Fosi v3 Mono - User Impressions | Owner's Thread

[Raxumit]

I received my order yesterday - two V3 monos and two 48v/5a power supplies. They sent only one XLR cable and one opamp. Have others received pairs of cables and opamps with their order of two V3 Monos?

I ordered the same, and received the same bonus. Not extremely useful, but hey it was a freebie, don't mind especially.

I'd trade anyone interested my opamp for their XLR cable, send me a message..

 

[jvdburgt]

I am basically going to be trying them on an identical system. Will be running them into Sonus faber lumina 2's ( a forum favorite) / sarcasm. I did the preorder so I wont know until august

So, hooked them up to my Marantz, and 31dB seems to be the way to go.

At this setting the power/volume seems to be similar to the Marantz own internal amplifier output. At 25dB I had to put the volume way way up compared to what I’m used to.

 

[Otovo]

Thanks for your advice! But I am pretty sure it comes from the "corner problem" - on the right side there's just so much more open space. For my comparisons of the two/three amps I had not used any DSP and my sub was silent That's why I had to turn the balance to the right quite a bit.
About speaker placement: basically everywhere it is recommended to pull the Dynaudios away from the wall, which is what I did in the beginning. When I got my UMIK-1 and started to measure and play around with speaker positioning it turned out that they should be much closer to the wall (in my case). Placing the sub was also counter intuitive - but the corner is just the right spot and it dials in great with the Minidsp with help from REW. Anyway, the Minidsp with Dirac was the biggest game changer in my Hifi journey. Quite amazing.

I did try to get a furry cat to take advantage of their legendary absorbance factor - as you see I got stuck with a short haired dog which he spreads liberally around the house.

Btw, I like this discussion much better now. Still listening to the Fosi Monos...
View attachment 380924

So how do you eventually deal with such issue??? Funny I met this very same problem once I paid bit more attention to listen to v3 monos. My soundstage is very much in left. Mainly as there is glass window on the left closer to the speaker and big open space on the right side... So its pretty clear what the problem is. Do you need to pull balance to other side or is there any other, more elegant way?

 

[Freshman1966]

So how do you eventually deal with such issue??? Funny I met this very same problem once I paid bit more attention to listen to v3 monos. My soundstage is very much in left. Mainly as there is glass window on the left closer to the speaker and big open space on the right side... So its pretty clear what the problem is. Do you need to pull balance to other side or is there any other, more elegant way?

Well, yes, of course, the most trivial way is to shift the balance. But in most cases that won't suffice because of the very individual room problems.
Personally, I have opted for a Minidsp Flex plus Dirac to tackle those issues. It also solved the problem to seamlessly integrate a sub. I am very happy with this solution and it made the biggest difference so far in sound quality - now the stage is centered, instruments and voices are much more defined in space and - the sound generally improved because the DSP could solve the biggest peaks I had in my response curve. Currently, I am left with a null round 40 hz but there's not much I can do (without getting divorced)

 

[ichonderoga]

Hi everybody, thanks for all your "two-cents" - Awesome community. I also wanted give mine

I just got 2 x V3 Mono and 2 x 48V/10A psu bricks. As a substitute for my trustworthy and very reliable TacT SDA2175 (oooold - which I bought new in the 00's as I recall it) - Which is still going strong. I was also considering Topping LA90 (Discrete) but for the price I couldn't resist trying the Monos.

And man (confirmation bias I know) am I pleased, I'm pretty sure I paid 6 times the price (not counting for inflation) for the TacT and wow! do these Monos pack a punch considering their size and (lack of) heft. I'm not bothered by the slight speaker "click" when being powered completely off from the wall, and absolutely love the relays clicking on when powered and changing between inputs. My biased and subjective impression: the pair plays just as loud as the TacT without distortion and just as clear.

TL;DR I'm very pleased with the Fosi V3 Monos, amazing what around €300 can get you these days!

ps. I can also confirm the power usage previously stated 5w per amp in standby (not the advertised ,5) and 10w ON and more when volume goes up
pps. they get toasty nomatter the volume, but don't worry they are made for those operating temps.

 

[jvdburgt]

also my 2 cents on heat; mine are in a fairly large cabinet that stores, amongst others, the mono’s, a Marantz receiver, a i3 based Home Assistant PC, an 8-port switch, and some other minor electronics. The cabinet has two 200mm fans (one for air intake, one for air output).

After several hours of playing, the mono’s are only warm to the touch, easy to hold my hand on it for prolonged time. Moral of the story: just a bit of airflow seems to do wonders.

PS. Before anyone asks: the cabinet is not in the living room, but in the adjacent laundry room, with connections going through the wall to the living room, so noise is not an issue (even though the 200mm fans are barely audible at all).

 

[SMen]

After several hours of playing, the mono’s are only warm to the touch, easy to hold my hand on it for prolonged time. Moral of the story: just a bit of airflow seems to do wonders.

Mine arrived today. My environment at the moment is quite hot - so 30+ degrees C during the afternoon, and mine are hot to the touch, but not so hot that I can't hold my fingers on them ... hot not warm ... so no fried eggs today.

Still, I think Fosi might have missed a trick by combining the side vents with the top holes they already have stamped into the top of the standard V3 stereo.

I am quite glad to have the single 10A supply. Looking forward to receiving the filter at some point but I am leaving here for three weeks in one week so did not want to wait. I quite understand other set ups preferring the 2x 5A.

I am comparing these to a modified stereo balanced unit with TPA3255 which dare I say it sounded surprisingly different and good with Muses01's.
I suspect the sound is going to change over the next 72 hours or so, so will give my tuppenny's worth then. Very different amplifiers sound wise despite the same 3255 on first listen.

Delighted I went with the mid size T Shirt! Seems a pretty much standard XL though it scarily says 5XL on the label!

 

[Megaken]

The gain switch only affects unbalanced connection is that correct? I saw someone say that XLR is set to 20db gain and that's that.

 

[EddNog]

The gain switch only affects unbalanced connection is that correct? I saw someone say that XLR is set to 20db gain and that's that.

Correct.

-Ed

 

[jvdburgt]

Btw, I got 4x Muse02 op-amp for anyone interested (in the Netherlands).

I think €10 per piece is a fair price?

 

[DavidM1]

Well, mine arrived on Tuesday and they are a joy. I realise my last amp probably dropped away a little higher in the bass so the impression is that these are fuller sounding down low. I’ve angled the speakers out a little to compensate. Hearing the low strings of the theorbo has been a bit of a revelation.

These amps are so quick and punchy. I’ve just listened to Robben Ford’s Bringing it Back Home album and the Hammond organ has that rhythmic edge that comes through so well.

I’m also enjoying the auto on and standby. I leave it on Auto and they are ready to go whenever I pick up the remote for the DAC.

 

[LukW]

Hello
I have a Rotel Rc-1572 preamplifier and Dynaudio Emit 50 speakers. Does buying two Fosi Audio V3 Monos make sense in my case?
I have concerns about whether the preamplifier will properly drive the power amps and secondly, my speakers, according to the manufacturer's information, the nominal impedance is 4 Ω, sensitivity 86 dB, the impedance characteristic has approx. 3-ohm minimum at 100 Hz. Will the monoblocks be sufficiently efficient in terms of current for my speakers?

 

[wybe]

Hi, does anyone here have experience with a Schiit Magni (any generation) as a preamp/volume control for the V3 Mono’s? From what I can find, this should work good together.

 

[EddNog]

Hi, does anyone here have experience with a Schiit Magni (any generation) as a preamp/volume control for the V3 Mono’s? From what I can find, this should work good together.

Don’t see why not as long as you don’t need a remote volume control.

-Ed

 

[wybe]

Don’t see why not as long as you don’t need a remote volume control.

-Ed

Thanks Ed, I see you are using a little better Schiit in combination the V3 mono’s. XLR probably? What I am curious about is, if the Magni serie can use the full potential from what the V3’s are capable off. So if there are people here with the experience, please share with us.

 

[EddNog]

Thanks Ed, I see you are using a little better Schiit in combination the V3 mono’s. XLR probably? What I am curious about is, if the Magni serie can use the full potential from what the V3’s are capable off. So if there are people here with the experience, please share with us.

Yes, I have the XLR outputs connected to the V3 Monos and my subwoofer connected to the RCA outputs.

-Ed

 

[HoweSound]

I ordered the same, and received the same bonus. Not extremely useful, but hey it was a freebie, don't mind especially.

I'd trade anyone interested my opamp for their XLR cable, send me a message..

I'm not a-Muse-d by the inclusion of only one opamp and one cable in my order for two amps. I would gladly trade my opamp for your XLR cable if you are in the greater Vancouver area. Recognizing that I am unlikely to find someone willing to make this swap and certain that I will not start rolling opamps, I will offer my opamp free to any taker. You can message me. One option - send me a self addressed stamped envelope and I will mail it to you.

 

[NTK]

Hello
I have a Rotel Rc-1572 preamplifier and Dynaudio Emit 50 speakers. Does buying two Fosi Audio V3 Monos make sense in my case?
I have concerns about whether the preamplifier will properly drive the power amps and secondly, my speakers, according to the manufacturer's information, the nominal impedance is 4 Ω, sensitivity 86 dB, the impedance characteristic has approx. 3-ohm minimum at 100 Hz. Will the monoblocks be sufficiently efficient in terms of current for my speakers?

Welcome to ASR!

The figures shown are from the TI's TPA3255 datasheet. The first figure is the max output (at 1% THD+N) when used in the stereo (2 output channels) mode. The blue dotted line indicates the supply voltage of 48 VDC. With 4 Ω load (black curve), the output is ~230 W. Assuming that the amp has reached is maximum output current with 4 Ω load, the maximum output with 3 Ω load is 230 * (3/4) = 173 W. (Since power = current^2 × load impedance, and when current limit is reached, max output power is drops with the load impedance.) The 173 W estimate is conservative as the current limit is likely not an abrupt hard limit, and the stereo amp can probably output a bit more than 173 W (1 % THD+N).

The second figure is for the mono (1 output channel) mode. With 4 Ω load (gray curve), the max output is marginally increased to ~255 W (~0.5 dB increase, a likely-not-noticeable difference). But since the current output capacity is doubled for the mono mode, the 3 Ω (red curve) max output is increased to 325 W, which is about 2.7 dB (at most) more than the stereo mode.

The summary is that there is little benefit if load impedance is over 4 Ω, with the mono setup the heat dissipation will be distributed to 2 amps instead of 1 and therefore less stress for the monos when power output demands are high. You'll need to decide for yourself whether the optimistic estimate of 2.7 dB power increase at 3 Ω is worth going with 2 monos vs 1 stereo.

 

[Freshman1966]

Hi, does anyone here have experience with a Schiit Magni (any generation) as a preamp/volume control for the V3 Mono’s? From what I can find, this should work good together.

As I wrote earlier, the Fosi has no problem driving my Dynaudio Heritage Specials with similar specs.

 

[wybe]

As I wrote earlier, the Fosi has no problem driving my Dynaudio Heritage Specials with similar specs.

Maybe I didn’t read all the comments carefully enough, but which Schiit Magni preamp did you use?