Fosi Audio V3 Mono Amplifier Review

[SMen]

Hello! My current system is - fosi zd3 + aiyima a70. The sound is fine, but I got the idea of replacing the aiyima a70 with two fosi v3 mono. Please tell me if it's worth doing or not? Maybe there is someone who owned them and compared them? Thanks)

I think the A70 is a step up from the previous A08 I had, and I moved to two V3 monos, but for me the pivot point is the relay volume control I now use with the Monos.

Where it comes to volume, I find having a small (they are not expensive) dB meter really useful, because, depending on the size of your room, speakers, efficiency etc. you may find that actually 85 db is very loud ... and having an amplifier that lets you play at 95dB instead of say 93 db (which you would not want to anyway) is superfluous.

So the monos bring other factors into play other than power, like slotting nicely under my tv for example (which the other shapes and sizes don't)!

 

[SMen]

Right, right... 10 lg (power_ratio) = 1.3dB ==> power_ratio = 10 ** 0.13 = 1.35 ==> power_ratio_increase_percent = 35%

I guess, my question is how you arrived at the perceived volume (loudness?) increase.

Yes + 1 for an interesting question for @antcollinet

 

[antcollinet]

Yes + 1 for an interesting question for @antcollinet

It is fairly well established that +10dB results in an approximate doubling of perceived volume (+100 %)

Since our perception of volume is similarly logarithmic, I tend to use the % of 10dB as the % of volume increase. In this case. 1.3dB is 13%. This is not strictly accurate - you can't have 10x 10%. increases from the previous level and then reach a total of 100% - but since the perception won't be precise (the auditory system consisting of a combination of meat-ware and wet-ware) and will similarly vary a little from person to person, I view it as "close enough for government work"


EDIT - having looked at it a bit more, each dB of power results in a multiple of perceived volume of near as damnit x1.072 (Assuming we accept 10dB = x2)

So for any dB figure, perceived volume multiplier is 1.072^(dB power change)

So 1.3dB is around 9% increase in perceived volume. (subject to meatware/wetware variation yada yada)

 

[MT_bassbone]

Has anyone figured out a way to eliminate the pop when the amp powers on from Auto mode? It's a huge thump through my speakers. I am running the Wiim Ultra through the Fosi ZD3 through the V3's. I am using the XLRs from the DAC to the amps. Could this damage my speakers?

 

[roog]

Has anyone figured out a way to eliminate the pop when the amp powers on from Auto mode? It's a huge thump through my speakers. I am running the Wiim Ultra through the Fosi ZD3 through the V3's. I am using the XLRs from the DAC to the amps. Could this damage my speakers?

I wonder why your system does this? My system uses the Wiim Ultra through a pair of V3 monos set to auto and they start up without a thump. I hear a faint click from the V3 relay

 

[antcollinet]

Has anyone figured out a way to eliminate the pop when the amp powers on from Auto mode? It's a huge thump through my speakers. I am running the Wiim Ultra through the Fosi ZD3 through the V3's. I am using the XLRs from the DAC to the amps. Could this damage my speakers?

I wonder why your system does this? My system uses the Wiim Ultra through a pair of V3 monos set to auto and they start up without a thump. I hear a faint click from the V3 relay

Perhaps the ZD3 is outputting some DC which is amplified and dropped onto the speakers at power on?

 

[roog]

Perhaps the ZD3 is outputting some DC which is amplified and dropped onto the speakers at power on?

It’s a possibility, given that it appears to be the main difference between our systems

 

[uktweaker]

I wonder why your system does this? My system uses the Wiim Ultra through a pair of V3 monos set to auto and they start up without a thump. I hear a faint click from the V3 relay

My v3 monos used to do this when run from a single 10A supply with dc filter. I suspect that if the two amps come out of standby at slightly different times you get this. I changed to 2 supplies (aiyama gain) and no longer does it.

 

[early rejecter]

My v3 monos used to do this when run from a single 10A supply with dc filter. I suspect that if the two amps come out of standby at slightly different times you get this.

I don’t think that’s it. I’m running both of mine through the single 10A supply and filter and have never gotten a pop or any other audible noise from the speakers when they switch on — and I do hear the relay clicks slightly out of sync.

 

[MT_bassbone]

Perhaps the ZD3 is outputting some DC which is amplified and dropped onto the speakers at power on?

It's the ZD3 with a slight lag when it's turned on via the 12v trigger. I removed the DAC from the equation and connected without the DAC using RCAs. No pop sound. Is there a solution that would allow me to keep the DAC and still keep the V3's in auto mode? I wonder if the same would occur if I had ZA3's in mono using the 12 v trigger from the DAC? Or should I just consider ditching the class D amps for a class AB amp?

 

[antcollinet]

It's the ZD3 with a slight lag when it's turned on via the 12v trigger. I removed the DAC from the equation and connected without the DAC using RCAs. No pop sound. Is there a solution that would allow me to keep the DAC and still keep the V3's in auto mode? I wonder if the same would occur if I had ZA3's in mono using the 12 v trigger from the DAC? Or should I just consider ditching the class D amps for a class AB amp?

Ditch the dac. It wont give you anything compared to the one in the ultra.

 

[MT_bassbone]

Ditch the dac. It wont give you anything compared to the one in the ultra.

It looks like that is the direction I am heading. I was hoping to test the reclocking idea proposed by Old Guy HiFi/Cheap Audioman using a SMSL PO100 Pro. A DAC would have to be involved.

 

[roog]

The SMSL PO100 Pro. Seems to be a USB to SPDIF /I2S converter, why do you need this in your signal chain?

 

[roog]

The whole separate mains supplies to each amp / streamer thing was a concern to me (my amps sit directly behind each of my stereo speakers and plug into different mains sockets, although almost certainly on the same circuit.)

And yet it doesn’t seem to matter how I turn on or off my system it behaves it’s self very well with no nasty noises whatsoever. I have even tried provoking it !

 

[MT_bassbone]

The SMSL PO100 Pro. Seems to be a USB to SPDIF /I2S converter, why do you need this in your signal chain?

They allege it reduces jitter from the digital signal. Essentially a reclocker. I am somewhat skeptical but also curious.

 

[antcollinet]

I was hoping to test the reclocking idea

Also utterly pointless.

They allege it reduces jitter from the digital signal. Essentially a reclocker. I am somewhat skeptical but also curious.

You should be skeptical. Jitter in modern DACS is rejected to at least an order of magnitude or two below audibility - even on an interface which carries the clock like Toslink. Further - if your input to the DAC is USB, there is no jitter in any case, since the DAC clock fully controls the clocking.

Re-clocking is another of those totally useless audiophile fetishes.

 

[Vlvvv]

Hello! Dear owners of this device, do you have any pop when turning on/off this device? Thank you)

 

[EddNog]

Hello! Dear owners of this device, do you have any pop when turning on/off this device? Thank you)

No.

-Ed

 

[DavidM1]

Hello! Dear owners of this device, do you have any pop when turning on/off this device? Thank you)

None. I use them on auto and they turn on and off with a solenoid click but no pop through the speakers. They turn off very slightly out of time with each other. If I turn my DAC off they turn themselves on for 10 minutes. If I turn my DAC on, they won’t notice until there is an audio signal.

 

[MT_bassbone]

Hello! Dear owners of this device, do you have any pop when turning on/off this device? Thank you)

I get two pops when my source triggers the Fosi ZD3 and then the auto feature on the V3's. I have been in communication with Fosi and recently sent them a video to see if they can solve the problem. Their customer service is great.