Class D Technology

Ah I see now glofi .    Let us know when you get it right.  

I've heard the Benchmark amp and was very impressed. 

I've observed part of the maturing  of Class D technology in recent years is that noise as Atmasphere mentions is a valid concern that may have been a more common issue earlier on in some cases when not handled properly but should not be and is not in practice an issue normally anymore with newer well designed and properly functioning Class D amps.

My advice for anyone on the fence is do your homework, listen and decide for yourself.   Only then will you know.

Well nothing’s perfect but in all honesty gotta say that Class D done well comes about as close in all ways that matter  as anything I’ve experienced in home/high end audio. Even without breaking the bank in some cases. If I were competing with it these days rather than benefiting I would definitely consider it a threat to my existence and take actions accordingly.

I think were already seeing digital/Class D integrated amps make significant headway. The technology is so good already (low noise floor and distortion compared to separates) that I see no need for a separate pre-amp these days anymore quite frankly. When time comes to replace my current pre-amp I will likely just go with a Class D integrated of some sort based on my experience to-date with digital Class D integrated in my second system.

Don’t listen to the negative propaganda especially from just one or two who repeat the same thing over and over. Just try them for yourselves if interested and see.

Myself, I’ve had way less trouble finding top notch sounding Class D amps than others. Will probably never go back to anything else. If I had unlimited budget and/or went only with very easy load speakers, perhaps it might be easier to find other amps to match overall performance and sound quality I have experienced with Class D. But even so I have no reason to ever go back to anything else. My Class D amps do it all as well or better than anything else I have heard in recent years. If I were to seek a particular unique flavor of sound only available with a tube amp, maybe.

A good Class D amp is like a high performance car engine. it makes the entire experience a lot more effortless and enjoyable. Those who discount or ignore the advantages inherent in newer more efficient and overall higher performance Class D technology are doing others a disservice. I know I’m glad I went with my gut which told me to actually see what this popular and innovative newer technology is actually capable of before resorting to older more familiar solutions that never seemed able to fit the bill for me 100%.

I do not have "ice modules" . i have stated repeatedly I have BelCanto Ref1000m amps. These use ice modules but also custom input and power circuitry and the price and sound reflects that accordingly.

Again generalizing and glazing over facts and details to help an argument helps nobody and is a disservice.

I would likely not have been satisfied using that older revision of vanilla Ice modules to drive my speakers which is why I opted for a better design. The original Bel Canto ref1000 was vanilla icepower (and much cheaper) and the differences between the two are well documented.


I don’t know what KEF uses or why. Its their choice so better to ask them. Probably just easier or cheaper or better for them to biamp in general which opens up options to use different amps for different purposes rather than try to get either one to do it all best at their price point. I’ve heard those those KEFs in my home and they are small power and current hungry speakers.   I'd definitely use Class D for teh bass with them but if biamped then many decent options for the less demanding  (power and current-wise) high end.

Can someone tell me what can be observed when measuring a class a/b amp that indicates its inferiority to pure class A?

I am off the opinion that Class A is the bomb when possible. However  class A amps to power less efficient speakers are large heavy expensive and power hungry.   So enter Class D as a practical option to inherently inferior (to class a amps) class ab amps. 

Here is another argument for Class D. It can be argued that once you get the bass right the rest is not so hard to sort out. I have found a lot of truth to that in recent years. Efficient Class D amps are both on paper and in practice hands down best at handling bass. That seems to be common knowledge based on application and sure enough I have found it to be true in practice. In a nutshell that’s mainly because of Class D high efficiency and the fact that doing extended bass well is exponentially more work for an amp than doing higher frequencies and efficient amps do it best. Just like efficient speakers make it easier for an amp to do bass well. The end result when done right (ie sufficient efficiency or efficiencies in play to facilitate doing the needed work) tends to sound similarly good in the end I find.

Erik I’m just trying to frame up the comparison between the various amp technologies in purely technical terms as an extension of georgelofis argument against Class D based purely on switching frequency.

I am of the mindset that understanding the technology helps to make decisions where needed but alone does not dictate what sounds best in the end. Technology alone cannot predict what sounds best in specific cases. A system together makes the sound not just one component. Its a team sport as they say. Plus individual preferences vary for many reasons though some technical people have a greater tendency to associate these with specific aspects of technology that matter to them whereas others (I’d like to think myself included) are not so fast to jump to conclusions.

So I think we are on the same page in practice.

Guess what? My Class D amps were preceded by two different Class A amps that were fine on their own terms but far from perfect in my application. The Class A amps were preceeded by many a Class A/B amp and even a 70’s vintage Class G that was nice overall in its day especially if space is limited but sound quality could not hold a bone compared to any good quality newer amp I compared it to.

I heard the Benchmark amp at Capital Audiofest last summer (along with every other kind of amp imaginable) and thought it to be a top performer easily in the same league with the best I heard there.  I would own it in a heartbeat.   I am strongly considering giving Benchmark preamp/DAC units I heard there a try which if if successful (as I expect it would be)  would finally happily eliminate the last tubed  gear in my house.  I'm all about the sound.   The technology used is just a means to the end.

Erik it seems reasonable to me to say Class A/B is technically inherently inferior to Class A for the reasons you cited. IS not good Class A always preferred over Class A/B for sound for the technical reasons you cited? Class A/B is used to keep cost power demands and size and weight down for the masses mainly (sound familiar?), not for better sound or performance. Whereas Class D is totally different and can actually challenge Class A especially as the technology continues to improve even further. Of course I prefer my Class D amps over any Class A/B amp I’ve tried already and even a lesser Class A I once owned.

The most unique value of Class D is when much power and current is needed (mainly for bass) as in case of many smaller more extended less efficient speakers that many prefer. As speakers get bigger, loads easier, and efficiency higher, then most any good quality amp can perform well without being too large, heavy and expensive for most, although each will still probably sound different and individual considerations including personal preferences come into play.

So practically, it really pays to decide what one wants or needs the physical profile of their gear to be to meet their needs then choose speakers and amps together accordingly to meet those needs. This practically is the most important thing to consider together I would say way more than any particular technical achiilles heel of any specific amp technology one might obsess on.

No amp including most Class A amps I would say are perfect so choose your poison.

In general., I find Class D amps are the best of all at taking total complete control of speaker which I find tends to yield the best results possible. The result is greater articulation and detail in the bass and a cleaner more dimensional sound overall. Cleaning up/controlling teh bass prevents masking detail at higher frequencies often buried by poor quality or muddy bass when amp is not up to the task of totally controlling the speakers, especially at the low end which is the most demanding and requires an amp to work hardest. Class D amps are MOST efficient and that helps enable achieve this more often than not compared to the competition I would say.

Bass reproduction requires the most work by far and is the biggest challenge for most amps. Class D does this best. For higher frequencies, other amps perform well as do the better Class D amps around these days so not as much to differentiate the technology there although skeptics will attack class D high end as its relative weakness which is a fair statement at least historically. But that "weakness" is one that seems to not matter at all practically as best I can tell these days. Even my modest newer BelCanto C5i integrated that I picked up for a mere $1000 used seems to have gotten everything just about as right as possible and that is a complete integrated amp with phono and DAC 60 watt amp and headphone amp. Its easily as good sounding as anything I have heard within its modest 60w/ch power limitation which will come into play in some cases. OF course no single sound will appease everyone so YM will always vary.

I think Grannyring is right. Even the fairly modest Bel Canto c5i digital integrated amp is evidence of the excellence that can be achieved with newer digital technologies integrated and done well and that it need not cost a fortune. It is a true revelation of the magnitude say of HDTV compared to what was prior. Totally disruptive of what came before and not just another minor tweak or minor improvement on older technologies.

The useful purpose of a custom input stage on most Icepower amps is to raise the input impedance  (10K to start with on older versions at least) to enable good performance with higher output impedance tube pre-amplifiers. Its a performance/integration enhancement not just there for "coloration". If pre-amp is lower output impedance SS there is no benefit at least on paper.

Benefits of improved power supply in any amplifier should be obvious.

Hifi sound is best when low distortion, effortless and dynamic. I experienced this as hoped in my larger room with larger speakers in particular when moved to 500w/ch Class D amps, but power and current hungry smaller monitors (more limited output in comparison) benefited similarly as well.

When I sold hifi back in 1978 (Tech Hifi), we had amps from 15 to 120w/ch available for comparison from many of the top lines of the day in a decent sized showroom.

Guess what? With any kind of decent speaker, the 120 w/ch model in a line always sounded best. Assuming realistic levels and dynamics matter. If not, or room is small, then not such a big deal.

Check this out:

http://www.enjoythemusic.com/magazine/equipment/0216/D_Sonic_M3_3000S_Dual_Mono_Amplifier_Review.htm

Them’s a lot of notes in the sound ratings at the bottom of the article!

Why would anyone with a need for monster power to drive their speakers best not consider something like this? The potential upside is huge for many.

Disclaimer: I am not that familiar with Dsonic, just citing this article as reference. Do not know return policy, customer service quality, etc., all things that matter.

I used to covet the Micro Seiki tables but they were out of my price range back then. I settled for a very nice affordable and snazzy Philips 312.

My system I bought while there (dorm room sized) was Hitachi 802 Class G receiver, Phillps 312 table, Grado cart, Aiwa AD6550 cassette deck ( I loved that sexy beast), and OHM L speakers. Still have the OHM Ls that I’ve maintained and upgraded myself since. They can still compete and sound better than ever with my Class D amps.

I upgraded to a Tandberg tr2080 receiver I also coveted while at tech a couple years later bought at Leonard Radio on Route 17 in paramus NJ, a wonderful local shop  at the time.

Geekboy I run arc sp16 tube preamp and mhdt Constantine DAC into my Bel Canto ref1000m amps. Also a Bel Canto c5i integrated in my second smaller system. . I spend many hours just listening and enjoying more so than ever. Class D amps and my Ohm Walsh style speakers together are the most likely to not be replaced anytime soon at this point.

BTW I have used Triangle Titus monitors now for many years with a lot of gear and these are currently running of Bel Canto C5i Class D integrated and the sound with these tiny very resolving monitors is the best ever. Absolutely no signs of brightness or edge which I have found to be possible with many amps.  The sound is just lovely overall. Same true with Dynaudio Contour 1.3mkII monitors I’ve used with the C5i. Both Dynaudio and Triangle sound absolutely marvelous with c5i (as do OHM Walsh speakers) but I lean towards the Triangles over the Dynaudios with the c5i mainly because they are more efficient than the Dynaudios and the 60 w/ch output of the c5i is plenty for the Triangles whereas the less efficient Dynaudios are not fully engaged with only 60w/ch.

erik last McIntosh demo I had was with Totem Mani 2 and other newer Totems. It was somewhat bright and glaring compared to other Totem demos I had heard. Other than that the Mani 2s left an impression and remain on my list of speakers I would like to own, especially with the right amp to make them shine.

I’ve also heard Goldenear Aeon monitors with folded ribbon tweets off NAD amps and there was no edge or glare at all there. In fact fatigue factor was extremely low, towards the polite side. I liked the Aeons a lot as well.

Its usually all in how well matched things are to work together in a manner that performs well and also suits the listener’s preferences (two different but related things).

erik can’t say for sure based on one or two example demos. These were about 3 years ago with newer larger SS Mc amps.

Personally I often would like to be able to hear an edge that’s not muted if in teh recording. Not in everything played categorically though. The Mcs would probably have been fine for this if set up the way I liked rather than how the dealer decided to do it.


Guaranteed the edge would be less on my OHM speakers versus with Totem or Dynaudio or many others that are not inherently more laid back in presentation. Only some modern pop .mp3 files I play from time to time have any edge at all with the OHMs. Much more so with Dynaudios in my smaller room with speakers not far from listening poisition and off same Class D amp. Most .mp3s which are inherently known for artifacts that can contribute to harshness/brightness are still quite listenable.


I’m a purest but not a pure purist.

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?

That will be interesting. 

I have a 40w/ch $85 Fosi Class D integrated amp with Bluetooth in use that sounds really good driving a vintage pair of Boston A40s. Audiophile worthy even, as long as you don’t ask too much of it. Cleaner/Better sounding than most comparable powered vintage receivers for sure. A better power supply would make it even better but add some cost. The TI chip used supports delivering even more power if wired up properly for that. It’s about the size of a pack of cigarettes to boot. So not a lot of bling, but otherwise....