Could Class D really be that good?


I've heard statements praising modern class D amplifiers all the time but was sort of hesitant to try. Lately, one particular model caught my eye, the Fosi V3, which costs sub $100 but is praised for having refined sound like class A/B. To fulfill my curiosity, I quickly ordered one and tried it with my Burchardt S400II and Wharfedale Linton speakers. Basically, this is a neutral sounding amp but, to my surprise, the sound is clean, open, airy, with full mids, wide soundstage, good imaging/separation, with nearly null traces of the edginess, dryness, or lean sound that traditional class D amplifiers have. The background is just as quiet as my current systems. The core is the TPA 3255 chip from TI and comes with a 32v, 5A power block, which is supposed to deliver approximately 65 watts per channel (into 8 ohms). It drives the S400II/Linton without any hesitation, as well as my 130-watt-per-channel high-current Parasound A23. Very impressive.

Measurement is not everything. However, according to the lab test results, when operated under 10-60 watts, the distortion level (THD) is below 0.003%, better than a lot of high-end (price) gears. I am going to build around it for my fourth system with upgraded op-amp and LPS. I believe it will outperform my current mid-end (price) amplifiers.

I know, I know, quite a few Audiogoners' systems are above $100k, and mentioning this kind of little giant that costs a fraction could be rather embarrassing. But I thought this is just like gold digging with a lot of surprises and fun. Don't you think?

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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.

 

 

ricevs

1,442 posts

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.

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 🍀.

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. 😃

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.