Fosi Audio V3 Mono Amplifier Review

[avdoc]

No, not at all.

You'll be far better off selling them to someone like me who would like a pair

I have a pair I won't be using. Feel free to reach out to purchase, I'm in the US (Ohio).

 

[Kayshot]

I have a pair I won't be using. Feel free to reach out to purchase, I'm in the US (Ohio).

I'm right on the border of Dayton, if gwing passes on this

 

[Jtabos]

I used to live behind the Sierra Nevada mountains in Andaluz and normal summer temps. were 38-40C and the last 7 weeks in 2009 were @ 1500 hours 45/6c. I had to stop using my KT88 power amp, it just got too hot.

I bought a Bada hybrid power amp I had a slate box made - no top or back panel, removed the base plate, raised the o/put tx off the top plate which allowed the mosfets and power resistors heat to escape, because conveniently there were slots cut into the top plate right over the mosfets. Using an adjustable computer fan placed underneath dramatically lowered the operating temperature. As I lined the box with car sound dampening material the fan was silent.

I like the look of your fan enclosures - where did you get them and how much did they cost? Fosi could have done a much better job at heat dissipation, it's always an after thought if at all. By designing enclosures to encourage a 'convection current' to be created in operation. These enclosures are so small they could have been made vertical with weighted bases.

I bought them at Amazon.es Here but are quite expensive; there is a cheaper option, sadly I found them after buying the AC Infinity.

 

[jvdburgt]

Just leave it on Auto? I don't turn things off at the wall plug, leaving them sleeping. The pre-amp is the same. The only sounds I get are the relays switching power on the monos'. They consume pretty much nothing and only warm up when working. The in-rush thermistor is the component I care about, the less action this sees the longer things work.

As far as I understand, the standby power consumption is >5W, i wouldn’t call that “pretty much nothing”

 

[Jtabos]

That's a great looking system btw - and room. Amazing to think that you have bit-perfect streaming, 10 band PEQ and plenty of clean power in that tiny package.

Thanks! ...And all for less than a thousand eur (the speakers and the sub were "Used-Like new" at Amz)

 

[Nuigurumi]

Well, one of the amps just killed itself a few minutes ago.

 

[Kayshot]

Well, one of the amps just killed itself a few minutes ago.

Of course a post like this pops up about an hour before mine arrive. What were the circumstances it died under?

 

[EddNog]

Well, one of the amps just killed itself a few minutes ago.

Fosi should be pretty good about replacing dead unit. The RCA connector for the right channel broke right off on one of my ZA3s and they sent a replacement board quite quickly from China directly.

-Ed

 

[Nuigurumi]

Of course a post like this pops up about an hour before mine arrive. What were the circumstances it died under?

Running 24/7 since I didn't like the constant on/off clicking of the amp.
Low volume 40-50db.
XLR output input.
6 ohm speakers (230w max).

 

[Nuigurumi]

Fosi should be pretty good about replacing dead unit. The RCA connector for the right channel broke right off on one of my ZA3s and they sent a replacement board quite quickly from China directly.

-Ed

Good to know, I just emailed support.

 

[Down South]

I bought them at Amazon.es Here but are quite expensive; there is a cheaper option, sadly I found them after buying the AC Infinity.

They maybe a little expensive but they have a good height so you could easily make simple enclosures leaving the back open and using sound deadening material on the inside which would kill virtually all noise, even using them near maximum - worth a thought.

 

[jvdburgt]

Running 24/7 since I didn't like the constant on/off clicking of the amp.
Low volume 40-50db.
XLR output input.
6 ohm speakers (230w max).

That sounds like bad news, sorry to hear. Can you elaborate a bit maybe? It died as in: not working anymore, or in a violent screechibng sounds, bursts of smoke and flames? Any signals of problems running up to the demise?

Very curious if this is a matter of very rare bad luck, or if we might expect similar stories to pop up here in the weeks to come...

 

[Nuigurumi]

That sounds like bad news, sorry to hear. Can you elaborate a bit maybe? It died as in: not working anymore, or in a violent screechibng sounds, bursts of smoke and flames? Any signals of problems running up to the demise?

Very curious if this is a matter of very rare bad luck, or if we might expect similar stories to pop up here in the weeks to come...

Playing a game at low volume.
Suddenly a loud noise from speaker. No screeching, mostly low frequency.
I first thought it was the speaker, but when I swapped the amps it was obviously the amp that died. No smell, no flames. Thing still turns on, just no sound.

 

[Down South]

As far as I understand, the standby power consumption is >5W, i wouldn’t call that “pretty much nothing”

I would. Once I've made a digital copy of my LPs and CDs on a small PC using SSD storage it is essential to keep it on charge, otherwise you can lose electrons and the music is lost - 5 watts is nothing to leave on 24/7.

 

[Kayshot]

I'm not leaving mine on 24/7 after the horror story I just witnessed. Lol.

 

[gwing]

I would. Once I've made a digital copy of my LPs and CDs on a small PC using SSD storage it is essential to keep it on charge, otherwise you can lose electrons and the music is lost - 5 watts is nothing to leave on 24/7.

Who told you that one?

SSD storage should retain data for over two years off charge without data loss, some manufacturers claim 20+ years so buy one of those makes if you are really worried.

Your electrons are not going to get lost on a system you use regularly even if you switch it off. And even if your SSD had a black hole in it that swallowed its electrons when starved of current you'd only need to keep your PC powered up not the amps which have connection with the SSDs at all.

 

[AaronJ]

Hmmmm...

I'm starting to be very doubtful about this range of class D amps. So this 120wpc amp would be much less powerful than my class AB of 80wpc (Sansui AU 9500)?!

It's very annoying...

Are you trying to replace a Sansui AU-9500 with the Fosi's? How much do you want for it?

 

[edgar-bcn]

@Keauval Just to clarify what is meant here.

Your sansui has an input sensitivity of 100mV (0.1V). Meaning only 0.1V input is needed to drive the amp to full power. This is typical of older gear from when sources output much lower voltages.

Your FOSI amp has an input sensitivity (8ohm) of 3.1V (31 times higher) meaning you need to drive it to 3.1V on the input to deliver 120W into 8ohms. This higher needed sensitivity is typical of more modern amps which expect to be driven by modern DACS which can output 2 or 4V (RCA or XLR) or more.

Your DAC can output 5.2V which is more than enough to drive full power from this amp, so you have no worries. But because of the lower gain, you will need the volume control at a higher level than you are used to to get there.

Where did you get the input sensitivity value from?

 

[Toroid]

Hmmm, my DAC got a 4V output on XLR, do you know which preamp could boost that ?
Thanks

I like the schiit kara with 12db extra gain in xlr mode

 

[Sokel]

Playing a game at low volume.
Suddenly a loud noise from speaker. No screeching, mostly low frequency.
I first thought it was the speaker, but when I swapped the amps it was obviously the amp that died. No smell, no flames. Thing still turns on, just no sound.

You would make a big favor to the friends here if you opened it and take some pictures up close at both sides.