Fosi Audio V3 Mono Amplifier Review

[rvsixer]

Mines all packed up ready to ship back to Amazon UK. Things I dont like.

1) I dont like the nasally glass like tone/sound of the amps.

2) ) Poor musicality/fatiguing

3) They run far to hot considering they are class d, I thought they where suppossed to run cooler.

4) The wiring inside looks a complete mess.

5) The inverted polarity fu#k up.

6) This is about the 6th class d amp i've purchased and they all sound shite.

7) Even the excellent measurements couldn't save it.

8) Back out of storage comes my lovely Arcam FMJ A39.
Lets make sweet music, Oh, how I've missed you.

9) Bye bye class d.

Blaming all the sound deficiencies on class D, when in actuality they are caused by entirely different things. Now the launch, qc, and reliability issues; those are real and the reason I am likely going to spend $295 USD more for a stereo Hypex over dual Fosi mono's.

 

[Lux_ury]

Quick test on 4ohms speakers with temperatures.
20db gain RCA.
Had about 10 odd hours of play back on different speakers. I think the thermal paste needs heat to settle as mines steady around 37C-39C Dropped about 4C since first turning it on.
By the way I clean with lint free cloths and use IPA alcohol just as Doodski explained (Thumbs up emoji)

 

[antcollinet]

I have several of them already delivered in two charges and don't know, if thermal paste has been applied during production or not. Thus I will have to unmantle them looking for that thermal paste. They seem to be getting rather warm or "hot", as stated by most of the users, who got them already and thermal paste improves coupling temperaturwise

Right - but that wont change the surface temperature of the device. It will only impact the internal temperature of the chips.


Power consumption is the same regardless of whether thermal paste is installed. It is power consumption that dicates how hot the amp gets overall. Paste is about getting power out of the chip with minimal chip temperature rise.

 

[rhing]

Oh very nice (turntable and cartridge)...!

I went for a Michael Fidler MMPro. Just got it, along with a balanced switch relay volume control. What stylus are you using with that V15 Type III? Just curious. Using an old Technics p205 myself (and a couple of others)... always hankered after an old V15 ... but not an option with that 'P' in front of the 205 (SL15).

Regardless, the V3 monos are a great match! No sense of anything lacking ... just a sense of everything being reproduced with power and transparency. Bargain indeed. Haven't tried the Muses02's. I'm sure I will at some point.

The Shure V15 Type III has the original VN35MR “Super Tracking” stylus. It’s a matter of time for replacing it, so I am prepared to acquire a suitable Jico replacement. The Dual 1229 is a family heirloom piece I inherited from my family. My uncle was an audiophile and he had an all McIntosh separates system with this Dual 1229 turntable. I sent it to Bill Neumann of Fix My Dual in Des Moine, Iowa. Bill is great to work with and his group restored the 50+ year old Dual 1229 idler wheel drive to “factory new” condition. I highly recommend him for purchasing rebuilt Dual turntables or rebuilding classic Dual turntables like the 1219, 1229 and 701.



With balanced connections from the phon stage preamp to the Fosi V3 Mono amps, my system is silent in idle and sounds very musical. I’m enjoying my vinyl.

 

[Doodski]

The Shure V15 Type III has the original VN35MR “Super Tracking” stylus. It’s a matter of time for replacing it, so I am prepared to acquire a suitable Jico replacement. The Dual 1229 is a family heirloom piece I inherited from my family. My uncle was an audiophile and he had an all McIntosh separates system with this Dual 1229 turntable. I sent it to Bill Neumann of Fix My Dual in Des Moine, Iowa. Bill is great to work with and his group restored the 50+ year old Dual 1229 idler wheel drive to “factory new” condition. I highly recommend him for purchasing rebuilt Dual turntables or rebuilding classic Dual turntables like the 1219, 1229 and 701.

View attachment 387232 View attachment 387233 View attachment 387234

With balanced connections from the phon stage preamp to the Fosi V3 Mono amps, my system is silent in idle and sounds very musical. I’m enjoying my vinyl.

That appears to be a nice system you arranged there. What is the big black amp?

 

[Jukka]

Nonsense, power is power independent of the “nationality”.

Power is often rated for 10 % distortion, but if quality is what you're after, then all Watts are not equal. If you look at Chinese web shops for the cheapest junk, you only see these inflated numbers.

 

[Doodski]

Power is often rated for 10 % distortion

WoW! Can you give examples so I can see the stuff they are offering with 10% distortion?

 

[rhing]

That is a Pass DIY Aleph J Class A SS amp I built during the COVID pandemic. I am a huge fan of Nelson Pass amplifiers including many of his Pass Labs, First Watt, Threshold and Adcom designs. The Aleph J gives my McIntosh MC240 tube amp a run for best sounding amps in my collection. I used high quality components including Kimber Kable internal wiring, Nichicon Muse capacitors, matched Vishay Dale resistors and original Toshiba JFETs. Surprisingly, it can drive my KEF LS50 speakers with its oversized power supply.



I also built a Pass DIY Class A amp using near-unobtainium NOS Sony VFET transistors with high quality components as well. That is a very special SS amp that sounds rich and warm like a tube amp, but with the speed and dynamic slam of a solid state amp.

I have been a Fosi Audio fan since purchasing a Fosi ZA-3 Class D amp last year. The V3 Monos are even more impressive with the PFFB and fully balanced topography. These measure very well against my DIY TPA3255 Class D stereo amp with PFFB.



This is essentially the same amp available as the Living Sounds Audio Discovery Warp-1 Class D amp designed by Viet Nguyen. He made his amp design available through diyAudio.com along with the balanced input buffer circuitry. The oversized switching power supply is a MicroAcoustics SMPS630-SO SMPS. The TPA3255 IC is mounted on the underside of the circuit board and thermally coupled to the 6mm Aluminum heat sink plate underneath and coupled to the perforated sheet metal base. This Class D amp is used in a system at my other home.

 

[Nopiano]

they all sound shite

Can you measure that? ;-)

 

[Doodski]

That is a Pass DIY Aleph J Class A SS amp I built during the COVID pandemic. I am a huge fan of Nelson Pass amplifiers including many of his Pass Labs, First Watt, Threshold and Adcom designs. The Aleph J gives my McIntosh MC240 tube amp a run for best sounding amps in my collection. I used high quality components including Kimber Kable internal wiring, Nichicon Muse capacitors, matched Vishay Dale resistors and original Toshiba JFETs. Surprisingly, it can drive my KEF LS50 speakers with its oversized power supply.

View attachment 387235 View attachment 387236

I also built a Pass DIY Class A amp using near-unobtainium NOS Sony VFET transistors with high quality components as well. That is a very special SS amp that sounds rich and warm like a tube amp, but with the speed and dynamic slam of a solid state amp.

I have been a Fosi Audio fan since purchasing a Fosi ZA-3 Class D amp last year. The V3 Monos are even more impressive with the PFFB and fully balanced topography. These measure very well against my DIY TPA3255 Class D stereo amp with PFFB.

View attachment 387237 View attachment 387238

This is essentially the same amp available as the Living Sounds Audio Discovery Warp-1 Class D amp designed by Viet Nguyen. He made his amp design available through diyAudio.com along with the balanced input buffer circuitry. The oversized switching power supply is a MicroAcoustics SMPS630-SO SMPS. The TPA3255 IC is mounted on the underside of the circuit board and thermally coupled to the 6mm Aluminum heat sink plate underneath and coupled to the perforated sheet metal base. This Class D amp is used in a system at my other home.

Very cool. I like the big amp the best of course. Nice assembly, very well laid out and organized. What kind of power output.

 

[Tell]

1) I dont like the nasally glass like tone/sound of the amps.

I've heard lots of weird audiophile words for describing audio, but "nasally glass like" really takes the price. What does that even mean?

 

[Bleib]

I've heard lots of weird audiophile words for describing audio, but "nasally glass like" really takes the price. What does that even mean?

I bet even his wife heard if from the kitchen

 

[burkm]

Right - but that wont change the surface temperature of the device. It will only impact the internal temperature of the chips.


Power consumption is the same regardless of whether thermal paste is installed. It is power consumption that dicates how hot the amp gets overall. Paste is about getting power out of the chip with minimal chip temperature rise.

Excactly. It is the TA3255 chips "internal" temperature I like to lower and this needs a medium called "thermal paste" That's all there is to it.
It helps to "cool" the inerts of that amp with the help of thermal paste and the heat sink (casing)...
That's, what every manufacturer is after, in't ist ?

 

[Doodski]

Excactly. It is the TA3255 chips "internal" temperature I like to lower and this needs a medium called "thermal paste" That's all there is to it.
It helps to "cool" the inerts of that amp with the help of thermal paste and the heat sink (casing)...
That's, what every manufacturer is after, in't ist ?

The name of the game is conduct heat away from the PCB and chip amp. So if you are into MODing then you are on the right track. If you can find a thermal paste with a guarantee of ~8 years life expectancy before breakdown that will be the best.

 

[burkm]

I am not going to "mod" something, just looking, if everything is as it is supposed to be...
If I should need thermal paste, I got some with extended life because I just reinstalled my CPU using it. If needed more for all, I will order some through Amazon...

 

[somebodyelse]

Oh, so I get a big dip when inverting phase, but not at the frequency I chose for crossover. I am new to using a sub and miniDsp etc so followed miniDsp instructions on setting up my Flex. I was a bit confused as to where they got their crossover frequency from in the online guide. I choose 85hz and to be honest it does drop on inversion but only by a few dB. But, at 103hz there’s a massive sharp drop on inversion. So, does that mean I should use 103hz as crossover and that the SVS sub is actually in phase with the V3 monos? All interesting stuff even if I don’t fully understand

Probably best to start a new thread for this as it's not really anything to do with the V3 Mono. You'll be more likely to get people with experience setting up subs with the Flex that way too.

 

[Petrushka]

I've heard lots of weird audiophile words for describing audio, but "nasally glass like" really takes the price. What does that even mean?

Bad speakers?

 

[mike70]

I bet even his wife heard if from the kitchen

and with class AB is like a veil was lifted from the speakers.

Blind test with levelled gain is the scientific tool to check that spectacular differences ... in other way ... only words.

 

[DavidM1]

I bet even his wife heard if from the kitchen

Lol.
There are two possibilities here. 1. The differences are entirely imaginary or 2. The listener was used to something that wasn’t as even in its response.

I posted a vid a few pages ago on aural illusions. Several showed the dependence of what we hear on what we see. One I liked instantly switched the sound of a word from “bear” to “fare” depending on which of two mouths one chose to look at, even though the recording itself was the same throughout.

 

[SMen]

The Shure V15 Type III has the original VN35MR “Super Tracking” stylus. It’s a matter of time for replacing it, so I am prepared to acquire a suitable Jico replacement. The Dual 1229 is a family heirloom piece I inherited from my family. My uncle was an audiophile and he had an all McIntosh separates system with this Dual 1229 turntable. I sent it to Bill Neumann of Fix My Dual in Des Moine, Iowa. Bill is great to work with and his group restored the 50+ year old Dual 1229 idler wheel drive to “factory new” condition. I highly recommend him for purchasing rebuilt Dual turntables or rebuilding classic Dual turntables like the 1219, 1229 and 701.

View attachment 387232 View attachment 387233 View attachment 387234

With balanced connections from the phon stage preamp to the Fosi V3 Mono amps, my system is silent in idle and sounds very musical. I’m enjoying my vinyl.

Cool. I'm a fan of those Jico SAS ... well only the borons which theoretically may well be best in many systems . Yes, just running balanced through everything is working for me.

It is great to read, keeping it in the family, and to see those pics. Thank you.