Fosi Audio V3 Amplifier Review

[grogi.giant]

2x yes

 

[Doodski]

1. Is it okay to leave this amp always on? It's a habit after years of powered speakers, I never turned them off.

It best for long life, less heat induced damage and less wear and tear to turn the unit off when not using it.

2. Will it be good enough to drive JBL 4312G? (Sensitivity (2.83V@1m) 90dB - Nominal Impedance 6 Ohm)

Plenty of power is available for these speakers.

 

[GGroch]

It best for long life, less heat induced damage and less wear and tear to turn the unit off when not using it.

So the pole is 1/1 so far grogi/doodski. Is there an ASR thread on the topic?

Googling whether amps, particularly class D amps should be turned off gets strong opinions on both sides.

I would guess in this case most of the power at idle would be used by the power brick, which is not affected by the amps switch. If you put a smart switch on the plug before the brick, you would get a major surge every time it is powered up.

In the case of the V3 there is some concern that using the volume/switch frequently will wear it out. I have left most of my amps on over the years, so I vote leave it on.

 

[Logix]

So the pole is 1/1 so far grogi/doodski. Is there an ASR thread on the topic?

Googling whether amps, particularly class D amps should be turned off gets strong opinions on both sides.

I would guess in this case most of the power at idle would be used by the power brick, which is not affected by the amps switch. If you put a smart switch on the plug before the brick, you would get a major surge every time it is powered up.

In the case of the V3 there is some concern that using the volume/switch frequently will wear it out. I have left most of my amps on over the years, so I vote leave it on.

I won't be able to reach it easily because I'm going to attach the V3 to the back side of my desk, that's why I bought it, for its smaller size.
Even if it will last for 3-4 years it will be worth the $100.

I forgot to ask one more thing:
What if my DAC have balanced output only? is it a problem for the V3?

 

[lewdish]

Any clue as to the power draw on idle? Does it have an auto shutoff function?

 

[bbjayo]

I forgot to ask one more thing:
What if my DAC have balanced output only? is it a problem for the V3?

Just get something like this.

 

[Logix]

I have the right cables, what I meant to ask is about the gain, the Fosi V3 has unbalanced inputs, and in some audio interfaces like RME their outputs can be both unbalanced (-10) or balanced (+4) (but what about DACs that can only send balanced out?

 

[375HP2482]

About the gain: the TPA3255 chip runs at 21.6 dB gain, plus another 6 dB voltage gain from this op-amp section. So, 26.6 dB total system gain. To reach full output (40 volts peak) requires an input signal of 1.9 volts peak, or 1.35 volts RMS. Most (balanced) DACs can do at least 4 volts peak-to-peak, so unbalanced-to-balanced (terminating one half) would still yield half that, or 2 volts peak, which is more than sufficient for full output.

 

[Lux_ury]

Sorry had stuff to do before I could reply Doodski
Can confirm volume has no effect on sub.
Was thinking about these options last night, wanted thoughts on both, as cost per usual is a factor.
U$20 £15 for the cable & summing box is a hugh U$37 £29.00, But has two true mono outputs!
Weirdly I wasn't worried about subwoofer, but it's the option to use one, or not that gets me. (Laugh emoji)
side note:
As for power idle it's like 5w I switch it off at plug when not in use and leave brick on for five minutes wait before load to ensure capacitors have been energised so not to shock the system.
Has anyone worked out cost of a new potentiometer vs cost of electricity yet?

 

[TonyJZX]

there's been a heap of positive reviews already.. i havent seen even a middling review

also he compares this to a ASR favorite amp

 

[dfgoiuj]

I've had this amp for a couple of days now. I didn't expect it to run so hot while idle! I left it switched on overnight and this morning the chassis was 40c sat in a cupboard with a 29c ambient temp. The Topping PA3s never felt more than warm to the touch, but perhaps it just doesn't conduct the heat to the chassis as effectively. I'm now considering a smart plug to turn it off when not in use.

 

[strawberry644]

I've had this amp for a couple of days now. I didn't expect it to run so hot while idle! I left it switched on overnight and this morning the chassis was 40c sat in a cupboard with a 29c ambient temp. The Topping PA3s never felt more than warm to the touch, but perhaps it just doesn't conduct the heat to the chassis as effectively. I'm now considering a smart plug to turn it off when not in use.

I use a smart plug with energy monitoring, just because I don't trust leaving cheaper SMPS and amps on 24/7 or unsupervised.
somewhere in my head I imagine my cat messing with it or it bursting into flames because I dare leave the room .

just open the cupboard from time to time 29C is pretty high and leaving electronics in wooden boxes leaves them with no fresh air.
reminds me all the people with TV stands with closing glass frames/doors to look clean and wonder why the AVR and consoles overheat.

 

[wpo7]

just to confirm.. op amp rolling on this amp is considered to be mainly placebo and not a serious scientific consideration?
I've read somewhere someone recommending a rc4558 swap out...

 

[dfgoiuj]

I use a smart plug with energy monitoring, just because I don't trust leaving cheaper SMPS and amps on 24/7 or unsupervised.
somewhere in my head I imagine my cat messing with it or it bursting into flames because I dare leave the room .

just open the cupboard from time to time 29C is pretty high and leaving electronics in wooden boxes leaves them with no fresh air.
reminds me all the people with TV stands with closing glass frames/doors to look clean and wonder why the AVR and consoles overheat.

Yeah, I attached a smart plug with energy monitoring today as it happens; it consumes 6 to 7 watts at idle assuming the reading is accurate. I'll have to see how the Topping compares.

I should probably ventilate the cupboard a little. I didn't see it as much of a priority with a small class D amp, but this one is significantly more powerful than the PA3s.

 

[Elgrosso]

Got the second pair in 32v and installed them this morning, typing with Vieux Farka Touré in the background right now, they work great.
Just did a quick tune with REW mostly for level match, around -6db, coherent with previous Gjallahorn power.
The impedance effect was visible on the compressions (faital hf108) with around +3db at 20Khz.
So I also added a BW24db at 20Khz to flatten it, I should not be able to hear it anyway but I'll test w/ and w/o.
Temp is lower by few degrees with 32v, both pairs are consistent now.
About the thumps on power I need more time as so far this was not consistent, but for sure not dramatic.
There is some white noise few feet off the CD though, and a tiny bit on the midrange (sensitivity 109 and 98db).
So I already know I will get at least one TP RA3 for the CDs.

 

[Joe Smith]

Mine stays very cool to the touch using the 32v/5a power brick playing at normal volumes (12 o' clock to 3 o' clock on the pot).

 

[grogi.giant]

So the pole is 1/1 so far grogi/doodski. Is there an ASR thread on the topic?

@Doodski has is all - more posts, more likes and better likes/post ratio!

Googling whether amps, particularly class D amps should be turned off gets strong opinions on both sides.

I would guess in this case most of the power at idle would be used by the power brick, which is not affected by the amps switch. If you put a smart switch on the plug before the brick, you would get a major surge every time it is powered up.

In the case of the V3 there is some concern that using the volume/switch frequently will wear it out. I have left most of my amps on over the years, so I vote leave it on.

When the amp is not playing, it will be cool. V3, with its improved ventilation, especially. Heat in the idle state will not affect longevity in any meaningful way.

The advantage of switching off the amp is slightly reduced power consumption. It still won't drop to zero though - the power brick will still consume something.

 

[Lux_ury]

The same issue will exist as the 3.5mm stereo to mono stuff.

I've tested the y splitter from Dac to amp and sub and this would be the best way to tap into source without using the pre out on the amp at all I don't think the impedance on both cables would effect the DACs quality of signal.
Sounds fine this way I can't hear any difference on speaker loads from the amp?
Any thoughts in doing it this way?

 

[Doodski]

I've tested the y splitter from Dac to amp and sub and this would be the best way to tap into source without using the pre out on the amp at all I don't think the impedance on both cables would effect the DACs quality of signal.
Sounds fine this way I can't hear any difference on speaker loads from the amp?
Any thoughts in doing it this way?

I'm not sure what you are doing because the images don't show anything other than a couple cables running through the image.

 

[Zek]

Any thoughts in doing it this way?

As far as I can see, you fed the signal to the subwoofer from only one channel (from the right channel).