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
desktopguy
335 posts
 

My nearfield desktop audio system is very crowded and had no space for an A/B or A amp of any kind when I switched to passive monitors ~6 years ago. Thus I was pushed into the alien (to me) world of class D amps. I did a ton of research, looking in particular for any class D amps described even occasionally as "musical" and pleasing to the ear. All that research led me to a gently used ICEPower design, the Wyred 4 Sound ST-500, which I sited standing on one side on my desk (w/the mfr’s OK). That cool running amp immediately worked well for me. It sounded great, had none of the obnoxious brightness and thin harmonics some ascribe to class Ds. Until a month ago I wasn’t tempted to change.

I never really stopped following class D, and had become curious about NCore modules used by various amp makers. The one other (to me, somewhat affordable) class D brand I read positive things about is Bel Canto. I looked for their stereo NCore amp, but instead found a cherry pair of 600M monos. After installing them  IMS, I can verify that they, too, sound quite musical. They have somewhat more resolution and better soundstaging than the ST-500, which is nice to have.

I got pushed into class D by space considerations but must say I’m quite impressed with the sound of the 3 examples I’ve used in my system. I've had 4 pairs of studio monitors here with these amps (ATCs, KEFs, Aerial Acoustics, Harbeths) and all worked extremely well with these amps.

lanx0003 OP
667 posts
 

@eddnog  I got in and pledged for two Monos with two 48v/5a PSUs. I felt fortunate making the last-minute decision and went with two independent PSUs because later today I saw this https://www.youtube.com/watch?v=wjWVSFCR5MI where the host experienced noise/interference issues using one block.

phd
1,280 posts
 

Do you not know that within each class of amplification there are good and not so good designs. This also holds true in Class D amps.

eddnog
41 posts
 

@phd believe it or not, there are people out there who simply write off Class D and some even Class AB right off the bat without so much as a blink.

-Ed

joekapahulu
240 posts
 

Interesting thread as I too need to replace a now dead integrated in my office system that took up too much space.  Right now I am using a backup ATI 1502 amp with a passive pre (also too big) driving Spendor S3/5s. I've been looking at Class AB options with smaller footprints. I have only heard one D amp, a Rogue Sphinx v1 5-6 years ago. I was not taken but it seems that so many manufacturers have gone to D amps that I have been "reading up". I am not incline to play with the small 3255 amps but sounds like enough folks have been sold on the other versions of D tech that it could be time. I cant hear any of them where I live so that is the rub but a good return policy does reduce the risk. I will keep reading this and other threads on this. Maybe old (preset bias) dogs can learn new tricks...

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