Fosi Audio V3 Mono Amplifier Review

[antcollinet]

This means they started putting the TIM on at the factory in later production runs. Those of us who were early backers did not yet receive it with the thermal interface material.

-Ed

Or they are randomly applying it based on the time of day/how hungover the operator is/A letter T in the month - etc.

Hopefully not, but who knows.

 

[burkm]

If they were in a hurry, they might have it - rarely - overlooked...

 

[courtesy]

My Fosi V3Monos arrived this past Friday. Pre-ordered from the Fosi site. They are fed by a WiiM Ultra and the setup is driving a pair of Ascend Acoustics Luna v2's...with an RSL-10e sub in my bedroom. Using it as Roon endpoint and using HDMI Arc from my TV(source is an AppleTV).
I had been using the WiiM Amp, the setup is noticeably different...the DAC, the amps, or both definitely making a difference.

FWIW - the amps have the reversed polarity issue, and also run pretty warm. I'll double check, but warmer seems to be in conjunction with how loud I play the system.

 

[Brian Hall]

I moved the V3 monos to my main setup and went back to using the ZA3 in my office setup.

The V3 monos sound great and have plenty of power. Using my DMP-A6 as a preamp/streamer/dac with balanced cables going to the V3s. Using the RCA outs as a sub out.

Listened to streaming, my CD transport and my turntable. The phono preamp is a Waxwing and I had the optical going into the DMP-A6. It sounded so good I ended up listening to both records from The Wall.

Both measured at 104.xF after two hours of listening. Room temperature was 73F. How hot is too hot for devices like this? The Loxjie A40 that these replaced never got above 90F and the ZA3 gets to about 92F.

It seems like they should have put holes in the top like they did on the regular V3 while leaving the side vents to get extra cooling from the chimney effect.

 

[Doodski]

I moved the V3 monos to my main setup and went back to using the ZA3 in my office setup.

The V3 monos sound great and have plenty of power. Using my DMP-A6 as a preamp/streamer/dac with balanced cables going to the V3s. Using the RCA outs as a sub out.

Listened to streaming, my CD transport and my turntable. The phono preamp is a Waxwing and I had the optical going into the DMP-A6. It sounded so good I ended up listening to both records from The Wall.

Both measured at 104.xF after two hours of listening. Room temperature was 73F. How hot is too hot for devices like this? The Loxjie A40 that these replaced never got above 90F and the ZA3 gets to about 92F.

It seems like they should have put holes in the top like they did on the regular V3 while leaving the side vents to get extra cooling from the chimney effect.

I have experience with extremely hot environments where calibrated electronics are used for metering temperature to 177C (350.6F), 20kPSI, torque and strain too. The operation purchased high quality ICs by several thousand at a time and then we qualified them in batches in a oven while they where connected to metering/monitoring gear. The qualification/success rate of operation while in the oven was low. Those that survived went on to further testing and calibration after being mounted on a PCB by a pick and place robot. So on the extreme end that is what it is....

There is also the thermal runaway specs for semi-conductors. The ranges I have read are typically 85C (185F) for domestic gear, 115C (239F) for medical and 130-135 (266F to 275F) for a military rating. So your gear should be stable if cooling is adequate to 85C before thermal runaway commences. Thermal runaway is the point where the high temperature causes increased conduction of the electrical energy and that causes more heat to build up and then more electrons equals more heat and it escalates till the semi-conductor strata fails completely and lets the smoke out.

 

[Brian Hall]

I have experience with extremely hot environments where calibrated electronics are used for metering temperature to 177C (350.6F), 20kPSI, torque and strain too. The operation purchased high quality ICs by several thousand at a time and then we qualified them in batches in a oven while they where connected to metering/monitoring gear. The qualification/success rate of operation while in the oven was low. Those that survived went on to further testing and calibration after being mounted on a PCB by a pick and place robot. So on the extreme end that is what it is....

There is also the thermal runaway specs for semi-conductors. The ranges I have read are typically 85C (185F) for domestic gear, 115C (239F) for medical and 130-135 (266F to 275F) for a military rating. So your gear should be stable if cooling is adequate to 85C before thermal runaway commences. Thermal runaway is the point where the high temperature causes increased conduction of the electrical energy and that causes more heat to build up and then more electrons equals more heat and it escalates till the semi-conductor strata fails completely and lets the smoke out.

I'll try to keep my room below 85C.

And below 85F too.

 

[burkm]

Most of the heat generating "events" appear to be in the bottom "department" were the TA3255 chip is situated. They might have to drill some holes on each side of the heat sink into the alu bottom of the casing to lessen that "effect" and have cool air enter that area from underneath the casing to generate additional cooling through convection. This needs higher feet then, to leave some space there, for having the air circulating. Some holes on top might enforce hot air escaping the top department of the box.
This could create a focus on heat management by Fosi Audio to be the next "big" thing

To drill those holes afterwards (!) makes removal of everything within the casing a needed prerequisite...

 

[Owis]

I see there’s an option to buy these without a power supply…If not from Fosi where else can you get one?

 

[Brian Hall]

Most of the heat generating "events" appear to be in the bottom "department". They might have to drill some holes on each side into the alu bottom of the casing to lessen that "effect" and have cool air enter that area from underneath the casing to generate some additional cooling through convection. This needs higher feet then, to leave some space there, for having the air circulating. Some holes on top might help to have hot air escape the top department of the box.

I will drill some holes in the top after the warranty period is over.

 

[Brian Hall]

I see there’s an option to buy these without a power supply…If not from Fosi where else can you get one?

That may be for people who already have power supplies from previous Fosi amps. I've got an extra 48v that came with a regular V3 that I'm not using.

 

[burkm]

I will drill some holes in the top after the warranty period is over.

Almost 2 years to go then...

 

[Brian Hall]

Almost 2 years to go then,,,

No rush.

 

[burkm]

I see there’s an option to buy these without a power supply…If not from Fosi where else can you get one?

Ebay in Germany offers V3 monos without power supplies.
But those are indirect offerings from Fosi Audio too, delivering items from German warehouses if needed...

 

[burkm]

No rush.

but You might be to lazy then to do it

 

[Brian Hall]

but You might be to lazy then to do it

Or will have something else by then. I just looked at the regular V3. It has holes on both the top and bottom.

 

[Sokel]

Or will have something else by then. I just looked at the regular V3. It has holes on both the top and bottom.

What's need to be cooled is the bottom where the chip is,holes only on top may not do much if no holes at the bottom too exist so to exchange heat.
And they will reduce the already inadequate heat dissipating area even more.

I would leave it be as is for as long as it lasts although I admit it will be fun to play with it after warranty,just to see.

 

[somebodyelse]

What's need to be cooled is the bottom where the chip is,holes only on top may not do much if no holes at the bottom too exist so to exchange heat.
And they will reduce the already inadequate heat dissipating area even more.

There's also the heat from the output inductors and regulators which often get forgotten.

 

[burkm]

It depends, what each measure will do for those previously measured temperatures (top, bottom, casing as a whole).
... and it needs redoing the thermal paste as usual, as it probably has been scrapped off during the action of removing (and insertion) the PCB from the case...

 

[Owis]

That may be for people who already have power supplies from previous Fosi amps. I've got an extra 48v that came with a regular V3 that I'm not using.

Thanks. The reason I ask is because Aliexpress has a sale currently (which works out cheaper than Fosi direct) but only have the Amp without PS in stock so I was wondering if there is a ‘universal’ one available or if any other 48v 5amp would work..

 

[Bleib]

I see there’s an option to buy these without a power supply…If not from Fosi where else can you get one?

There's an AIYIMA 48v 5A that is cheaper. No idea of it's better or worse though, says 6.3A max