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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 12 1.9%
  • 2. Not terrible (postman panther)

    Votes: 19 3.0%
  • 3. Fine (happy panther)

    Votes: 122 19.5%
  • 4. Great (golfing panther)

    Votes: 473 75.6%

  • Total voters
    626
i forgot to turn on my small fan on the side of the fosi v3 mono amplifier, and only half of the album is playing and it's very hot.

i'm using SB acoustics full range 8 inch speakers and discrete blameless preamp (DIY, no opamps no headache), i like the sound and and yes the heat generated by these little amps is also good. i have a V3 stereo 32v and it doesn't get as hot as this.
 

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LOL , 5 months waiting i don´t have patience ? It´s easy to talk when is everything ok... I ´m not a rich person, of course i have to be upset with all this situation... The main error here, is i´m customer who became from the kickstarter project.. After that customers from other stores as Amazon receive their monos... Fosi wait to much to try to solve the problem, which in fact not solve , yet.
bought mine from a local store, and received it in 4 days. there may be something wrong with your shipping service.
 
Is there a reason I need to turn the preamp volume up higher for the v3 monos to get the same loudness as a single ZA3?
My preamp volume never reach 10 o'clock, sir. But maybe different speakers.
 
For anyone interested: i am extremely happy with AC Infinity MULTIFAN S7-P 120mm fans. I am using them together with some extremely cheap chinese temperature controller with its probe put on top of the v3 mono case. It reads the temperature of the case without fans at about 50C, with AC Infinity fans it goes down to 32C after solid 2 hours of music playing, which is outstanding, not something i'd expect. Set the temperature controller to turn the fans on at 35C and turn them off at 31C.

View attachment 393358
i use 24v fan with P1 PSU 12v, and stack v3 mono, and put that fan beside it. no noise sir.
 
I checked the amperage of the "upHere" 120 mm USB fan (switchable 3 speeds) at those 3 speeds with my USB measuring instrument: at "Low" it needs 0.14A, at "Medium" it needs 0.17A and at "High"its amperage is 0.20A. Fan noise is very low to inaudible, but haven't tested the highest speed. Even at the lowest speed the V3 Mono temperature (placed underneath the horizontally mounted amp) in idle state (continously ON for about 8 hours) is appr. 30.8°C / 87.08°F. Under full load it's probably somewhat higher...

I then turned on both fans and the amperage measurements shown were 0.35A at "Low", 0.38A at "Medium" and 0,41A at "High" speed. USB-Voltage indicated was 5.22VDC.
Thus a simple 1A USB power supply is needed. This would still work for 3 fans min, if the amperage would add up further as expected. Given the low cost of those instruments those measurements should be OK...
 
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I have eight V3M amps now. Use two in my office (balanced) and 6 in my HT system (SE). I bought all direct from Fosi (first two on kickstarter) with totally seamless transactions and quick shipping (to PNW USA). I did have a problem with one but I think it was caused by user error in that I may have hot swapped it with an RCA connection. Fosi had great customer service with response within 24 hours and no language problems. Replacement amp was sent and all they asked was for me to ship the old one back so they could analyse the problem. They reimbursed my shipping. Based on my experience with Fosi I can’t say I have ever had better experience with a direct marketed product.

I did add two passive (finned) heat sinks to the office amps because they are in a cabinet. The 6 HT amps are out in the open so heat is not really a problem.

Oh yeah, the amps work and sound fine for my application in these two systems.
 
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After having these amps since the KS launch I am mostly quite happy with them. In terms of sound and power, I’m completely satisfied.

The one area where they are a bit frustrating is the Auto-On function. Just turning on lights on the same circuit seems to trip it. I unplugged the speaker cable in case it was poor power filtering from my preamp but that wasn’t the issue - the amps still turn on with just power connected.

This wouldn’t bother me that much except for that a) the relay click is fairly loud - someone not used to it thinks they’ve done something wrong by flipping the light switch and b) they do seem to use a decent amount of power while on. It also begs the question, how good is the power filtering if simply using other things on the same circuit trips the Auto function?
 
It depends what You mean by "...other things...", because a) the function is been activated by some "electronic dirt" coming through by the chosen input or b) some spikes on the power supply input has triggered it. As long, as nobody has identified it with some trustworthy idea or measurements, it is hard to tell, what really had triggered that function...
Depending on the outcome, I would be reluctant to provide an opinion on this right now...
 
I checked the amperage of the "upHere" 120 mm USB fan (switchable 3 speeds) at those 3 speeds with my USB measuring instrument: at "Low" it needs 0.14A, at "Medium" it needs 0.17A and at "High"its amperage is 0.20A. Fan noise is very low to inaudible, but haven't tested the highest speed. Even at the lowest speed the V3 Mono temperature (placed underneath the horizontally mounted amp) in idle state (continously ON for about 8 hours) is appr. 30.8°C / 87.08°F. Under full load it's probably somewhat higher...

I then turned on both fans and the amperage measurements shown were 0.35A at "Low", 0.38A at "Medium" and 0,41A at "High" speed. USB-Voltage indicated was 5.22VDC.
Thus a simple 1A USB power supply is needed. This would still work for 3 fans min, if the amperage would add up further as expected. Given the low cost of those instruments those measurements should be OK...

I checked the temperatures of both V3 Mono amps after about 4 hours in "idle state" (fans setting for "Low"): 30.4°C. I re-checked them after more than 10 hours running (XLR input) and they are at about 30°C. I might try it lateron with some content playing endlessly (loop) :)
 
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After having these amps since the KS launch I am mostly quite happy with them. In terms of sound and power, I’m completely satisfied.

The one area where they are a bit frustrating is the Auto-On function. Just turning on lights on the same circuit seems to trip it. I unplugged the speaker cable in case it was poor power filtering from my preamp but that wasn’t the issue - the amps still turn on with just power connected.

This wouldn’t bother me that much except for that a) the relay click is fairly loud - someone not used to it thinks they’ve done something wrong by flipping the light switch and b) they do seem to use a decent amount of power while on. It also begs the question, how good is the power filtering if simply using other things on the same circuit trips the Auto function?
I stopped using the auto on setting as they seem to be triggered by both input changes and also a voltage changes. Not a big issue on my stereo system in my office but with the 6 in my HT system the relays could become disruptive. Instead I use a strip outlet with a switch with the added benefit of the PSs turned off and no current draw.
 
Has anyone tried the fosi 125mm cooling fans? I am wondering how quiet they are or maybe I should try some other brand cooling fans.
 
Because they look quite similar to some other fans on Amazon, I would propose, that they are about 18-19 db on their lowest speed setting. For two (channels) it would then add up to 21 - 22db for both. I would suggest middle speed at the most for this application (depends on Your preferences) and at its highest speed setting again a bit higher. I don't have those numbers right now at hand because I use only their lowest speed setting. They are quite a bit cheaper so (Amazon).
Those other ones are quiet dual ball bearing types 120mm USB fans with a splitter, so You need only one ordinary (low cost) standard USB power supply of ~1A with one outlet. Life expectancy is stated as 60.00 - 70.000 on-hours. The dimension "125mm" is probably measured with the support rubber feet on top... The amps just fit snuggly on those 120 mm fans... Otherwise I don't know of any 125mm fan types and my believe is, that Fosi Audio is just an OEM of those brand(s) behind it. They are a reseller...
 
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Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.
 
Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.
In the "Audio Settings" menu in the Wiim Home app, at the bottom you can enable "Fade-in & Fade-Out Effects".
 
Thats enabled. I mean really Bad pops from speaker. A bit scared for my Lintons to be honest.
Sounds odd. I assume analog out from the Wiim Pro Plus? And it pops when switching song?

Try as an experiment to go in EQ in the app choose graphical EQ and pull the bar at 31 Hz all the way down.
 
Sounds odd. I assume analog out from the Wiim Pro Plus? And it pops when switching song?

Try as an experiment to go in EQ in the app choose graphical EQ and pull the bar at 31 Hz all the way down.
I will try that.

I think its a defect V3 mono though. One of them has bent rca, rattling inside, power LED not working. At the moment i have it disconnected and only other side playing and no problems so far.
 
I will try that.

I think its a defect V3 mono though. One of them has bent rca, rattling inside, power LED not working. At the moment i have it disconnected and only other side playing and no problems so far.
Ah. Well yes. It would be a good place to start with the defect amplifier of course! ;)
 
Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.
Are you using the auto power setting on the V3M? Try just using the manual on setting if so.
 
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