Fosi Audio V3 Amplifier Review

[nathan]

Indianaline arboir 5.04


speaker type: 3-way, bass reflex
suggested amplifier: 30÷120 Watt
impedance: 4÷8 Ohm
sensitivity (2.83 V/1m): 91 dB
frequency response: 46÷22000 Hz
crossover frequency: 70 / 3100 Hz
crossover slope: 12 / 12 / 12 dB/oct
units: shielded magnet
woofer diameter: 135 mm
midrange diameter: 135 mm
tweeter dome diameter: 26 mm
dimensions: 170 x 339 x 290 mm
weight: 6.4 Kg
design: real wood, cherry colour

Thanks for the model info. This is easier to read:
Suggested amp 30 to 120 watts
Impedance: 4 to 8 ohms

The Fosi is probably a very good match in terms of power output. To know whether it is perfect we would need to see what the impedance is at 20khz.

 

[musica]

can you understand anything from these graphs?

 

[nathan]

View attachment 387223can you understand anything from these graphs?

Oh yes super easy for the Fosi but might sound bright. The last graph of yours show impedance is above 10ohms above 1khz which the Fosi reacts (at least above 10khz) to by making those frequencies louder. So you will want to use EQ to correct that.

If you want to run a system without EQ then this may not be the best choice amp. I would get the Fosi v3 MONO but it is twice the price.

The key is that the Fosi v3 stereo (unlike the higher priced mono) tends to be sensitive to higher (numerically) impedance loads in the high frequencies of a speaker as indicated in this graph — and your speaker has a (numerically) high impedance in those frequencies. A speaker with a four ohm load in the upper frequencies would be a better match.

 

[musica]

I have to use the Fosi v3 as a power amplifier
its source will be the miniDSP (digital equalizer), are they compatible as impedances and sensitivity?

 

[nathan]

AFAIK, yes. And use the miniDSP to get flatter response in the treble. I’m not sure how difficult or effective that would be. The speakers I drive with the v3 stereo have more like 6ohm impedance in the 10-20k hz region and I don’t worry about or hear any issues. But your impedance is quite different.

 

[musica]

AFAIK, yes. And use the miniDSP to get flatter response in the treble. I’m not sure how difficult or effective that would be. The speakers I drive with the v3 stereo have more like 6ohm impedance in the 10-20k hz region and I don’t worry about or hear any issues. But your impedance is quite different.

will i feel the highs a lot?

 

[nathan]

Depends on your hearing I suppose. Many men above age 40 won’t hear anything up above 10k very well.

 

[Doodski]

Depends on your hearing I suppose. Many men above age 40 won’t hear anything up above 10k very well.

I'm older and I can hear to ~13 k Hz. I have a history of working with lots of noisy outdoor equipment and working in very very noisy environments indoors.

 

[musica]

It also depends on the listening environment and mine absorbs a lot of highs, so I think I'll be fine

 

[musica]

this is what I can do, is it possible?

 

[antcollinet]

I have to use the Fosi v3 as a power amplifier
its source will be the miniDSP (digital equalizer), are they compatible as impedances and sensitivity?

View attachment 387257
this is what I can do, is it possible?

Yes that is fine.

Depending on your sources, and your DSP, you might be able to eliminate the Denon. I use a MiniDSP Flex as my preamp, with two digital, and one analogue source.

 

[musica]

I have the mini DSP 2/4 and I want to use the Denon for both the sources and to control the general volume, satellite speakers driven by the Fosi v3 and the active subwoofer connected to the mini DSP. Can I do it or is there too much incompatibility between the components?

 

[antcollinet]

I have the mini DSP 2/4 and I want to use the Denon for both the sources and to control the general volume, satellite speakers driven by the Fosi v3 and the active subwoofer connected to the mini DSP. Can I do it or is there too much incompatibility between the components?

No, you can do it. It will work fine.

 

[musica]

is it okay if I leave the Fosi v3 with the volume knob at max and turn it on and off at the same time as the Donon with the remote control?

 

[gwing]

is it okay if I leave the Fosi v3 with the volume knob at max and turn it on and off at the same time as the Donon with the remote control?

I prefer to always power up my sources first, then pre-amps, then power amps in that sequence. If you want to power them up together from that remote I don't think its good practice but may be OK - test it with the power amp set to low volume first.

 

[musica]

yes, it works well, there is no noise in the speakers even with the Fosi v3 at maximum volume.

 

[Subway2400]

Hi,

Using the Fosi V3 for a desktop setup, I recently switched to the Fosi 32V power supply instead of the 48V that came with the V3. I decided this change because the Fosi V3 would get hotter than I would like it to with the 48V PSU and the low power required for a nearfield listening. Using a subwoofer (90 Hz crossover for both speakers and sub), there is not that much power demand.

Testing the setup while sending full range signal to the speakers, there is no change in measurement frequency reponse or perceived sound between the two PSU and my speakers (4" Wharfedale Diamond 12.0) show distorsion in low bass way before the amplifier. To be honest I did not hear any distorsion comming from the amplifier even at high desktop levels.

Now with the 32V PSU the V3 gets barely warm to the touch, while it would get warm with the 48V PSU. For nearfield use, I think that the 48V PSU is really overkill and would reduce the V3 reliability because of more the heat stress.

 

[musica]

I checked better and I can hear a small boom in the speakers, is it dangerous for them?

 

[Jimbob54]

The thump combined with the fact that you could accidentally have your denon and fosi at full volume when you press play would lead me to suggest either :

You turn the fosi down after /before use OR

You turn the Denon to max and the fosi to min, press play with some loud music and turn the fosi up to the loudest you would ever want to listen, then leave it there and use the Denon volume.

 

[musica]

The thump combined with the fact that you could accidentally have your denon and fosi at full volume when you press play would lead me to suggest either :

You turn the fosi down after /before use OR

You turn the Denon to max and the fosi to min, press play with some loud music and turn the fosi up to the loudest you would ever want to listen, then leave it there and use the Denon volume.

I turn the Fosi v3 off and on at the same time with the 15 o'clock position and the Denon at 9 o'clock, while listening I control the volume only with the Denon knob, I always lower only the Denon volume when I turn it off. but I hear a small boom in the speakers

the Fosi and the Denon will never have the volumes at maximum