Fosi Audio V3 Mono Amplifier Review

[telemike]

Anyone use the +31 option?

 

[SeaBeef]

My new setup

Exactly the same as me! Not running the Fosi cooling fans on the mono’s? I just ordered some fans, will be using the Ultra remote trigger, a 3.5mm TRS cable and 12V automotive relay to get them to auto on/off

 

[telemike]

Exactly the same as me! Not running the Fosi cooling fans on the mono’s? I just ordered some fans, will be using the Ultra remote trigger, a 3.5mm TRS cable and 12V automotive relay to get them to auto on/off

View attachment 424098

I ordered some heatsinks to put on top of the cases. I'm using the auto option on the amp.

https://a.co/d/27vi5Oc

 

[telemike]

I added some heatsinks to the top of the amps. Hopefully that will let them dissipate heat better.

 

[Bleib]

I added some heatsinks to the top of the amps. Hopefully that will let them dissipate heat better.

Yes it helps, what's the cd player you have? (sorry for off topic)

 

[telemike]

Yes it helps, what's the cd player you have? (sorry for off topic)

Shanling CR60

 

[gchuva]

I added some heatsinks to the top of the amps. Hopefully that will let them dissipate heat better.

What do you have under them? The stands?

 

[gchuva]

Can I power Paradigm Sig S8 v3 with these monoblocks? Right now I am using an old Denon 3805 receiver

 

[telemike]

What do you have under them? The stands?

Fosi Audio V3 Mono Monoblock Amplifier Stand by lanwanman | Download free STL model | Printables.com

Stand to raise the Fosi V3 Mono amplifier for better cooling. | Download free 3D printable STL models

www.printables.com

 

[telemike]

Can I power Paradigm Sig S8 v3 with these monoblocks? Right now I am using an old Denon 3805 receiver

Why not? 100 wpc @ 8 ohms

 

[Miser_Audioman]

Can I power Paradigm Sig S8 v3 with these monoblocks? Right now I am using an old Denon 3805 receiver

Yes and the efficiency is similar to the Paradigms I’m running at 80 dBA @10 feet away or so. Zero heat issues for my use case (not using any high pass filters, but active sub contributing a bit to overall spl..). Should be good to go.

 

[AudioChap]

I've been reading this thread since the beginning. I was an early backer for the V3 mono and have been happy with the ones I have in service so far. However, I tried to order another to make it a 5 amp set up. When I added the latest amp, I noticed that when using RCA to RCA, the volume was significantly lower on the speaker hooked to that amp than the others. I switched cables, switched speaker pre-outs on the receiver, but always the speaker connected to the 5th Fosi was lower in volume. I contacted Fosi and here are their replies, see below. It seems they changed the output gain without changing the markings on the case or the specification section on the website. Has anyone else ordered a Fosi V3 Mono lately that might be this "new" version, post Jan. 1, 2025? The gain on the XLR appears to be unchanged.

 

[FERCSA]

I've been reading this thread since the beginning. I was an early backer for the V3 mono and have been happy with the ones I have in service so far. However, I tried to order another to make it a 5 amp set up. When I added the latest amp, I noticed that when using RCA to RCA, the volume was significantly lower on the speaker hooked to that amp than the others. I switched cables, switched speaker pre-outs on the receiver, but always the speaker connected to the 5th Fosi was lower in volume. I contacted Fosi and here are their replies, see below. It seems they changed the output gain without changing the markings on the case or the specification section on the website. Has anyone else ordered a Fosi V3 Mono lately that might be this "new" version, post Jan. 1, 2025? The gain on the XLR appears to be unchanged.

That's a nasty practice from fosi.. I disappointed.
Changing the power supply rail can affect the performance as well. At least you can still use the 25dB settings on every unit to make them sound the same.

 

[testp]

@AudioChap, i feel for your endevour with this..

i just placed an order for 2 fosi monos, for me personally i actually would prefer the lower gain cause as i understand old low-gain reaches max. Watts with 1.6 1.7 volts from RCA -, new low gain would require more volts, but dont know how much myself.

..but sure, new markings for a new gain for a product should be standard practice.

 

[DavidMcRoy]

I have 6 early Fosi Audio V3 Monos with 31dB/25dB gain switches that don't do anything. Some early production irregularities, I guess. I haven't measured the actual gain on these units.

 

[Rotel75]

I'm looking for solutions to reduce the gain internally.
What did they change in the current revision? Pictures please
Does anyone have the schematics?

Monacor Attenuator ILA 1020​

 

[AudioChap]

That's a nasty practice from fosi.. I disappointed.
Changing the power supply rail can affect the performance as well. At least you can still use the 25dB settings on every unit to make them sound the same.

They could all be set at 25. But 4 are already set to 31 and I actually prefer that as then I don't have to set a higher gain at the pre-out on the source receiver, Denon AVR-X3800H, to feed the Fosies (Fosis?). The setup is 7.2.2, so there are still speakers running off the Denon. The L/R/C and FH L/R are run off of the Fosies. I could use the different one for the center. But the disappointing thing is the change without any concern for documentation or labeling on the product.

 

[Bleib]

I have 6 early Fosi Audio V3 Monos with 31dB/25dB gain switches that don't do anything. Some early production irregularities, I guess. I haven't measured the actual gain on these units.

You're using RCA or XLR? The latter has a locked value

 

[testp]

mhmm, i can't find the math right now, but RCA gain 19db was kinda lowish from the gen. excel sheet graph..

maybe someone with a math degree can chime in

 

[DavidMcRoy]

You're using RCA or XLR? The latter has a locked value

RCA