Fosi Audio V3 Mono Amplifier Review

[edgar-bcn]

Because Marantz has ten times lower input sensitivity compared to Fosi.

View attachment 380048

Uhmm, but this only applies when I use the Marantz solely as an amplifier (which I tried connecting the miniDSP to its 7.1 CH IN inputs), but when I used only the AV receiver?

Do you mean I need a more powerful amplifier because of the higher input sensitivity?

 

[edgar-bcn]

Once again, please try to read and understand the comments of those who help you, there is no lack of power.

Sorry for bothering! I'm struggling trying to understand why I haven't gotten the results I was looking for.

 

[Keauval]

Are you trying to replace a Sansui AU-9500 with the Fosi's? How much do you want for it?

I Can make you an offer of 230$ for the 2 V3 Mono with 48V 5A PSUs

 

[Keauval]

I like the schiit kara with 12db extra gain in xlr mode

But if the Fosi V3 Mono Can reach 2x120W with 5V inside, why shoule I put 100V inside ?

 

[Talisman]

Sorry for bothering! I'm struggling trying to understand why I haven't gotten the results I was looking for.

In the previous pages you will find excellent explanations of @antcollinet , you cannot expect him to explain everything again every time a new user makes this observation.
There is no power problem, it is just a question of the gain of the amplifier which needs a higher voltage input signal to reach its maximum power.
Turn that volume knob, the trend of listening volume at 9 o'clock is over

 

[SMen]

Turn that volume knob, the trend of listening volume at 9 o'clock is over

This is a good thing and good advice and I hope so...

Sorry for bothering! I'm struggling trying to understand why I haven't gotten the results I was looking for.

Too often manufacturers would try and give the impression of "power" by having "loud" at 9 o'clock. And I still read people equating power with where they get to on the volume dial... It also becomes much harder to make subtle changes to volume when it max's out so early in the dial rotation.

 

[antcollinet]

Uhmm, but this only applies when I use the Marantz solely as an amplifier (which I tried connecting the miniDSP to its 7.1 CH IN inputs), but when I used only the AV receiver?

Do you mean I need a more powerful amplifier because of the higher input sensitivity?

Your Maranz only needs 0.2V input for full power.

The FOSI needs nearly 2V (in 25dB gain) or nearly 1V in 31dB gain.

Your Mini DSP can output 2V (I assume you have the RCA Version) so you just need to turn the volume up. Near full volume on the DSP will take you to near full power

IF your program material (the music) is close to full level.

You might be more comfortable with the higher gain (31dB) setting on the amp.

 

[mike70]

People try to justify their preconceived concepts ... thinking over scientific and right arguments is much more harder. The brain is programmed to maintain us alive and happy.. and that includes not changing the status quo.

Then you see that "but, did you read what was posted?" moments.

 

[Guddu]

Sorry for bothering! I'm struggling trying to understand why I haven't gotten the results I was looking for.

Let me try putting it simply.
The amplifier has a certain gain or amplification factor, so now your total output power depends on your input signal strength vs input signal strength needed by amplifier for its optimal operation i.e., input sensitivity.
Fosi v3 mono needs 1.8 - 2 volts which any modern DAC or pre-amp should be able to provide.
Fosi v3 mono is a power amplifier, and its pretty normal for a power amplifier to require about 2v input signal on RCA, and about 4v on XLR/TRS.
Integrated amplifiers might work with lower input signal as well, as normally they have pre-amp in-built to manage input signal strength (volts).

So, it’s just about matching DAC/pre-amp that you need for your Fosi v3 mono for optimal output.

P.E. I saw later that @antcollinet already explained the same

 

[Sokel]

Amir has established the 25dB gain measurement for several reasons,one of them is that is easy to get sources that can drive such an amp.
It depends though,high power ones (>600W) will still need more than 4V for full output at such a gain.

 

[edgar-bcn]

I'm not at home to confirm it but now I realize that I was probably using the miniDSP preset that I use to watch TV at night, and in which I lower all the channels by 10 decibels except the center one ... opening the umbrella...

Thank you very much anyway for your answers, I have learned a lot!

 

[amix]

Worth noting....they are 43 degree C when warmed up, even without anything playing anything, unless you put them into auto mode.

The CPU of my NAS is at 47°C when idling. Just saying...

 

[Nyarlathotep]

The CPU of my NAS is at 47°C when idling. Just saying...

They do run a bit hotter than I would prefer, even with no load. Certainly a bit uncomfortable to an extended touch. I picked up a couple of USB fans, linked earlier in the thread, and at the low setting they keep the case much cooler with the monos under a light load. I haven't pushed my monos under a heavy load yet, so not sure how much warmer these get when driven moderate to hard.

 

[Keauval]

I really dont understand whats the point with the heat... People love to touch their amp while playing music ?

With 120W I do Hope those little monsters get warm

 

[spandy]

I like this passive cooling concept of case=heatsink. Has anyone opened theirs to see if they ended up with thermal compound at the interface?

 

[EddNog]

I like this passive cooling concept of case=heatsink. Has anyone opened theirs to see if they ended up with thermal compound at the interface?

The V3 Mono and stereo V3 do not come from the factory with thermal interface material between the heatsink and the case. The ZA3 does.

-Ed

 

[PJ_Schmidt]

I really dont understand whats the point with the heat... People love to touch their amp while playing music ?

With 120W I do Hope those little monsters get warm

I watched Dune Part 1 with the volume high (reference levels) using my monos and after 3 hours they were only a few degrees warmer (48c) than when set to ON for an extended period (46c). I'm running a 2.1 system so the bass is being shipped off to the subwoofer. Maybe my amps would be warmer if I was running full range towers?

 

[Nyarlathotep]

I really dont understand whats the point with the heat... People love to touch their amp while playing music ?

With 120W I do Hope those little monsters get warm

Lol, no not in my case anyway. I have had consumer electronic slowly cook themselves in the past due to being equipped from the factory with less cooling then they aught to have had. High enough heat is often the enemy of some components, e.g. electrolytic capacitors. I just make sure my equipment is given its best opportunity to survive for years and years.

 

[Cal_Cobra]

I watched Dune Part 1 with the volume high (reference levels) using my monos and after 3 hours they were only a few degrees warmer (48c) than when set to ON for an extended period (46c). I'm running a 2.1 system so the bass is being shipped off to the subwoofer. Maybe my amps would be warmer if I was running full range towers?

I decided to cave and order the Wiim Ultra to use as a preamp, with room correction, PEQ, and a sub out along with bass management. Hell everything else on there's a bonus as far as I'm concerned I'll run optical out to my DAC and then XLR out to the V3 monos for a [semi] balanced setup.

How are you connecting your subwoofer?

 

[antcollinet]

I'll run optical out to my DAC and then XLR out to the V3 monos for a [semi] balanced setup

That's fully balanced as far as I'm concerned.