Fosi Audio V3 Mono Amplifier Review

[antcollinet]

I am wondering if this amp (or looking for other suggestions) would be a good addition to my setup.

I currently use a Denon AVR but it can only power 9 channels and so it is running 7.2.2 but I am looking for a separate amp to get to the 7.2.4 setup that I want.

I initially was thinking of getting a cheap amp for my atmos speakers but now I am thinking why not buy an amp for the L+R channels (and use the AVR pre-outs) as that would free up a lot of the power on the AVR and probably sound better for the main speakers as well.

Anyway, I have been looking for cheap amps that would be an improvement over the Denon AVR and thought this might fit the bill.

I listen to music and home theater content 50:50
My speakers are DIYSG HTM 12v2 (sensitivity 91
I listen at 2m distance.

I have been looking into the 3e Audio A5/7 and the Fosi V3 Mono but wondering if people think those would work for me and if they thought one would be better than the other or if there are other amplifiers that I should consider.

Thanks for any suggestions!

In your shoes, I'd be looking at exactly those amp.

I don't think there will be anything to choose between them sonically though.

 

[drodgers]

I initially was thinking of getting a cheap amp for my atmos speakers but now I am thinking why not buy an amp for the L+R channels (and use the AVR pre-outs) as that would free up a lot of the power on the AVR and probably sound better for the main speakers as well.

I did exactly that... and then upgraded my centre and surround speakers to 4Ω models that my AVR couldn't handle, so I ended up with 7 Fosi V3 Mono channels. It's been great! The auto-sensing feature is particularly nice. Here they are in a 3D-printed stand:

 

[Old_School_Brad]

As is often the case with certain products, cheaper alternatives -whether blatant knockoffs or unbranded OEM options -are now available.
@Bushellj made this thread, that fans of budget amplifiers, like Fosi, might want to check out.

 

[90sNintendoKid]

I did exactly that... and then upgraded my centre and surround speakers to 4Ω models that my AVR couldn't handle, so I ended up with 7 Fosi V3 Mono channels. It's been great! The auto-sensing feature is particularly nice. Here they are in a 3D-printed stand:View attachment 422193

This looks awesome and I think I will end up copying this.

What are the thermals like for this setup?

 

[drodgers]

The temps are fine; there’s a space below the Fosis for air to flow in, but no fan. They don’t get noticeably hotter than many other things.

 

[Bushellj]

I guess I am wondering if class a/b rated at 60 watts per channel is cleaner than class D at 100+ watts per channel especially at extreme volumes both soft and loud. The reviews seem to suggest listening at loud volume causes distortion above 85 db. Or is this a stupid question?

I think you would find any of these Stereo Digital Amplfiers would be more than adequate to fill you room with sound at all volumes and certainly better than most average AB Amplifiers of 60 watts. We have used Aiyima A04, A07 and D03 and Fosi amplfiers with great success with a range of bookshelf or at least smaller speakers from KEF, Mission and others. I have also used them with EV ZX1 PA Speakers also with no complaints at really high volumes for events.

I have just purchased a Stereo Fosi V3 to add to my amplifier collection and with probably purchase a 3e Audio A5 or A7 soon.

 

[Doodski]

I am wondering if class a/b rated at 60 watts per channel is cleaner than class D at 100+ watts per channel especially at extreme volumes both soft and loud.

The class is not a determination of being cleaner. It is the implementation of the design that matters and so one cannot just say this class is better than that class for cleanness of output. Both class AB and class D can be done poorly or very well. So it is a case by case basis. There is more to the sound quality than the cleanness of output as you say.

 

[Colonel7]

I did exactly that... and then upgraded my centre and surround speakers to 4Ω models that my AVR couldn't handle, so I ended up with 7 Fosi V3 Mono channels. It's been great! The auto-sensing feature is particularly nice. Here they are in a 3D-printed stand:View attachment 422193

Cool. Have you shared the 3D printed stand design on Thingiverse or elsewhere?

 

[SeaBeef]

Would you guys recommend a V3 Stereo or 2x V3 Mono’s for my setup? I have a Wiim Ultra as source which would go into a V3 Stereo or 2x V3 Mono’s which would power my Elipson XLS 15 passive speakers. Speakers are rated 200W @ 6ohm 92db sensitivity (dropping down to 3.2ohm). From the measurements I’ve seen, both the Mono and Stereo output around the same power per channel, so not entirely sure what the benefits of running 2x Mono’s would be over a Stereo, other than better channel separation

 

[EddNog]

Would you guys recommend a V3 Stereo or 2x V3 Mono’s for my setup? I have a Wiim Ultra as source which would go into a V3 Stereo or 2x V3 Mono’s which would power my Elipson XLS 15 passive speakers. Speakers are rated 200W @ 6ohm 92db sensitivity (dropping down to 3.2ohm). From the measurements I’ve seen, both the Mono and Stereo output around the same power per channel, so not entirely sure what the benefits of running 2x Mono’s would be over a Stereo, other than better channel separation

The original stereo V3 gets a SINAD of only 88 whereas V3 Mono hits 100. Also, the V3 Mono’s PFFB implementation means that it is fully flat across the audible frequency spectrum, whereas the original V3’s lack of PFFB results in load-dependent frequency response in the ultra high frequency range.

-Ed

 

[antcollinet]

Would you guys recommend a V3 Stereo or 2x V3 Mono’s for my setup? I have a Wiim Ultra as source which would go into a V3 Stereo or 2x V3 Mono’s which would power my Elipson XLS 15 passive speakers. Speakers are rated 200W @ 6ohm 92db sensitivity (dropping down to 3.2ohm). From the measurements I’ve seen, both the Mono and Stereo output around the same power per channel, so not entirely sure what the benefits of running 2x Mono’s would be over a Stereo, other than better channel separation

I'd be going mono.

It has max power of 243 compared with 161 of the stereo (into 4 ohms - your speakers are 6 dipping to 5 so will have some of this benefit), and has oodles of current capability to drive dips in the impedance characteristic of any speaker.

More importantly it has post filter feed back which essentially eliminates the load dependency of the v3 stereo.

 

[SeaBeef]

The original stereo V3 gets a SINAD of only 88 whereas V3 Mono hits 100. Also, the V3 Mono’s PFFB implementation means that it is fully flat across the audible frequency spectrum, whereas the original V3’s lack of PFFB results in load-dependent frequency response in the ultra high frequency range.

-Ed

I'd be going mono.

It has max power of 243 compared with 161 of the stereo (into 4 ohms - your speakers are 6 dipping to 5 so will have some of this benefit), and has oodles of current capability to drive dips in the impedance characteristic of any speaker.

More importantly it has post filter feed back which essentially eliminates the load dependency of the v3 stereo.

Thanks guys, V3 Mono it is!

Would it be worthwhile getting 2x 48V/10A power supplies, or would the 5A suffice?

 

[antcollinet]

Thanks guys, V3 Mono it is!

Would it be worthwhile getting 2x 48V/10A power supplies, or would the 5A suffice?

There is no benefit of the 10A over the 5A if having two supplies.

 

[SeaBeef]

There is no benefit of the 10A over the 5A if having two supplies.

Is there still noise when splitting a single 10A into 2 Mono’s?

Also any idea if the Auto On sensing works well?

 

[antcollinet]

Is there still noise when splitting a single 10A into 2 Mono’s?

Also any idea if the Auto On sensing works well?

They are supplying a filter with the 10A now, but I've read anecdotal reports that is still not perfect. At best you are going to be throwing away the complete channel separation that mono amps give you.

I've no idea how well the auto sensing works.

 

[EddNog]

Thanks guys, V3 Mono it is!

Would it be worthwhile getting 2x 48V/10A power supplies, or would the 5A suffice?

Safest bet two separate 48V PSUs, only need 5A each.

-Ed

 

[NTK]

Is there still noise when splitting a single 10A into 2 Mono’s?

Using one power supply for 2 amps is not recommended unless the two amp chips are synchronized (which will not be the case here).
See TI application report: ti.com/lit/an/slaa787/slaa787.pdf

 

[early rejecter]

Is there still noise when splitting a single 10A into 2 Mono’s?

Also any idea if the Auto On sensing works well?

Auto sensing has been working perfectly on both of mine; been using them since Kickstarter delivery.

(Also have had no noise or other issues running both from a single 10A power supply with filter, though it seems this is generally not recommended.)

 

[DavidM1]

Love the auto sensing on mine. It clicks on readily and off again if no signal for 10min.

 

[SeaBeef]

I’ll be using Wiim Ultra as source which only has RCA out. Would using RCA to XLR cables into the V3 Mono’s offer any improvements? I know the signal would still be unbalanced, however wondering if using RCA to XLR cables could offer lower noise and higher dynamic range, as V3 is rated to perform better with XLR input