Fosi Audio V3 Mono Amplifier Review

[Rajvbs]

What does the current device chain with the V3 Monos look like?

The current setup
Dell G15 Laptop -> Fiio BTR5 USB Type-C -> Ayiyima Tube A3 Pro -> Fosi V3 Monoblocks - Bookshelf speakers. All RCA connections up until the speakers.

Somehow, I am not getting the depth/low end with this setup which I used to get with the earlier setup:
the same as above except the Aiyima Stereo Power Amp instead of the 2 Fosi Mono blocks.

Should I return the V3s? I am a bit confused even though I like the V3's wide soundstage and cleaner stereo separation. This only lacks the punch.

Sharing the photos of the Pre and Mono blocks, just for info.

 

[Rajvbs]

PFFB vs non-PFFB, perhaps?

-Ed

PFFB ones. The link is here : Fosi V3 Monoblocks for the specifications.

 

[EddNog]

PFFB ones. The link is here : Fosi V3 Monoblocks for the specifications.

Sorry, I meant the audible difference may be due to the Fosi having PFFB but the older setup does not.

-Ed

 

[SMen]

The current setup
Dell G15 Laptop -> Fiio BTR5 USB Type-C -> Ayiyima Tube A3 Pro -> Fosi V3 Monoblocks - Bookshelf speakers. All RCA connections up until the speakers.

Somehow, I am not getting the depth/low end with this setup which I used to get with the earlier setup:
the same as above except the Aiyima Stereo Power Amp instead of the 2 Fosi Mono blocks.

Should I return the V3s? I am a bit confused even though I like the V3's wide soundstage and cleaner stereo separation. This only lacks the punch.

Sharing the photos of the Pre and Mono blocks, just for info.

The thing about using something like the A07, is that you can 'reach high volume' quickly. Also, the rest of your gear - your sources - might be 'lower bandwidth' than you think, but the combination with the Aiyima gives a sense of 'punch' as you wind the volume up - could be a kind of 'nice compression' you are getting.

Too many variables, but it sounds to me that the Fosi's are requiring wholescale changes ... see if you can get a hold of a different balanced DAC - maybe from a mate - or on trial with amazon - with a lossless volume control and good output, and see how it sounds with your speakers ... or return the Fosi's as they are not a match for your set up (but I would not hold it against them - just a synergy thing ).

 

[Roland68]

The current setup
Dell G15 Laptop -> Fiio BTR5 USB Type-C -> Ayiyima Tube A3 Pro -> Fosi V3 Monoblocks - Bookshelf speakers. All RCA connections up until the speakers.

Somehow, I am not getting the depth/low end with this setup which I used to get with the earlier setup:
the same as above except the Aiyima Stereo Power Amp instead of the 2 Fosi Mono blocks.

Should I return the V3s? I am a bit confused even though I like the V3's wide soundstage and cleaner stereo separation. This only lacks the punch.

Sharing the photos of the Pre and Mono blocks, just for info.

Which power supplies exactly?

 

[Rajvbs]

48v/5a that comes with the Fosi. For Aiyima, I went for a power brick DC48V from Aiyima itself. Btw, I returned the Fosis today and ordering Aiyima A70 mono blocks. I will try these and decide which one is for my liking. Also, I like the sub out in the Aiyima with the volume control. But at the end of the day, I will only keep it if the sound signature meets my taste.

 

[kingkoolkris]

Hi,
Yesterday I installed three v3 mono units for the LRC channels on my Denon 4800. Unfortunately, all three channels are constantly humming. If i remove the rca cable, silence on that channel, the others continue to hum in the same way.
Did it do the same to you? Did i understand you have the rca jack in the onkyo and the xlr in the fosi?

Thanks

Yep, I used some cheap RCA male (Onkyo AVR preout) to XLR male (V3 input) cables from ebay and it 100% eliminated my humming.

 

[ArturroD]

Hello everyone!

I apologize for my English right away.

Nice measurements, but one of my V3 monos burned out on the first day. I know there are more cases like that.

V3 mono has poor heat dissipation. It is a poorly designed device and probably not carefully assembled. Fast mass production. Too small a safety margin. It has too small a radiator. With such a small space inside, it boils inside.

First of all, there should be thermal protection. The amplifier should turn off and work after cooling down. This morning I connected it cold to test. One works and the other is dead, only the indicator light is on and the relay clicked.

In my case, the cooler one failed. So it probably gave off less heat. Underneath there is a radiator connected to the housing with thermal paste, like in a computer processor. The housing should give off heat because it is also a radiator. Apparently there was too little paste or poor adhesion.

- I would disassemble it as if I were replacing opamps. I would buy the best processor paste possible, remove the old one and carefully install the new one.

- Second thing, the feet are too low. Air should flow underneath. I would install some small metal spikes to make some air space. Alternatively, I would place the amplifier on a nice black radiator as a base, gluing it to the bottom with a thermal pad.

- Or indeed, put some slow-running, quiet fan under the amplifier. Of course, there has to be air flow. The manufacturer knows about overheating, because they sell fans for $37. They should be included with every V3 mono.

But it will all ruin the design, which is quite nice in a way. That's all you can do I'm calling the seller right now and saying goodbye to Fosi.
My rating - a headless panther.

 

[somebodyelse]

Hello everyone!

Hello, and welcome.

Nice measurements, but one of my V3 monos burned out on the first day. I know there are more cases like that.

This sounds like typical 'bathtub curve' early device failure, or possibly a manufacturing fault. A failure like this should be a simple replacement by the seller. There have certainly been others as you say. What we don't know is whether the early failure rate is unusually high or typical for consumer electronics.

V3 mono has poor heat dissipation. It is a poorly designed device and probably not carefully assembled. Fast mass production. Too small a safety margin. It has too small a radiator. With such a small space inside, it boils inside.

It's not great, but it's better than most TPA325x based amps. It should manage more sustained output than the A07, but I doubt it'll sustain full output for long. I hope they keep improving, but it'll probably push the price up. That may take it uncomfortably close to budget nCore based competition.

First of all, there should be thermal protection.

There is. It's built into the TPA325x amp chip and I see no way to bypass it in the datasheet. This is why overheating of the amp chip seems an unlikely cause of failure.

 

[ArturroD]

The problem with overheating is because the manufacturer sells stands with fans. I think the housing sheet should be pressed in the shape of teeth or a zigzag. The heat dissipation surface would be much larger. Class D equipment should not heat up so much or break down after a few hours. I have an smsl q5 pro amplifier and it has been working reliably with large 4 ohm speakers for over 4 years without a break. It is only slightly warm. That is why I thought Fosi would be newer and better. Too bad, because I liked it

 

[BDWoody]

Some posts moved to the ongoing Op-Amp thread.

 

[kingkoolkris]

One of my two V3s (latest revision) just died after just a few weeks of using them. It's still powered judging by the LED but no sound at all. Cross checked with the other channel, nothing.
Anyone elses V3s failing yet?

 

[ArturroD]

One of my two V3s (latest revision) just died after just a few weeks of using them. It's still powered judging by the LED but no sound at all. Cross checked with the other channel, nothing.
Anyone elses V3s failing yet?

I had the same thing. My Fosi went back to the dealer. They need to improve the design because there are more situations like this.

 

[OdiusEX]

I had the same thing. My Fosi went back to the dealer. They need to improve the design because there are more situations like this.

Until today, mine lasted for almost TWO months...and had a very hot chassis from the beginning...I can say it had a lot of good sounding power...Luckily, was given a refund...

 

[jeffaegrim]

Sad to report that a friend of mine also bought two of those for his desktop system and discovered problems with both. One of the amps had something rattling inside and soon stopped producing sound. There were apparently also irregularities with the second one. They will be going back to Amazon, from what I hear

 

[Brian Hall]

Ordered mine on August 15th. Got them on the 17th. One had something rattling around and would light up, but no sound. Got it replaced. They have been working great since the 19th of August. They are side by side with a two inch gap between them and I have a small desk fan blowing over them and the cases stay nice and cool to the touch.

They are used at least 4 or 5 hours every day.

 

[GabrielPhoto]

I got two of them stacked with a small fan pushing air from the left and another pulling from the right. I run them in what I consider very demanding usage as it is driving tactile devices pushing very low frequencies (one is pushing a shaker and the other a jbl sub used as a Heze FootTR device) and both have been rock solid neven during my intense back to back to back demo scenes. Knock on wood

 

[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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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

WOW! yeah gonna beg borrow s...l 2 get me a pair soon. Thanks Amir. U R the best gift to us 72 y.o. audiophile of yore.

 

[Psinet]

I ended up returning all 4 of my V3 monos. I bought 2x 2 sets with 10 amp power supply. 1 of 4 amps died fairly quickly, although I was torture testing them beyond what any normal person would do (although the one that died was on lightest duty @ around 90 W into 8 Ohm continuous for many hours). Their form factor is too small for the power they CAN put out. I drove them pretty hard, and they performed. But without extra cooling, they couldn't cut it.

Two of them handled 2 Ohm each on either side of a dual voice coil monster sub. In the end it did feel underpowered, but they were impressive nonetheless.

Replaced with real 2.4 kW Class D sub amp, and Topping PA7 Plus for highs (since they available locally and much less cables and power supplies for basically the same performance - although closing in on dbl the price). Great if you want a "desktop" monoblock system, or even a simple monoblock floor standing setup on a budget.

But I need more reliable, and certainly more power in low Ohm bass. Worth the experiment, very capable little units for the price.

 

[strawberry644]

Hello everyone!

I apologize for my English right away.

Nice measurements, but one of my V3 monos burned out on the first day. I know there are more cases like that.

V3 mono has poor heat dissipation. It is a poorly designed device and probably not carefully assembled. Fast mass production. Too small a safety margin. It has too small a radiator. With such a small space inside, it boils inside.

First of all, there should be thermal protection. The amplifier should turn off and work after cooling down. This morning I connected it cold to test. One works and the other is dead, only the indicator light is on and the relay clicked.

In my case, the cooler one failed. So it probably gave off less heat. Underneath there is a radiator connected to the housing with thermal paste, like in a computer processor. The housing should give off heat because it is also a radiator. Apparently there was too little paste or poor adhesion.

- I would disassemble it as if I were replacing opamps. I would buy the best processor paste possible, remove the old one and carefully install the new one.

- Second thing, the feet are too low. Air should flow underneath. I would install some small metal spikes to make some air space. Alternatively, I would place the amplifier on a nice black radiator as a base, gluing it to the bottom with a thermal pad.

- Or indeed, put some slow-running, quiet fan under the amplifier. Of course, there has to be air flow. The manufacturer knows about overheating, because they sell fans for $37. They should be included with every V3 mono.

But it will all ruin the design, which is quite nice in a way. That's all you can do I'm calling the seller right now and saying goodbye to Fosi.
My rating - a headless panther.

to add to this when i opened my two and changed Opamps, i noticed very little thermal paste on one and a lot more on the second amp but still a small blob in the center of the heatsink. wish I took photos but it was a off white oily cheap looking paste too, I replaced it with MX-6 which happens to be a thicker paste on the chip and on the heatsink. but before putting it back in, I spread it across the whole block thick and evenly so i can get the most out of the plate moving heat with a fan nearby. another thing i would say is the orange panels they use as dust filters don't really allow much air to pass through if you slide those out while the amp is open you can see that the bar holding the amp together inside from front to back blocks airflow too.

so i do agree there is some short comings to the design that had to be done to make such a cheap amp and better QC should be happening for these units that are broken recently.