2. amps-preamps
  3. 189470-161121

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?

lanx0003
atmasphere's avatar
atmasphere
11,841 posts
 

@lanx0003 The differences you hear in the sound of amps, if FR isn't an issue (which most of the time it isn't) is the difference in distortion of whatever amps are being compared.

There are three things that define those differences. What frequency, if any, that distortion rises (IMO/IME this aspect of amplifier distortion is the most important), the distortion spectra and finally how much distortion. There's no filter that would make a solid state amp sound like tubes; just the distortion signature. So if a class D has the same distortion signature as a good tube amp, it will sound like a  good tube amp simply on that account. 

This is because our ears use harmonics to identify any sound. So you can see that if an amp is to sound musical, its distortion signature must be as innocuous as possible. To that end, the 2nd or 3rd must be significantly higher amplitude than succeeding orders, so as to mask them. That is literally what has kept tubes in business these last 60 years.

 

tubeguy80
84 posts
 

I agree that class D is well past the point of being "mature", by at least a few generations at this point. Class D amps can be amazing, or sometimes mediocre, just like tube designs or class A etc.

Nice to see quality become available at such a low price like this amp. I'll be looking into it for a small bedroom system.

pindac's avatar
pindac
2,864 posts
 

@tubeguy80 DIY Audio Forum, will offer up extended info from builders on these Amp Designs, Bruno Putzey is  a point of reference.

jonasandezekiel
158 posts
 

I’ve really grown to like class d, and I’ve certainly noticed how different modules bring a differing palate of sound to your speakers. They can be neutral as heck, or, like the older ICEpower modules, have tons of slam. Having said that, has anyone tried to contact Red Dragon audio? I’ve sent the guy several emails, and no response. Are they going out of business? I was interested in one of their amps, because based on the reviews I’ve read, they seem to have the sound signature that I like from class d. 
Any info would be appreciated.

cdc
1,792 posts
 

Let's get real. While the Fosi stuff is good, especially for the money, amps such as Technics SU-G700M2 at 10x the cost are 2-3x better.

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