Fosi Audio V3 Mono Amplifier Review

[almandude]

Look to your source first. The thing about these modern amps is that they raise the 'base level' with regard to quality for not very much outlay, so the whole way of trying amps out has changed. We can buy and sell on.

However Naim still operate with dealers so you could always find out for yourself ...

I preferred the 3e A7 to the Monos - but I confess to loving my Aiyima T20 that I'm using to feed it! But that is source and not a power consideration - and slightly scuppers my credibility I am sure!

May I ask what you preferred about the 3e? I have some fosi units but am eyeing 3e for another setup in the future.

 

[mike70]

There are a few more conditions than that, like the output impedance being low enough over the audible frequency range to avoid frequency response being load dependent. Mostly we see this with Class D amps without post-filter feedback having sufficient load dependency to give potentially audible frequency response variations with some fairly mainstream speakers, but there are other transistor outliers like the Amp Camp Amp.

When you need to explain something complex in a simple way... you use a simplified model of reality.

Yes, there are some class D implementations with a little load dependency (think compared to a valve amplifier), generally the TI chips based ones, and only the older ones. The "better" ones, Hypex / Purify / 3e, etc not at all.

So, in a general way, low output impedance and load independency is a property of almost all transistor based amplifiers.

Searching for differences in that kind of amplifiers doesn't sound good.

 

[jEDGEc0m]

Old debat : amps do they change sound signatures or not ? Some say it is obvious, others say it doesn't exist.
I don't have enough experience to judge.

If you want to try your own ear...

Do all amplifiers sound the same? Level matched listening test

Do all amplifiers sound the same? Level matched listening test One more to this neverending discussion. Two very different amplifiers are tested, however both with very flat frequency response in the audio band. The test level is set such that 0dBFS of digital data corresponds to THD = 0.9% for...

www.audiosciencereview.com

 

[Sokel]

Here in NC standby with 2 units using 48v 5a power suppliers equates to roughly $24/year. I don’t worry too much about it but folks look at things differently and I can understand that.

It's not a lot i'm asking for, a simple standby mode that's actually "standby". I like these little amps and i'm still using them, however i'd prefer if they consumed less power. Don't get me wrong, it's just something i'm looking forward to in case they create another version. Things that can be improved exist all the time and i hope it will be one of them.

I never said anything about electricity prices, why would you think that is the case? To me the engineering imperfection is far more annoying here.

There's no way on earth 10W to be standby, standby over 0.5W is totally illegal in Europe, they wouldn't be able to export them here.
It's probably some other state, other than standby you're talking about, amp disable or something.

 

[stigger]

My amp arrived a couple of days ago, so I tried powering it through a lab supply. On - 5.2W, Auto - 3W, Off - 0W. So indeed, when it's off, it's off, and the rest is the PSU idle consumption.

 

[JRowland]

There's no way on earth 10W to be standby, standby over 0.5W is totally illegal in Europe, they wouldn't be able to export them here.
It's probably some other state, other than standby you're talking about, amp disable or something.

I’ve got no dog in that fight. A couple folks responded to a new owner, sort of raining on his parade if you will. I felt it appropriate to do the math and let him know it’s not worth worrying about in the big picture, my opinion of course.

 

[gwing]

There's no way on earth 10W to be standby, standby over 0.5W is totally illegal in Europe, they wouldn't be able to export them here.
It's probably some other state, other than standby you're talking about, amp disable or something.

Europe is a big place. Not all of its component countries have the same laws. Such restrictions on standby current are not universal.

And, in practice, the amp when in its very useful and appreciated standby mode is pleasantly warm to the touch, certainly warmer than my laptop in standby, and quite likely would reach 10W if I was bothered enough to measure it, which I'm not.

 

[Sokel]

Europe is a big place. Not all of its component countries have the same laws

Right about that, only EU countries, it's mandatory to them (us) .
It's now 0.5W going to 0.3W from 2027 I think, and it's a law.

Look at Regulation (EU) 2023/826 .

 

[gwing]

Right about that, only EU countries, it's mandatory to them (us) .
It's now 0.5W going to 0.3W from 2027 I think, and it's a law.

Look at Regulation (EU) 2023/826 .

Maybe the law has a few loopholes in it or is not rigorously enforced as the amp is available in the EU. Perhaps best not to make a noise about it if that might result in an excellent economical little product becoming unavailable to you good folks across the ditch.

 

[Sokel]

Perhaps best not to make a noise about it if that might result in an excellent economical little product becoming unavailable to you good folks across the ditch.

That's only true if they formally (as a company) describe this state as "standby".
They may very well describe it as "amp disable" or something, no one will go after them with that.

 

[Freezak]

That's only true if they formally (as a company) describe this state as "standby".
They may very well describe it as "amp disable" or something, no one will go after them with that.

https://i00.eu/file/24/5003-v3mono-240326-compressed.pdf

 

[boblingted]

It's also on the main web page for the Fosi Audio V3 Mono

"Auto Standby Mode ​

Automatically enters standby after 10 minutes of no signal input, extending device lifespan and reducing power consumption"

Using an Ikea smart plug, I measured instantaneous measured power at about 4W in 'auto' with no bright power LED
and 10W with the relay tripped and playing music.
No music playing didn't change this much at all - if the power LED was bright it was reporting 9.8W
When the relay clicks off it's back to about 4W.
When switched off it was more like 0.3W and that's likely to be what the smart plug consumes.

 

[MajorTom]

If you want to try your own ear...

Do all amplifiers sound the same? Level matched listening test

Do all amplifiers sound the same? Level matched listening test One more to this neverending discussion. Two very different amplifiers are tested, however both with very flat frequency response in the audio band. The test level is set such that 0dBFS of digital data corresponds to THD = 0.9% for...

www.audiosciencereview.com

I couldn't make any difference .Would be curious to know the 2 amps...
So if I understand, the challenge is to find the right amp regarding the speakers (which is the most important link in the chain). I think the fosi v3 monos are a good match with my focal profile 918.

For info, my source is a dac aiyima T8 (connected to a pc, library mostly in flac on music bee + deezer)

 

[Freezak]

I couldn't make any difference .Would be curious to know the 2 amps...
So if I understand, the challenge is to find the right amp regarding the speakers (which is the most important link in the chain). I think the fosi v3 monos are a good match with my focal profile 918.

For info, my source is a dac aiyima T8 (connected to a pc, library mostly in flac on music bee + deezer)

They are good match for any speakers as long as the power they provide is sufficient for your setup - these amps are essentially transparent.

 

[jEDGEc0m]

I couldn't make any difference .Would be curious to know the 2 amps...
So if I understand, the challenge is to find the right amp regarding the speakers (which is the most important link in the chain). I think the fosi v3 monos are a good match with my focal profile 918.

For info, my source is a dac aiyima T8 (connected to a pc, library mostly in flac on music bee + deezer)

the reveal of that amp listening test - links/mention of the amps.

Do all amplifiers sound the same? Level matched listening test

H2 (deuterium) is an isotope of hydrogen. H2 is also hydrogen gas.

www.audiosciencereview.com

I don't know the line out voltage of the Aiyima T8 nor how loud you want to listen - the fosi v3 mono are not particularly sensitive, though with RCA you'll get a choice (seems later versions are 19dB or 25dB) - as long as your source isn't too weak, you should be able to get quite a lot of power potential from them.

 

[vrobec]

I have the Fosi V3 mono amplifiers. Unfortunately on one of the amps the orange LED is broken, not emiting light. I don't want to pay expensive return shipping, so if someone know the specs or LED type I can use as replacement.

Thanks!

 

[Hjbct]

I have the Fosi V3 mono amplifiers. Unfortunately on one of the amps the orange LED is broken, not emiting light. I don't want to pay expensive return shipping, so if someone know the specs or LED type I can use as replacement.

Thanks!

Hi - did you take apart and reassemble for any reason? I read somewhere that someone who was doing this said the LED can get physically missaligned with the hole on the case making it look like it was not working from the outside - just a thought.

Fosi Audio Community | Hi! One LED on my Fosi Audio V3 Mono is very dim | Facebook

Hi! One LED on my Fosi Audio V3 Mono is very dim. Any know how this is possible? I only have these amps for a few days and the top one switched off while I touched it the other day. Other than that...

www.facebook.com

 

[vrobec]

Hi - did you take apart and reassemble for any reason? I read somewhere that someone who was doing this said the LED can get physically missaligned with the hole on the case making it look like it was not working from the outside - just a thought.

Fosi Audio Community | Hi! One LED on my Fosi Audio V3 Mono is very dim | Facebook

Hi! One LED on my Fosi Audio V3 Mono is very dim. Any know how this is possible? I only have these amps for a few days and the top one switched off while I touched it the other day. Other than that...

www.facebook.com

Yes I take it apart, the LED is definitely broken no light from it.

 

[RandomEar]

Yes I take it apart, the LED is definitely broken no light from it.

Did you check if the LED legs are touching? The way Fosi mounted them, it's possible to short the legs and cause the LED to stay dark.

Other than that, just measure the diameter and get a 10-pack of the right size on eBay. For LEDs of the same color, the forward voltage will be very similar and the standard ones are all specced at 20 mA current. If the replaced LED happens to be slightly brighter, dimmer or of marginally different color than the original one, you can still replace the LED in your second unit, too. That way, they will match again.

 

[MajorTom]

I had the opportunity to borrow a rega brio-r and I'm currently testing it on my system in place of the v3 monos. This amp was not recommended for my speakers because of its 2x50w only. In general, the measurments are in favor of the Fosi.
And yet, the rega moves easily my speakers, surprisingly as easily as the v3 monos. Actually, the two amps sound very good, but after hours of listening, I can say that the rega "brings me more emotion".
It is the first time I can make this kind of comparaison and until then I was convinced that amp didn't make a sound difference as long as they provide enough power with low distorsion before clipping.
So I'm confused...