2. amps-preamps
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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
asctim
479 posts
 

I don’t know how to get those results that will put my name in lights. If I did, I’d do it. The method is easy, just do double blind tests on signals that measure identically and show that people are statistically identifying them correctly as different. The method is easy. Getting the result is the hard part.

As for op-amps, if you just swap different op-amps in and out of a circuit, it is not too unlikely that significant changes might occur that can be audible - and measurable. Op-amps need to be in a circuit designed for them to be transparent. So yes, it is generally agreed that if you want to tweak the sound, you have a good chance of doing so by randomly popping new op-amps into a circuit without adjusting the circuit accordingly. You may hear something you really like!

lanx0003 OP
832 posts
 

Agreed on the audible improvements, though I'm not sure about measurable evidence, as I couldn't find any supporting data. Nevertheless, I recently swapped in an op amp called "Oracle II dual" on the Fosi V3, based on the recommendation from VirtualHiFi.

https://www.youtube.com/watch?v=kNDX7SCN6Jc  

These Oracle op amps were made in China and shipped from there, so the wait time might be a bit longer. However, they arrived earlier than expected. The build quality seems better than most cheap op amps, which often have flaky pins. The No. 1 pin, which needs to be aligned with the notch on the riser supporting the default op amp, is marked by a dot on the upper face. Ensure you have oriented it correctly. Other than that, the installation is pretty straightforward.

Immediately after switching on the "new" Fosi V3, I noticed a more immersive soundstage that extends beyond my speakers, with noticeably better separation. The bass also goes a bit deeper. However, it still doesn't completely eliminate the undesirable sibilance. But, considering these are $28 op amps, I might be asking too much. The well-known Sparkos 3602 might perform better, but it costs more than what I paid for the amp. Overall, my experience with the Fosi V3, paired with the Oracle II and Wiim Pro Plus combo, is very positive. I would recommend it to anyone looking to explore low-end (pricewise) Hi-Fi gear without reservation.

@asctim As for op-amps, if you just swap different op-amps in and out of a circuit, it is not too unlikely that significant changes might occur that can be audible - and measurable.

eddnog
54 posts
 

My V3 Monos came in, I immediately rolled them with a pair of Sparkos SS3602 op-amps per unit. Sound wonderful, and a small, but noticeable improvement over the pair of ZA3s I was running previously.

-Ed

asctim
479 posts
 

This seems like a serious thread from people who have really done a lot of work with op-amps over on ASR. Seems like there are a lot of gotchas if you don't choose and test carefully. Objective changes for the worse or better in terms of noise and distortion seem to be readily measured. Subjective preference of course is up to each listener.

 

lanx0003 OP
832 posts
 

@eddnog Did you also receive two complimentary MUSES 02 op amps?  It would be interesting to compare those with Sparkos...

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