Could Class D really be that good?

Do you not know that within each class of amplification there are good and not so good designs. This also holds true in Class D amps.

@eddnog  I got in and pledged for two Monos with two 48v/5a PSUs. I felt fortunate making the last-minute decision and went with two independent PSUs because later today I saw this https://www.youtube.com/watch?v=wjWVSFCR5MI where the host experienced noise/interference issues using one block.

My nearfield desktop audio system is very crowded and had no space for an A/B or A amp of any kind when I switched to passive monitors ~6 years ago. Thus I was pushed into the alien (to me) world of class D amps. I did a ton of research, looking in particular for any class D amps described even occasionally as "musical" and pleasing to the ear. All that research led me to a gently used ICEPower design, the Wyred 4 Sound ST-500, which I sited standing on one side on my desk (w/the mfr’s OK). That cool running amp immediately worked well for me. It sounded great, had none of the obnoxious brightness and thin harmonics some ascribe to class Ds. Until a month ago I wasn’t tempted to change.

I never really stopped following class D, and had become curious about NCore modules used by various amp makers. The one other (to me, somewhat affordable) class D brand I read positive things about is Bel Canto. I looked for their stereo NCore amp, but instead found a cherry pair of 600M monos. After installing them  IMS, I can verify that they, too, sound quite musical. They have somewhat more resolution and better soundstaging than the ST-500, which is nice to have.

I got pushed into class D by space considerations but must say I’m quite impressed with the sound of the 3 examples I’ve used in my system. I've had 4 pairs of studio monitors here with these amps (ATCs, KEFs, Aerial Acoustics, Harbeths) and all worked extremely well with these amps.

Class D got better.

I had a Krell FPB 200:amp, with a Pass Labs Aleph P preamp driving a pair of Martin Logan ReQuest speakers, and a dealer talked me into trying a Peachtree Nova 220:se to replace my Krell am and Pass preamp. I was totally amazed at the sound quality and performance of the Peachtree integrated amp, which was a class d amp. I let my ears make the decision……I sold the Krell amp, and Pass Aleph P preamp and used the Peachtree from then on out. The Krell and Pass systems were both Stereophile grade A systems.

The first time I read the asr Link is today in the last few minutes, I am glad my description of listening to this Amp design, supplied Signal from a Vinyl Source and Soulution Pre Amp', seemingly suggests the measured performance is able to produce sound that is quite attractive to some individuals preferences for a produced sound.

Some of the Neurochrome owners I know, and have been instrumental in their becoming users of Neurochrome designs are now, seriously investigating (actually building) up to date designs from Purifi, which is the evolved design from Bruno Putzey. 

@pindac ,

That's terrific!

Thank you for taking the time to search this up.

@thecarpathian To acquire an answer to this inquiry, will take a little time as I am out of touch with the person who presented the Power Amp.

Plan B, I have trawled the mails of the Amp owner on their preferred forum, I am 99% sure the Link in the follow up post is the Amp I was able to be demo’d. ( I'll Post Link separately incase this post gets dumped if the link is refused). 

What I do know is the Amp’s were a Punt Purchase by an individual who is a adept EE and has a lot of DIY Builds under their belt. Also the Amp was purchased to be part of OB Speaker DSP Amp assembly.

The Amp was in the owners view so impressive for the outlay, the owner wanted it to be experienced as a Monoblock for the entirety of the Frequency Range.

I also know the Amp’s in question had a couple of changes to the original schematic/topology, as a few components were swapped for parts the Amp’s owner had in their spare parts collection. I recollect talk of a change in the Power Supply Module. I also know through the discussion had, that the changes were not expensive or complex and thought of as quite simplistic.

Whilst Trawling the Amp Owners mails, I have learned the Owner is now a vociferous advocate of the Neurochrome 686 Power Amp’s, I my self can not disagree, I have very positive indelible memories from all experiences had, where these Amp designs are used.

The Amp Owner makes the statement ’World Class for Extremely Sensible Monies’. To make such a statement is of interest, as one very good friend of this person, is the owner of LDA who does make World Class Amplification.

@lanx0003 I am not sure if it will be detrimental to performance, and I imagine a lot of factors come into play (efficiency/sensitivity of your speakers, listening volume level, driving impedance/load of the speakers, etc.). I didn’t see any results from anywhere testing the V3 Mono specifically with a 5A power supply versus a 10A, making it even more difficult to say.

-Ed

I have also made known on this forum in another thread about a Import Chinese Origin, Four Box Modular Class D Power Amp compared to a £50K Soulution Power Amp on a £200K system, or £150 400 system with the Import Amp.

@pindac ,

What is the name of the amp you're referring to?

@eddnog I am a bit lenient. Could always wait until June from Amazon. I plan to use a 48v/10a psu to power them with a splitter cable, primarily to save space. Do you think will that compromise SQ in any way?

@lanx0003 Yes, I am hoping to make that cut as well. I have a feeling first 200 will go FAST. I plan to get a pair without power supplies as I already have a pair of 48V/10A units that I currently use with my ZA3s. Once the V3 Monos arrive, I’ll roll over the op-amps to the new V3 Monos, put the stock op-amps back into the ZA3s and then sell them with the 48V/5A power supplies I have sitting around.

-Ed

@eddnog Yep, thank you for the reminder​​ Ed​​​​. 11 AM EDT. I had the site open. I was told biggest discount will be limited to the first 200 participants.

(disclaimer: I am not affiliated with FOSI)

@lanx0003 a little under 3 hours until the Kickstarter for V3 Mono opens up!!!

-Ed

I added a THD (%) scale, which corresponds to the dB scale, into the graph for comparing more affordable NAD C268 ($1k) and the Bel Canto S300iu ($2.5k) with the Fosi V3. As shown, the NAD C268 is comparable to the Fosi V3, but the Bel Canto is far inferior. Again, measurements do not mean everything, but the THD measure does give an indication of the sound clarity. I just provided you with the data in one place for your convenience, and it is your discretion how you interpret the data.

The gato dia 400s class d very good. 

After years of running different amp / int amp combos, tube and A/B solid state, I decided to try a low cost used Class D Int amp from Bel Canto S-300iu feeding ML Ethos. After 3 months I remain blown away by the clarity, imaging, (add other superlatives here)... My journey is over...class D works well.

I just bought a Nad c268, just to experiment with class D and to use as a second, or maybe third set up. I’m not using a conventional preamp, but instead running two sources into the amp. The sources, a Music Hall A3 Analogue phono stage, and a Smls Pl 200 top load cd player, both of which have their own volume controls. Thus far, I’m pretty well pleased with the sound, although not as good as my class A or class AB stuff (Sugden & Accuphase). I ended up buying a second Nad c268 to try bridging, as my Tannoys are a pretty stable load @ 8 ohms, and 89 dB sensitivity. I'll see how that goes. I'm hearing the cheap c268 has a warmer sound signature compared to its big brother, the c298, although that one looks real nice too. The Nad c268 has all kinds of options for its use, great versatility. Even ASR recomended it, lol. Not many reviews for it, as opposed to the c298. Guess I'm a guinea pig. 😃

There are plenty of low budget class D amps,integrated. If you want class D on another level such as AAvic 280 integrated you can get one for around $10 k 

I have heard side by side at audio gatherings in the last few months .

mmore power ,far lower noise floor because of many technologies and very natural.

one friend just traded in Luxmans top integrated for this ,

Boilder,pass labs Accuphase you name it even at $15k nothing betteredit in many to all areas . For one they use a nonmetallic cabinet ,No RF,no magnetism ,or vibration ,they use many Active Tesla coils to reduce noise in multiples .

Denmark audio group ,everything is built in synergy even their Ethernet switch, they all use similar technologies ,they change the sign wave for lower noise 

power supplies from Japan medical grade vs cheap switch mode types ,even on output special stage to ramp up current on demand as needed , their Axxis Forte series 1,2,3 has streamer,dac, and 100wpc integrated for $5500 very good ,

my brother has a whole system with the Borresen Loudspeakers in the Z series and Ansuz great Ethernet switch ,most people don’t realize,digital noise travels from house to house because it is not grounded, these guys solved this again starting with their own grounding methods and Tesla coils what a difference .

my brother had the $3k innuos Ethernet switch ,the $2500 Ansuz much better ,he traded it in and bought their mid grade D3 switch far better still ,and their cables are special, theD2 cables actually are active ground shielded to the switch,streaming now sounds like good Flac files or cd .thsts saying a lot , Their power cords and system cables are beating top Nordost and others and much less  $$

power cord same thing , I am very impressed ,Go out of your way to hear them .

i have heard all their X series speakers ,the $5500 stand mount with $1k stands can compete with any monitor 2x+ with Ease , i want  the X3 speakers but with new home addition and landscaping,not happening , Xmas 🎅 🎄 if I am lucky 🍀.

ricevs

1,442 posts

04-15-2024 at 01:33pm

Fosi V3 with a ton of mods is the best amp using a DAC that I have ever heard......and that includes my own wild dual mono Class A amps. Please see the bottom of this page for details and a pic.

http://tweakaudio.com/EVS-2/DIY_Bi-amped_super_speaker.html

My new open baffle speakers should be up and running next week.....check back for more info.....this is fun!

Fun writeup, that link, @ricevs . Thank you.

Closest I got to using cheap chip amp boards in my main setup was 3x units 36V 10A-powered TDA 7498E’s. Yeah, off the shelf direct-from-factory generic PSU’s - judge away 😜

I didn’t find a suitable multi-multi RCA’s-out passive preamp (and wasn’t set to conveniently make one), so I went back to integrated amps for convenience. At some point I aim to circle back to the chip amps. Sure was interesting to have vertically variable power to the “lines” be separate from DSP.

Although Perca ($$$10k) does not publish its load-dependent distortion level, its average THD of 0.0003% (corresponding to -110 dB) puts itself closely against the Benchmark AHB2 (0.0001% or -115 dB; $$3.5k). Perca's high efficiency lies in its inherent nature of being a class D design, whereas the AHB2 is essentially a class A/B (technically class H) design but manages to achieve 92% efficiency thanks to its 'railing modulation' technology implemented on its voltage stage. In practical terms, the AHB2 generates a lot less heat compared to regular class A/B and runs as cool as a class D. Therefore, I concur with a few folks saying that the dividing lines among classifications become less and less clear; i.e., the class A/B amplifiers can be very efficient, and vice versa, the class D can be as smooth/musical as the class A/B, even though the fundamental PWM output waveform remains unchanged.

To me, if I could afford a few grands for a high-fidelity, high-end amplifier, I would jump on the AHB2 any time. Not only is it much more affordable, but the inherently smoother sinusoidal sound wave also wins me over. Despite various types of modulation, filtering, and feedback techniques implemented on modern class D amplifiers to make them sound better, I still believe in retaining the purity of the original sound wave as the ultimate avenue to achieve ultimate sound quality.

As has been mentioned before, Class D continues to evolve.  But the company that brought the NCore module to the market (Hypex) has continued to refine and engineer the technology to impressive new levels.  With the introduction of the Mola Mola Perca stereo amplifier (Hypex's premium product and brand) we are now 5 generations beyond NCore.  The new modules being called Trajectum.  Putting the technical aspects aside for just a moment, the Perca stereo amp is simply a fantastic sounding amplifier, regardless of which class of operation the amplifier is based on.  To me, and those who have purchased or experienced it, the Perca represents the BEST of this technology, with the resulting sound quality as evidence.   

Is this thread studiously avoiding mention of Class D GanFets?

@eddnog 

I was further confirmed with the 4/20 on Kickstarter which is initially informed by @jackjohnson316 and Fosi also told me that it will hit Amazon in US on June.  I am interested in SS3602 myself too but wonder why don't you consider the 2nd SS3602 instead of V7 Vivids since SS3602 is half the price and the review is good?  How does SS3602 stack up with V7 Vivids?

No it can not but can be better than cheap inexpensive class A/B

I currently run the following chain and love it:

Musician Draco -> Schiit Freya+ rolled with matched quad Psvane CV181-T MkII tubes ->  a pair of Fosi ZA3 power amplifiers with rolled op-amps (Burson V7 Vivid in the left channel gain, Sparkos SS3602 in the XLR input) run as monoblocs in stereo mode each with a 48V/10A power supply -> LS50 Metas and also an SVS SB-3000 hooked up to the single ended outputs on the Freya+.

This chain absolutely blows away the same chain with a PS Audio GCC-100 in place of the Fosi amps. I am hotly anticipating the release of their V3 Monos, and am considering putting in a preorder, but I’ve been in touch with them and it looks like in order to roll op-amps, you will need a pair of the same ones for each amplifier in gain section and I’m not sure if I’m willing to invest in an extra pair of Burson V7 Vivids (I would roll over the op-amps from my current amps except I currently only have one pair of the Bursons).

-Ed

Fosi Audio V3 mono power Amplifier as mono blocks, xlr &rca inputs, with 300 watts balanced power coming to kickstarter April 20th. 

YES !!!! But you need some Tubey goodness or a damn good jfet input section or preamp.

Fosi V3 with a ton of mods is the best amp using a DAC that I have ever heard......and that includes my own wild dual mono Class A amps.  Please see the bottom of this page for details and a pic. 

http://tweakaudio.com/EVS-2/DIY_Bi-amped_super_speaker.html

My new open baffle speakers should be up and running next week.....check back for more info.....this is fun!

I heard a Belcanto class D amp with A $50K pair of Vimberg Floor standers. $10K  Gutwire Speaker cables. The system was in a smaller room, and sounded Amazing. I thought Class D was the bottom of the food chain, I was wrong. to be honest it sounded almost too perfect. 

Bear in mind a fully loaded PCP for a Purifi Design as a DIY Build / Commission Completion can be acquired for between £300 and £600.

I would think that if the casing is not OTT on the aesthetic, the end Amp will be close to the £1K pricing for the upper cost model, even with Pure Copper RCA / XLR used and PC Triple C used as Hook Up wiring.

When assembled in a Casing there is little to compete, unless another wad of £0000's is spent. 

I have also made known on this forum in another thread about a Import Chinese Origin, Four Box Modular Class D Power Amp compared to a £50K Soulution Power Amp on a £200K system, or £150 400 system with the Import Amp.

The system owner was completely bamboozled by the Import Amp being such a performer, the Soulution out performed it, but at £49 600 to attain the difference on offer. For the individual who was with the experience of the comparison, that becomes a very difficult decision to even consider.

Even more painful, is that on the same occasion, a Neurchrome 365 at approx' £2K built, at times with certain tracks  was much more attractive than the Soulution.   

I marvel similarly about high res 4K video streams on a good modern 4K tv. So much better than 20th century TV technology. 

I have bought 5 different TPA3255 amp boards and have built all 5.  I upgraded filtering on all of them.... I have found a reasonably small 10mfd cbb cap that I use on the inputs. I always upgrade the filter caps normally 63v caps, sometimes higher, but I switch them to the highest capacitance that I can get to fit.  I look at coil quality, occasionally replace those, but not always.  Outside of the input, I upgrade electrolytic to mkp/cbb where I can, If not, I upgrade the electrolytic and bypass with good caps (mkp or film & foil) on bottom of the board. Always make sure the 3255 chip is properly mounted and has decent heat distribution. I use 36 to 46v smps supplies that I add significant filtering between supply and board.  These amps have ranged anywhere from pretty good to flat out excellent.  I have 2 more in my sites.  I have enjoyed these amplifiers very much.  

Myself hear a Lot of gear and owned a Audio store for a decade.

Danish Audio Group  AAvic integrated amplifiers ,

and their  Great  Forte series that has integrated dac,and streamer the model 1 starting at $5500.  A bunch of trickle down technologies . Using multiples of different types of Active Tesla coils , better then anything  in its class.

just go out of your way to hear them. The Borresen X series Loudspeakers are true game  changers at their price point and above ,these guys are thinking way above the norm.

@hifinut51  There is a pre-out terminal on the back designed to bypass the amplifier's built-in power amplification stage.  SE only but, if you want xlr, go with Za3 which is supposed to similar SQ based on the review.

here's a PS to my comment The only thing I would change is I wouldn't get there wiring because OCC single crystal rectangular is far better and even the OCC single crystal round is better than anything OFC at any price

@lanx0003 does this integrated amp have a preamp bypass (HT) input?

Is it balanced or single -ended?

you should listen to the electronics from audio group Denmark their class d is phenomenal sounding haven't heard it in person but even online it sounds fantastic you can get a full system from there with their entry level stuff for between 30 and 50,000 I've heard the 50,000 and the $30,000 systems and they sound incredible especially for that money.

I won a V3 in a YouTube contest. Already had a cheap Fosi integrated amp, the TB10D driving some desktop PC speakers (repurposed crappy Polks suitable for PC audio) so I sold the TB10D to a coworker. Ended up getting the matching "tube input stage" P3 preamp. Think the combination is not as detailed as feeding the V3 directly, but it sounds nice.

I would simply say these cheap devices do their jobs but are not "giant killers". I’ve read where they have some issue with not controlling bass very well, especially on 4 Ohm speakers, but what can you expect for ~$100?

The TI 3255 chip in question is OK, but you can’t really compare it to a GREAT implementation of Class-D using Purifi, icePower, or Hypex chips (for a lot more money).

But hey, if these cheap Chi-Fi devices get someone started in audio, then good.

For desktop use (or in a garage or outbuilding) they serve a good purpose, but if I were putting together a low-cost "system", I’d look at cheap integrated receivers by Yamaha or Sony that offer a lot more connectivity, one even a phono stage, and legitimate remotes. Those can often be found for well under $200.

you should listen to the electronics from audio group Denmark their class d is phenomenal sounding haven't heard it in person but even online it sounds fantastic you can get a full system from there with their entry level stuff for between 30 and 50,000 I've heard the 50,000 and the $30,000 systems and they sound incredible especially for that money.

Class D, class A, class W...

Don’t care. That this is class D is of no relevance to me. What is relevant is if it sounds that good for that little lay out, I’m grabbing one just for the fun of it!

Might as well grab the preamp at $79 while I’m at it.

That’s still less than the cost of a nice dinner out.

@erik_squires I went back to you post (pls do the same) and found no mention of "sound quality" and "1990" How is one supposed to know what you were "trying" to say big shot. BTW, it is not an accurate statement that, back in 1990, the class D with PWM has already sound comparably well with sinusoidal sound wave.

@lanx0003 - Thanks for responding to a point I was not making.

I was trying to say that the subjective "sound quality" cliches that were made in the 1990's about Class D amps no longer apply today.  All the measurements you point out may be accurate but tell us little about how well a class of amplifier today may actually sound vs. another. 

@erik_squires 

The basic principle of classification still defines the efficiency, cost, and form factor of a power amplifier essentially. How the audio industry implements technology on top of and around this principle to make them perform well sonically in measurements and actual listening experience is still a ongoing progress, not a cliche understatement you were making at all. See below how the forthcoming Fosi V3 Mono (priced at $280/pair) bridges the gap nicely with the noise/distortion level of the state-of-the-art Benchmark AHB2 that costs $3,500.  

(from Amirm @ASR, April 2024)

@jasonbourne71 

Thank you for pointing me to ASR, where I found these charts that Amirm nicely made. I see that at the maximum power rating of 32 volts SMPS, the 48 volts SMPS does not have a few dB noise advantage. And the 48 volts block gives more headroom/current to serve the peak loads as well when called for. However, at my usual listening level, I don't crank the volume knob to acquire that much power, and I am craving for more clean power from LPS. Also, the op-amp rolling will potentially render sonic improvement just like tube rolling on the tube amp. We will see.

Try a Douk E6 in front of it with the upgrade that is referred to in certain posts.

I do think the Budget Class D and Budget DHT Pre will find a very pleasing synergy.

I put a few friends onto the E6, and one is after a period of trial, now seriously considering it for being a replacement for their Django TVC. This was unexpected, as I thought of the E6 as a very affordable dipping of ones toes into a DHT type Pre Amp.

The E6 was only presented to the group of friends, as another friend in the group, who is a very competent EE, has investigated quite a few £000's in another UK based EE's DHT Pre Amp Design, that was getting good appraisals during the  Honeymoon Period of its use. 

Not heard the DHT yet in any of the types now available, but do know the report on the UK based EE's design has claimed it has transformed SS Power Amp's relegated from the Top of the Listing for their favour to a whole new level of presentation that are very attractive when experienced.  

Nope Class A/B are best because that's what i have (LOL)

If companies like ATI ,  Atma-Sphere, Jeff Rowland , and even McIntosh are building them I would say they are...