Fosi Audio V3 Mono Amplifier Review

[SeaBeef]

New media/music room has been completed featuring 2x V3 mono’s. Question about gain structure…

Okay so I have a V3 mono per speaker, I’ve got a Wiim Ultra as preamp. You can adjust the line out voltage on the Wiim, default is 2V, but you can lower to 1V, 500mV, 200mV etc. If I leave it at 2V, normal listening preamp volume is about 20%.

I’m wondering if it would be better to lower the line out to like 1V or 500mV, that way I can have the preamp volume up higher to like 70%. The preamp volume attenuates the digital signal, so my thought and understanding is less attenuation on the digital signal could result in better dynamics?

 

[testp]

New media/music room has been completed featuring 2x V3 mono’s. Question about gain structure…

Okay so I have a V3 mono per speaker, I’ve got a Wiim Ultra as preamp. You can adjust the line out voltage on the Wiim, default is 2V, but you can lower to 1V, 500mV, 200mV etc. If I leave it at 2V, normal listening preamp volume is about 20%.

I’m wondering if it would be better to lower the line out to like 1V or 500mV, that way I can have the preamp volume up higher to like 70%. The preamp volume attenuates the digital signal, so my thought and understanding is less attenuation on the digital signal could result in better dynamics?

good question, i was planning on buying a voltage meter for this, so i can measure the analog output/voltage, if amir measures dacs he seems to get the right voltage at certain dac volume level, but that indicates voltage changes with dac volume level..?

 

[gwing]

good question, i was planning on buying a voltage meter for this, so i can measure the analog output/voltage, if amir measures dacs he seems to get the right voltage at certain dac volume level, but that indicates voltage changes with dac volume level..?

As long as the combined effect of pre-amp gain and RCA output level give you sufficient volume from the power amp and you aren't overloading the power amps maximum input voltage then you are fine. The default of 2V should work really well with the 2xV3s.

 

[SeaBeef]

As long as the combined effect of pre-amp gain and RCA output level give you sufficient volume from the power amp and you aren't overloading the power amps maximum input voltage then you are fine. The default of 2V should work really well with the 2xV3s.

The issue is my speakers are very sensitive @ 95db, so normal listening levels has my Wiim Ultra preamp at about 20% volume which is a lot of digital attenuation…

 

[Old_School_Brad]

The issue is my speakers are very sensitive @ 95db, so normal listening levels has my Wiim Ultra preamp at about 20% volume which is a lot of digital attenuation…

If you don't hear any noise, you're in the clear.

 

[SeaBeef]

No noise, but wouldn’t running a lower line out voltage and having a higher preamp digital volume result in better dynamics with less digital attenuation?

 

[Old_School_Brad]

No noise, but wouldn’t running a lower line out voltage and having a higher preamp digital volume result in better dynamics with less digital attenuation?

Not if you don't hear any noise.

 

[testp]

No noise, but wouldn’t running a lower line out voltage and having a higher preamp digital volume result in better dynamics with less digital attenuation?

if you like, test it, go with what works for you. i definetely am not gone like volume at 20%, bc eventually remote volume +/- needs to be less sensitive.

another thing to try is rca-to-xlr, reading from previous posts that was supposed to halve the amp power (not sure), but does it matter if 2 volts to xlr is too much amplfication -> volume to your ears... (prob. is for me for sure)

 

[SeaBeef]

Not if you don't hear any noise.

I didn’t think attenuating digital signal introduced noise? My understanding is the digital amplitude is represented by the binary values, so reducing the amplitude through attenuation effectively reduces the range of possible values which is dynamics

 

[testp]

I didn’t think attenuating digital signal introduced noise? My understanding is the digital amplitude is represented by the binary values, so reducing the amplitude through attenuation effectively reduces the range of possible values which is dynamics

yes but, wasnt volume control 30bit? anyway, most definetely if you use eq/peq on Wiim - audio is converted to ~96khz/24 bit? which means you get headroom for eq/peq. including volume control for sure

 

[gwing]

I didn’t think attenuating digital signal introduced noise? My understanding is the digital amplitude is represented by the binary values, so reducing the amplitude through attenuation effectively reduces the range of possible values which is dynamics

Yes, but these days such digital attenuation is normally done by the device on the internal hi bit value rather than the actual bits in the incoming digital signal so there are plenty of bits to play with without reducing dynamics.

 

[SeaBeef]

yes but, wasnt volume control 30bit? anyway, most definetely if you use eq/peq on Wiim - audio is converted to ~96khz/24 bit? which means you get headroom for eq/peq. including volume control for sure

Yes, but these days such digital attenuation is normally done by the device on the internal hi bit value rather than the actual bits in the incoming digital signal so there are plenty of bits to play with without reducing dynamics.

I’m not actually sure what bit depth the Wiim Ultra processes volume adjustment at, I just thought it would be at 24bit. Upon further research, it seems Wiim Ultra processes volume adjustment at 32bit, so there 8bits to loose. This should mean the volume at only 20% should be fine after all shouldn’t it?

 

[gwing]

I’m not actually sure what bit depth the Wiim Ultra processes volume adjustment at, I just thought it would be at 24bit. Upon further research, it seems Wiim Ultra processes volume adjustment at 32bit, so there 8bits to loose. This should mean the volume at only 20% should be fine after all shouldn’t it?

Yes, with 8 bits headroom it would presumably be zero degradation up to 1/256th adjustment. i.e. a 99+% reduction.

 

[Guy.Cohen]

Hi, did someone compare the V3 mono to 3E A7 mono or their diy boards?
A link will be useful
Thanks

 

[Rotel75]

I read through all the msgs one time, but I can't remember.
Did we ever find out if the phase issue is on both RCA and XLR input?
Did anyone ever do a listening test / hear a reproducable difference (phase correct/wrong)?

 

[EddNog]

I read through all the msgs one time, but I can't remember.
Did we ever find out if the phase issue is on both RCA and XLR input?
Did anyone ever do a listening test / hear a reproducable difference?

Fosi stated that on early production units like mine, it affects both inputs.

-Ed

 

[AudioChap]

I read through all the msgs one time, but I can't remember.
Did we ever find out if the phase issue is on both RCA and XLR input?
Did anyone ever do a listening test / hear a reproducable difference (phase correct/wrong)?

Are you talking about the recent changes to the design or whether the switch works on older units?

 

[SMen]

I read through all the msgs one time, but I can't remember.
Did we ever find out if the phase issue is on both RCA and XLR input?
Did anyone ever do a listening test / hear a reproducable difference (phase correct/wrong)?

It was simply the internal speaker connections from the board to the speaker sockets - not an issue in stereo implementations, but you would detect the incorrect phase in multi-speaker set up - or possibly with subwoofer (without phase adjustment).

 

[Rotel75]

google is your friend
post #3063

https://support.fosiaudio.com/hc/en-us/articles/35730754097689-Official-Statement-Regarding-the-Inverted-Phase-of-the-V3-Mono

mixing revisions (used market, replacement on defect) has really become a nightmare.. phase and gain

 

[AudioChap]

google is your friend
post #3063
View attachment 427803

https://support.fosiaudio.com/hc/en-us/articles/35730754097689-Official-Statement-Regarding-the-Inverted-Phase-of-the-V3-Mono

mixing revisions (used market, replacement on defect) has really become a nightmare.. phase and gain

I would agree with this. The phase issue is simple enough - if you can remember (or mark) which of your amps need to have their terminals switched. But the gain issue is particularly troubling, especially since, as in the case of the unit I received, the markings are the same as on the earlier versions.