Fosi Audio V3 Mono Amplifier Review

[avdoc]

Just received mine yesterday and have noticeable hum from both midrange drivers at idle which does not increase with volume. I am using the preamp output from my Allnic 300b tube amp.
I have four different amps in my system and have no hum from any of them, so the Fosi does seem to be the culprit. I did swap the polarity of the speaker cables, being aware of the phase issues. This removed the hum from one channel but not the other.
I do have a Fosi P3 preamp and a vintage Sansui with a preamp out so will try it with those and see if the issue remains.
I bought the Fosi out of curiosity to see if it can retain the character of the 300b amp while giving it more oomf when driving my Wharfedale Elysian-4s.
Any thoughts or similar experiences?

What gain are you using? I have no noise on RCAs using the low gain setting.

 

[JimFarrell29]

Firstly, my speakers seem to have survived my abuse. So far, anyway. Thanks all for reminding me of the basics.
Secondly, with my P3 as preamp and my Revel speakers in a second system the V3 are silent.

 

[kolestonin]

I use a boXem Arthur 3409/N2(nc252mp) Poweramp with a pair of KEF R3 Meta.
Would replacing my current amp with two Fossi V3 Mono make any sense? Are there any potential benefits? or I will just add a power supply and some more cables in my living room for no reason?
(specs of my poweramp in the attachments)

 

[avdoc]

I use a boXem Arthur 3409/N2(nc252mp) Poweramp with a pair of KEF R3 Meta.
Would replacing my current amp with two Fossi V3 Mono make any sense? Are there any potential benefits? or I will just add a power supply and some more cables in my living room for no reason?
(specs of my poweramp in the attachments)

The smaller boXem amp has been reviewed on ASR previously. While have not heard it, the specs and internals look superior to the Fosi V3M. I don't see any reason to purchase the V3M. See: https://www.audiosciencereview.com/...-2408-n2-review-stereo-power-amplifier.18710/

 

[antcollinet]

I use a boXem Arthur 3409/N2(nc252mp) Poweramp with a pair of KEF R3 Meta.
Would replacing my current amp with two Fossi V3 Mono make any sense? Are there any potential benefits? or I will just add a power supply and some more cables in my living room for no reason?
(specs of my poweramp in the attachments)

No benefit at all. The Boxem is a better amp.

 

[Guddu]

I use a boXem Arthur 3409/N2(nc252mp) Poweramp with a pair of KEF R3 Meta.
Would replacing my current amp with two Fossi V3 Mono make any sense? Are there any potential benefits? or I will just add a power supply and some more cables in my living room for no reason?
(specs of my poweramp in the attachments)

If you do then you would get many potential buyers here if you decide to sell boxem… pls count me the first, I am always interested in trying a boxem amp and put it against all these tpa3255 amps I have got.

 

[SMen]

If you do then you would get many potential buyers here if you decide to sell boxem… pls count me the first, I am always interested in trying a boxem amp and put it against all these tpa3255 amps I have got.

The Boxem is quite a bit more expensive?

No benefit at all. The Boxem is a better amp.

Yes, just looking here on ASR it is not 'cut and dry' looking at the Buckeye nc252mp reviewed here that 'better' is a 'given'.

In fact many would "chip" in on here that measurement wise hearing a difference would not be a 'given' either

 

[MCH]

I use a boXem Arthur 3409/N2(nc252mp) Poweramp with a pair of KEF R3 Meta.
Would replacing my current amp with two Fossi V3 Mono make any sense? Are there any potential benefits? or I will just add a power supply and some more cables in my living room for no reason?
(specs of my poweramp in the attachments)

I have that boxem Arthur amp. Some differences with the Fosi based on comments in this thread:
- Power consumption in stand by (audio sense) mode < 0.5 W
- does not goes on when I switch on the light as someone reported a few posts back
- stays at room temperature in normal usage

 

[antcollinet]

In fact many would "chip" in on here that measurement wise hearing a difference would not be a 'given' either

Not a given - but 16 bits vs 11 bits of distortion free range may (albeit unlikely) be audible for some. (IMD test)

Plus - a little more power.

More importantly - better build quality and established track record of the modules.
Nicer Aesthetics (subjective, I know)
Built in PSU and consequent larger rear panel with more space for the binding posts.
Clipping indicator

And the lower heat and auto power on stability mentioned by @MCH.

All adds up to quite a bit.

 

[SMen]

Not a given - but 16 bits vs 11 bits of distortion free range may (albeit unlikely) be audible for some. (IMD test)

Plus - a little more power.

More importantly - better build quality and established track record of the modules.
Nicer Aesthetics (subjective, I know)
Built in PSU and consequent larger rear panel with more space for the binding posts.
Clipping indicator

And the lower heat and auto power on stability mentioned by @MCH.

All adds up to quite a bit.

Looking these up I think it is 800euros vs much much less for these monos on kickstarter. Perhaps this is not a fair comparison.
Someone I am sure has listened to both these and the more expensive hypex NC252MP modules.

Probably this is a bit of a diversion / distraction ... but a worthwhile comparison by someone who has both.

 

[antcollinet]

Perhaps this is not a fair comparison.

Of course not - it is not intended to be.

The person I was replying to already has the Boxem. He was asking if he should "upgrade" to the Monos.

So in this case, the "upgrade" for lower objective performance, plus all the other differences discussed would cost additional money. It would clearly make no sense.

He has the better amp already.

 

[JimFarrell29]

Indeed.
I bought the Fosi because I wanted a flavour of Class D without the big price tag. If I could justify it I would get a Purifi Eigentakt based amp from someone like Boxem.
Unfortunately (or fortunately) I have a wide selection of Class A and AB amps I am very attached to.

Of course not - it is not intended to be.

The person I was replying to already has the Boxem. He was asking if he should "upgrade" to the Monos.

So in this case, the "upgrade" for lower objective performance, plus all the other differences discussed would cost additional money. It would clearly make no sense.

He has the better amp already.

D

 

[Doodski]

Indeed.
I bought the Fosi because I wanted a flavour of Class D without the big price tag. If I could justify it I would get a Purifi Eigentakt based amp from someone like Boxem.
Unfortunately (or fortunately) I have a wide selection of Class A and AB amps I am very attached to.

D

Hey Jim @JimFarrell29 are you from British Columbia south area? I grew up with a Jim Farrell.

 

[MichaelJ]

I just received two V3 Monos. They're replacing two ZA3s that were running in "mono" so that I can repurpose the ZA3s to other smaller systems in the house (and because I couldn't help seeing how the new V3 Monos compare...)

The system is digital and uses XLR connectors: MiniDSP SHD > (2x) Topping D30PRO > (2x) V3 Monos > passive bookshelves (I handle bass management in the SHD and cross over to (2x) powered subs)

First thing I noticed was that the gain on the V3 monos was much less that the ZA3s, which I had previously set to maximum on the volume knob. I ran in-room measurements at my listening position, and the difference is about 10db. I had to dial down the gain on my powered subs to match.

Is this what we'd expect? My assumption was that the ZA3 at full volume would be the same as the set gain on the V3 Mono.

 

[Deleted member 72219]

I just received two V3 Monos. They're replacing two ZA3s that were running in "mono" so that I can repurpose the ZA3s to other smaller systems in the house (and because I couldn't help seeing how the new V3 Monos compare...)

The system is digital and uses XLR connectors: MiniDSP SHD > (2x) Topping D30PRO > (2x) V3 Monos > passive bookshelves (I handle bass management in the SHD and cross over to (2x) powered subs)

First thing I noticed was that the gain on the V3 monos was much less that the ZA3s, which I had previously set to maximum on the volume knob. I ran in-room measurements at my listening position, and the difference is about 10db. I had to dial down the gain on my powered subs to match.

Is this what we'd expect? My assumption was that the ZA3 at full volume would be the same as the set gain on the V3 Mono.

No, I found the same. Comparing XLR to XLR, ZA3 at full volume is much louder than V3 Mono.

-Ed

 

[gwing]

I just received two V3 Monos. They're replacing two ZA3s that were running in "mono" so that I can repurpose the ZA3s to other smaller systems in the house (and because I couldn't help seeing how the new V3 Monos compare...)

The system is digital and uses XLR connectors: MiniDSP SHD > (2x) Topping D30PRO > (2x) V3 Monos > passive bookshelves (I handle bass management in the SHD and cross over to (2x) powered subs)

First thing I noticed was that the gain on the V3 monos was much less that the ZA3s, which I had previously set to maximum on the volume knob. I ran in-room measurements at my listening position, and the difference is about 10db. I had to dial down the gain on my powered subs to match.

Is this what we'd expect? My assumption was that the ZA3 at full volume would be the same as the set gain on the V3 Mono.

It will depend on the gain of your components but I'm a bit surprised. I run Wiim-> Aurora DAC/Pre -> XLR Monos ->89db speakers and there is many times the gain I need available - I run the pre at just a quarter turn on the volume knob to protect against full signal output.

 

[rwnano]

Harman Kardon AVR 3550 (2002) vs. [Harman Kardon AVR 240 with pre-outs + Fosi V3 next gen twin monoblocks] - projected difference in sound quality?​

Which system would sound better -

1. The Harman Kardon AVR 3550

https://www.fein-hifi.de/Surround-R...on-AVR3550-Digital-5-1-AV-Receiver::3557.html

vs.

2. HK AVR 240 with Fosi V3 next gen twin monoblocks on the Pre-Outs

https://www.newegg.com/harman-kardo...gKcp24j9IBeuyULqbh2xwZi3nEkhiI5XUUOFaiVa5VKeK

with SPEAKERS:

1. 89 dB inefficient Transmission Line speakers - Irving M Fried Signature A 6 &
2. Focal 706 V2

Rest of the chain:

Ubuntu Linux Laptop Spotify - Topping D10s DAC --> Amplifier --> speakers

* I use a cheap home theatre subwoofer thus its a 2.1 configuration

 

[NTK]

I just received two V3 Monos. They're replacing two ZA3s that were running in "mono" so that I can repurpose the ZA3s to other smaller systems in the house (and because I couldn't help seeing how the new V3 Monos compare...)

The system is digital and uses XLR connectors: MiniDSP SHD > (2x) Topping D30PRO > (2x) V3 Monos > passive bookshelves (I handle bass management in the SHD and cross over to (2x) powered subs)

First thing I noticed was that the gain on the V3 monos was much less that the ZA3s, which I had previously set to maximum on the volume knob. I ran in-room measurements at my listening position, and the difference is about 10db. I had to dial down the gain on my powered subs to match.

Is this what we'd expect? My assumption was that the ZA3 at full volume would be the same as the set gain on the V3 Mono.

If PFFB is implemented per the TI application note, part of the gain of the TPA chip is consumed by the feedback. See below for the example in the app note using TPA3251. The normal gain of the chip is 20 dB. 7.2 dB is used up by the PFFB in the example, leaving the gain of the final PFFB amplifier to be 12.8 dB.

 

[drmevo]

No, I found the same. Comparing XLR to XLR, ZA3 at full volume is much louder than V3 Mono.

-Ed

I found the same comparing to my Aiyima A07 Max, albeit using RCA for both.

However, the the V3Ms are roughly equivalent volume-wise to the Pascal amp in my integrated amp, which is now being used as a preamp. I find myself settling on the same volume levels for different inputs that I used previously. When I used the Aiyima for a short stint, I left its volume knob a few notches away from full to achieve the same. So, the V3Ms certainly don't seem underpowered or anything.

 

[Deleted member 72219]

I found the same comparing to my Aiyima A07 Max, albeit using RCA for both.

However, the the V3Ms are roughly equivalent volume-wise to the Pascal amp in my integrated amp, which is now being used as a preamp. I find myself settling on the same volume levels for different inputs that I used previously. When I used the Aiyima for a short stint, I left its volume knob a few notches away from full to achieve the same. So, the V3Ms certainly don't seem underpowered or anything.

No, definitely not underpowered. Just lower gain than ZA3 by a large amount. Not the same.

-Ed