Fosi Audio V3 Mono Amplifier Review

[Fosi Audio]

Both are the same power supply. The Model number (HKA30048063-7D which means 300W, 48V 6.3A) is the same, the input current is the same. The actual output power is the same. I think it's a little dishonest/misleading to state that the second PS provides 10A(max), people may believe this is a 480W power supply.
The real question is , do we really need all that power? With the 4Vrms input signal we provide at -12dBFS or even -14dBFS attenuation(x0.2 to x0.25) , and the total amplifier gain of 20.5dB or x10.6, the output voltage the amp can produce is 4V x0.20 x10.5= 8.4V, at 4Ohm we have 8.4^2 / 4= 17.64W

This means that a 8.4V DC/0.707 = 12V DC Power supply with 2A is more than capable of providing power for this particular use case. This is in "theory" because we know the TPA3255 needs at least 18V and 10.8V for the other digital circuitry:
View attachment 369480

Hello there, please ignore the model number on the power supply. This 48V/10A power supply is custom-made with Huntkey, and we will correct the model name. We have previously released the relevant test report and test video for this power supply. For details, please refer to here.

Fosi Audio V3 Mono Amplifier Review

@amirm this should be titled "...dbW" at the top? The graph shows Vrms.

audiosciencereview.com

 

[jvdburgt]

Fosi posted details about their SP601 speaker, asking users’ inout on which calibration they prefer.

Thoughts?

 

[Talisman]

View attachment 369955Fosi posted details about their SP601 speaker, asking users’ inout on which calibration they prefer.

Thoughts?

I think it's a frequency response recorded in the room, so I don't really understand what we're supposed to infer

 

[Jeromeof]

I think it's a frequency response recorded in the room, so I don't really understand what we're supposed to infer

Exactly - they should have provided some quasi-anechoic measurements at least

 

[Sokel]

I see they use an LMS analyzer though.
Results should be comparable between measurements.

 

[ovi]

https://www.kickstarter.com/projects/fosiaudio/fosi-audio-v3-mono-power-amplifier/

Rated power depends on the load impedance and power supply.

You can calculate input sensitivity with
sqrt(Rated power [W] * load impedance [Ω]) * 10 ^ (gain [dB] * -1 / 20)

So for 240W at 4Ω, XLR input you need sqrt(240*4)*10^(-20.5/20)=2.93Vrms

With RCA in, it's sqrt(240*4)*10^(-25.5/20)=1.64Vrms

Thanks for the formula it helped me understand a lot more about this subject

 

[staticV3]

Thanks for the formula it helped me understand a lot more about this subject

Check this out, may be useful:

Fosi Audio V3 Mono Amplifier Review

That's amazing, thanks for the review. I would pair three of those with an Onkyo rz-50. Since I have to buy cables anyway, are there any benefits in going rca-xlr vs rca-rca? According to Amir's review of the rz-50, it can output up to about 3.5 volt

www.audiosciencereview.com

 

[amix]

Does anybody know the V3 Mono's damping factor? And does it change with the 10A PSU? @Fosi Audio

 

[Rover]

Hello there, please ignore the model number on the power supply. This 48V/10A power supply is custom-made with Huntkey, and we will correct the model name. We have previously released the relevant test report and test video for this power supply. For details, please refer to here.

Fosi Audio V3 Mono Amplifier Review

@amirm this should be titled "...dbW" at the top? The graph shows Vrms.

audiosciencereview.com

Hi.When will the Fosi Audio M3 Mono be available?

 

[antcollinet]

Hi.When will the Fosi Audio M3 Mono be available?

Kickstarter has June as an estimate.

 

[Atryx10]

I'm new here, so IDK if this should be in its own thread or not, but how would you connect these up in a 2.1 surround setup? I was considering getting a DAC and headphone amp (that could be used as pre-amp), so I'd have something that I could use for both headphones and speakers, but I don't understand how it'd be possible to connect that with three Fosi V3 Mono for a 2.1 setup, since as far as I can tell, headphone amps don't seem to have the capability for more than 2.0. I was thinking of getting a FiiO K19, but maybe I should just give up on trying to get this to work...
Would greatly appreciate help with understanding more about this.

Edit: Thanks for the answers! That has made me get some additional questions, but as it's going to stray from the main topic of this thread, it's better for me to wait with replying until this gets moved to its own thread
Though, from what I gather so far, it's going to be for the best if I get a separate DAC and headphone amp, with the headphone amp having pre-amp capabilities and a sub out. If my understanding is correct, I should be able to make do with my FiiO Q15 as the DAC, and just try to find a headphone amp with a sub out. Perchance
Now, I wonder how cursed it would be if I were to use a FiiO K19 plugged into a Denon AVC-X3800H, that then plugs into the Fosi V3 Mono amps. This stack would after all have the ability for IEM and headphone driving, alongside the ability to do surround up to 7.4.4

 

[antcollinet]

Options:

1 - You need a Dac or other device with a built in crossover, and output for a sub. One example would be a mini DSP flex.
2 - You split the 2.0 output, and send it both to the main amps, and to the sub. Then use the low pass filter on the sub to perform the crossover. No high pass for the main speakers this way though.

 

[DTTOM37]

I'm new here, so IDK if this should be in its own thread or not, but how would you connect these up in a 2.1 surround setup? I was considering getting a DAC and headphone amp (that could be used as pre-amp), so I'd have something that I could use for both headphones and speakers, but I don't understand how it'd be possible to connect that with three Fosi V3 Mono for a 2.1 setup, since as far as I can tell, headphone amps don't seem to have the capability for more than 2.0. I was thinking of getting a FiiO K19, but maybe I should just give up on trying to get this to work...
Would greatly appreciate help with understanding more about this.

Hi, Bienvenue ;-)
1rst: Usually the .1 may be an active subwoofer, which means it already has integrated amplifaction. You would only need a third amplifier in case you use a third passive speaker/sub (unamplified)

2nd: In case you use an active sub, you could get a DAC (like the SMSL D6/6s) that allows dual full range signal output via a) balanced/TRS and b) unbalanced/RCA outputs, which could feed a) you speakers with the Mono V3 and b) the active sub. Imho, one of the cheaper options, and quite doable if your sub does low pass filtering.

3rd: Alternatively you could look at the WIIM range, which may - with the all new WIIM Ultra - may allow pre-amp functionality & 2.1 output.
Afaik, it's still assumed that its parametric EQ will receive high pass / low pass functionality quite soon. (pehaps it already has and I am not up to date ?)

Means: HP: Signal above selected frequency will be outpt to the speaker amp, LP: Signal below selected frequency will be sent to subwoofer only.

As often, the more you invest the better are your options for your specific use case. AFAIK

 

[rvsixer]

I'm new here, so IDK if this should be in its own thread or not, but how would you connect these up in a 2.1 surround setup? I was considering getting a DAC and headphone amp (that could be used as pre-amp), so I'd have something that I could use for both headphones and speakers, but I don't understand how it'd be possible to connect that with three Fosi V3 Mono for a 2.1 setup, since as far as I can tell, headphone amps don't seem to have the capability for more than 2.0. I was thinking of getting a FiiO K19, but maybe I should just give up on trying to get this to work...
Would greatly appreciate help with understanding more about this.

IMO should be in its own generic thread, but onwards:
1) 2.x, by definition, is not a surround setup (you need surround speakers for that, 2.x is just front/left/x subs)
2) Headphones (generally) only support 2.0 (no sub input or output). Of the few that do support a "sub" inside of them, the crossover is internal to them so still only need 2.0 input.
3) Many ways to skin this cat, what I would setup:
- miniDSP Flex Eight as already mentioned (assuming all your sources are digital).
- Fosi mono blocs for the 2.x output to speakers (make sure your passive sub(s) are okay with the Fosi output limits, otherwise just use a different amp for the sub(s)). If your subs are active that negates the need for external amp(s).
- Headphone amp for your headphones
- Would make for a very compact and versatile base setup, easy to change up amps/speakers etc. in the future
- Always use more than one sub but that's a whole other discussion

 

[ppdl3]

Hello there. Newbie here (this is my first post). Firstly, thank you so much to this amazing community; I've learned so much! I am, of course, still learning, so that's why I'm reaching out now. I've read all 84 pages of this thread and and still have two questions regarding this amp (one I think useful to the whole community and one that is selfish--please feel free to disregard the selfish one). So, if you have the chance to explain, I'd greatly appreciate it.

1. I've read enough about the difference in power supplies, but I'm still unclear: What would be the benefit of two 48v 10a over two 48v 5a power supplies? The price difference is significant enough to call this into question for me (as one person here explained it: it's enough to hurt the value proposition a bit).

2. (Selfish question). Prior to learning from this community, at the beginning of my audiophile journey I purchased a Musical Fidelity m2Si (fortunately used and for a great deal). Unfortunately, it hasn't been too well reviewed here. The gist is that the preamp is good, the power amp is not. So... would I be well served adding these mono blocks in an effort to better drive my Focal 615 towers? There is a sub question here that is perhaps philosophical: Should I instead invest in something different altogether? This is my main system, so I'm willing to invest, but I am a teacher and this is one of many hobbies, so I can't go too crazy spending several thousand. Many mention this as not something that will replace higher end gear, or wouldn't even be part of a main system. Well, why not? If the measurements are good, are there things not captured in the measurements selected that should mean going to class a/b or to a higher end class d like Apollon?

Thanks in advance!

 

[Doodski]

1. I've read enough about the difference in power supplies, but I'm still unclear: What would be the benefit of two 48v 10a over two 48v 5a power supplies? The price difference is significant enough to call this into question for me (as one person here explained it: it's enough to hurt the value proposition a bit).

I will try to simplify while remaining accurate to the processes.

With one power supply:
As power is delivered to the speaker there are peaks in the power amp output and those cause the amp power supply to be depleted/drained of electrons and that can cause sound quality issues.

With 2 power supplies:
Higher speaker dynamic headroom is available due to there being more electron storage/drive in the power supply(s). As one channel draws more electrons the other is independent and not affected by the other channel.

If you would like a more technical explanation just ask and I'll elaborate on the subject.

 

[staticV3]

What would be the benefit of two 48v 10a over two 48v 5a power supplies?

According to Fosi: No advantage. The 48V5A supply is enough to saturate the Amp.

We're still waiting for 3rd party testing to confirm this.

would I be well served adding these mono blocks in an effort to better drive my Focal 615 towers?

Only if you currently have some sort of issue, driving your Focals with the m2si. Something like too little power, or audible hiss at your MLP.

There is a sub question here that is perhaps philosophical: Should I instead invest in something different altogether?

The greatest return in sound quality you'll typically see with new speakers, room correction, or room treatment.
Electronics are secondary.

 

[JeremyFife]

Hello there. Newbie here (this is my first post). Firstly, thank you so much to this amazing community; I've learned so much! I am, of course, still learning, so that's why I'm reaching out now. I've read all 84 pages of this thread and and still have two questions regarding this amp (one I think useful to the whole community and one that is selfish--please feel free to disregard the selfish one). So, if you have the chance to explain, I'd greatly appreciate it.

1. I've read enough about the difference in power supplies, but I'm still unclear: What would be the benefit of two 48v 10a over two 48v 5a power supplies? The price difference is significant enough to call this into question for me (as one person here explained it: it's enough to hurt the value proposition a bit).

2. (Selfish question). Prior to learning from this community, at the beginning of my audiophile journey I purchased a Musical Fidelity m2Si (fortunately used and for a great deal). Unfortunately, it hasn't been too well reviewed here. The gist is that the preamp is good, the power amp is not. So... would I be well served adding these mono blocks in an effort to better drive my Focal 615 towers? There is a sub question here that is perhaps philosophical: Should I instead invest in something different altogether? This is my main system, so I'm willing to invest, but I am a teacher and this is one of many hobbies, so I can't go too crazy spending several thousand. Many mention this as not something that will replace higher end gear, or wouldn't even be part of a main system. Well, why not? If the measurements are good, are there things not captured in the measurements selected that should mean going to class a/b or to a higher end class d like Apollon?

Thanks in advance!

Hi, and welcome

Just a thought on your second question - your Amp. The measurements weren't all bad, apart from clipping behaviour. If you don't hear unpleasant noises, and your amp isn't shutting down then it's probably not affecting your system. Don't worry about it.

If budget is limited (always is!) then perhaps invest in a measurement microphone and start understanding how your system is behaving in your room. That's a great platform to make changes from.

Changing the power amp won't improve your sound

 

[ppdl3]

Got it. Thanks, all. Very helpful. Perhaps I'll still get these and build a second system!

 

[edgar-bcn]

Newbie here, hello everyone!

I need something to drive my LCR speakers, at first I was looking for 3-channels power amps like the Emotiva BasX A3.

How this compares with others budget AB amplifiers?

Thanks!