7 for both types unless I'm away for a day or more. I think that's fairly significant savings, especially projected over a full year.
The switch also allowed my audio gear to be streamlined due to the new equipment occupying roughly half the space. The top shelf of a new much smaller rack containing just my Oppo straddled by both D-Sonic monos on small maple isolation stands with all remaining gear located in an enclosed shelf below. Aesthetically a breath of fresh air with less gear, less visible gear, with a more pleasing symmetry, better air circulation and minimal heat.

In conclusion, I think we can all agree that there are many tube, class A, and even some class A/B, amps that achieve a stellar performance level when properly matched to quality speakers.  I have no doubt because I've personally listened to many examples.  However, I also have no doubt that high quality class D amps can achieve similar stellar performance levels when properly matched to quality speakers but I realize everyone is not ready to acknowledge this quite yet.  Resistance could be due to deeply held beliefs in the superiority of certain amp design types or perhaps a reluctance to concede a relative equal status to such an upstart newcomer.  But, after reading this thread and listening to some of the comments, it seems increasingly obvious to me that many have simply not heard a high quality class D amp driving a pair of high quality speakers and how closely it approaches the sound quality of even the best of the class A amps.  

And you don't need to believe me when I proclaim my opinion that class D is the likely wave of the future in high end amp design not only due to its excellent sound quality but also due to its many ancillary benefits such as lower weight, smaller size, lower heat, higher reliability, lower maintenance costs, lower R$D costs due to amp module designers/manufacturers taking on this responsibility and lower production costs caused by completed amp sellers simply buying the amp modules they prefer from 3rd parties.  All you need to do is look at the many stalwart amp manufacturers (Jeff Rowland, Theta, Mark Levinson, Audio Research, Rotel, NAD, Technics, Yamaha, Marantz, Cary, Halcro, etc.) that are now offering class D amps.  They're doing this because they've compared the sound quality of their traditional amp designs to the ever increasing and improving class D amp module typologies and decided they offer high quality sound along with many ancillary benefits:

Amp module designers assume many R$D costs=Lowered internal R$D costs
Lowered heat=Increased reliability=lowered warranty repair costs and increased company amps'  reputation as being reliable 
Lowered weight/size=lowered shipping costs
Higher efficiency=lowered customer electricity usage=a 'greener' product
Increased amp module suppliers=freedom of company amp designers to tailor sound to their preference via amp module selection and design of custom input stages
Other likely benefits I'm not thinking of right now because I'm tired

It is evident there is a slew of benefits to traditional amp sellers increasing class D offerings with minimal associated risks that could result in a class D wave of the future and the proverbial win-win situation between amp sellers and amp buyers that I believe has already begun.

Sorry my post turned out so lengthy but I was trying to be as thorough as possible,
    Tim
 
      

     



 

 



















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Thank you maplegrovemusic and Kijanski,

    I'm glad you thought it was a useful post.

   I  did a lot of research on class D amps and technology before buying my 1st one about a few years ago.  Guido Corona, mapman and atmasphere   helped me a lot on this site and I really appreciated it.. I now own 3 different brands and have gained some personal experience with them over time.  

    I'm glad I have some somewhat decent knowledge to pass on to others looking for similar knowledge.as I was.  I also have learned along the way that class D is a great choice for myself and many others but not right for everyone. 

Thanks,
  Tim

      

" Mid fi has a negative connotation in these parts. That’s all. One can either laugh or be insulted. Best to not use the term unless that is the message intended."

     Well said, mapman.

Ralph (atmasphere) stated:

" What I'm seeing in class D is something I've not seen in audio before- amplifiers that use the same parts as a mid fi amp as in a high end amp. In fact its safe to say that class D has lifted mid fi performance to what many would have called 'high end' only a decade earlier."

Georgelofi acknowledges the benefits of class D but mentions its low cost in a manner that suggests it's not a further benefit, implying that sound quality and low cost are mutually exclusive and that we should, therefore, look down upon this technology that dares to sound so good and be so affordable at the same time.  

     I'm a fan of all good class D amps and admit it's a bit annoying to hear them described as 'mid-fi'. But it is true that class D amps today are in a wide range of products that do cover a wide spectrum of sound quality: from 'mid-fi' applications such as car audio, boom boxes, home receivers and powered full-range speakers/subs (that enabled better sound for less cost than the previous amps used)  to  'high-end' applications  such as the state of the art line of modules from Hypex ,  Anaview/Abletec and Pascal modules that are used in world-class amps from Jeff Rowland, D-Sonic, Mark Levinson, Marten, Merrill Audio, Audio Research, Halcro and possibly even Atma -Sphere in the near future.
     .
     These are just some thoughts from my perspective from the outside as a consumer looking in.  I have no amp design experience or knowledge and wish all amp companies, regardless of the amplification type employed,  continued success.

Tim    

   
 

Hi George,

     I didn't intend to twist your words, sorry.

     I reread your posts and I get that you are waiting for the switching frequency to be significantly raised before you'd be willing to 'switch' to one.

   I understand the theory that the current class D switching frequency is too low and affects the sound in the audible range but I can honestly say I don't hear any irregularities when listening intently to my system.  You may be completely correct but I'm just having a hard time faulting what I hear.  When I listen explicitly for switching frequency issues I mainly concentrate on the highest frequencies to make sure they are well extended and to make sure that spatial cues are present and the sound stage is well defined and stable both laterally and front to back.  

     Am I listening for the wrong things?

     Is there a simpler method to determine if the  switching frequency is too low and is  affecting anything in the audible band?

   I'm not really disputing the theory that a higher switching frequency  would upgrade class D amp performance.  I was just hoping to gain a better understanding of exactly how.

 Any assistance is greatly appreciated,
     Tim

























i honestly I  

Erik,

     I agree with you that, if I can't detect any issues in the audible range on my current class D amps due to their switching frequency being not high enough, than there is no need for concern and I should just enjoy them and my music.  Actually, this is what I've been doing since I installed the amps, I just tried to intently listen for any issues for a short period when I first heard of this theoretical issue.  

      Once an affordable class d amp with a switching frequency in the 3-5 mega hz range is on the market and there are any objective or even subjective reports that it sounds significantly better than current amps, I'll audition one.   I believe this is a more effective approach than not using class D until the theoretical  performance benefits of a 3-5 mega hz switching frequency becomes a reality, since the numerous benefits of class D amplification will not be utilized and enjoyed between now and then.      
      I would think just 2 of class D's benefits, sound quality and electricity cost savings, would be sufficiently convincing for many to switch right now.  If it's only going to get better, upgrade to class D now and then upgrade again whenever you determine future improvements are worth it.  The cost of world-class amplification has never been less expensive,as long as you're willing to be open minded, a bit more adventurous and let your ears guide you.


Enjoy,
 Tim  
 

     I've read about all this supposed noise produced by my class D monos due to their SMPS rather than a typical analog power supply and all the noise produced in the audible band due to their switching frequency being too low. However, the only noise I can actually hear is from claims of all this class D noise  that no one can hear.  
     I'm no scientist but I understand the difference between theoretical noise and actual verifiable noise and that, empirically, only the actual noise can actually be heard. by us humans.  Noise needs to be heard to exist.  
     In my experience, and apparently many others experience, class D amp noise is being exposed as a myth. I have yet to hear from any class D amp listener or user hearing any noise issues.  In fact, I have yet to hear any descriptions of how this theoretical noise would audibly manifest itself.  

   I'm trying to keep an open mind but I'm not going to believe in dragons without at least 1 charred sheep or human.


Tim 
    

     

Question:
     If a tree falls in the forest, but no one was there to hear it, does it still make a sound?

Answer: 
     Yes, the theory being the tree hitting the ground moved the air and created the sound.  Because  someone was not there to hear this sound does not mean the sound did not exist.

Question:
     If a class D amp is playing in a system, but no one could hear anything other than finely reproduced music, does noise still exist?

Answer:
     Who cares, although there are theories that state the SMPS and a low switching frequency has affects on the sound in the audible band,  no human has ever claimed to hear these affects or even describe what these affects would sound like.

Thought this might be helpful,
     Tim

Hi Guido,

     Very good summary of the evolution of class D over the last few decades.  I've become familiar with your thorough knowledge of most things class D over the last few years and I'll take your word for it that early class D amps did suffer from some of the ills that the op and george have discussed..  Luckily, I avoided the early disappointments by not using class D until the last 2-3 yrs.  I've experienced no high frequency harshness, brightness or any other negative treble qualities and thought they were referring  to more recent class D amps.

     I'm not a fan of  bright sounding amps of any type and, if any of the class D amps I currently use shared any of those qualities, I would not have kept them and definitely would not be recommending them to anyone.

 Guido said::     

"Please note that exactly like proclaiming that all class D amplifiers are inherently flawed constitutes a logical fallacy, so would be the assertion of the opposite... Reality is, that with all topologies, some amps will meet our particular taste in music reproduction, some will miss by a country mile, and some will be somewhere in between."

     I agree with your summation completely.I think you're correct, the reason I enjoy my current D-Sonic M3-600M amps so much is because they match my taste in musical reproduction so well:

Very good bass response that is deep, solid but also nuanced when required.

Very low noise floor that enables details to be heard.

Powerful for good dynamics and a relaxed and effortless quality on all content that allows music to sound very natural and life-like.

Dense, solid and stable imaging that allows for the illusion of a 3-D sound stage both laterally and front to back.

A smooth mid-range and treble that also manages to be highly detailed.

A generally accurate and neutral presentation that is capable of conveying warmth when it's contained in the music and captured on the recording.

     This is a summary of what I hear when I listen to my class D amps.  It is a combination that suits my tastes well but I realize may not suit others tastes and I realize not everyone will even .hear the same qualities from these amps in their system and room.  as I do in mine, it's to be expected.

Tim       

atmasphere,

     Good points about class D amps being immune from noise due to their modules or the  smps but that  RF radiated noise could be a problem for other equipment nearby and even pacemakers and other electronics either within or separate from one's system.   I was warned of possible RF radiation about the same time I purchased my first D amp.  

     I read a tip that a portable am/fm radio could be used as a crude detector for any RF radiation emitted by a component. The instructions were to tune to a spot on the dial that is between stations that is relatively quiet,  turn the volume control to about 3/4 and  move the portable radio slowly around all sides of the tested component.  The point being that if the component is radiating any RF signals/interference it will be indicated by the portable radio producing a change in sound once it is in the proximity of  any component being checked.  I did this test on my D amps on the am and pm bands (since the tipster didn't specify a specific band) and I noticed no changes in sound coming from the portable radio but I hope this was a valid method for RF radiation detection.  

     Seanheis1 stated:

" Maybe we will start seeing Class D pre-amps then... "

  My understanding is that class D pre-amps would not have  any significant advantages over traditional tubed and ss pre-amps,  that I believe all operate in class A.  This is mainly due to the signal amplification being so small in class A  pre-amps  that heat and energy efficiency are not significant issues as they are in tubed,class A and class A/B amps.  

Tim   

georgelofi,

     Thank you for the further clarification.  I just tried your suggestion  with an older (non-muting) portable radio in the 500-800 khz am/band range on my amps with results being no discernible change in sound.or level.  Reassuring results.

Thanks again,
  Tim

timrhu,

     I agree, class C amps are not for you.  But have you heard about the latest class D amps?  WOWIE WOW!  Where should I start?......

Later,
 Tim

     seanheis,

     I thought that anyone wanting to learn more about class D amplification may want to hear from the horse's mouth,inventor of UcD (Universal class D) and the much newer NCore class D devices Bruno Putzey,, from interviews he has given on the links below.    




http://ultraaudio.com/index.php/feat...audio-part-one

http://ultraaudio.com/index.php/feat...audio-part-two


     He discusses many interesting specifics about class D in a manner that is articulate and informative without needing to be an electrical engineer to understand.  I found his discussion of the feedback loop (" there is no such thing as too much feedback") and switching frequencies ("A reasonable switching frequency for a class D amplifier is just under 500khz") especially relevant to this thread's content thus far.

     Please read these attachments.

Thanks,
 Tim

mitch2,

     Thank you for your reply, I agree with all you stated and now have a better understanding of your thoughts, situation and position.  

     I'm glad we were able to clarify and think it's a good sign that we were both able to find amplification that we're pleased with utilizing different amp types.

Later,
 Tim

savdllc,

     You stated: " but if one is chasing greater efficiency than Class A without sacrificing as much fidelity as Class D tends to do, Class G and H amplifier tech would seem to be the best choice."

     This statement implies that class D requires you to sacrifice significant fidelity when compared to class A/B.  As a user of various decent quality  class A/B amps exclusively for about 30 yrs (beginning with Adcom and then McCormak and  most recently Aragon) before trying various good quality class D amps (beginning 2 yrs ago with a budget ClassD Audio SDS440SC  then an Emerald Physics EP-100.2SE and currently D-Sonic M3-600-M mono-blocks), I can assure you I never felt I was sacrificing any fidelity with class D.  

    With all 3 class D amps I actually experienced quite the opposite; immediately noticing significant improvements in noise level, bass response, mid-treble fidelity being very similar to class A/B with my initial budget class D and clearly superior to my former class A/B amps with my admittedly better quality most recent class D amps.

     I know there are many here on Audiogon who have discovered  switching to class D is all gain with honestly no pain.   I'm concerned that comments like yours, and other posters earlier in this thread, may give readers the false impression that switching to class D involves some sacrifices in sound quality.
      I want to make it clear to everyone considering a switch from class A/B to class D amplification that these sort of comments may have been accurate for some early lower quality class D amps but are definitely not valid for current good quality class D amps.  

     Once you've experienced the extraordinary improvements a good recent class D amp will make in your system, you'll begin to realize how inaccurate, no longer relevant and simply untrue these types of comments are.    

     I can only rationalize these sorts of comments by assuming that these individuals have obviously never auditioned a recent good quality class D amp in their system or anywhere else.  Although it's possible  they're just parroting comments they've heard years ago about early examples of class D. 

     I'm grateful I ignored these class D myths and opted for an open minded home trial and suggest others do the same.

    Concerning class G and H, I have never heard either but I'm interested in hearing them.  Being an extension of class A and A/B amps, however, I would expect them not to have the same advantages of reduced weight and size that class D allows.

Thanks,
  Tim

randy-11,

     I believe the Benchmark ABH2 is considered a class H amp.

Tim

mitch2,

     My comments in my previous post were solely in response to savdllc's/David's post on 12/31.and were not directed at you at all.

     After reading your post and the review you linked to on the Mola-Mola class D preamp and amps, you are clearly not included in the group of posters that have never heard a good class D amp in their system.  

     I concede your point that some have compared class A and A/B amps to 'current good class D amps', not just the early class D amps,and still preferred the class A or A/B amp.

     In regards to what I consider ' current good quality class D amps',   I would include any amps utilizing the NCore-1200 modules (Acoustic Imagery Atsah, Merrill Veritas, Theta Prometheus, etc.) as well as those utilizing Abletec and Pascal power modules (Marten, D-Sonic and Rowland).  There are also other current good quality class D amps such as H2O, W4S, Red Dragon and Bel Canto. Sorry,  I probably missed a few other current good quality class D amps,too.

     Your attached review of the Mola-Mola preamp and amps were one of the few  reviews I've seen on the Kaluga monos that was not extremely positive.  The review was not totally negative but it seemed to me like the reviewer had such high expectations going in that only near perfection would result in a positive review.

     Both you and the reviewer mentioned 'a lack of musicality' which is a quality that is very subjective  and uniquely perceived by each listener. Regardless of how each person defines it and perceives it, however, I think 'musicality' is probably the most important quality a home music system needs to possess.   I understand it's a quality you require in your amp and I feel the same. 

     I believe we both perceive the bass,power, tone, body and lack of noise in good class D amps (NCore-1200 based  amps in your case and Abletec based amps in my case). but you also perceive a lack of 'musicality' whereas I do not.  

     As a result, I'm much more enthusiastic about good class D then you are.  You're very pleased with your class A or A/B amps and I'm pleased with my class D amps. I'd call that a win-win scenario, congrats.

     I believe no amp technology has a monopoly on good sound quality and think we both agree that class D is not right for everyone.

 No big deal, right?
      Tim  

David,

     My main points of contention are with your earlier post in which you implied that class D amps have inherent compromises in sound quality and your last post in which you said class D sacrifices sound quality for efficiency.  You don't specify what these supposed compromises are and I consider it irresponsible to mention sonic compromises in class D as if they were well known and givens.

      As a result, I feel the need to respond by stating that I noticed no sonic compromises when I replaced my class A/B  amps with class D amps.  

     In fairness,mitch2 did state in a subsequent post to yours that, when he compared some class A amps to the very good class D Acoustic Imagery amps (based on the NCore 1200 module),  he thought these class D amps had some very good qualities (bass, tone, power, body and lack of noise) but  they lacked the  'musicality'  that he perceived with his class A options.   
     Fair enough, in his system he preferred the class A ( not class A/B) amps because they sounded more 'musical' than the class D amps.  This 'musical' quality, by which I think he means that his system portrays a realistic sense that he is in the original venue listening to the actual performance, is obviously a very important quality to him as it is to me.  

     While I didn't directly compare class D amps to class A amps in my system I did compare them to my former class A/B amps.  I do not perceive a lack of 'musicality' in my class D amps (D-Sonic M3-600-M mono-blocks) in my system and room.  I have no interest in arguing the point or about why we had such different results.   I just think we're both fortunate to have found such good amp solutions and we both should enjoy our systems no matter what type of amps we use.

     The main point I want to convey is that current good quality class D amps perform very well.  Based on my experience they outperform my former good quality class A/B amps- Adcom, McCormak and Aragon-in all categories that count for sound quality.

    Getting back to the OP's original question:

"If it weren't for efficiency & power, would there be any reason to own a Class D amp? Do they beat Class A in any other categories that count for sound quality?"

      My answer is I do not think class D amps beat Class A in any categories that count for sound quality yet, based on others opinions who have compared them directly in their systems and my auditions of class A amps in dealer systems.  
     However, class D amps have so many other advantages over class A (reduced price,electricity consumption,heat, size and weight) that some may opt for class D anyway.   Then there are class G and H amps which I'm keeping an open mind about until I learn more and hopefully hear them.

     Other than the above, David, I have no issues with you.  However, I am a bit curious whether or not you utilize or offer class D amps in your HT business.

     I certainly have no issues with you voicing your opinions just as I think you have no issues with others voicing their opinions.  After all, I think that's the whole purpose of this very good forum.

Thanks,
 Tim        

     i Wonder which class D power module PS is  using in the Stellar monos?  I would think they'd be sharp enough to audition the newer Abletec and Pascal modules and compare them to the Ice and Hypex to use the best performer.  Anyone know?  Guido?

Thanks,
  Tim

h2oaudio/Henry,

     Makes sense that PS is using the B&O ASC700 Ice module when comparing specs. I think you're right since I found this quote from Ps Audio owner, Paul McGowan, in one of his newsletters:

" The Stellar mate to the Gain Cell DAC, the Stellar S300 and Stellar M700 amplifiers have B and O modules in them for their power amplifier outputs, and what we call an Analog Cell for their inputs. I’ll explain what that is in future posts. It really makes them quite magical sounding."

Thanks,
  Tim

 

Hi Guido,

     I think you're correct that the D-Sonic stereo amp (M3-3000S) uses the Pascal X-Pro2 module, the same module JRRG uses in their C2 integrated,  and their top of the line mono-blocks(M3-1500M) utilize Pascal X-Pro1 modules. 

    The D-Sonic M2-1500M received an excellent review by 6Moons. According to Dennis, the M2 and M3 1500 monos are the exact same and both utilize Pascal X-Pro1 modules.  Here's a link to the review:

http://www.6moons.com/audioreviews/dsonic/1.html

Thanks,
Tim

Guido,

     You are correct that the Rowland Continuum C2 contains the Pascal M-Pro2 module, not the Pascal X-Pro2 module.  My mistake,
   
Thanks,
   Tim

" he fact is that its too new for Class D's..... the sound is just not there.   There is a class D that can compete, (Merrill - but it costs many thousands)....but for now, they are just not musical."

stringreen,

     You obviously need to either reread this entire thread or gain some personal experience by auditioning some of the many very good and reasonably priced class D amps  currently available.

Tim

mapman" Hadn’t thought of DSonic in a while but looks like they are still offering a lot of bang for the buck.
Nice website.....lots of useful specs and measurements.
What Class D modules do they use these days?"

Hello mapman,

     On their current M3a-600-M monoblocks, I know they're using the Pascal Pro2 class D modules, which have the smps built into the module and are the same ones used in the Rowland Continuum 2 integrated amp.  
     I have the slightly older M3-600-M monoblocks and they use the Anaview/Abletec modules.

Tim

     Hello mitch2,

      From some of your past replies on other threads, I remember learning of your disappointments with the performance of some high quality class D amps you've tried in your system.  From what I've read, however, the class A Lamm and Clayton amps sound and perform about as good or better than just about any other amps, regardless of amp type.  I also believe they're both much more expensive mono-block amps than the Acoustic Imagery and many of the other higher quality class D amps. 
     So, I just wanted to point out that class D amps offer what I believe many would consider very good full range sound quality, typically at a very reasonable price and, therefore, would be considered a better bargain and amp option by those with limited budgets.  
     Yes, the main benefits of current class D amps are still power and control, unsurpassed electrical efficiency, ridiculously low distortion and noise floor levels, extremely small size, weight, operating temperatures and relative price. 
     Sure, their overall full range sound quality may not currently and universally be considered the best in absolute terms.  As class D technology continues its steady upward trend in overall full range sound quality performance in absolute terms, however, I believe it currently represents the best, and certainly the most affordable, pathway to high-end sound quality. 
      In my opinion, it'll also likely just be a matter of time before it's universally considered the premiere amp type, especially considering its near-future DSP technology inclusion and potential.  It should at least be very interesting.

Tim  

Hello mitch2,

     You've utilized quite a few good and varied amps with your Aerial speakers. I've had much more limited amp experience, only using high current class AB amps (Adcom,McCormack and Aragon) initially and then several  different high-powered class D amps subsequently with  Magnepan speakers, my favorite being my current pair of D-Sonic monoblocks. 
     It seems like class D amps have been a better match with my speakers than they've been with yours.  I was actually considering buying a pair of Acoustic Imagery Atsah monoblocks before I decided to go with the DSonic M3-600-M monoblocks because they were almost $7K less expensive and had gotten good reviews here from some members. 
     They've performed great for me,outperforming my former class AB stereo amps in virtually all the sound qualities I consider important. But I'd still love to try out a good quality class A amp with my speakers since I've never used one and mainly out of curiosity about performance differences I'd perceive. OTOH, I'm currently completely satisfied with the D-Sonic class D monos and have no desire to actually switch amps; they're 1,200 w at 4 ohms, have a very low noise floor, are highly detailed, very dynamic, always smooth, natural and never harsh in the treble plus I'm able to leave them on 24/7. 

Hello kijanki,

     Yes, I've read several very positive reviews on the Benchmark AHB2 class AB amp.  One review that I found very interesting was a review of the AHB2 combined with the Benchmark LA4 preamp.I remember the review because it combined something I've always wanted to try out in my system, a very neutral, detailed, low distortion and low noise amp with a preamp having the exact same qualities. 
     I was seriously considering buying the LA4 preamp to try out with my very neutral, detailed, low distortion and low noise class D amps about a year ago.  But I was offered a Mark Levinson S326 preamp, that's also very neutral, detailed, low distortion and low noise, at a very good price and I bought that instead.  So, I was still able to try out the neutral, detailed, low distortion and low noise amps and preamp combo concept. 
     It's provided very good results in my system, using mainly hi-res sources through a Lumin D2 dac/streamer.  The overall sound is very neutral and detailed but it also really lets the qualities of the recording and music become the focus with a highly realistic and 3 dimensional sound stage that has the musicians seemingly playing in the room.  It's very palpable, detailed and enjoyable, especially on good recordings.

Tim   
         
     

Hello atmasphere,

     As I understand class D technology as a layman, timlub could be referring to 1 of 2 different possible types of distortion:

1. Distortion caused by the output transistors not turning on and off quickly enough- Most current class D amps utilize MOSFET transistors that have a limit to how fast they can switch from completely off to on and vice versa.  Any lag time between the transistor being fully in the on or off state is termed 'dead time' and can cause signal distortion.

2. Distortion caused by the carrier frequency being too low- This is a possible form of distortion that georgehifi claims is audible but has never provided any valid evidence to support his claim.  Basically, he claims the ultra-sonic frequencies (typically in the 300-600 kHz range), that class D amps modulate to carry the audio signal and subsequently completely filter out the frequency leaving just the signal, are too low and somehow affect or distort frequencies in the uppermost audible frequency range.  He claims carrier frequencies need to be above at least 1 mHz in order not to affect or distort frequencies in the audible range.

     I've never subjectively perceived any distortions or sonic artifacts on the many class D amps I've owned or heard.  However,I know some amps are beginning to utilize the newer, ultra-fast switching GAN output transistors and I believe at least 1 company, Technics, offers a class D amp model with a carrier frequency above 1 mHz.

Tim

Hello atmashere,

     I'm always learning useful and interesting stuff from you.

Thank you,
   Tim

guidocorona:

"I cannot hear any trace of harmonic distortions on the 3rd or any other partials when I play music with my class D Rowland M925 monos or class D Rowland Daemon integrated.... Nor do they intermodulate. They are as sweet and stunning as can be."

+1  guidocorona

          I also hear no traces of harmonic distortions on the 3rd or any other partials when I play music with my, much less expensive, class D D-Sonic M3-600-M monos or 2 other class D amps that I formerly used for music but currently use for HT 5.1 surround sound, an Emerald Physics EP100.2-SE and a Class D Audio SDS-440-CS, which are both excellent performing and very reasonably priced stereo class D amps.

      In general, I view class D amps as an excellent alternative to the more traditional ss and tube amp types that represent a bit of a revolutionary approach and a breath of fresh air.  They're the very competent, silent, efficient, straight talking and cool running guys in the amp neighborhood who just even handedly and confidently tell us what's what without distortion or ever getting overheated.  

    No, they don't all sound the same, not everyone likes them, some refuse to even listen to them, some are prejudiced or jealous and others just bad mouth them out of habit.  But these confident, competent and cool guys don't care.  They know how good they already are, that they're constantly only getting even better and that their technological future is bright.

Tim