Fosi Audio V3 Mono Amplifier Review

[kelesh]

Amazon is going to have a replacement for the bad one here Monday as well as having UPS pick up my return item the same day. Good customer service.

By any chance, have you checked if the Amazon units currently shipping in the US are "phase corrected" or "original" ? Just curious.

 

[Brian Hall]

By any chance, have you checked if the Amazon units currently shipping in the US are "phase corrected" or "original" ? Just curious.

I didn't check. Just hooked them up and they sounded good.

 

[badie]

Ok after 4 hours of non stop playing I recorded a temperature of 41C when I first powered it up.
The second picture is the maximum temperature of 35.5C
Ambient 22.C-22.5C
lower temp of 5.5C after the passive radiator and thermal pad costing me U$6.00 dollars per 1C drop (Laugh emoji)

Have you thought about putting your temp probes inside the casing, e.g. on the board directly over the chip?
(i only have an infrared temp hand gun)

 

[Lux_ury]

Very similar findings here. Our room is usually between 20 and 22C ambient and I’ve checked the amps each day since last weekend when I first started using them. My highest reading is 39.1C.

I’m using a medical thermometer that has an object setting too. You can see a little kettle symbol in the window.

As much space as I can give the Monos, they are on an old Quadraspire bamboo turntable platform, and that’s sitting on my Pass Labs XA25 protected from inadvertent scratches by a rectangle of leather-cloth.

View attachment 388225

View attachment 388226

I did notice that the Oak underneath the amps got hot as wood is not conductive. I raised the airflow with some aluminium speaker isolator feet.
Yours looks great I was going to use bamboo raisers at one stage for the looks.

 

[Lux_ury]

Have you thought about putting your temp probes inside the casing, e.g. on the board directly over the chip?
(i only have an infrared temp hand gun)

Hi badie the probs are metal ends and conductive. Probably would short out something?
My logic has been opening the case and disturbing the TIM paste would be fruitless unless I absolutely needed to as any thermal paste needs to settle with heat and use.
Just like a PC Die.
It's important people understand the heat does not disappear all you are doing is moving it away from the place its generating from.
Hand held probs are useful, still shocked at the cost of new Flukes these days (Roll eyes emoji) May be we start taking temperatures directly underneath? (rub chin emoji )

 

[Nopiano]

I did notice that the Oak underneath the amps got hot as wood is not conductive. I raised the airflow with some aluminium speaker isolator feet.
Yours looks great I was going to use bamboo raisers at one stage for the looks.

Yes, I realise no conduction with the wood, but I think if I want to achieve more air flow I have all sorts of sundry feet, spacers, cones etc., accumulated over the years which could raise them a little. The bamboo cutout may help a little, and it adds to the visuals!

Prompted by your reply, I had a look in the spares (!) and found a set of 16mm diameter metal disks to protect flooring from speaker spikes that would be ideal. They go by various names like Skeets, or in my case Precision Geek speaker pads!

I agree the wood definitely enhances the look, something I hadn’t anticipated. Here it is from behind.

 

[badie]

May be we start taking temperatures directly underneath? (rub chin emoji )

Yeah - this sounds a better place for your probes then.
-------

I raised the airflow with some aluminium speaker isolator feet.

I did measure top, front, bottom (without taking any notes)
All readings made with a infrared hand gun thermometer type.
Same finding here: Raising the units just one cm resulted in up to -2°C on the underside/under the chip.
(Left them running side by side, one raised, one flat on the wood)
Now they are standing on 30yrs-old aluminium cones (my first speakers feet), which are a whopping 2,5cm high
--------

It's important people understand the heat does not disappear all you are doing is moving it away from the place its generating from.

+1 - the faster we take the heat away, the cooler the chip
--------
Max recorded temps here >41°C
--------
With my speakers 90db sensibility I am not drawing more than the idle 10W per unit (1x48V 10A PSU+Filter)

will write more on this ...

 

[Sokel]

Are we seriously talking about 5° ambient room differences here?
Seriously?

Amps suppose to work at all sane conditions,even in a cold or hot room.
Here's an example of one of the monos driving my lows (1200as) :

Had a look around at other,nicer class D than this one and the range is even broader.

 

[galego100]

So disapointed with @Fosi Audio , pledger Nº1256 ( May) both monos are stuck on Spain customs since 20 July , i´m at Portugal... @Fosi Audio don´t provide any solution , and the tracking stop since 20 July. Friends of mine bought from Amazon( Europe) and already receive it pretty fast ... No money , no monos, no answers, nothing...

 

[badie]

Amps suppose to work at all sane conditions,even in a cold or hot room.

+1
----,,

As I am running a two way active system ...

V3 Stereo driving Bass - cutoff 250Hz
PSU GaN 48V 5A (Fosi)
mean wattage draw 27W

2xV3 Mono driving FullRange
PSU ??? 48V 10A+Filter (Fosi)
mean wattage dram 22W -> 11W per unit

Meaning the V3 Stereo is dealing with 2,45 (27/11) times the power (drawn from the wall) running through its internals.
All units on cone feet 2,5cm high

Running this for the last 45 Minutes and fiddling a little with the numbers i got these temps and relations:

Meaning the V3 Monos are running ~14% cooler when on two fifths / 40% of the power running through the V3 Stereo (Measured on the bottom) (LOL).

Have to find a way to send more power through the monos without blowing my ears.
I am really interested in the thermal performance when in party mode, driving more power hungry speakers.
----..

More to come

 

[Lux_ury]

Are we seriously talking about 5° ambient room differences here?
Seriously?

Amps suppose to work at all sane conditions,even in a cold or hot room.
Here's an example of one of the monos driving my lows (1200as) :


View attachment 388295

Had a look around at other,nicer class D than this one and the range is even broader.

It's academic to me it's design is to take alot more heat before terminating. I'm doing the extra cooling for fun, but fancier D class usually have Internal heat spreaders that don't touch the chassis. My v3 audio has the same chip and the chassis doesn't get hot because its not using the chassis as a heatsink, but it has a few air holes at the top. I just spent over 24 odd dollars to yield 5C drop. I think someone posted a comments about one amp being cooler than the other and a member rightly said "I would be worried about the cooler one" (Wink emoji)

 

[burkm]

So disapointed with @Fosi Audio , pledger Nº1256 ( May) both monos are stuck on Spain customs since 20 July , i´m at Portugal... @Fosi Audio don´t provide any solution , and the tracking stop since 20 July. Friends of mine bought from Amazon( Europe) and already receive it pretty fast ... No money , no monos, no answers, nothing...

Your problem lies on the Spanish customs, not Fosi Audio. Thus they can't do anything except waiting. They know, where it is, but can't do anything about it, because it is the responsibility of the logistics company and/or Spanish customs to get this cleared. There must be a reason, why Spanisch (?) customs is keeping Your set of Fosi Audio V3 mono, which I don't know. Do You have any idea, why Spanisch (!) customs is holding the amps and why they are envolved at all ? Did You ask them ? Are the items damaged or the destination address not readable and why is Spanish customs envolved and not Portugese customs ...
Note: Amazon probably got them first and probably ahead of time before every one else...

You name it...

 

[Mauric]

Hi everyone, can you somebody tell me if I can use a pair of these amps to drive a pair of speakers with a nominal impedance of 16 ohms, and a rated power of 150 W.

Thanks!

 

[LSPhil]

mono is rather for low speaker impedance up to 2 Ohms, and stereo without any problems.

 

[antcollinet]

Hi everyone, can you somebody tell me if I can use a pair of these amps to drive a pair of speakers with a nominal impedance of 16 ohms, and a rated power of 150 W.

Thanks!

It will work, but only deliver half the power compared to 8 ohm speakers. So around 60W (1% distortion).

 

[galego100]

Your problem lies on the Spanish customs, not Fosi Audio. Thus they can't do anything except waiting. They know, where it is, but can't do anything about it, because it is the responsibility of the logistics company and/or Spanish customs to get this cleared. There must be a reason, why Spanisch (?) customs is keeping Your set of Fosi Audio V3 mono, which I don't know. Do You have any idea, why Spanisch (!) customs is holding the amps and why they are envolved at all ? Did You ask them ? Are the items damaged or the destination address not readable and why is Spanish customs envolved and not Portugese customs ...
Note: Amazon probably got them first and probably ahead of time before every one else...

You name it...

Fosi after all this time must provide a solution . I have no fault of this situation and why Fosi send it through Spain . Fosi doesn´t answer to my messages . I ´m the one here, who pledge , and have no money and no product. Fosi told me about amonth ago to send pictures from the receipt of the credit card and print screen from kickstarter, so they can show it so Spanish Customs. Fosi always said they will assume any duties taxes, the problem is , last news was 20 July...

 

[burkm]

But Fosi Audio is not responsible for the logistiscs, customs, taxes etc. as long as they follow the rules and did, what they where supposed to do.
They handed their responsebility over to the logistics company, which ist transporting Your goods, but they are not responsible for the Spanish customs and so on. Thus there exists now a contract between the logistics company and Fosi Audio. They probably have questioned the logistics company about Your goods but I don't know what the logistics company answered, if they did.
Fosi might be reembursed, If the goods are lost, damaged or anything else and they don't reach the address, they have provided on their label, within a given time period, which I don't know.

Usually this "hackling" with Spanish authorities might take several month before anything happens. Even corresponding with Spanish authorities might be a problem and might even "take a long time" due to translation problems on either side. Fosi might have sent their goods to their closest warehouse (Spain) near Portugal to forward it then to Your Portugese address. It's close to impossible for me to know, why their products have been withheld by the Spanish customs authority then. You probably have to wait and try to contact the Fosi service department again and again... It might have to do with unpaid duties or taxes or...

It's your money and you have to spent the time to "fight" for it.... Unfortunately it's (China) a Non-EU country, with another (foreign) language, and it might eventually be hard to get a valid answer from them. Did Fosi Audio contact their Spanish warehouse about it. What did they answer ??? Did You buy it through Kickstarter ? What is Fosi obliged to do as a seller ? How did You pay for it ? PayPal ?

 

[Mauric]

It will work, but only deliver half the power compared to 8 ohm speakers. So around 60W (1% distortion).

Thank you so much!

 

[Mauric]

If I'm not mistaken, a few months ago, I saw a post discussing about the power supply, the biggest one shared for two amps. What I remember is that this option used to have problems.

Is it still the case? Should I buy a power supply for each amp?

Probably I'm confused, is this is the case, please forgive my question.

 

[triangel100]

Hey i got a question I got a audiosystem with 9 channels and a monoblock in there that is about 20 centemeters wide
It has a black aluminium casing but there is no brand on it.
on the back is a silvercolor on button i think it has been used as a amplifier to put speakers on.
The total lenght of this amplifier is 1.5meters by 25 centimeters.

My question is does anyone know what kind of brand this amplifier could be?
Thanks in advance