Fosi Audio V3 Mono Amplifier Review

[DavidMcRoy]

google is your friend
post #3063
View attachment 427803

https://support.fosiaudio.com/hc/en-us/articles/35730754097689-Official-Statement-Regarding-the-Inverted-Phase-of-the-V3-Mono

mixing revisions (used market, replacement on defect) has really become a nightmare.. phase and gain

I'm using V3 Monos and V3 Stereos in DIY 4-way/7-driver speakers. Fortunately all the V3 Monos are I have are the same vintage (early, but just after the first production run) so they all "match."

 

[SeaBeef]

Is it normal for the V3 Mono’s to be warm to the touch even in standby? I noticed the orange LED’s stay on too?

 

[Negatywny]

Yeah, it's normal, stanby doesn't work as it should.

 

[Nyarlathotep]

Is it normal for the V3 Mono’s to be warm to the touch even in standby? I noticed the orange LED’s stay on too?

Yes, they tend to run a bit on the warm side. They shouldn't be too hot to the touch, but they definitely put off some heat.

When they go into standby, the orange LED near the On/Auto/Off should dim in standby when toggled to auto

 

[Matt1974]

Yes, they tend to run a bit on the warm side. They shouldn't be too hot to the touch, but they definitely put off some heat.

When they go into standby, the orange LED near the On/Auto/Off should dim in standby when toggled to auto

Mine are cold after turning off (i.e. set to auto) and moderately warm only during use. I was prepared to use fans, but so far no need. Quite surprised given so many reported experiences of a very hot amp.

 

[badie]

Especially hot, when compared to a V3 Stereo (which has holes on top and bottom).

Here are some infrared measurements from last summer. This is Delta-Temp. (Difference betwenn Room Temp and device temp)

Yeah, it's normal, stanby doesn't work as it should.

i would add, that i would not call that "Standby".
In Europe Standby should be less than 0,5W. And we are far from that. (Have to measure again).
My units get warm even in Auto "saving a little energy mode"

 

[Mr SuperNobody]

The speaker binding posts are tiny, the Y splitter needs an extra filter box with cable, the unit runs too hot, the standby doesn’t work as it should (?), the gain setting doesn’t work as it should, opinions divided on whether one PSU is enough although luckily the phase issue has been sorted… I better go and check the amazing measurements as I’m getting rather nervous waiting for my units to arrive.

 

[SMen]

The speaker binding posts are tiny, the Y splitter needs an extra filter box with cable, the unit runs too hot, the standby doesn’t work as it should (?), the gain setting doesn’t work as it should, opinions divided on whether one PSU is enough although luckily the phase issue has been sorted… I better go and check the amazing measurements as I’m getting rather nervous waiting for my units to arrive.

The speaker binding posts are OK ... the extra filter was probably overkill ... and just because they could sell a filter (or address concerns) ... I've had no problems running one PSU, in some use cases this makes sense, in other use cases (placing next to speakers) two power supplies makes sense, phase issue was a bit silly yes, but minor.

They do run quite hot though especially in a hot environment, and changing the gain would concern me if I was adding additional units to ones I have already (say in a cinema set up). They 'sound' nice though - quite 'forgiving' is the best word I could use - as well as powerful - others models sound more 'pristine', so sources upstream might matter slightly less with the Monos vs others.

My take after a few months using.

 

[EddNog]

The speaker binding posts are OK ... the extra filter was probably overkill ... and just because they could sell a filter (or address concerns) ... I've had no problems running one PSU, in some use cases this makes sense, in other use cases (placing next to speakers) two power supplies makes sense, phase issue was a bit silly yes, but minor.

They do run quite hot though especially in a hot environment, and changing the gain would concern me if I was adding additional units to ones I have already (say in a cinema set up). They 'sound' nice though - quite 'forgiving' is the best word I could use - as well as powerful - others models sound more 'pristine', so sources upstream might matter slightly less with the Monos vs others.

My take after a few months using.

Can confirm, they do run quite warm. Am one of the original crowdfunders so my pair are among the ones with the most hours of use in them so far, and they’ve been reliable without issue, despite how hot they get.

One could argue that when they are properly transferring heat from the amp IC away to the chassis, the chassis will get warmer as a result.

I’m not running fans on mine, either.

-Ed

 

[Mr SuperNobody]

The speaker binding posts are OK ... the extra filter was probably overkill ... and just because they could sell a filter (or address concerns) ... I've had no problems running one PSU, in some use cases this makes sense, in other use cases (placing next to speakers) two power supplies makes sense, phase issue was a bit silly yes, but minor.

They do run quite hot though especially in a hot environment, and changing the gain would concern me if I was adding additional units to ones I have already (say in a cinema set up). They 'sound' nice though - quite 'forgiving' is the best word I could use - as well as powerful - others models sound more 'pristine', so sources upstream might matter slightly less with the Monos vs others.

My take after a few months using.

Thanks!
I feel a bit less nervous after reading your reply. Hopefully everything works out okay for me, ie; no probs with binding posts! If so I may get some heat sinks and another PSU at a later date, I don’t mind upgrades but it’s hard to justify spending two three times the price of the units on accessories.
Are you running the amps using the rca connections and with the original op amps?

 

[badie]

I cannot remember, where I have seen it ...

But i saw an excerpt from Texas Instruments, where it said something like:
Do not use one power supply for several TPA3255, unless they are synced.

Fosis Filter (when using one power supply for two amps with splitter cable) was needed, cause they were problems without it.
Still with the Filter, when switching off one of the two monos, there is substantial noise.

I ordered another Aiyama (way cheaper than Fosis) GaN 48V 5A (now my V3 Monos have both their own power supply, both GaN 5A)
And the 48V 10A from Fosi is now powering my Fosi V3 Stereo (which is driving two 12`` Woofers)

I do not know (and like to know) whats inside the "Filter", can´t find a way to open it up. At the moment its out of the chain.

 

[SMen]

Thanks!
I feel a bit less nervous after reading your reply. Hopefully everything works out okay for me, ie; no probs with binding posts! If so I may get some heat sinks and another PSU at a later date, I don’t mind upgrades but it’s hard to justify spending two three times the price of the units on accessories.
Are you running the amps using the rca connections and with the original op amps?

I'm running them with the original op amps, and I'd go further and suggest that these were (probably) the ones used for the primary design. I was an original crowd funder and so I also received a couple of Muses02's which I tried. I don't want to get into op amp debates (I don't mean you ... just in general) and the character of the amp did change (for me).

I just thought that the essential, as supplied amplifier has a slight 'ease' about it that is detailed, powerful, and well, perfectly fine as designed. They also have x4 op amps to change for a stereo pair ...

I am using them in balanced via a balanced volume control from balanced DAC - I have not really used them via RCA.

 

[testp]

i got mine beginning of february, used rca and low-gain setting (don't know was it 19/25), room temp ~20°C, when On really only moderatly warm nothing to worry about, when auto-standby i believe mildly warm if even that..
i currently switched back to lower spec. Loxjie amp. for amplification, i have my speakers at the same corner next to my TV and i don't know what it is but with Fosi & Wiim Ultra peq i could not lower my room mode i guess that is happening there, so Wiim - Loxjie works better there for some wierd reason. will see later what to do, maybe change speakers location, but currently happy with this setup

 

[Mr SuperNobody]

I'm running them with the original op amps, and I'd go further and suggest that these were (probably) the ones used for the primary design. I was an original crowd funder and so I also received a couple of Muses02's which I tried. I don't want to get into op amp debates (I don't mean you ... just in general) and the character of the amp did change (for me).

I just thought that the essential, as supplied amplifier has a slight 'ease' about it that is detailed, powerful, and well, perfectly fine as designed. They also have x4 op amps to change for a stereo pair ...

I am using them in balanced via a balanced volume control from balanced DAC - I have not really used them via RCA.

I'm running them with the original op amps, and I'd go further and suggest that these were (probably) the ones used for the primary design. I was an original crowd funder and so I also received a couple of Muses02's which I tried. I don't want to get into op amp debates (I don't mean you ... just in general) and the character of the amp did change (for me).

I just thought that the essential, as supplied amplifier has a slight 'ease' about it that is detailed, powerful, and well, perfectly fine as designed. They also have x4 op amps to change for a stereo pair ...

I am using them in balanced via a balanced volume control from balanced DAC - I have not really used them via RCA.

i got mine beginning of february, used rca and low-gain setting (don't know was it 19/25), room temp ~20°C, when On really only moderatly warm nothing to worry about, when auto-standby i believe mildly warm if even that..
i currently switched back to lower spec. Loxjie amp. for amplification, i have my speakers at the same corner next to my TV and i don't know what it is but with Fosi & Wiim Ultra peq i could not lower my room mode i guess that is happening there, so Wiim - Loxjie works better there for some wierd reason. will see later what to do, maybe change speakers location, but currently happy with this setup

What does “could not lower my room mode” mean?

 

[testp]

What does “could not lower my room mode” mean?

i'm using wiim ultra and tried to lower frequencies in 100-250hz area to lower room modes that are excited by the corner placement for both speakers

 

[TheRealLGC]

For anyone that's on the fence, on making the purchase. The Z3s bundle (2x V3 mono + a filter + a splitter + 48v 10a GAN adapter) is currently $212, on Amazon.

The vendor is not Fosi, but otherwise, the transaction is being handled by Amazon, including returns. I don't know what it says, that this vendor is selling the bundle for so much under the standard pricing.

 

[Mr SuperNobody]

For anyone that's on the fence, on making the purchase. The Z3s bundle (2x V3 mono + a filter + a splitter + 48v 10a GAN adapter) is currently $212, on Amazon.

The vendor is not Fosi, but otherwise, the transaction is being handled by Amazon, including returns. I don't know what it says, that this vendor is selling the bundle for so much under the standard pricing.

I recently ordered my bundle from fosi, not the GAN but standard 48volt 10a for £201, they didn’t seem to have the GAN when I ordered. I think it’s quite common for Chiney company’s to have regular discount offers.

 

[andyholmes]

I recently ordered my bundle from fosi, not the GAN but standard 48volt 10a for £201, they didn’t seem to have the GAN when I ordered. I think it’s quite common for Chiney company’s to have regular discount offers.

Wow, where from?
Ive currently got a pair of XTZ99.25mk2's and a BK Monolith running off an Anthem MRX520 AV amp as i used to run an AV setup. I watch movies in 2.1 now and i feel for listening to music I need to get rid of the current amp. thinking a pair of these monoblocks and a wiim ultra is likely to fit purpose with out breaking the bank...

 

[hoovey]

I recently ordered my bundle from fosi, not the GAN but standard 48volt 10a for £201, they didn’t seem to have the GAN when I ordered. I think it’s quite common for Chiney company’s to have regular discount offers.

They're on sale for $170 CAD each now on Amazon, great deal considering what you get. I paid a little more ($380 CAD) for 2x V3 Mono and 2x 48V 5A GaN power supplies. I read that there's an issue with using a single power supply for two amps, otherwise I would've bought the 10A bundle. I wish the 10A power supplies weren't so expensive on their own.

 

[TheRealLGC]

They're on sale for $170 CAD each now on Amazon, great deal considering what you get. I paid a little more ($380 CAD) for 2x V3 Mono and 2x 48V 5A GaN power supplies. I read that there's an issue with using a single power supply for two amps, otherwise I would've bought the 10A bundle. I wish the 10A power supplies weren't so expensive on their own.

I'm currently running an Aiyima 48v 10a GAN adapter (from Amazon), on a Fosi mono; which is only about 2/3 of the cost, of the Fosi equivalent. It's been only 24 hrs. but so far, so good.