Fosi v3 Mono - User Impressions | Owner's Thread

[gwing]

So I just unplugged one of the amps from the PSU and turned on the other, it is now dead silent. I can only guess from this that the issue is with the PSU. I was hoping as such as I plan to replace it anyways.

It is worth trying the single supply without the filter to see if that is the problem. I know there were initially problem reports when running the single supply without filter but adding that filter made no audible difference for me. Maybe if you are pushing the power supply to its limits that is not the case but at my normal listening levels it is having a very easy time.

It's worth knowing if the problem is the amps, the power supply, or the filter - if it's the filter you'll only need to buy a second additional power supply and can then dispense with said filter. Or maybe just dispense with the filter and continue using your existing power supply at zero cost. Another useful test is to switch the (rca?) input leads to the two amps and see if the noise moves with the input signal or not.

 

[early rejecter]

Anyone running a pair of these off the larger single PSU and with the Fosi DC power filter?

That’s my setup, and I also get noise when only a single amp is on. I never have occasion to use only a single amp though, and no audible noise whatsoever with both on, so hadn’t considered it to be an issue.

 

[Crash Alpha]

It is worth trying the single supply without the filter to see if that is the problem. I know there were initially problem reports when running the single supply without filter but adding that filter made no audible difference for me. Maybe if you are pushing the power supply to its limits that is not the case but at my normal listening levels it is having a very easy time.

It's worth knowing if the problem is the amps, the power supply, or the filter - if it's the filter you'll only need to buy a second additional power supply and can then dispense with said filter. Or maybe just dispense with the filter and continue using your existing power supply at zero cost. Another useful test is to switch the (rca?) input leads to the two amps and see if the noise moves with the input signal or not.

Unfortunately the cabling provided does not allow me to bypass the filter when using both amps. The issue occurs even at no volume when the amps aren't being pushed at all.

 

[Crash Alpha]

That’s my setup, and I also get noise when only a single amp is on. I never have occasion to use only a single amp though, and no audible noise whatsoever with both on, so hadn’t considered it to be an issue.

Interesting, glad to hear I am not alone! It wouldn't really bother me if I left them on all the time but when running them in auto, one usually turns on/off before the other and I have to hear this odd sound every time it does.

 

[gwing]

Unfortunately the cabling provided does not allow me to bypass the filter when using both amps. The issue occurs even at no volume when the amps aren't being pushed at all.

The cable Fosi provided for this setup (before they brought out the filter) was a simple single Y cable, one female to 2x male. Fosi can probably supply one - I still have one myself so if you live in the UK you can try with mine.

 

[early rejecter]

when running them in auto, one usually turns on/off before the other and I have to hear this odd sound every time it does.

Ah yeah that makes sense. I run in Auto as well but they turn on/off within a fraction of a second of each other so never noticed. In fact I only discovered the noise last week when my cat switched one of them off (I’m sure it’s not ideal for airflow, but he likes to stretch out across them once they’ve warmed up).

 

[Crash Alpha]

The cable Fosi provided for this setup (before they brought out the filter) was a simple single Y cable, one

Ah yeah that makes sense. I run in Auto as well but they turn on/off within a fraction of a second of each other so never noticed. In fact I only discovered the noise last week when my cat switched one of them off (I’m sure it’s not ideal for airflow, but he likes to stretch out across them once they’ve warmed up).

Yeah sometimes I listen at really low volume and one amp is more sensitive than the other when turning on auto, it will turn on with almost no signal, where the other one needs a bit more volume before it kicks in, so it was easy for me to hear that sound.

 

[gwing]

Yeah sometimes I listen at really low volume and one amp is more sensitive than the other when turning on auto, it will turn on with almost no signal, where the other one needs a bit more volume before it kicks in, so it was easy for me to hear that sound.

Do you still get this noise if you disconnect the RCA/XLR input cables ?

 

[Crash Alpha]

Do you still get this noise if you disconnect the RCA/XLR input cables ?

I hadn't tried that, but after explaining the issue to FOSI, they seem to know what it is and are sending me some filters. So we shall see.

 

[wwjokerk]

Fosi will send two new boards, I will already receive the updated version with adjusted gain of 19/25 dB instead of 25/31 dB. That's why I insisted on getting two new boards and not only one. And I assume that my second amp will die shortly as well.... Maybe there is a mistake in one charge during production.

I received the boards yesterday...

Still the old version with 25/31 dB gain. No thermal paste included, according to Fosi it is not required anymore. The thermal pads under my old boards is also not included anymore.... Actually I had in mind to get a ZD3 DAC for a small budget setup, no thanks Fosi. Will get a Geshelli J2S, better quality and better sound most likely as well.

I am a bit disappointed by Fosi's service and quality.

 

[Crash Alpha]

Noise problem solved. Dead silent now. Fosi rocks!

 

[wwjokerk]

What kind of power splitter is that?

 

[Crash Alpha]

What kind of power splitter is that?

Its the same as the filter included in the V3 Monos package but larger and doesn't use the y adaptor

 

[wwjokerk]

And where did you purchase it? The y cable is one major drawback.

 

[telemike]

Its the same as the filter included in the V3 Monos package but larger and doesn't use the y adaptor

Looks like it's Fosi branded but I do not see it on the Fosi website

 

[Slave IV]

Very curious about the power splitter as well. I’d like to get a 10A power supply to run my 2 V3 Monos instead of separate 5A supplies and the previous version I’ve seen looks clunky.

 

[Crash Alpha]

And where did you purchase it? The y cable is one major drawback.

They don't seem to sell it, at least not yet anyways. It was sent to me by Fosi service as I was having issues with the original that came with the V3 kit.

 

[Crash Alpha]

Very curious about the power splitter as well. I’d like to get a 10A power supply to run my 2 V3 Monos instead of separate 5A supplies and the previous version I’ve seen looks clunky.

The Fosi 48v10a PSU works well with the V3 monos. I am guessing most people do not have the noise issues I was having with the DC filter that comes in the package. It may work perfectly fine for you. If not, contact thier service and they will take care of you

 

[Slave IV]

The Fosi 48v10a PSU works well with the V3 monos. I am guessing most people do not have the noise issues I was having with the DC filter that comes in the package. It may work perfectly fine for you. If not, contact thier service and they will take care of you

I don't have any noise issues but just like that power supply you have over the generic block with the Y-Splitter. Since they don't seem to sell it, I guess I will wait or contact them about what you got. Thanks!

 

[antcollinet]

I don't have any noise issues but just like that power supply you have over the generic block with the Y-Splitter. Since they don't seem to sell it, I guess I will wait or contact them about what you got. Thanks!

If I understand correctly, that is not a power supply. Just a different filter that fits between the 'generic power block' and amp.

It just happens that this on has two outputs, so that a splitter cable isn't needed.