Class D Mono Blocks vs Class A/B

[vizcal]

Seeking advise from members . There has been lot of reviews about the trend of Class D switching Amps compared to A/B amps.
Have been told that Nuprime evolution one mono block, Legacy powerbloc 2, Benchmark AHB2 will out perform A/B Monoblock like Bryston cubed or even Tube mono blocks using KT150 Tubes. This is hard to believe unless my ears can listen to them. I don't have the opportunity to listen to the Class D. amps, unless I pay and return with in 30days for full refund only cost would be shipping the equipment back. Would love to simultaneous test but will not. have funds to buy couple at a time.

I presently have Auris Audio Forte 150 mono's powering Focal Sopra N3 speakers, Audiovale Eclipse preamp and.Linn Klimax DSM streamer/Dac.
I think as you get older the hearing is also undergoing changes. I am probably looking for more tonal detail in mids and highs rather than deep bass that I already have with my system. some of these lesser known companies that make Class D switching amps seem to have great product , may be not marketed well or they do direct selling. Some results are hard to believe on distortion level , S/N, some of them have even over 500 WPC that can drive any hungry speakers and priced at 25-40% of well known A/B amps. I am curious to hear the opinion from experienced fellow members. I have the time to do this now while maintaining social distance and playing safe .

 

[gds7368]

About 8 years ago I owned Nuforce Reference 18 class D monoblock amplfiers for a couple years, which I used in a 2nd system playing Gallo Reference 5LS speakers. While that wouldn’t be the most revealing setup, the amps were so light and portable that a few times I brought them for comparison to my main basement system to replace my Classe CA-M600 class A monoblock amplifiers (using the Classe amps as Nuforce amp stands!).

I really enjoyed my time with the Nuforce class D amps, and they did some things very well. The lower the frequency, the better they were. Bass was just wonderful though the highs didn’t sound as much like actual instruments as my reference class A amplifiers. For example, the leading edge of cymbals were a bit sharp, and violins were a touch etched rather than appropriately soft.

About 5 years I also had a one-month home comparison demo of the Devialet (class D) 200 vs Boulder (class AB) 865 integrated amplifier and came to a similar conclusion that the highs just weren’t as natural on the class D unit. However, not a fair comparison as the Devialet had a built-in DAC where the Boulder was paired with a Boulder CD player. So that’s not apples to apples and should probably be left out.

Class D and class A seem like opposition ends of the amplfier world - light/new/improving/often affordable vs traditional/hot/heavy/expensive. I found the strength of class D - all from memory - to be ease of use, fantastic bass, compact size/weight, and design (they looked great). If your musical priorities are just listening to and enjoying music, I would suggest a class D home demo. I’ve read good things about newer class D designs, like Bell Canto for example, but only in magazines that then sprout up adds by the same companies that just received a favorable review. I don’t know how difficult it would be to run a magazine, but such coincidence gives me pause. As an aside, I always wondered if pairing a class D amplifier with a tube preamplifier would soften those leading edges while still retaining the rock solid bass. Class D could look and function great in a modern home where WAF might kill a more traditional looking system, like right in the center of the living room. Where mine was.

 

[vizcal]

gds7368 I appreciate your feed back. 4years ago I had the Devialet 200, it was all in one box , very simplified in form and function, less bulky cluttering of wires, it was AD amp. Was pricy $10,000 CAN. Less than a year Devialet came out with an upgrade at a cost of $3500 CAN. It was not worth a upgrade ,I sold it.
I had the opportunity to try out the Nuprime IDA16. For 1/3 of the price of Devialet it was sonically stunning. I was very impressed it drove Focal Sopra N3 effortlessly. I bypassed the internal preamp using a tube pre amp. It made a lot of difference, brought out the details, vocal was warmer.
Then I decided to go fully tube path. Now that I want to go back to sleeker components I think Class D seems to be a good option. They seem to have good level of refinement and resolution, I wouldn't doubt they would be life like. They may not be quite like A/B amp brands which cost 5 times more. There could be subtle difference. I want to keep my budget below $8K CAN only for Mono amps.
I think I need to relay on my ears to try out at least 2 to 3 different Class D mono's. Most of the reviews almost looks have been paid to blabber tech details that are inaudible. The same reviewer contradicts his statement when he switches brands.

 

[musicfirst1]

I feel, having owned the best (IMHO) of both class D, class A/B and class A, that the middle and upper registers of all class D I've heard are quite simply not as good as current SOTA class A/B amps (I've owned my current (class A/B) Audionet AMPs, the MSB M203 class A amps, the Devialet D400 class A/Ds, and the Nuforce Ref9SE class Ds over the last 5 years). Respectfully, I think people who believe otherwise do not have the overall system resolution or have not heard the current crop of SOTA A/B amps to come to this conclusion. Of course, the SOTA continues to move in almost all aspects of amplification, so my opinion will most likely change and or shift.

 

[Golum]

Maybe I can chime in with my first hand experience on this topic. Namely I have ARC Ref75 power amp with KT150 tubes and D class power amp based on latest Ice modules 1200s2. Both of them are being driven with ARC Ref6 preamp. Beauty of the thing is that Ref6 has two power amp outputs so my both power amps are connected at the same time and depending on the mood I turn on either D class or Tube one, while just quickly swapping speaker cables at the speaker end.
As such I was the one being super skeptical regarding the D class, but truth to be told, with this power amp I feel no remorse having it in the system and I can not hear no major drawbacks vs Ref75 (if any).
I have several friends using same D class power amp (with great systems) owing great tube preamplifiers and the results are just great/fantastic as this particular one is extremely neutral as such and based on what you feed him you have the according end result.
Just my two cents on this one...

 

[Sablon Audio]

@vizcal, I have owned a wide variety of tube amps followed by a few class d models but would recommend that you look into the latest GaN options as this technology seems very promising. The cheapest commercial entry point would be the Orchard Bosc monoblocks though I have a Java integrated on order which combines GaN output stage with an LDR volume control.

 

[vizcal]

@Golum - what class D power amp are you referring to?

 

[wisnon]

@Golum - what class D power amp are you referring to?

Acoustic Invader.

 

[shakti]

as with all amps: It is not! the technology in use, which makes a difference, it is the quality of implementation.

Everybody is a ware, that tube amps can sound different.
Even in the top end, you can discuss hours about the difference of Kagura and Engstroem monos.
The difference between the two starts, that they have different preamplifier requirements, So the best for Kagura might not be the best for Engstroem.

Same Same for Class a and Class A/B comparisons.

I joined many amplifier shoot outs. Mostly the amplifier won, where the best pairing with the Preamplifer was given.

If you want to understand Class D, you have to see the differences first. Hypex, ICE, and so on do sell modules.
But due to different implementation, they can sound very different.
(please compare to a KRON 300B tube. it is always the same tube, but in different amps, the result, the sound can be very different)

Personally I do not like Devialet too much. They have a sounding to be warm and cosy, but still have no resolution at all....
a Tube amp like NAT is more neutral and has higher resolution...

My last experience with classD was, as I visited a dealer to listen to Goldmund Telos 2500 monos. I was not really satisfied, so I asked, if the dealer can switch on a Jeff Rowland Amp for comparison purpose. At that time I was not really familiar with the current JRDG line up. The stereo amp was great, for my ears much better than the Goldmund. So I did a spontaneous buy.
At home I found out, that I bought a JRDG M825 class D! amp.

And this amp makes me happy until today (being paired with a matching PreAmp from JRDG)

My music gear is switched on every day like 14 hours. Means I do enjoy the low power consumption of the class D amp as well

So if someone is interested in class D: Give it a fair chance, Do not look for the cheapest solution to get the newest module from Hypex or ICE, try to find the best implementation instead, even, if it is an older class D module. And pair it with the best matching preamp!

 

[analyzer]

Generally speaking, my esperience varying in the past generation of class D amps. I listened and tried a few of these based on ICE Power modules and Hypex. I had Kharma, Belcanto ref, Nuforce until model 9, and a few others.
I confirm all you can read in the web: superb bass, firm and accurate in lower octaves (so... extension) and especially in how they are able to distinguish the bass lines, very articulated, also attack is excellent.
They slightly fall in the critical medium/mediumhigh frequency where strings, violins, and especially the pianos are often tonally edged and shifted, a sort of un-natural imprint that afflicts just a few classes of instruments. On the contrary brass and trumpets I find that are more convincingly and realistic.
Furthermore, I found that if detail is generally preserved in an Easy listening and pop-rock music. When the music begun complex and with more instruments sections (i.e. a great Symphonic orchestra) class D amps are less revealing; second orchestral lines or sections that plays softer are less audible and with a sort of approximation; this is strange to me but at my ears Is clear and also decay and ambient noises are fastly truncated as the amp was running too fast.
I Hope that my English is not too bad to understand my opinion...
Marco

 

[musicfirst1]

Generally speaking, my esperience varying in the past generation of class D amps. I listened and tried a few of these based on ICE Power modules and Hypex. I had Kharma, Belcanto ref, Nuforce until model 9, and a few others.
I confirm all you can read in the web: superb bass, firm and accurate in lower octaves (so... extension) and especially in how they are able to distinguish the bass lines, very articulated, also attack is excellent.
They slightly fall in the critical medium/mediumhigh frequency where strings, violins, and especially the pianos are often tonally edged and shifted, a sort of un-natural imprint that afflicts just a few classes of instruments. On the contrary brass and trumpets I find that are more convincingly and realistic.
Furthermore, I found that if detail is generally preserved in an Easy listening and pop-rock music. When the music begun complex and with more instruments sections (i.e. a great Symphonic orchestra) class D amps are less revealing; second orchestral lines or sections that plays softer are less audible and with a sort of approximation; this is strange to me but at my ears Is clear and also decay and ambient noises are fastly truncated as the amp was running too fast.
I Hope that my English is not too bad to understand my opinion...
Marco

This is an excellent description Marco, and I hear what you hear, but I also realize that I have not heard the latest generation of class D. It will be interesting to hear if the latest gens address these issues.

 

[vizcal]

I appreciate members voices on ClassD. I am better understanding that Class D, does not necessarily mean full digital like Devialet, with newer design using audio signal modulation other than Ice and Hypex ,sound almost like tube . I agree with shakti preamp plays a big role.
My opinion the marketing and advertisement of Class D is nearly not as good compared to the 'big players'. Probably dealers/retailers mark up is not as much and they also sell factory direct. Why would a dealer forgo his 30-40% margin selling cheaper Class D. I now see more online dealers pushing Class D Amps. Some of them are so confident they offer 30 days return policy. Hifi Audiophile have their ears trained for inaudible details that represents numbers on spec that most people don't hear.

 

[hifinutt]

Had 2 lots of class d amps recently [ one set of modest monoblocks ] . totally surprised me in that the icepower asx50 mono`s were actually warm sounding . I have been researching the benchmark ahb2 , this amp measures incredibly well but a reviewer I have great regard for wrote some interesting views in a review in hi fi critic .

this is what i wrote on one forum

I am researching a class AB amp 3.3k with a switch mode power supply that gives 190 watts into 4 ohms , currently that measures incredibly on the audio science review forum , you may know this forum is pretty hard hitting with a lot of stuff . This same well measured amp in a review from chris bryant who is well known .
these are his thoughts [ excerpts]
"The initial impression was that this power amplifier sounded incredibly clean and detailed and its silent backgrounds were very welcome . it drives speakers well .... The bass is quite solid but pitch changes and transient edges arn`t particularly well defined so there`s a loss of tunefullness,........
The midrange lacks both the fine timing detail and the micro dynamic structure that lets you know precisely what the musician intended . ...It sounds a little forward in the upper midrange and the lower treble has a mildly hard and forced impression. In my opinion this ..... is unable to render complex music to the standard of good integrated amps like the naim supernait 2 ....
I spent an extended period listening to a wide variety of music types covering most forms , but remained a little dissapointed . I tried other pre amps , both active and passive including auto-formers but failed to achieve the desired results
Everybody`s frame of reference is different so if intense detail and raw power that this amp is cabable of delivering is all that is needed, then it would score quite highly
This amp simply failed to hold my attention when compared to the best at its price point . And with this set up driving the very low distortion Magico M5 loudspeakers , its possible to experience one of the lowest distortion audio systems around and almost certainly the lowest i`d heard to date . But it failed to impress in terms of musical involvement attaining an overall score of just 45 points . "
I may try this amp at some point but it is interesting that an amp that measures so well fails to catch this guys attention

this is what the audioscience review said

I hope your jaw is on the floor just like mine was when I saw this picture emerge! 113 dB THD+N in a power amplifier? Are you kidding me?
Look at the harmonic distortion. The worst case spike is below -130 dB! This is insanely good. Of course this type of SINAD (signal and noise ratio) crowns the Benchmark AHB2 as the best I have ever tested:
The performance was so good I literally had to rebuild my dummy load to get there. Even the quality of the metal used in the connectors matters to get to this level of distortion. I replace all my dummy loads with higher precision ones that have much less VCR (voltage coefficient of resistance). Resistor values can become voltage dependent creating distortions of their own. Up to about 105 dB of THD+N, it doesn't matter but beyond that, the VCR was the dominant distortion, not the Benchmark AHB2 amplifier!
Even in high gain, the AHB2 easily outperforms the DIY Hypex NC400 I had tested before which used to be the best amp I had tested.
https://www.audiosciencereview.com/...-and-measurements-of-benchmark-ahb2-amp.7628/

 

[hifinutt]

So far with my horns class d have been good 95% of the time , amazing air and sense of palpable realism BUT not as forgiving and unbelievably real as the Silbatone valve hybrid . That is ahead in terms of vocals and violin and playing old recordings , the class d on the horns got a bit hard with violins . but if you played rodrigo y gabriela it was utterly spellbinding with the class D [ bel canto ref 500s 2.5k power amp]

The Silbatone [10.5k] just did EVERYThing well . So far out of the many amps from naim , lavardin , firebottle, schiit , arcam , sugden , i am still trying to find an affordable amp that gives enough zing to make those drums come alive , enough holographics to make you feel you are there . Currently its not too bad with the organic bel canto pre 3 vbs and an arcam a85 used as a power amp , strangely the arcam despite its lowly cost has been one of the best matches

Its a different story with the tannoys , they sound 100% superb with the same class D amps and are totally different to the horns , zing, presence , holographics and engaging sound without sending you to total boredom

Vizcal... tread very carefully with the focals , having had 2 sets including utopia . If you can have a look at some gato pwr 222 monoblocks which are class AB

 

[Gregadd]

I prefer a/b tubes.
However at CAF 2019 Gary(Genesis) was running a very nice pair of class D monoblocks. Very nice. See my report.
Update: Merril Audio

 

[Kal Rubinson]

There has been lot of reviews about the trend of Class D switching Amps compared to A/B amps.
Have been told that Nuprime evolution one mono block, Legacy powerbloc 2, Benchmark AHB2 will out perform A/B Monoblock like Bryston cubed or even Tube mono blocks using KT150 Tubes.

First of all, the Benchmark AHB2 is, despite its small size, not Class D. Benchmark describes it this way:

The audio path in the AHB2 is an entirely linear design. It uses a parallel structure that includes a class-AB amplifier and a class-A feed-forward correction amplifier. The class-AB amplifier operates inside of class-H tracking rails that are also fully linear. The tracking rails provide efficiency that approaches that of a class-D amplifier while entirely avoiding the noise and distortion produced by class-D designs.

The important difference between the AHB2 and class-D amplifiers is that the AHB2 does not produce switching noise. Class-D amplifiers are measured with brick-wall AES17 filters that ignore the switching noise above 20 kHz or 40 kHz.

Second, it is a brilliantly transparent device and, imho, those who are disappointed because it fails "to hold my attention" are looking for something other than that.

 

[CKKeung]

Seeking advise from members . There has been lot of reviews about the trend of Class D switching Amps compared to A/B amps.
Have been told that Nuprime evolution one mono block, Legacy powerbloc 2, Benchmark AHB2 will out perform A/B Monoblock like Bryston cubed or even Tube mono blocks using KT150 Tubes. This is hard to believe unless my ears can listen to them. I don't have the opportunity to listen to the Class D. amps, unless I pay and return with in 30days for full refund only cost would be shipping the equipment back. Would love to simultaneous test but will not. have funds to buy couple at a time.

I presently have Auris Audio Forte 150 mono's powering Focal Sopra N3 speakers, Audiovale Eclipse preamp and.Linn Klimax DSM streamer/Dac.
I think as you get older the hearing is also undergoing changes. I am probably looking for more tonal detail in mids and highs rather than deep bass that I already have with my system. some of these lesser known companies that make Class D switching amps seem to have great product , may be not marketed well or they do direct selling. Some results are hard to believe on distortion level , S/N, some of them have even over 500 WPC that can drive any hungry speakers and priced at 25-40% of well known A/B amps. I am curious to hear the opinion from experienced fellow members. I have the time to do this now while maintaining social distance and playing safe .

Hello Vizcal,
The new Gallium Nitride transistor amps and those with the new Purifi modules shall be your investigation targets.

I wrote short comments on the former (Merrill Audio Element Series).
And will try to listen to the latter once I have got the opportunity in Hong Kong.

 

[vizcal]

I am so grateful to all the responses from experienced members. Your feedback is of great help. I am going to try out couple of the ClassD amps.
I love my tube mono blocks but want to have a set of SS mono block to switch with between them. I was never found of Bryston found them very metallic but I was told the Cubed version has sonic improvement. Good thing about Bryston is they hold value unlike the newer Class D amps.

 

[Ron Resnick]

. . . It is not! the technology in use, which makes a difference, it is the quality of implementation.

. . .

+1

 

[hifinutt]

you can read the review of the benchmark amp in hi fi critic which is a pretty highly regarded amp , the reviewer was involved with my msb amps in the past

https://www.hificritic.com/store/p130/HIFICRITIC_Vol_10_No_2.html

at the end of the day its what works in your system that matters

if you get a chance to hear some silbatone amps that will blow you away and work exceedingly well with your Focals

https://www.whatsbestforum.com/threads/new-silbatone-amps-for-2020.29665/