Fosi Audio V3 Mono Amplifier Review

[Bernard23]

The general consensus seems to be, that 2x 48VDC / 5A is to prefer, because the 1x 10A with a filter and splitter seems to generate some interactions between both mono amps (distortion, noise etc.) plus it produces some additional hum/noise, if only on amp is active. The 2x 48VDC / 5A version uses two power bricks and has therefor no additional intermodulation distortion (=> true mono). Space requirements are almost the same, although the 10A power brick is larger by itself, and an additional filter is provided / needed, on its output side which at least seems to reduce some interactions through the splitter (filter) between both amps.
The 10A power brick does not provide any additonal (output-)advantages as stated by Fosi Audio themself.

Note: Both 48VDC power supplies lead to a "hotter" amp (higher output voltage and power), reaching about 43°C or its equivalent in Fahrenheit in its idle state and about 50°C or 122°F during full use. Higher temperatures shorten the life expectancy of electrolytic capacitors and resistors.

Where is this general concensus and based on what data?

Seems to generate some interactions - either it does or doesn't.

It definitely produces an annoying hum in the live channel when the other amp is switched off, both on = silent (using the internationally recognised standard method of ear against the tweeter at 0db volume setting on your system). Though no one is ever going to listen to just one channel, right?

The temperature issue could be solved by using a lower voltage PSU. You might get as much output but that's unlikely to be a problem for most buyers of these amps ie a second / bed room system

 

[ninetylol]

Im still deciding between 2x monos with 48V5A or a Fosi V3 Stereo with 48V10A.

Seems to result in same power for half the price without pffb.

Any impressions?

 

[Bleib]

Im still deciding between 2x monos with 48V5A or a Fosi V3 Stereo with 48V10A.

Seems to result in same power for half the price without pffb.

Any impressions?

If one unit is important then I'd wait for a stereo release for the mono.

 

[burkm]

@Bernhard23
Just read through different threads on the Fosi Audio V3 mono and You will find the "general consensus"
All "phenomenons" have been described in detail, and even that problem, that not all "disturbances" have been cured by filtering the DC power input and then some are still left - more or less - probably because of interactions between both amps through the filter. This results in those recommendations, that two 5A power supplies are better then one 10A power brick plus filter...

Fosi Audio did provide at the beginning of its delivery (kickstarter) NO filter, but then decided due to unfavorable experiences by users to develop and deliver its own filter for the 10A power supply. But even then some left over problems did still exist, which caused Fosi Audio to rethink its filter design and decide to improve on it in the "near future", meaning after its 1st batch had been sold out. How this will come out is still "open" not even decided, if the current filter will be exchanged for "no cost". Even then there seems something to be left on the table, because no "true mono design" with all its desirable effects like - theoretically - "complete isolation" and "infinite channel separation" still remain unresolved by one 10A power supply and filter + splitter.

 

[totti1965]

Im still deciding between 2x monos with 48V5A or a Fosi V3 Stereo with 48V10A.

Seems to result in same power for half the price without pffb.

Any impressions?

If your speakers are flat 6 Ohms in the range between - lets say - 7 kHz and 20 kHz - then the Fosi V3 is a good choice.
No need for the 10 A Power Switch. As you can see in some posts here, 48 Volt 5 A results in practically the same power (within a 5 to 10 % range).
That is so for the Monos and there is no reason to think it is different for the stereo.
If your set up tends to be a bit bright and your speakers are more about 4 Ohms in the 7 kHz to 20 kHz range:
The V3 stereo will sound a bit milder in the heights than a PFFT amp. Perhaps that is what you are searching for.
If your speaker has not enough "kick" in high frequencies but is more on the 8 Ohm side - it will sound brighter and perhaps more pleasant than any PFFT amp.
So the V3 Stereo can be a winner in some situations.

 

[burkm]

Responsible for the power output of the V3 mono is mostly the 48VDC voltage, not the 10A. Fosi Audio itself wrote, that power output would be "approximately" the same with both power supplies. Space requirements are - almost - equal because of that needed additional DC filter plus splitter cabling, thus "space savings" will not happen. I therefore still favor the 2x 48VDC/5A power supply due to all the other arguments provided

 

[ninetylol]

I think Fosi is not lieing when they say theres almost no profit with 48v10a over 5a with the V3 Mono . But their own specs say, that a V3 Stereo with a 48v10a gives the same output per channel than a Mono with 48V5A.

 

[antcollinet]

That is so for the Monos and there is no reason to think it is different for the stereo.

Except with the monos you have 5A available for each channel. For the same power capability in a stereo amp 10A is needed.

 

[Down South]

So in the 70s we had golden ears that could hear things we couldn't measure? Really? What exactly is "shite" as a measure of a device? Surely what you mean is that at that time, they were not measuring the important characteristics that influenced SQ; so what is measured today that is, but wasn't back then?

No, but then people listened to music instead of thinking about it, so a crap sound was easy to distinguish from good sounding equipment. There are a lot of people making negative psychological comments about 'others' who don't realise they are exposing their own irrational mentality.

Of course measurements are very important but to hear what 'sound' a piece of equipment is producing you have to actually listen. If you are thinking, then you are projecting ie. putting filters in front of the sound., why because thought can only operate in space-time, which of course is the past. To really hear music without filtering it you have to stop thinking and operate on input only. Sadly many cannot do that so they never really hear music. To describe others as delusional or 'influenced by price' is a defence system. To project onto others that you have never met or listened to a piece of music with is irrational.

Long ago I got really bored by true believers always using the hoary old excuse that hearing is influenced by price. I've heard very expensive gear that I and others thought sounded like crap. There are plenty that are impressed by bling, more fool them. I don't care what physical image a piece of gear has but I know there are plenty who will buy simply by how 'good' something looks.

All music equipment should be constructed with only two objectives - to maximise sound quality and longevity of use. The visual aspect should be of secondary importance.

 

[Down South]

Wait, so which studio did he prefer and get better results from?

-Ed

Not surprising you've missed the point completely. Mark spent a lot of money putting together a completely analogue studio. He was interviewed on the brilliant BBC radio show Late Night Junction by Verity Sharpe. He wished he had put this project together a lot earlier, it would have cost him a lot less. Now why do you think he built this studio 'after' the digital one - think about it?

 

[totti1965]

Except with the monos you have 5A available for each channel. For the same power capability in a stereo amp 10A is needed.

But I don´t think that one TI-TPA3255 is capable of bringing 190 Watts at 4 Ohm. With the stereo V3 clean 140 Watt may be the limit. And 10A won´t push the power (by much).

 

[EddNog]

Not surprising you've missed the point completely. Mark spent a lot of money putting together a completely analogue studio. He was interviewed on the brilliant BBC radio show Late Night Junction by Verity Sharpe. He wished he had put this project together a lot earlier, it would have cost him a lot less. Now why do you think he built this studio 'after' the digital one - think about it?

I don’t make assumptions. Are you suggesting that he had to because of disappointment with the digital one? I can’t make that assumption. For all I know, he ended up doing it after the fact because he felt the need to do the actual comparison itself. Hence why I ask the question. By the way, I think you might be under the assumption that I’m one of these people around here that look at numbers instead of listening with my ears—you would be wrong. I’m generally on your side here, so please watch your friendly fire. Being aggressively defensive will take us all down together in a forum called Audio SCIENCE Review.

-Ed

 

[Mr Swing King]

Why would anyone trust a musician who was touring from way before we implemented hearing protection?
Also just because you’re a genius at your instrument doesn’t necessarily mean that you know anything about the science of sound.
I personally wouldn’t trust a gardener’s insight on biology just because he’s been cutting grass the past 5 decades.

 

[Talisman]

Ultimately didn't sound any different to my Yamaha so they're back in the box ready to be returned tomorrow.
It's been a fun ride.

So you bought two well engineered amps expecting to hear a difference?
And you are returning the fosi because you don't hear a difference with your good yamaha amp?
Forgive me but it seems like a stupid thing to do.... What did you think was going to happen?

 

[early rejecter]

So you bought two well engineered amps expecting to hear a difference?

Forgive me but it seems like a stupid thing to do.... What did you think was going to happen?

That’s not what happened. See this post. He already owned and had been using the Yamaha; he only bought the V3Ms because he thought his new Wiim streamer/pre-amp required a dedicated power amp.

 

[LSPhil]

But I don´t think that one TI-TPA3255 is capable of bringing 190 Watts at 4 Ohm. With the stereo V3 clean 140 Watt may be the limit. And 10A won´t push the power (by much).

Well, I can calm you down, with my RSP 200 48 I was continuously reaching a Vrms = 27.71V at 3.9Ohm when it comes to the network consumption of 220W. Here my power supply is the needle ear. Today a network of 600W is likely to be delivered to the house. The test circuit is prepared and I report what my TPA3255 can deliver to performance.

Here's another addition: The power supply drops the voltage from 48V to 44V, which corresponds to a possible output of 200W.

 

[Killingbeans]

Of course measurements are very important but to hear what 'sound' a piece of equipment is producing you have to actually listen. If you are thinking, then you are projecting ie. putting filters in front of the sound., why because thought can only operate in space-time, which of course is the past. To really hear music without filtering it you have to stop thinking and operate on input only. Sadly many cannot do that so they never really hear music. To describe others as delusional or 'influenced by price' is a defence system. To project onto others that you have never met or listened to a piece of music with is irrational.

Nobody can do that. Brains are prediction machines at their very core. We have no way of switching that off.

 

[LSPhil]

The 600W industrial power supply has arrived. The power from the socket is 250W European, and at 3.9 Ohm Vrms0 30V, which corresponds to a power of around 230W.
The conclusion is that this TPA3255 delivers what its manufacturer promises.
I personally doubt the desktop power supplies. From around 160W input power, the fan on the industrial power supply starts to turn on and makes a lot of noise. It is a Mean Well.

 

[Bernard23]

So you bought two well engineered amps expecting to hear a difference?
And you are returning the fosi because you don't hear a difference with your good yamaha amp?
Forgive me but it seems like a stupid thing to do.... What did you think was going to happen?

Well if you'd bothered to read the thread then you'd have grasped it.

 

[Bernard23]

No, but then people listened to music instead of thinking about it, so a crap sound was easy to distinguish from good sounding equipment. There are a lot of people making negative psychological comments about 'others' who don't realise they are exposing their own irrational mentality.

Of course measurements are very important but to hear what 'sound' a piece of equipment is producing you have to actually listen. If you are thinking, then you are projecting ie. putting filters in front of the sound., why because thought can only operate in space-time, which of course is the past. To really hear music without filtering it you have to stop thinking and operate on input only. Sadly many cannot do that so they never really hear music. To describe others as delusional or 'influenced by price' is a defence system. To project onto others that you have never met or listened to a piece of music with is irrational.

Long ago I got really bored by true believers always using the hoary old excuse that hearing is influenced by price. I've heard very expensive gear that I and others thought sounded like crap. There are plenty that are impressed by bling, more fool them. I don't care what physical image a piece of gear has but I know there are plenty who will buy simply by how 'good' something looks.

All music equipment should be constructed with only two objectives - to maximise sound quality and longevity of use. The visual aspect should be of secondary importance.

That's fine, and like you I listen with my ears too, I don't blindly buy something because it measures well, but I'm not surprised that I like the sound of stuff that does. However, I've spent years on forums like what hifi when the most ridiculous claims are frequently made about equipment all based on a subjective opinion that is in many cases biased by the cost and investment in ownership, and this why the consumer audio industry is riddled with snake oil.
We use measurement data as a language to communicate details about something in a consistent and reliable manner. I was simply making the point that what "sounds shit" to you might not to me whereas 10% distortion does whoever you are.