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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
lanx0003 OP
819 posts
 

@pindac Truly amazing stuff that Audiophonics has accomplished. Built on Purifi/Hypex modules/ps, the HPA S400-ET has been highly praised by ASR based on its excellent measurements. The compact size version, LPA S400-ET, has almost identical specs and performance in a half-size chassis. Similar to the Fosi Mono, the S400-ET offers multiple gain settings, dual replaceable op-amps, XLR inputs, and quality parts inside. The upgraded binding posts in the back are attractive. The sound quality is also highly regarded, surpassing class A/B or even class A based on the limited reviews I could find. I really don’t need to repeat all the positive reviews, but without exception, let me include its performance curve in the chart for the last time before wrapping up. It is almost neck-and-neck there with the Benchmark. The Fosi Mono starts losing its pace at higher loads, but that’s understandable given its price disparity.

You know what? This beast only weighs 12 lbs, so I could easily carry it back on the next trip to France. I guess that is one of the advantages of class D.

 

There actually was an extensive discussion on Audiogon a year ago.

https://forum.audiogon.com/discussions/new-class-d-amplifiers/post?postid=2543479

 

 

pindac's avatar
pindac
2,864 posts
 

@lanx0003 In the not too distant, I will put up a link to a Build of the latest Purifi design I have linked previously within this thread.

There are already some build tweaks already known for this design and these are being incorporated into the build I am following.

When all is in use, I will ad the link to the build thread.

This as a design will be cheaper than the Audiophonics Option and be a few steps forward in the design choices. It may even be cheaper as a commission build, if the DIY idea is not appealing.

bolong
601 posts
 

Further miniaturization of everything everywhere is inevitable.

lanx0003 OP
819 posts
 

@pindac Please forward the link once you have it. I also dived into the DIY project based on Purifi 1ET400A and Hypex NC400. I am particularly interested in the hybrid one with tube buffer made by VTV. Although its price tag is relatively pricier, marrying a tube buffer might be a rather good idea. The idea is not new and, the more I think about it, the more I feel it is doable. We could biamp a tube amp (or low-wattage class A) and these powerful class D modules, where the tube amp/class A is used for the tweeter/midrange and the class D is used for the bass driver.  What do you think?

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