Fosi Audio V3 Mono Amplifier Review

[TheBatsEar]

I have this PSU, is there really any benefit to the GaN aspect?

The way i see it:

• GaN is smaller, this is mainly why it was developed.
• It might run cooler, because of slightly higher efficiency than regular switching supplies and far higher switching frequency.
• It has no impact on fidelity.
• It costs more.
• If you buy it, your hifi buddies will say "Ohh, GaN! You must be from the future!"
• If i meet you i will say "Ohh boy, GaN, you must have money to burn."

So yes, there are benefits to GaN power supplies. I'll get a 100W USB GaN power supply for my backpack eventually, as it seems Thinkpads and every other mobile device uses USB-C now for charging. But i see no benefit for this particular application.

I personally would also advice against the shared 10A power supply for the mono blocks. Yes, today you will use them stacked on your desk with the Y-cable, but maybe not in a few years. Better get 5A to make sure they can be used meters apart.

I also don't see the benefit of a 10A power supply for a single V3 mono, as there are no measurements made by "our guys" that show a clear benefit. If there are benefits, they are at the very edge of performance for these chipamps, where i never will run them.

In summary:

• ignore GaN for this application
• 2x 5A is more flexible than 1x 10A
• 5A gives you the performance as it was measured by Amir

April 20th 5PM CEST

i don't get it, isn't 20.04 started like half an hour ago?

April 20th, 15:00 UTC.

Fosi v3 mono, first product video trailer:

Great video, i like the parts jumping around on their PCB

BTW, so far we haven't heard anything about cost. Saving 30% is nice and all, but what are we saving it on?

 

[sikahr]

At the You tube channel Scientific Audiophile
today You can expect review of V3 Mono @ long term (significant) continuous power regarding thermal behavior using 48V 10A PSU.

 

[SMen]

Unless I am a whole day out Kickstarter opens 4pm

If you are in the UK ...

 

[SMen]

The way i see it:

• GaN is smaller, this is mainly why it was developed.
• It might run cooler, because of slightly higher efficiency than regular switching supplies and far higher switching frequency.
• It has no impact on fidelity.
• It costs more.
• If you buy it, your hifi buddies will say "Ohh, GaN! You must be from the future!"
• If i meet you i will say "Ohh boy, GaN, you must have money to burn."

So yes, there are benefits to GaN power supplies. I'll get a 100W USB GaN power supply for my backpack eventually, as it seems Thinkpads and every other mobile device uses USB-C now for charging. But i see no benefit for this particular application.

I personally would also advice against the shared 10A power supply for the mono blocks. Yes, today you will use them stacked on your desk with the Y-cable, but maybe not in a few years. Better get 5A to make sure they can be used meters apart.

I also don't see the benefit of a 10A power supply for a single V3 mono, as there are no measurements made by "our guys" that show a clear benefit. If there are benefits, they are at the very edge of performance for these chipamps, where i never will run them.

In summary:

• ignore GaN for this application
• 2x 5A is more flexible than 1x 10A
• 5A gives you the performance as it was measured by Amir

April 20th, 15:00 UTC.


Great video, i like the parts jumping around on their PCB

BTW, so far we haven't heard anything about cost. Saving 30% is nice and all, but what are we saving it on?

I think that it is interesting that running these in mono seems to reduce the requirement for amps. The difference between 5A and 10A is small at 8ohms.
Probably the measurements at 2 ohms would be even better with dual 10A? Closer to the 3e mono, which has 6.5A without air cooling. I wonder how hot the 10A might get?

Just surmising.

 

[Deleted member 72219]

Brilliant. So jumpy-up 8 pin Op Amps for "rolling". Question to @Fosi Audio , will you share specs/tolerances for suitable replacement op amps? Assuming there are alternatives that offer pure sonic differences. And advise which V3 op amps to roll, as I have seen that it does not always make sense to swap out all op amps? Thanks

I’ve managed to get the information from Fosi on this. The V3 Mono has a total of three rollable op-amps. One near the back is for the -correction-SINGLE-ENDED/RCA-correction- input. Then the gain stage has two, even though it is mono. They said you can experiment and change only one or both of those two and they don’t have to match, but personally I plan to run a pair of the same there (Burson V7 Vivid).

They didn’t say what specific specifications or models are compatible to me, though. Here is the exact chat:

-Ed

 

[Kimbrough Xu]

I’ve managed to get the information from Fosi on this. The V3 Mono has a total of three rollable op-amps. One near the back is for the XLR input (same as ZA3). Then the gain stage has two, even though it is mono. They said you can experiment and change only one or both of those two and they don’t have to match, but personally I plan to run a pair of the same there (Burson V7 Vivid).

They didn’t say what specific specifications or models are compatible to me, though. Here is the exact chat:

View attachment 364835

View attachment 364836

-Ed

How did you get the V3 MONO?

 

[Deleted member 72219]

How did you get the V3 MONO?

I did not get the unit yet, I’m waiting for the Kickstarter. I simply got the information from Fosi regarding the rollable op-amps, and I indicated my own plans for them based on experimentation with the ZA3s that I currently own.

-Ed

 

[SMen]

I’ve managed to get the information from Fosi on this. The V3 Mono has a total of three rollable op-amps. One near the back is for the XLR input (same as ZA3). Then the gain stage has two, even though it is mono. They said you can experiment and change only one or both of those two and they don’t have to match, but personally I plan to run a pair of the same there (Burson V7 Vivid).

They didn’t say what specific specifications or models are compatible to me, though. Here is the exact chat:

View attachment 364835

View attachment 364836

-Ed

Just pointing out that the op amp 1 is for the RCA input and not the XLR if I have read the FOSI comment correctly. It converts unbalanced to balanced.

 

[Deleted member 72219]

Just pointing out that the op amp 1 is for the RCA input and not the XLR if I have read the FOSI comment correctly. It converts unbalanced to balanced.

You’re right; I misinterpreted what they were saying. It appears it converts the unbalanced single-ended input signal into a balanced signal in order for the amplifier to be compatible. Thanks for the correction! Perhaps this is part of the reason for the reduction in SINAD with single-ended hook-up as opposed to balanced input.

-Ed

 

[avdoc]

The way i see it:

• GaN is smaller, this is mainly why it was developed.
• It might run cooler, because of slightly higher efficiency than regular switching supplies and far higher switching frequency.
• It has no impact on fidelity.
• It costs more.
• If you buy it, your hifi buddies will say "Ohh, GaN! You must be from the future!"
• If i meet you i will say "Ohh boy, GaN, you must have money to burn."

So yes, there are benefits to GaN power supplies. I'll get a 100W USB GaN power supply for my backpack eventually, as it seems Thinkpads and every other mobile device uses USB-C now for charging. But i see no benefit for this particular application.

I personally would also advice against the shared 10A power supply for the mono blocks. Yes, today you will use them stacked on your desk with the Y-cable, but maybe not in a few years. Better get 5A to make sure they can be used meters apart.

I also don't see the benefit of a 10A power supply for a single V3 mono, as there are no measurements made by "our guys" that show a clear benefit. If there are benefits, they are at the very edge of performance for these chipamps, where i never will run them.

In summary:

• ignore GaN for this application
• 2x 5A is more flexible than 1x 10A
• 5A gives you the performance as it was measured by Amir

April 20th, 15:00 UTC.


Great video, i like the parts jumping around on their PCB

BTW, so far we haven't heard anything about cost. Saving 30% is nice and all, but what are we saving it on?

My understanding from Amirm's review is that the MSRP on a single mono amp is $130 USD, for 2 mono amps with single 10A power supply is $260 USD. I don't think prices for any other combination or the speakers have been released.

 

[SMen]

I don't understand Fosi's explanation for the op amps 2 and 3. Surely these are running in parallel? Pre-Filter Parallel Bridge-Tied Load (PBTL)
Can anyone explain? Just curious.

 

[Deleted member 72219]

I don't understand Fosi's explanation for the op amps 2 and 3. Surely these are running in parallel? Pre-Filter Parallel Bridge-Tied Load (PBTL)
Can anyone explain? Just curious.

Right, that’s why I plan to roll the same type of op-amp into both. I think they’re just saying that it will still work fine if you don’t put matching op-amps into the two slots.

-Ed

 

[avdoc]

I’ve managed to get the information from Fosi on this. The V3 Mono has a total of three rollable op-amps. One near the back is for the -correction-SINGLE-ENDED/RCA-correction- input. Then the gain stage has two, even though it is mono. They said you can experiment and change only one or both of those two and they don’t have to match, but personally I plan to run a pair of the same there (Burson V7 Vivid).

They didn’t say what specific specifications or models are compatible to me, though. Here is the exact chat:

View attachment 364835

View attachment 364836

-Ed

My understanding is that the case for the V3 mono is the same size as the ZA3. Based on this, does anyone know the physical dimensions that will limit the OpAmp sizes? Also, will risers be required for the SparkoS chips (since they're wider)? Thanks.

 

[Ze Frog]

This is from Fosi FB page, they are offering very attractive early bird discounts:
Don't miss it !!!

View attachment 364676

Oh nice, didn't know Fosi did speakers as well. I'm guessing these would be pretty decent as well.

 

[Sokel]

I'm sorry for asking,but you people are actually using 100 euro op-amps at an amp which costs,just about the same for no actual audible benefit?
I mean it's your money,fine,but saving a little more could get you a nicer amp with built in PSU,etc.

 

[Ze Frog]

My understanding is that the case for the V3 mono is the same size as the ZA3. Based on this, does anyone know the physical dimensions that will limit the OpAmp sizes? Also, will risers be required for the SparkoS chips (since they're wider)? Thanks.

Looking at internal pictures, I think you will have trouble fitting those larger OP amp's. To be honest though, doubt there would be a massive difference anyway.

 

[SMen]

I'm sorry for asking,but you people are actually using 100 euro op-amps at an amp which costs,just about the same for no actual audible benefit?
I mean it's your money,fine,but saving a little more could get you a nicer amp with built in PSU,etc.

Personally, the interesting part of your observation is actually how do the Fosi monoblocks compare to something like the 3e or Sylph boards with internal power supplies. If I understand Amir's tests, differences should be below audibility.

The other interesting question is how close these get, with PFFB to significantly more expensive units from hypex etc.

 

[Ze Frog]

I'm sorry for asking,but you people are actually using 100 euro op-amps at an amp which costs,just about the same for no actual audible benefit?
I mean it's your money,fine,but saving a little more could get you a nicer amp with built in PSU,etc.

I knew a guy through work who brought a cheap class D amp a few years back from Amazon, can't remember the model etc but was saying about power supply noise, lol, he'd clearly been drinking the influencer cool aid and went on about some fancy power supply worth far more than the amplifier's. I didn't know him very well so basically said nothing, plus didn't want to spoil the magic, lol.

 

[olieb]

I'm sorry for asking,but you people are actually using 100 euro op-amps at an amp which costs,just about the same for no actual audible benefit?
I mean it's your money,fine,but saving a little more could get you a nicer amp with built in PSU,etc.

Maybe we have to change perspective. What if it is not about an amp at all, but instead about a test bed for opamp-rolling?
Then the V3mono is the choice of the day.
EDIT: Next week they might buy something else to roll their opamps (edited ;( in and out.

 

[Deleted member 72219]

I'm sorry for asking,but you people are actually using 100 euro op-amps at an amp which costs,just about the same for no actual audible benefit?
I mean it's your money,fine,but saving a little more could get you a nicer amp with built in PSU,etc.

For people like us, we like the fact that we can roll different op-amps and experiment with the sound. It’s like ordering a custom-tailored suit rather than just buying off-the-rack. Same reason I love my Schiit Freya+, because I was able to tune the distortion to my liking by rolling tubes.

-Ed