Fosi Audio V3 Amplifier Review

[MajorTom]

Thx guys

 

[Zabava]

Is there a possibility of repairing a Fosi Audio V3, as the sound volume is not the same on the left and right speakers? This is particularly noticeable when the volume is at, for example, 10%, because then one speaker doesn't play at all. Only later, when I increase the volume, does the second speaker "wake up," and it's not noticeable when I listen loudly. When I swap the cables, the other speaker doesn't play sound when listening at a low volume.

My setup: https://www.audiosciencereview.com/...and-dac-for-monitor-audio-bronze-50-6g.66885/

 

[MajorTom]

Yes it should be possible. I had the same issue with a fda alientek d8. Audiophonics repaired it. (It was under warranty).

 

[somebodyelse]

Is there a possibility of repairing a Fosi Audio V3, as the sound volume is not the same on the left and right speakers? This is particularly noticeable when the volume is at, for example, 10%, because then one speaker doesn't play at all. Only later, when I increase the volume, does the second speaker "wake up," and it's not noticeable when I listen loudly. When I swap the cables, the other speaker doesn't play sound when listening at a low volume.

My setup: https://www.audiosciencereview.com/...and-dac-for-monitor-audio-bronze-50-6g.66885/

That sounds like a faulty volume pot, although there's often some mismatch at very low volume levels. Check whether the supplier will do a warranty replacement. Otherwise the cheapest solution is probably an inline attenuator, or turning down the volume upstream (DAC?) so you don't have to have the volume control where it's a problem. Replacing the pot is probably an easy job for a repairer, but more expensive. If you have a local repair cafe or makerspace they would probably help you replace it.

 

[OhmSweetOhm]

I posted this question in another thread as well, but it probably belongs here in the dedicated Fosi V3 discussion. There is a lot of debate about the power supply setups for two V3 Mono amps. Im probably going to buy a x3800h or x4800h for a 5.1 setup and the v3 mono will drive my mains : MA Gold 100 g5 (4 ohm).

The options are:

• one 48V / 10A supply combined with the power filter

• two individual 48V / 5A supplies

(two individual 48V / 10A supplies)


The problem is that the information out there is all over the place. Different reviewers and users share conflicting experiences, so I’m not sure which route makes the most sense. Any clear guidance would be very welcome.

 

[antcollinet]

I posted this question in another thread as well, but it probably belongs here in the dedicated Fosi V3 discussion. There is a lot of debate about the power supply setups for two V3 Mono amps. Im probably going to buy a x3800h or x4800h for a 5.1 setup and the v3 mono will drive my mains : MA Gold 100 g5 (4 ohm).

The options are:

• one 48V / 10A supply combined with the power filter

• two individual 48V / 5A supplies

(two individual 48V / 10A supplies)


The problem is that the information out there is all over the place. Different reviewers and users share conflicting experiences, so I’m not sure which route makes the most sense. Any clear guidance would be very welcome.

I would go for 2 x 5A. The filter (to me) is a bit of a cludge to solve a noise issue. Fosi have stated there is little benefit to the 10A supply compared to the 5A supply.

 

[OhmSweetOhm]

I would go for 2 x 5A. The filter (to me) is a bit of a cludge to solve a noise issue. Fosi have stated there is little benefit to the 10A supply compared to the 5A supply.

Fair enough. They sell many combo packages at Fosi but 2 x v3 & 2 x 5A is not one of them so I was wondering why.

 

[antcollinet]

Fair enough. They sell many combo packages at Fosi but 2 x v3 & 2 x 5A is not one of them so I was wondering why.

I can't help you with that.

 

[OhmSweetOhm]

Thx! I decided to buy to separate PSU.

I have the option to buy from amazon for 149 euro with the new 25/19 dB gain switch.

Or another trusted vendor with the old 31/25 dB gain switch for 127 euro.

Is new gain switch worth 2 x 22 =44 euro? Or should I go for the cheaper one? Some people in this thread were disappointed by the fact they received the 31/25, not sure why since volume is adjusted by the DAC or AVR etc.

 

[maudio]

Fosi V3 Sparkos 48V/7A SPS
perfect match with Russell K Red 50
here fed with LTA MZ3 Siemens Triple Mica E82CC
Holo Spring 2 KTE
@fosiaudio you haff no idea what you created! it’s a whole new category of amps. Even the V3 monos are not like stereo anymore cos of the post-processing which influences the sound.
HC/straight edge!

 

[OhmSweetOhm]

View attachment 496614

Fosi V3 Sparkos 48V/7A SPS
perfect match with Russell K Red 50
here fed with LTA MZ3 Siemens Triple Mica E82CC
Holo Spring 2 KTE
@fosiaudio you haff no idea what you created! it’s a whole new category of amps. Even the V3 monos are not like stereo anymore cos of the post-processing which influences the sound.
HC/straight edge!

What do you mean with V3 postprocessing? Its just a simple class D amp. There is no processing going on..

 

[maudio]

What do you mean with V3 postprocessing? Its just a simple class D amp. There is no processing going on..

What i mean V3 Monos have post-filter feedback (PFFB) circuitry for the known reasons but i prefere it simpler without it.

 

[antcollinet]

What i mean V3 Monos have post-filter feedback (PFFB) circuitry for the known reasons but i prefere it simpler without it.

So you prefer your amps to have frequency response that varies depending on the characteristic of your speaker?

Weird.

Oh, and the *influence* of the PFFB on the sound (like all well implemented feedback) - is to make it more accurate - more as it is delivered to you in the file or CD.

 

[Shanebow]

This is a review and detailed measurements of the Fosi Audio V3 stereo amplifier. It was sent to me by the company and costs US $89.99 with stock 32 volt supply. Price goes up to $109.99 with the 48 volt supply. There is a $10 discount coupon right now.
View attachment 293692
Despite its budget price, the V3 manages to look elegant with the hole pattern on top and large and smooth feeling Volume/On/Off control. Power supply is external and as noted, you get a choice:

View attachment 293693
As you will see later, you really want the 48 volt version:
View attachment 293694

Yes, it is a larger supply but you are going to hide it behind your desk anyway so might as well live the good life with the increased power there.

The amplifier is based on TI TPA3255 class D amplifier IC. There are replaceable op-amps for those of you who have nothing better to do than mess with the design.

When I took the amplifier out of the package, I noticed something rattling in there. Fearing the worst, I took the unit apart. Turns out one of the two large power supply caps had lost its adhesion to the PCB. The putty used is to keep the cap glued to the PCB was too flexible and had broken loose. No harm though as the cap is laying on its side and can't go anywhere. The sound I was hearing was it moving just a hair up and down and hitting the top of the case. Suggest company use a different material to fix this.

I will post the pictures of the insides later. For now, a large aluminum couples the amplifier IC to the case. There is no thermal grease but the amp ran cool enough that I don't think you need to worry about it. But if you are, this you can remedy yourself. Despite me pushing the amp to max power repeatedly, it just got warm to touch. The protection circuit was the best kind with high tolerance of clipping and audio-restart.

Fosi Audio V3 Amplifier Measurements
I performed the low power tests using the 32 volt supply. The rest is done with both. So let's start with our usual dashboard:
View attachment 293696

Distortion is nicely kept to -100 dB so we are noise limited causing SINAD to land around 88 dB. This is well above average for all amplifiers tested:
View attachment 293697

Notice how many amplifiers it beats to the right of it!

Noise performance is also quite good for the class, almost clearing the hurdle for 16 bit content at just 5 watts:

View attachment 293698

Frequency response shows load dependency which all class D amplifiers in this price range show:
View attachment 293699
In English, this means that depending on which speaker you use, the sound may be a bit bright or a bit dull if your hearing extends to 20 kHz. You can counter with EQ (which you better have for good sound in your room).

Multitone and 19+20 kHz show good performance for the class:
View attachment 293700
View attachment 293701

Edit: forgot to post crosstalk measurement:
View attachment 293839

Let's see how much power we can get out of this little box into 4 ohm:
View attachment 293702
You normally wouldn't expect to get more power with a 48 volt supply compared to 32 volt when their current ratings are the same. But as I noted in the picture at the start, the larger power supply is conservatively rated and is able to pump out more current for peaks. We can see this in our short-term power measurements:
View attachment 293703

View attachment 293704

With 8 ohm volt, we are more in need of voltage so naturally we get tons more there as well with the 48 volt supply:
View attachment 293705

Transfer function is quite good for class D and I was especially impressed with its ability to pump out same power at high frequencies as many amplifiers go into protection there:

View attachment 293706

There is some pop noise when turning on and off but it is very mild:
View attachment 293707

The amplifier is stable on power up:
View attachment 293708

Some of you have been aiming at creating more work for me by asking for for efficiency tests. I developed a test that is semi-automatic and provides reasonable accuracy (within 5%):

View attachment 293709

Note that part of the heat is dissipated in the power supply and part in the amp. The X axis is power per channel, not total (amp is driven in stereo).

Edit: here are the teardown pictures:
View attachment 294418

View attachment 294419
Conclusions
State of the art DACs run on highly performant silicon that when well implemented, produces the best performance we have seen. We are seeing similar development with these class D IC amplifiers. Noise and distortion is quite low and beats many amplifiers in the market. They bring two drawbacks: external power supplies and load dependencies. If the latter is resolved, these amplifiers would obsolete large segment of the audio market!

The Fosi Audio V3 is well implemented and brings nice looks and design at a bargain price. Company is also quite receptive to customer input and is a delight to work with behind the scenes. I don't know what else we could ask for!

I am going to recommend the Fosi Audio V3 stereo amplifier.

EDIT: a few pages in the thread claim was made that the input buffer opamp must be fake as they don't look like the official TI chip packaging. Company chimed in a couple of days later saying they bought the ICs directly from TI. And showed the purchase order proving the same. It seems the "internet got this wrong" as far as what constitutes a fake as TI is using two different factories with different packaging.

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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/

So will it run a set of Maggies without losing any of the Maggyness or should I look elsewhere? Sure looks good on paper, especially for the price. If I get these Magnepans I will be on a super tight budget so hear I am. The 48V version should perform nicely even when the speakers go down to the 2 ohm area. Plus I can afford the Fosi preamp as well. These appear to be more affordable than the traditional used amp and preamp sets out there that I would have to use. Thanks

 

[Joe Smith]

So will it run a set of Maggies without losing any of the Maggyness or should I look elsewhere? Sure looks good on paper, especially for the price. If I get these Magnepans I will be on a super tight budget so hear I am. The 48V version should perform nicely even when the speakers go down to the 2 ohm area. Plus I can afford the Fosi preamp as well. These appear to be more affordable than the traditional used amp and preamp sets out there that I would have to use. Thanks

I don't believe Magnepan speakers would be happy with the stereo V3 amplifier, even using a 48v supply, for anything but low level listening. You might be able to use the V3 Monos or other inexpensive monoblock amplifiers and have an OK experience.

I'm sure others will weigh in, but I'm concerned that's not a good speakers-amp pairing.

 

[gwing]

If you can afford a pair of Maggies you can afford a pair of V3 monos

I used to run a pair of 3As on a tiny 10W valve amp to start with and they were OKish at low to medium listening levels but were one of the few speakers that really benefited from a stronger amp. You don't need something exotic costing a fortune but I'd suggest something with a bit more grunt than the ZA3 and ideally also with PFFB.

 

[HighFutility]

Based out of Canada. When I bought this unit, it came with a 38V power supply.

Looking to get a 48-volt power supply now for some more headroom. Is there a huge difference between these units? Im suspicious of no-name brands. I have bought a few off brand Li-ion batteries for my power tools from amazon, and they are definitely not specified as listed.

 

[gwing]

There isn't much difference in price between the Fosi 48v5a power supply and the unbranded one so you might as well get the genuine article. Or get the 10A model if you need the extra power or instead their (considerably more expensive) 5A Gaan model which may run cooler and be more efficient.

 

[HighFutility]

There isn't much difference in price between the Fosi 48v5a power supply and the unbranded one so you might as well get the genuine article. Or get the 10A model if you need the extra power of their (considerably more expensive) Gaan model which should perhaps run a bit cooler and be more efficient.

Can the fosi v3 use the higher current of the 10a vs 5? Or is it capped at 5a?

 

[Deleted member 88178]

So will it run a set of Maggies without losing any of the Maggyness or should I look elsewhere? Sure looks good on paper, especially for the price. If I get these Magnepans I will be on a super tight budget so hear I am. The 48V version should perform nicely even when the speakers go down to the 2 ohm area. Plus I can afford the Fosi preamp as well. These appear to be more affordable than the traditional used amp and preamp sets out there that I would have to use. Thanks

For the magnepans an XLS Crown power amp seems to be a better choice IMHO, since they are 2Ω stable and (given the Magnepan's sensitivity) the S/N Ratio and THD of the XLS series is probably enough. Pricewise they can be found for 400-500€