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Fosi v3 Mono - User Impressions | Owner's Thread

...One of my 620 amps went South a few days ago (again) and I decided to change course. Instead of rebuilding it I got two more V3M amps and installed them on the backside of the front heat sink facia of the 620. Works great and who will know?

Good heavens! By all that's holy, this is like tearing apart the relics of a sainted martyr and then merrily relieving yourself on his grave! Honestly, a little respect wouldn’t go amiss.
Pass that gear on to someone who will appreciate it.
 
Good heavens! By all that's holy, this is like tearing apart the relics of a sainted martyr and then merrily relieving yourself on his grave! Honestly, a little respect wouldn’t go amiss.
Pass that gear on to someone who will appreciate it.
Ha! I knew some purist would object. I assure you the mod is totally and easily reversible. I basically just borrowed the front facia heat sink from the 620 amp and it can be easily returned.

These 620 amps were not Nakamichi’s best effort. They are notorious for going bad. They were famous for taking speakers out BITD. I have rebuilt mine several times and they simply are not reliable. They also have very modest performance but they do look cool.

I greatly appreciate the System One. I remember walking into a stereo store back when I was a hungry college student and seeing them when new (1977-78). Really nothing else like them back then or ever. Unfortunately, new they cost as much as a used BMW so was not going to happen but I swore I would own one someday. It took me years to get all the parts together for one. I actually was able to build two complete System Ones and sold the other a couple years ago.

This one is quite unique. The System One rack could only hold four Nakamichi 600 series components so if you wanted to use two 620 amps you had to sacrifice either the cassette player (600 or 600II), Tuner (610) or control preamplifier (630). They also made a small ‘Black Box’ series of products to use with the System One but no real place to put them. I use the adjustable active crossover black box with separate PS black box in this system to bi-amp my L1290s. I found an old rack to canabilize to extend my rack about 6” so everything fits nicely into one rack. Again totally reversible if needed but really cool setup.

For digital I use an old iPod in a Pure dock.

I’m sure to rebuild the original amp again but right now I just use this system to rock out in my garage :)

 
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It is difficult for me to place a high value on the Fossi V3 mono because of its size, weight and cost. I 've showed it to people and no one takes it seriously. Yet its output is impressive, stable, full, and even-handed across the frequency range; and so far it has been reliable. This product challenges my beliefs and bias. It is not a toy. It is not a run of the mill piece of electronica. Or is it in this new era of electronics? I cannot get my head around it. Maybe something should be done with the case to make it more classic looking or substantial. I kind of want to squeeze the mono amp, say, into a larger I phone to give it appeal. In any event, by accident I ordered and received two sets of these amps and will sell one set with a set of the 48volt power supply for $200. How many amplifiers does one need?
 
OK, it's been about a month with my V3 Mono amps so here is my review and impressions:

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  • Power – The power output of these compact amplifiers is impressive. Their ability to handle speakers down to 4 ohms (actually 2 ohms when I looked at the specs again), effectively doubling the output from 8 ohms, showcases excellent amplifier design. This feature is exactly what I needed to drive my power-hungry 4-ohm speakers. The extremely low distortion at rated power also allows these amps to push my speakers at any volume I am comfortable listening to with no unwanted noise.
  • Quality – The V3 Mono has a solid, compact chassis that feels durable. The switches have a satisfying, firm click, making it easy to feel confident about mode selection. The connections on the back offer several options including fully balanced, another sign of the quality and intended use of these amps. The speaker posts are on the small side, but that is understandable considering how small the amp is overall. While the posts are fully functional, they are best suited for banana plugs and that is perfectly fine for me since that is my preferred method to connect speakers anyways.
  • Features – Since I wanted external amps to use with my AVR, I didn’t need any additional processing, volume controls or anything other than simply amplifying the signals to my speakers without any additional steps for me each time I want to listen. Before the V3 Mono, most Fosi options included volume or tone controls, and many required a separate power switch, meaning I would have to turn each amp on and off manually. The auto sensing on/off feature on the V3 Mono works perfectly and along with no volume or tone controls is exactly what I wanted so my AVR can handle all the processing and automations. Having RCA and XLR/1/4” connections are really important to me since my AVR only has RCA but I want the flexibility when I eventually upgrade to a standalone processor. While not needed in my case, the gain control is another good addition to ensure more compatibility without overloading the unit with unnecessary features. The elegant design includes a small, unobtrusive power indicator and contrasting side vents that give my system a unique look when I set them up sideways on either side of my AVR (pictured) and allows me to use shorter cables.
  • Value – I’ve been evaluating audio components most my life and although I’ve wanted amplifiers like the V3 Mono for a long time, everything else I’ve noticed that are comparable to me have been around 10 times the cost. Not much more to say about value other than these amplifiers should be an easy choice for anyone with similar requirements.
  • Reputation – I never heard of Fosi until a few years ago when I was looking for a solution to add quality sound to my bedroom. I wanted to be able to connect to my TV since I’ve never been able to settle for built in TV speakers and I also wanted to modernize with the ability to stream my local music library or from other online services. The most obvious options were either very expensive music streaming amplifiers or smart speakers but neither seemed to be good values or fit to me. Then I came across the Fosi T20 and it intrigued me, but I was unsure of the quality. After doing some research and reading a lot of reviews, I learned that Fosi was a new brand that was serious about delivering quality sound to audiophiles at a reasonable price. I was still a bit skeptical but decided to try out the T20 since it seemed like the perfect fit for what I was looking for. I was immediately blown away after I set it up with various extra speakers that I had around and all of them sounded better than they ever did with this tiny and very inexpensive amp! This made me a Fosi believer ever since and I really like how they seem to be taking feedback directly from the audiophile community to develop products that we want and need. I’ve been patiently watching Fosi releases since the next sound project I planned would be to lighten the load off my living room AVR and upgrade the amplification to my home theater. When I saw the V3 Mono announced, it was a no-brainer to add these to my system.

Listening impressions:
To establish a baseline, I initially compared the V3 Monos to the T20 model I previously mentioned. Using a Fosi LC30 meter/switcher, I could seamlessly toggle between the T20 and V3s across two speaker sets. I was surprised and somewhat disappointed during this comparison because I was expecting the newer, more powerful V3s to outperform the T20 but what I discovered was to my ears, they sounded nearly identical to each other. I had someone else listening with me who did not know what amps or speakers were playing at any time. I just asked them to describe the sound each time I switched anything. According to their descriptions, I noted there were differences that made each combination sound better for different content. Overall, the T20 seemed to produce a more live sound that paired well with a variety of vocals and the V3 seemed more transparent, which paired better with instrumentals and possibly with more finely recorded material. In the end, this comparison was not so much a disappointment for the V3 Mono, it was more of a testament of how good the T20 also is and demonstrated the consistency of Fosi products to me.

The next test was using the V3 Monos to replace some of the internal amps of my AVR in the living room. The living room is much larger, with high ceilings and more room for error so I’ve been hoping to add any advantage I can to help improve the sound there. This was precisely why I purchased the V3s, so I was eager to see if they’d provide the sound quality boost I hoped for. We first listened to the AVR using the same tracks as we used in the earlier test to get a better sense of how it sounded on its own in various modes. It was tested in stereo mode, pure direct stereo and surround mode (Dolby & DTS interpreted from stereo music feeds). My complaint with the AVR, which was apparent in these tests to the other person as well was the sounds are muddy with less separation and definition to the vocals and instruments. We also listened to a movie using Dolby Digital because another issue is we often have trouble hearing dialogue through the center channel as clearly as we would like.

The first test here was to replace the front left and right channels of the AVR using the preouts to the two V3 Mono amps. In stereo mode, the immediate impression from both of us was the sound livened up and separated significantly and I also noticed more defined punch in the bass and mid-bass in the frequency range above the subwoofer that the V3 Mono driven fronts were handling. Off to a good start, the next test was to use just one V3 Mono to run the center channel. We noticed the same thing where the center channel came to life with increased clarity and a more effortless delivery. Taking the heavier load of the 4 ohm center speaker off the AVR also seemed to help it drive the other speakers better although the fronts still could not deliver the same bass I noted when they were connected to the V3s. So far, this configuration produced the best overall sound from the home theater setup and while it gave no improvement to stereo listening, our main purpose here is to consume content using surround modes. Finally, since my speakers have two sets of binding posts for bi-amping and I have the extra V3 to spare, I split the center signal and ran both amps to the center speaker to give that a try. Not as much of a difference in this configuration if any from just using the single V3 but the extra headroom made vocals, sound effects and dialogue the most defined that we’ve ever heard from this center speaker so until I can get a third V3 Mono to cover the three front (LCR) channels, I’ll most likely leave it as is.

Conclusion:
Overall, the Fosi V3 Mono is an outstanding amplifier that performs beyond what one might expect given its size and price. It’s incredible how far technology has gone to make something like these amps possible. I think the V3 Mono is the perfect amplifier for my application and I highly recommend it for any system where you have existing control processors and just need pure, transparent amplification if it meets your output requirements (it has plenty of power that should satisfy most). I look forward to future product from Fosi like the V3 Mono in a stereo or multi-channel version to use for surround channels or specialized for fully active setups.

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Disclaimer: Yes, I know not all my listening tests were "scientific" enough and it is impossible for these amps to produce some sounds as I described any differently than the AVR according to the science here but all I can say is I did do some level matched blind tests and after a month of listening to my system with these amps in place, I no longer have the same complaints/issues I had with the system before I got them so we can call it cognitive bias, but either way, I'm a happy camper.
 
Hello to everyone .
I just wanted to show the mini sistem i have with the fosi v3 monos .
My sistem is multipurpose - home cinema and listening to music stereo with the same front speakers - some german floor standers Canton speakers .
So then Denon X3500H - RCA Emotiva Basx A300 power amp - front speakers .

The second configuration is PC - DAC Topping D50 III - XLR Fosi V3 monos (separate 48V 5A x 2 pieces) - front speakers .

I like the sound from the Fosi V3 monos , i don't really feel i loose anything besides the db volume if i want to really crank the volume, but the quality of the sound is i would say better than Emotiva .
When i bought the Fosi V3 mono first thing i replaced the opamps pos 2 and 3 with Muses02 and position 1 with OPA 2134 and replaced the cooling paste , i really added more then it had from factory .

Regarding the temperature , if i push the volume really high, they are hot to the touch, i have a zigbee temperature device , it says 40 degrees Celsius .
After 2 days of using it like that the fans arrived , they really make a difference , i push the volume to max and then i have 30 degrees maximum with fans running on medium speed .

Also i have a Neohipo ET30 switcher , really makes everything easier to switch between Denon and Fosi V3 monos .
I also bought a RCA switch but didnt arrive yet , hope it is good, i really needed a remote with it . The one i had was really good and good price , but it had that 2 rca on the front , so design wise, was not really ok , so i bought the one in the link , something with HIFI . I will put the one i used with really really good success, i only replace it because of the 2 rca on the front .

I hope i am allowed to put links with what i bought .

Thank you




 

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