Fosi Audio V3 Mono Amplifier Review

[Stoutblock]

After having these amps since the KS launch I am mostly quite happy with them. In terms of sound and power, I’m completely satisfied.

The one area where they are a bit frustrating is the Auto-On function. Just turning on lights on the same circuit seems to trip it. I unplugged the speaker cable in case it was poor power filtering from my preamp but that wasn’t the issue - the amps still turn on with just power connected.

This wouldn’t bother me that much except for that a) the relay click is fairly loud - someone not used to it thinks they’ve done something wrong by flipping the light switch and b) they do seem to use a decent amount of power while on. It also begs the question, how good is the power filtering if simply using other things on the same circuit trips the Auto function?

I stopped using the auto on setting as they seem to be triggered by both input changes and also a voltage changes. Not a big issue on my stereo system in my office but with the 6 in my HT system the relays could become disruptive. Instead I use a strip outlet with a switch with the added benefit of the PSs turned off and no current draw.

 

[Ellisr63]

Has anyone tried the fosi 125mm cooling fans? I am wondering how quiet they are or maybe I should try some other brand cooling fans.

 

[burkm]

Because they look quite similar to some other fans on Amazon, I would propose, that they are about 18-19 db on their lowest speed setting. For two (channels) it would then add up to 21 - 22db for both. I would suggest middle speed at the most for this application (depends on Your preferences) and at its highest speed setting again a bit higher. I don't have those numbers right now at hand because I use only their lowest speed setting. They are quite a bit cheaper so (Amazon).
Those other ones are quiet dual ball bearing types 120mm USB fans with a splitter, so You need only one ordinary (low cost) standard USB power supply of ~1A with one outlet. Life expectancy is stated as 60.00 - 70.000 on-hours. The dimension "125mm" is probably measured with the support rubber feet on top... The amps just fit snuggly on those 120 mm fans... Otherwise I don't know of any 125mm fan types and my believe is, that Fosi Audio is just an OEM of those brand(s) behind it. They are a reseller...

 

[ninetylol]

Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.

 

[Old_School_Brad]

Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.

In the "Audio Settings" menu in the Wiim Home app, at the bottom you can enable "Fade-in & Fade-Out Effects".

 

[ninetylol]

In the "Audio Settings" menu in the Wiim Home app, at the bottom you can enable "Fade-in & Fade-Out Effects".

Thats enabled. I mean really Bad pops from speaker. A bit scared for my Lintons to be honest.

 

[Old_School_Brad]

Thats enabled. I mean really Bad pops from speaker. A bit scared for my Lintons to be honest.

Sounds odd. I assume analog out from the Wiim Pro Plus? And it pops when switching song?

Try as an experiment to go in EQ in the app choose graphical EQ and pull the bar at 31 Hz all the way down.

 

[ninetylol]

Sounds odd. I assume analog out from the Wiim Pro Plus? And it pops when switching song?

Try as an experiment to go in EQ in the app choose graphical EQ and pull the bar at 31 Hz all the way down.

I will try that.

I think its a defect V3 mono though. One of them has bent rca, rattling inside, power LED not working. At the moment i have it disconnected and only other side playing and no problems so far.

 

[Old_School_Brad]

I will try that.

I think its a defect V3 mono though. One of them has bent rca, rattling inside, power LED not working. At the moment i have it disconnected and only other side playing and no problems so far.

Ah. Well yes. It would be a good place to start with the defect amplifier of course!

 

[Stoutblock]

Anybody else sometimes got very loud pops with these? I feel its especially during Song changes (maybe sample rate change in Tidal)

But I never had the problem with my Wiim Pro Plus with any other amps.

Are you using the auto power setting on the V3M? Try just using the manual on setting if so.

 

[amix]

Auto-On function. Just turning on lights on the same circuit seems to trip it

Just posted in thread 'Fosi v3 Mono - User Impressions | Owner's Thread' about the same issue. I feel with you.

 

[ninetylol]

Just posted in thread 'Fosi v3 Mono - User Impressions | Owner's Thread' about the same issue. I feel with you.

Same here. I Was already wondering if demons are in my room.

 

[badie]

Well ... Fosi made a well-working thermal design on the V3 Stereo.

As stated on their website the thermal design of the V3 monos is "advanced" (i believed it, as i do own a V3 stereo).
But I was really surprised when I unpacked the V3 monos and found out that the ventilation holes on top and bottom got cancelled.

Measuring temp side by side the thermal design of the V3 monos is clearly way worse.

Why did they got rid of the holes on bottom and top??? (this is very basic thermal dynamics)???
Tried to use incencse sticks to see if there is any significant airflow through/in/out the orange side-ventilation and guess what?
Pretty much nothing.

Maybe I find the time to elaborate on this but for the moment this post must suffice.

 

[badie]

regarding ventilation:

They really sell the V3 monos with a ventilation setup now! (see fosis website)

Well. I put one average-quality 120mm PC vent (with an old 5V 350mA phone wall brick) that is throwing air over all my three units (V3 Stereo and 2xV3 mono) ... everything is down to ~30 °C.

So i think a very faint breeze of air make a huge difference. No need for individual fans under each unit.
(Hope to find the time to make some measurements)

 

[antcollinet]

Op-amp rolling is the new tube rolling. You’re looking for your preferred flavor of distortion coloring, not a perfect signal.

Take a Big Mac and then put something else in it—BBQ sauce, fried onions, ranch dressing, banana peppers, whatever…it’s no longer a, “perfect Big Mac,” it’s your own twist.

ASR crowd doesn’t understand anything other than the perfect Big Mac, but these people want it their way; they’re the Burger King types.

-Ed

ASR crowd understand that you are not putting a flavoursome BBQ sauce on your big mac, but an undetectable tiny micro drop of water.

It is not that “ASR Crowd” only want a perfect big mac - it is that they recognise op amps as bringing only micro drops of water rather than a good dollop of BBQ/onion/etc flavour.

It is of course possible (though unlikely) that an op amp swap might go badly wrong and bring a big squirt of sewerage to the burger - but it is unlikely that anyone would prefer that.

Hope that helps.

 

[antcollinet]

Typically 30-40x for the TPA3255 chip.
It's fine.

That would be without post filter feedback though, wouldn’t it?

 

[Sokel]

That would be without post filter feedback though, wouldn’t it?

Yes,in Fosi's case is close to 150x (300x at 8 Ohm),I wrote couple of posts after that.

 

[antcollinet]

Yes,in Fosi's case is close to 150x (300x at 8 Ohm),I wrote couple of posts after that.

So you did. I am travelling, and just catching up.

 

[Inertiaman]

Measuring temp side by side the thermal design of the V3 monos is clearly way worse.

Why did they got rid of the holes on bottom and top??? (this is very basic thermal dynamics)???
Tried to use incencse sticks to see if there is any significant airflow through/in/out the orange side-ventilation and guess what?
Pretty much nothing.

It does seem a rather dumb design choice. Even if one accepts a design requirement to not have holes on the top (avoiding dust ingress or god forbid fluid spills), there are thermally better ways to vent than their current mid-panel side vents. For example, holes on the bottom combined with holes on the very top edges of the sides would provide passive flow-through nearly as well as holes in the top.

 

[antcollinet]

It does seem a rather dumb design choice. Even if one accepts a design requirement to not have holes on the top (avoiding dust ingress or god forbid fluid spills), there are thermally better ways to vent than their current mid-panel side vents. For example, holes on the bottom combined with holes on the very top edges of the sides would provide passive flow-through nearly as well as holes in the top.

There is (and can be) almost no vertical air flow in this design. The entire area is blocked by the PCB - where are you expecting air entering the bottom of the case to go?. The thermal design relies almost entirely on conducting heat to the chassis. There will be some small trickle of air out of the side vents, fed though the small gap between the edges of the PCB and the housing.