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?
Erin just shows the test result today. 'Single' means single amp fed by 48v, 5A psu and 'Double' means double amps fed by 48v, 10A psu. Having individual 48v, 5A psu feeding to the v3 mono does have 10dB advantage in THD. Interesting.
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@lanx0003 well…guess I should be glad that I went with the dual 48V/5A option, then! Granted, I always believed that in the spirit of actually running separate monoblocs, it would imply powering them with actually separate power supplies as well. It should not be a huge surprise that there are actual benefits to doing it this way. The detriment is always to the wallet, yeah? But in the grand scheme of our beautiful hobby, this specific cost difference isn’t all that huge. -Ed |
@eddnog Same here. I made a last-minute switch to the separates based on my instinct. I recalled that the overall package deals were identical during the pledge. |
This statement contradicts this one:
I have found over the years that when someone is willing to contradict themselves in an argument, its never about the truth of the matter; its only about trying to make the other person wrong.
(emphasis added) Despite the obvious syntax error, the above statement suggests that no attempt was made to measure any of the changes introduced. The reason you would want to do measurements after changing anything in a class D circuit is noise and parasitics can show up, which can interfere with other equipment, for example an FM tuner or digital equipment sitting nearby. Bruno, the designer of the Purifi and Hypex modules, is very emphatic about this in his papers. @lanx0003 BTW, if anyone tells you they have 6N (6 Nines, IOW 99.9999% copper) copper wire, if you are in their presence it might be sensible to turn and run as hard as you can. 6Ns copper is a myth; it does not exist. Wire manufacturers just laugh if you suggest this sort of thing to them. What is real is OFC (Oxygen Free Copper), which was not developed for audiophile applications (see the link). |
