Fosi Audio V3 Mono Amplifier Review

[musicforcities]

The distance between source and speakers always remains the same, with or without monobloc, if you want to shorten the power cables you will have to lengthen the signal cables and vice versa, no free lunch. Between the two options I prefer to have longer speaker cables than signal cables.
As far as I'm concerned, the advantage of monoblocks is the elimination of crosstalk

Unless one is using wireless for the line level, I suppose.

Buy yeah, monoblocks for channel separation and independent power supplies.

Or center channel I guess.

And because…they are cool.

 

[tomtoo]

Two high end monoblocks with sinad 100++. 400W at 2ohms stable. For under 400 bucks??? Thats amazing!

 

[musicforcities]

Not bad, the price is right even if we would have preferred a Stereo version...

Now two things:

1) The DC connector is too close to the binding post and we mentioned this to Fosi on the prototyped version...what a pity !

View attachment 360799

2) About the Current VS Voltage controversy (Note that this mono block has two main competitors, the 3E Audio module 3e audio 480-1-29A and the Sylph Audio FB360 module). As you can see, for this type of Mono PBTL configuration, there is no need for a PSU above 48V/5A, it hardly adds anything...

View attachment 360819

No place else to put that dc jack as far as I can tell. Unless one is using big spade connectors or carelessly using bare wire, the chances of the speaker shorting to the dc power plug is very very tiny considering that the dc plug is insulated.

And if the nearest jack is a negative terminal, and the outside sleeve of the dc plug is also negative, then depending on the circuit it might be fine even if they do touch if they share a ground.

 

[daniboun]

Post removed by Moderation.

My bad did no know this. My grandmother was a historian at Yad Vashem in addition... my apologies for my clumsiness

 

[AdamG]

My bad did no know this. My grandmother was a historian at Yad Vashem in addition... my apologies for my clumsiness

Poster has apologized. That is sufficient and the photo has been removed. End this discussion here.

 

[Jimster480]

This is a power amp.

Yes, several people replied to me and explained this. Including Amir himself. I finally know what "PreAmps" are for.
Always wondered what the purpose of this was and why you would need a volume control that goes into an amp when Amps have volume control.
I apologize for my ignorance because I only live in the headphone world. I have no powered speakers outside of powered monitors.

 

[musicforcities]

Good design (it closely follows the 10 principles of Good Design by Dieter Rams), good build, very good price.

You have a winner.

Waiting for the stereo version. I know that it will be harder, but not impossible.



Regarding the TI PFFB implementation, it seems that most implementers read the 2018 TI paper SLAA788A.pdf (mostly by Dan Kisling) and forget to read the original 2016 paper SLAA702.pdf (mostly by Matthew Beardsworth), which has some valuable tuning insights regarding IMD, Gain Compensation and Zobel network (loudspeaker impedance issues).
It seems that 3e Audio has not missed out on either paper.
Fosi seems to be a fast learner.

2 ohm friendly ? With loads of power at 2 ohm?

Velcro tape one of these on the back of an apogee ribbon speaker or magnapan.

 

[tomtoo]

I like to see a real thermal test of this badass suckers at 2 ohms 300W. I give them 3mins before thermal protect. Come on i like to know what they realy can do?

 

[Endibol]

Thanks, found it now. I zoomed the page and this part was hidden from me

I have been looking for half an hour.. still can’t find this “early bird” button… Am I getting crazy?

 

[Graham849]

Is it overkill to use this as a subwoofer amp driven by SMSL AO200?

 

[Talisman]

I like to see a real thermal test of this badass suckers at 2 ohms 300W. I give them 3mins before thermal protect. Come on i like to know what they realy can do?

this isn't a test, it's just pointless torture to a piece of hardware

 

[Doodski]

I like to see a real thermal test of this badass suckers at 2 ohms 300W. I give them 3mins before thermal protect. Come on i like to know what they realy can do?

I like to know the limits too but this 2 Ohms sine wave stress test is a destructive test.

 

[Talisman]

I like to know the limits too but this 2 Ohms sine wave stress test is a destructive test.

Yes, but it is much more like a morbid curiosity to see how long it will take to destroy itself, without any real value. Clearly that little guy isn't designed to deliver 300 watts continuously at 2 ohms, but the mere fact that it can briefly deliver that power under such a harsh load is in itself absolutely exceptional. It seems like unnecessary cruelty to me

 

[Endibol]

It was there for me - just filled it in:View attachment 360880

These buttons don't show up on my page. Perhaps because I am located in Europe?

 

[kemmler3D]

an extra $25 at the manufacturing level

I'd be surprised if one of these costs much more than $25 in BOM costs altogether - so a $25 case would double the price. Just saying.

 

[gvl]

I seriously doubt there is any issue or much sinaid gain from greater distance. I would surmise it’s not different from the output of a traditional linear ps amp rails. It’s bit like its next to the line level inputs and there is not going to be long runs of speaker out wiring running parallel to the dc power in. it’s not like running 120v ac in parallel for a few feet with rca cables.

I think it was a concern about mechanical interference, not electrical. I would have liked to see a locking power plug of sorts to prevent accidental disconnection.

 

[Rick Sykora]

not sure what's your point but Fosi V3 is like half the price, not including DIY time/cost for the other project. I would be fine with the slightly higher yet inaudible distortion

Am not sure what his point is either. Not only is the Fosi a finished product but has many features/benefits above and beyond the promoted DIY kit...

1. Gain selection options
2. Auto-on/off
3. XLR and RCA inputs
4. Factory built and tested
5. A manufacturer warranty and return policy

No disrespect to 3e Audio's technical accomplishment but is not much of a contest in my opinion.

 

[antcollinet]

These buttons don't show up on my page. Perhaps because I am located in Europe?

Well I'm in UK

Someone suggested page zoom can mess it up. Check your browser isn't zoomed (CTRL-0)

 

[Inertiaman]

Am not sure what his point is either. Not only is the Fosi a finished product but has many features/benefits above and beyond the promoted DIY kit...

1. Trigger input

No arguing your larger point (V3 Mono vs 3e is apples/oranges) but for clarity, the V3 Mono doesn't include a trigger input.

I wish it did, since I prefer a dedicated 12V trigger to an auto-sense/auto-standby. Once these are out in the wild, I'll be curious to see the auto-power-up time, if it works consistently, and what the power draw is in standby.

 

[Rick Sykora]

No arguing your larger point (V3 Mono vs 3e is apples/oranges) but for clarity, the V3 Mono doesn't include a trigger input.

I wish it did, since I prefer a dedicated 12V trigger to an auto-sense/auto-standby. Once these are out in the wild, I'll be curious to see the auto-power-up time, if it works consistently, and what the power draw is in standby.

Oops, some wishful thinking and reading too many reviews apparently.

Will fix that. Thanks!