Fosi Audio V3 Mono Amplifier Review

[girtab]

Just a thought, but you both mentioned earlier that you needed 200W amps which would normally drive 87dB speakers to ear damaging levels in any normal domestic listening situation and also mention possible clipping here, which shouldn't e anywhere near happening. Are you by any chance applying heavy EQ at loud volumes to extend bass response? Doing that could require extreme power levels and be responsible for driving the amps into protection/clipping.

Ear damaging levels usually applies to continuous noise, not music which is composed of peak volumes. Amir has a thread on this matter. But no, 200W really isn’t that much especially when most of my songs never really hit 0dBFS, let alone -10. But like I said, all I did was apply a low pass filter to be able to confirm that the tweeter is indeed crackling when it’s plugged to the defective amp. (Otherwise the crackling would’ve been masked by the HF content of the music and it wouldn’t be as audible). When I switch amps (to the functioning one) the crackling disappears completely.

 

[DavidR]

I don't want to derail this thread, but I thought I'd link to the user's thread where I had input and measurments of two V3 Monos purchased through Amazon that I returned. I never used them in a system, I measured them for distortion and was very dissatisfied with the results. I still have my original V3 Mono purchased earlier and use it exclusively in my distortion rig for speaker testing. Given the posts here about some failures, I thought this link might be worth providing.

V3 Mono User Thread post

 

[girtab]

V3 Monos purchased through Amazon

I think Amazon just sends out returned faulty Amps to people atp

 

[DavidR]

I think Amazon just sends out returned faulty Amps to people atp

That's what I assume. It may be that the distortion I measured is inaudible, but not a risk I was willing to take. I never even unwrapped the power cords, I used my existing one, so the packaging and amps were still "like new".

 

[Deleted member 97805]

I think Amazon just sends out returned faulty Amps to people atp

Amazon really does that. I got two used items in a row, despite ordering them new and even returning the first one for obviously being used. I dont even think they are checking items below a certain price. Maybe a quick glance if everything is inside the packaging but nothing more.

 

[Deleted member 97805]

I don't want to derail this thread, but I thought I'd link to the user's thread where I had input and measurments of two V3 Monos purchased through Amazon that I returned. I never used them in a system, I measured them for distortion and was very dissatisfied with the results. I still have my original V3 Mono purchased earlier and use it exclusively in my distortion rig for speaker testing. Given the posts here about some failures, I thought this link might be worth providing.

V3 Mono User Thread post

I believe Fosi doesn't truly QC many of their products. They are a high volume seller after all. If its defective, the customer should just send it back and get a new one. Its probably easier and cheaper that way, instead of hiring actual employees for QC.

 

[1066]

Reading through verified Amazon owner’s reviews the heat is affecting reliability and confidence in these units.

Fosi needs a better cooling solution.

I saw one instance where owner 3-d printed a cooling enclosure/fan.

Also, reports of a lowering of gain during production run.

 

[burkm]

Lowering the gain has probably other reasons, not the temperature....

 

[RandomEar]

Reading through verified Amazon owner’s reviews the heat is affecting reliability and confidence in these units.

Fosi needs a better cooling solution.

I saw one instance where owner 3-d printed a cooling enclosure/fan.

Also, reports of a lowering of gain during production run.

The only reliable data I could find where people actually measured temps and not just made up numbers based on feel suggests that the cases end up between 42 and 49°C [1, 2, 3], depending on the speaker load, efficiency and SPL. That's not critical at all. It seems to me that people are concerned without there actually being a reason for it.

• Are some units failing?
  • Yes.
• Is it possible Fosi does have problems with QC?
  • Absolutely.
• Could the units run cooler?
  • Yes - with bigger cases or with an added fan, for more money.
• Are the current temperatures problematic?
  • I see no evidence for this.
• Are the current temperatures in any way related to unit failures?
  • I see no evidence for this. Doesn't mean it's not possible, but there just isn't any data which supports a link between temps and failures.

I have seen multiple pictures of disassembled V3 Monos where the aluminium heatsink plate connecting the TI chip to the case does not have much thermal paste applied. This could be problematic and is a QC issue. I have also read the report in this thread that units fail when connected to a switchable power strip which is being turned on/off regularily. This would point to a design problem with either the PSU or the DC circuitry in the amp (e.g. a missing TVS diode). This would be a pretty bad oversight, but not related to the units running hot(ter).

 

[antcollinet]

The only reliable data I could find where people actually measured temps and not just made up numbers based on feel suggests that the cases end up between 42 and 49°C [1, 2, 3], depending on the speaker load, efficiency and SPL. That's not critical at all. It seems to me that people are concerned without there actually being a reason for it.

• Are some units failing?
  • Yes.
• Is it possible Fosi does have problems with QC?
  • Absolutely.
• Could the units run cooler?
  • Yes - with bigger cases or with an added fan, for more money.
• Are the current temperatures problematic?
  • I see no evidence for this.
• Are the current temperatures in any way related to unit failures?
  • I see no evidence for this. Doesn't mean it's not possible, but there just isn't any data which supports a link between temps and failures.

I have seen multiple pictures of disassembled V3 Monos where the aluminium heatsink plate connecting the TI chip to the case does not have much thermal paste applied. This could be problematic and is a QC issue. I have also read the report in this thread that units fail when connected to a switchable power strip which is being turned on/off regularily. This would point to a design problem with either the PSU or the DC circuitry in the amp (e.g. a missing TVS diode). This would be a pretty bad oversight, but not related to the units running hot(ter).

Absolutely this.

 

[xxxkichaxxx]

thats why I went with the fosis instead of topping la90s. I need at least 200WPC for my 87db floorstanders. Even 200WPC is pretty low for me atm. I probably need to look at hypex stuff but those are outrageously expensive

Just get e3 Audio A7 monoblocs for your floor standers. They are way better to handle high current than fosi audio v3 mono and are build with much better quality control. You can check review here as well. I personally drive Focal Vestia N3s with them and have no issues. Just don't forget to pair them with 48v 10a PSU with each monoblock to have enough headroom.

 

[Kali-]

I think Amazon just sends out returned faulty Amps to people atp

Should be nice to know where the fault come from
I bought ZD3 from Amazon, i sent it back 2 times and for 3 times i received a clearly used/returned product!
I opened a ticket to Amazon and they sayd the issue come from vendor, not from amazon

 

[girtab]

Should be nice to know where the fault come from
I bought ZD3 from Amazon, i sent it back 2 times and for 3 times i received a clearly used/returned product!
I opened a ticket to Amazon and they sayd the issue come from vendor, not from amazon

Yeah idk if it’s the vendor or amazon but Fosi said they’re sending me a new one because Amazon didn’t let me return it

 

[girtab]

Just get e3 Audio A7 monoblocs for your floor standers. They are way better to handle high current than fosi audio v3 mono and are build with much better quality control. You can check review here as well. I personally drive Focal Vestia N3s with them and have no issues. Just don't forget to pair them with 48v 10a PSU with each monoblock to have enough headroom.

I would have done that but e3 audio unfortunately doesn’t ship to my country

 

[john61ct]

Buying from Amazon directly as the seller

is COMPLETELY different from third party sellers through their website-as-platform marketplace.

The latter is more like Ali or eBay.

 

[Groovy]

Does Audiophonics in France ship to you? https://www.audiophonics.fr/en/integrated-amplifiers/3e-audio-a7-p-20372.html
I bought mine there, quick delivery to Germany, no problems. You are from Austria, right? Buying in Europe, you get retailer warranty. When you order at Amazon, you're buying from a Chinese seller

 

[xxxkichaxxx]

I would have done that but e3 audio unfortunately doesn’t ship to my country

I can vouch to what John61ct and Groovy told you. If you can find 3E audio A7 delivered to you with reasonable support it is definitely much better than Fosi audio v3 mono and it is worth ordering.

Just get monoblocs and pair them with 48v 10a or 52v 9a PSUs, as some towers have taught impedance dips (e.g. my ones dip to 2.9 Ohms at 100hz) and that requires quite a bit of power delivered to them. I heard noticeable difference between 2 monoblocs with 48v 5a PSUs and with the same amps, but with 48v 10a PSUs. I.e. if you get a stereo with 48v 10a PSU, you will only get 5amps per channel and that might not be enough.

 

[girtab]

I had to purchase my amps from Amazon on order to get rid of Amazon store credit, I would’ve liked a 3e audio A7 but they could only provide the amp if I purchased from aliexpress or audiophonics but that seems overpriced. As for the impedance dips I see that Amir tested the v3 mono and it seems to be relatively stable even at 2 ohms so I don’t think I should worry right?

 

[antcollinet]

I had to purchase my amps from Amazon on order to get rid of Amazon store credit, I would’ve liked a 3e audio A7 but they could only provide the amp if I purchased from aliexpress or audiophonics but that seems overpriced. As for the impedance dips I see that Amir tested the v3 mono and it seems to be relatively stable even at 2 ohms so I don’t think I should worry right?

Right.

 

[Pulkass]

This is a review and detailed measurements of the Fosi Audio V3 Mono class D amplifier. It was sent to me by the company. The price with the power supply I tested is US $139.99.
View attachment 360697
I must say the concept of a "monoblock" amplifier in such a small size runs foul of any expectation a longtime audiophile would have! But monblock it is even though it is a very small block. Controls are on/off/trigger audio and selection of XLR vs RCA inputs -- just like the big boys! I am not showing the sides of the amp but there are very large holes with attractive orange color grid showing through. Nice. Back panel is again a bit of a shock to the system seeing XLR input:
View attachment 360698

The power supply as noted, is quite beefy with 48 volts at 5 amps on tap (240 watts). The amplifier is stated to have PFFB implementation which for a class D amplifier means it should have no load dependency together with lower distortion. Let's see if we get these with our measurements.

Fosi Audio V3 Mono Amplifier Measurements
Let's start with XLR input:
View attachment 360699
Wow, I did not expect this class of amplifier to break through the 100 dB SINAD barrier but the V3 Mono does exactly that, placing it in our prestigious category of "excellent:
View attachment 360700
View attachment 360701

RCA input costs you some performance but I was relieved to not see any mains interference:
View attachment 360702

Distortion is still at provably inaudible -115 dB. I like that the gain is nominal 25 which is my new recommendation for amplifiers.

Noise performance is excellent and at full power, darn near approaches sate of the art:
View attachment 360703

Now the all important frequency response and load dependency test:
View attachment 360704

There is essentially no impact up to 20 kHz between the 4 and 8 ohm indicating very low output impedance, albeit with a bit of peaking. Compare that to non-PFFB amps such as Fosi Audio V3 stereo Amp:

Above we have 2 dB differential at 20 kHz.

Distortion is very low and only increases with frequency:
View attachment 360706

View attachment 360707

Let's see how much power we can get out of this little box:

View attachment 360709

View attachment 360710
Efficiency must be quite high as we get essentially the power we put in (the power supply likely has some headroom).

There is decent amount of power even with 8 ohm and with very low noise:
View attachment 360712

As note though, distortion does rise at higher frequencies:
View attachment 360713

Fortunately it is good where our hearing is very sensitive (below 5 kHz).

I also threw my suite of my punishing reactive loads at it:
View attachment 360717

Translating into watts:

View attachment 360716

Amazing that this little amplifier can handle even 2 ohm load! Note that these are short term power ratings.

There may be a bit of power on noise:
View attachment 360718

Conclusions
All I can say is wow! It is incredible how far these small amplifiers have come. It is the result of a manufacturer listening to our needs, implementing features such as balanced and trigger inputs, and proper feedback mechanism to essentially eliminate load dependency. I can't imagine asking for more from Fosi when it comes to such an amplifier. Everything is as good as you could possibly want.

It is my pleasure to recommend Fosi Audio V3 Mono amplifier.

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Arrived two monos. One is powered by a 48 V 10 Amperes. The others one by a 48 V 5 Amperes. The led of the more powered is brighter (!).