Fosi Audio V3 Mono Amplifier Review

[NeLey169]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

And should I buy the version with two power supplies or the one with a single power supply and adapter, which is about $50 cheaper?

And I have a pair of Fosi ZA3 speakers, can I use their 48W power supply with my Fosi V3 mono speaker?

@Fosi Audio Help me.

 

[drodgers]

Not in my experience. I've got them running both stacked on their side and on top of each other in different setups and they get warm, but not hot enough to worry.

Either PSU is fine, though the dual one doesn't let you put the two amps far apart (eg. next to each speaker) because the Y-shaped cable isn't very long.

 

[Mark185]

Mine get warm but do not overheat but I do not run them at high power for long periods of time. They drive my speakers to fairly high volumes without high power. It will depend on your speakers. Use of cooling fans will also mitigate the problem. Fosi sells a small amplifier rack with perforations and mounting holes for cooling fans. I have usb powered cooling fans that I use with a very old Class A/B 6 channel power amp that can heat a small room. They would work well with the Fosi amps but I have not seen the need yet. I have separate 48 volt power supplies for each V3 Mono and can't comment on the single power supply option.

Keep in mind that these are small enclosures that act as heatsinks. If you push these amps hard, they will get hot. First thing to degrade from high temps will be the capacitors. If you are going to drive inefficient speakers and play them loud, then get cooling fans.

 

[Roland68]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

And should I buy the version with two power supplies or the one with a single power supply and adapter, which is about $50 cheaper?

And I have a pair of Fosi ZA3 speakers, can I use their 48W power supply with my Fosi V3 mono speaker?

@Fosi Audio Help me.

View attachment 520567View attachment 520566

Do you have an example of a V3 Mono actually overheating?
If not, you're another victim of this heat hysteria.
Back in the day, most amplifiers would get up to 45-50°C internally and still last 30 years. And now amplifiers are supposed to break down at 40°C?
Strange, isn't it?

Don't worry, it's just fear-mongering.

Personally, I would always recommend separate power supplies, and you can also use other 48-volt power supplies as long as the output is sufficient.

 

[jmdesignz2]

Do you have an example of a V3 Mono actually overheating?
If not, you're another victim of this heat hysteria.
Back in the day, most amplifiers would get up to 45-50°C internally and still last 30 years. And now amplifiers are supposed to break down at 40°C?
Strange, isn't it?

Don't worry, it's just fear-mongering.

Personally, I would always recommend separate power supplies, and you can also use other 48-volt power supplies as long as the output is sufficient.

Get separate power supplies. Get some $6 cooling fins and thermal tape and some $5 thermal paste. Problem solved.

 

[Svetlio]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

And should I buy the version with two power supplies or the one with a single power supply and adapter, which is about $50 cheaper?

And I have a pair of Fosi ZA3 speakers, can I use their 48W power supply with my Fosi V3 mono speaker?

@Fosi Audio Help me.

View attachment 520567View attachment 520566

The idea of Fosi is the housing to act like a heatsink itself. The bottom of the amplifier board is attached to the metal via thermal paste and thermal tape, so yes, the housing gets quite hot but that means it disapates the heat from the amplifier board. I would worry if the metal is not hot, that means that therma paste and tape needs to be changed.

 

[Endibol]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

And should I buy the version with two power supplies or the one with a single power supply and adapter, which is about $50 cheaper?

And I have a pair of Fosi ZA3 speakers, can I use their 48W power supply with my Fosi V3 mono speaker?

@Fosi Audio Help me.

View attachment 520567View attachment 520566

Mine don't get hotter than about 45 degree C.

 

[burkm]

Mine (5x) V3 Mono amps don't get really "hot" but warm when used extensively. Because there were some reports of "problems" (noise) with the combined 48V/10A power supply, when using only one of the V3 mono amps, I have chosen the (safe) version using independent external 2x 48V/5A power supplies. Fosi audio doesn't really suggest anything else for the standard V3 amp and output power either doesn't seem to change when using 2x 48V/5A vs. one (cheaper) 48V/10A PS. Though they do look "ugly" and take more space than the one 48V/10A PS provided as a cheaper alternative.
I tried the temperature controlled fan version as an alternative, but is it really needed ? I doubt it... case temperature never exceeded 45°C.
Earlier class A amps got really hot but none of the users mentioned a reduced lifetime due to this.

 

[NeLey169]

Has Fosi still not solved this problem? And GaN power supplies are quite expensive; are they really worth the money?

Mine (5x) V3 Mono amps don't get really "hot" but warm when used extensively. Because there were some reports of "problems" (noise) with the combined 48V/10A power supply, when using only one of the V3 mono amps, I have chosen the (safe) version using independent external 2x 48V/5A power supplies. Fosi audio doesn't really suggest anything else for the standard V3 amp and output power either doesn't seem to change when using 2x 48V/5A vs. one (cheaper) 48V/10A PS. Though they do look "ugly" and take more space than the one 48V/10A PS provided as a cheaper alternative.
I tried the temperature controlled fan version as an alternative, but is it really needed ? I doubt it... case temperature never exceeded 45°C.
Earlier class A amps got really hot but none of the users mentioned a reduced lifetime due to this.

 

[john61ct]

Gaan is just more compact

and trivially more efficient conversion.

RF noise is a separate issue.

Volts are volts, amps are amps.

 

[NeLey169]

Gaan is just more compact

and trivially more efficient conversion.

RF noise is a separate issue.

Volts are volts, amps are amps.

A pair of V3 mono power supplies with GaN power supplies costs about $85 more than the standard version. Is it worth the extra money?

 

[DavidMcRoy]

Has Fosi still not solved this problem? And GaN power supplies are quite expensive; are they really worth the money?

What problem? They don't overheat.

 

[antcollinet]

A pair of V3 mono power supplies with GaN power supplies costs about $85 more than the standard version. Is it worth the extra money?

Only if you are willing to pay $85 for more compact power supplies. There are no other benefits. Only you can answer that question.

 

[antcollinet]

What problem? They don't overheat.

As I explained to him 10 months ago in a post he "liked" 4 minutes before creating the post #661 above.

 

[NeLey169]

As I explained to him 10 months ago in a post he "liked" 4 minutes before creating the post #661 above.

View attachment 520597

I watched Erin's video and he burned out his Fosi V3 mono due to overheating, so I'm really worried and asking again.

Only if you are willing to pay $85 for more compact power supplies. There are no other benefits. Only you can answer that question.

Is there a significant improvement in sound quality when using a GaN power supply?

 

[Bleib]

I watched Erin's video and he burned out his Fosi V3 mono due to overheating, so I'm really worried and asking again.

Is there a significant improvement in sound quality when using a GaN power supply?

Erin's tests are more difficult than normal speakers so I wouldn't worry.

There are some folks on YouTube who measure the amps, I'd basically just expect a slight efficiency improvement

 

[burkm]

Has Fosi still not solved this problem? And GaN power supplies are quite expensive; are they really worth the money?

Reviews are mixed, but most of them are rather "old". If it is solved completly: fine. I still think, one should get the 48VDC/5A version, but - never mind...

 

[burkm]

I don't think, the GaN power supply does change anything sonically. It's somewhat smaller, but that is all there is. I don't think, it's worth the additional cost...

 

[mike70]

Is there a significant improvement in sound quality when using a GaN power supply?

Amir's review was made with standard power supply and the results are very good, totally transparent amplifier.
You can improve an inaudible SINAD? ... well, for your dog maybe yes.

 

[RandomEar]

I watched Erin's video and he burned out his Fosi V3 mono due to overheating, so I'm really worried and asking again.

Because he was literally running test tones through them at full power for hours - he said so himself, in the video. Nobody listening to real music will reach that level of throughput, because music does not consist of full scale 0 dB sine waves - if you really push it, maybe you'll get to 10% of that as average RMS power. That would still mean 102 dB of average (!) SPL with typical speakers (85 dB/W @ 1 m). I still think it shouldn't have blown and should have gone into protection. But the heat was likely not the issue here.

People often think "I'm listening to some pretty loud music!" and fail to realize that they're typically sipping below 5 W of power from their amp, often even significantly below 1 W.

Is there a significant improvement in sound quality when using a GaN power supply?

None whatsoever. If you watched Erins video, you should know that the device actually measures better when using two seperate 5 A supplies than when using the 10 A GaN brick with a Y-splitter.