• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 7 1.5%
  • 2. Not terrible (postman panther)

    Votes: 11 2.3%
  • 3. Fine (happy panther)

    Votes: 95 20.0%
  • 4. Great (golfing panther)

    Votes: 362 76.2%

  • Total voters
    475

EddNog

Active Member
Joined
Mar 1, 2024
Messages
109
Likes
114
Looks like Erin from Erin’s Audio Corner has ascertained that there is, in fact, a measurable improvement using two separate 48V/5A power supplies rather than a single 48V/10A supply for two amps at once:
IMG_2744.png


-Ed
 

kemmler3D

Major Contributor
Forum Donor
Joined
Aug 25, 2022
Messages
3,559
Likes
7,253
Location
San Francisco
Looks like Erin from Erin’s Audio Corner has ascertained that there is, in fact, a measurable improvement using two separate 48V/5A power supplies rather than a single 48V/10A supply for two amps at once:
View attachment 367282

-Ed
He also ascertained that you can fry one by pushing it into protection repeatedly... so I guess the lesson is don't do that.
 

EddNog

Active Member
Joined
Mar 1, 2024
Messages
109
Likes
114
He also ascertained that you can fry one by pushing it into protection repeatedly... so I guess the lesson is don't do that.
Yes that just seems very…extra.

-Ed
 

drmevo

Active Member
Joined
Feb 10, 2022
Messages
137
Likes
131
Looks like Erin from Erin’s Audio Corner has ascertained that there is, in fact, a measurable improvement using two separate 48V/5A power supplies rather than a single 48V/10A supply for two amps at once:
View attachment 367282

-Ed
Welp, I changed my pledge to two 5A power supplies. Not just because of this - I was on the fence already. There’s too much uncertainty with the single 10A power supply for me. The cords will be hidden anyways in my set up so it’s just a matter of taking up an extra outlet.
 

Negatywny

Member
Joined
Jul 2, 2019
Messages
58
Likes
77
Location
warsaw
it's very mediocre review, much needed measurements, but overally mostly irrational complains (this amp has 200W, oh i like 500W! Thats how quirky I'am - might be the stupidest thing said by the reviewer i've heart this year) Also measurements without any comments or context: oh the graph look like this, now f*ck off. And also Fosi stop sending mi these i don't like to review this amps (Wtf?). Oh, and one got fried, haha, so funny. I haven't seen such an unfair review in a long time.

But apart from the diva reviewer, looks like two power supplies is the way to go (5A or more).
 

Bleib

Major Contributor
Joined
May 13, 2021
Messages
1,385
Likes
2,459
Location
Sweden
it's very mediocre review, much needed measurements, but overally mostly irrational complains (this amp has 200W, oh i like 500W! Thats how quirky I'am - might be the stupidest thing said by the reviewer i've heart this year) Also measurements without any comments or context: oh the graph look like this, now f*ck off. And also Fosi stop sending mi these i don't like to review this amps (Wtf?). Oh, and one got fried, haha, so funny. I haven't seen such an unfair review in a long time.

But apart from the diva rewiever, looks like two power supplies is the way to go (5A or more).
Erin is easily among the better reviewers because he actually cares to measure, usually he has more on his website but so far nothing on this
I don't care that much that one of the amps got fried because when watching movies or listening to music it be anywhere near the same load as his tests..
 

Negatywny

Member
Joined
Jul 2, 2019
Messages
58
Likes
77
Location
warsaw
Erin is easily among the better reviewers because he actually cares to measure.
I saw almost all his reviews and cant remember as bad as this one. It seems that even a review based on measurements can be covered with subjective, irrational gibberish if for some reason someone feels the need to do so:

This is small amp, i don't need small amps, so this is completely useless device, look at me throw it to the trash can, haha.

I don't care that much that one of the amps got fried because when watching movies or listening to music it be anywhere near the same load as his tests..
We know that, but most people probably doesn't know that, so his review is very very misleading.
 
Last edited:

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,293
Likes
6,438
We know that, but most people probably doesn't know that, so his review is very very misleading.
People are all over the place so it's good to point out that it's not sensible to drive subs with these for example.
Or,in a system with EQ filling dips (not a nice thing to do but people do it anyway) demands can skyrocket and it won't be far from this if combined with the typical already insensitive small 2-ways.

Anything exposing potential weaknesses is good for the potential buyer in my book.
 

Negatywny

Member
Joined
Jul 2, 2019
Messages
58
Likes
77
Location
warsaw
of course, but this is the contekst he should have provided, not you or enyone else on some obscure forum. From hes review it only look like: hey i plugged this amp, tested it and it fried, so it's firy little amp.

and definetely he should have statet that normal usage is nowhere neer 150% constant load for several hours. As Amirm aleways does in this situations.

Also i understand that the problem was mostly using one power supply for two amps, that what fried it. With two separates everything was grate?
 
Last edited:

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,293
Likes
6,438
Also i understand that the problem was mostly using one power supply for two amps, that what fried it. With two separates everything was grate?
The problem was not the PSU,the problem was heat by driving it repeatedly to/or near to it's physical heat dissipation limits.
Let's not forget the size (hence the heat dissipation area) .
 

Boppo84

Member
Joined
Aug 3, 2020
Messages
9
Likes
29
Yeah, it's a little worse than not fair to look for the limitations, push it over the boundries and than complain that it can't handdle it. No surprise there. But at the same time something that might have been prevented by some form of thermal protection.
 

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,293
Likes
6,438
Yeah, it's a little worse than not fair to look for the limitations, push it over the boundries and than complain that it can't handdle it. No surprise there. But at the same time something that might have been prevented by some form of thermal protection.
The chip itself HAS thermal protection,he states so as it kicked in some times. TI's data sheet is clear about it.
But components around it (caps,resistors,etc) don't have such protections.Anything can fail if not spec'ed for such temperatures.

Edit:No one in the right mind expects mil spec'ed,ultra low ppm (so their values don't drift) resistors for example at this price range.
 

Negatywny

Member
Joined
Jul 2, 2019
Messages
58
Likes
77
Location
warsaw
The problem was not the PSU,the problem was heat by driving it repeatedly to/or near to it's physical heat dissipation limits.
Yeah, but the protection kicked in several times during using one power supply for two amps (as for other reviewer posted here), and then one amp fried? With one power supply per amp everything worked fine.
 

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,293
Likes
6,438
Yeah, but the protection kicked in several times during using one power supply for two amps (as for other reviewer posted here), and then one amp fried? With one power supply per amp everything worked fine.
It's about time.No matter what PSU used,if it could bring the amp to/near it's limit it was just a matter of time.
Speakers/load demands and amp tries to deliver.If there's enough juice it does,the PSU is just there to follow.
 

SMen

Active Member
Joined
Jan 2, 2022
Messages
177
Likes
91
I think it's a useful review - interesting about his ABX Comparator - there is a review of it here. https://www.dagogo.com/audio-by-van-alstine-abx-comparator-review-part-1-audio-store-wiring/

He demonstrates graphically the effect of PFFB between the V3 mono and the ZA3 and then goes on to challenge whether he can actually hear it / any differences using the comparator! The frequency shaping of the Dayton valve amp he refers to (boosted lows for warmth) was both audible and measurable, but for him V3 vs ZA3 not.

Seems like good stuff.

I think he over does the failure of one unit as I do get the impression he might have been on a bit of a mission to stress them to death! Reassure himself vs those other 500w beasts he has and loves ...

But we still need @Fosi Audio to confirm about this 10a power amp rating, whether super early birds can decide on two 5a instead, and indeed what the revised / finalized stretch goal rewards will be ...
 

Negatywny

Member
Joined
Jul 2, 2019
Messages
58
Likes
77
Location
warsaw
No matter what PSU used,if it could bring the amp to/near it's limit it was just a matter of time.
isnt that quite the opposite?
One psu two amps can't drive amp to its limits, but can fry it - but one psu one amp can drive the amp to its limits and doesn't fry it...
 

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,293
Likes
6,438
isnt that quite the opposite?
One psu two amps can't drive amp to its limits, but can fry it - but one psu one amp can drive the amp to its limits and doesn't fry it...
No,the amp doesn't care about the PSU as long as it is adequate.
Amp's protection are overheat,undervoltage,overvoltage and overcurrent.
As long as these are in check doesn't matter.
If the shared PSU could not follow the voltage demand the amp would just go into protection (that's on paper at least).

There is a chance for the PSU to go crazy too but that would be evident.
 
Top Bottom