Fosi Audio V3 Mono Amplifier Review

[Brian Hall]

I received the replacement today for the one that failed. Got them both hooked up again. Working and sounding great.

 

[hjwh]

ZA3s came from factory with thermal interface material applied. V3 and V3 Monos did not have any TIM from the factory.

-Ed

My V3 monos came with thermal pasre between case and PCB.

 

[EddNog]

My V3 monos came with thermal pasre between case and PCB.

Were yours kickstarter initial batch or a later batch? Mine were kickstarter release units.

-Ed

 

[hjwh]

Top case temperatures 39 - 40 degC, bottom 41-42 degC while playing at normal volume.

 

[hjwh]

Were yours kickstarter initial batch or a later batch? Mine were kickstarter release units.

-Ed

bought via Amazon.nl

 

[EddNog]

bought via Amazon.nl

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

 

[hjwh]

delivered last week from Italy warehouse

 

[EddNog]

delivered last week from Italy warehouse

Yeah mine came straight from China.

-Ed

 

[burkm]

It looks to me, as if the use of thermal paste is "standard" by the maufacturer. But it might be sometimes "forgotten". Thus I am checking it by myself. I have done that many times on my (and the company) PCs already and this for quite some time too
Note: Its part of my profession...

 

[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...