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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 8 1.6%
  • 2. Not terrible (postman panther)

    Votes: 12 2.4%
  • 3. Fine (happy panther)

    Votes: 100 19.7%
  • 4. Great (golfing panther)

    Votes: 387 76.3%

  • Total voters
    507

Severian

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I am not particularly concerned with the quality/reliability of SMPS selected by Fosi... but I really dislike having a big external power brick at all. I use an Aiyima A07 at my desk and it's so annoying needing to stash the power brick somewhere. I far prefer the internal power supplies with my two ICEpower amps in Ghent Audio cases. Sure they are larger, but still relatively compact.
 

DavidM1

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The durability question is interesting. I think some folks here will get bored and move onto something new long before the gear gives up. The affordability of alternatives is a bigger threat to longevity than the components or design.

Personally, my interest in amps will likely evaporate after this purchase, much like my interest in DACs did after buying an SMSL. This setup will probably be around for a long while.
 

Lednek

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Are you able to connect a subwoofer via high level to the monoblocks? Thanks.
Edit! I was wrong. I was thinking about the subwoofer, not the amplifier. This could possibly damage the amplifier.
 
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Negatywny

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The durability question is interesting. I think some folks here will get bored and move onto something new long before the gear gives up. The affordability of alternatives is a bigger threat to longevity than the components or design.

Personally, my interest in amps will likely evaporate after this purchase, much like my interest in DACs did after buying an SMSL. This setup will probably be around for a long while.
Yeah, my aiyima has almost 4 years , 0 problems. Several topping DACs, couple of years - one got this screen deterioration, but apart from that everything is fine. My fancy audiophile (thou still reasonable and grate audio quality) amplifier breaks like every two years, right now its under repair cause whole left channel power amplifier got crazy and shuts down at random.

Really looking forward for V3 monos, "audiophile" sound quality and most propably reliability is not existing issue, but if something goes wrong? Power brick went down? Buy new for 30$ (almost less than shipping 20kg amplifier to service (and risking it another damage in transport)). One channel dead, buy whole new one for 150$ (my big boy left channel fix almost certainly will be costlier). A month ago i paid 175$ for changing a broken potentiometer in CA 740A (and it wasn't first time it needed technician), so c'mon, its almost the same as i paid for topping Mx3s.

I got it that there ware some models with problems but looking at the whole market they're even statystically irrelevant.
 

antcollinet

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Of course, if your subwoofer has speaker level inputs, it will work just like any other amplifier.
No, not necessarily. Many subs have a grounded black terminal for high level inputs - which is not compatible with a class D amp with bridge tied load such as this one. Best to check with the sub manufacturer.

In that case it is usually possible to connect one speaker terminal to the red channel of the sub, and connect the black terminal of the sub back to an earth point on the amp - ususallly the ring of an unused RCA connector. However, again it is necessary to check with the sub manufacturer the compatibility of this approach.
 

R.J.

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What is the continuous output power specification in W RMS of the V3 mono?
 

SMen

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No, not necessarily. Many subs have a grounded black terminal for high level inputs - which is not compatible with a class D amp with bridge tied load such as this one. Best to check with the sub manufacturer.

In that case it is usually possible to connect one speaker terminal to the red channel of the sub, and connect the black terminal of the sub back to an earth point on the amp - ususallly the ring of an unused RCA connector. However, again it is necessary to check with the sub manufacturer the compatibility of this approach.
Am I right that this is the case with the vast majority of class D, so these Fosi monos are not at all unusual, and it would be the same with say, an Aiyima A07.

I have speaker level inputs and the manufacturers advice is to make sure that the line levels are not connected at the same time.
But another manufacturer (REL) suggested connecting with the line level to line level, but with the line level volume down.

So quite confusing.
 

gwing

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Am I right that this is the case with the vast majority of class D, so these Fosi monos are not at all unusual, and it would be the same with say, an Aiyima A07.

I have speaker level inputs and the manufacturers advice is to make sure that the line levels are not connected at the same time.
But another manufacturer (REL) suggested connecting with the line level to line level, but with the line level volume down.

So quite confusing.
Yes this is a common problem with many class D amps. Not that the problem is exclusive to class D but it is much less common for 'conventional' amps to be bridged.

I know REL say different, but generally using line level connections to the sub is the best way to go instead of using speaker level connections.
 

SMen

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Yes this is a common problem with many class D amps. Not that the problem is exclusive to class D but it is much less common for 'conventional' amps to be bridged.

I know REL say different, but generally using line level connections to the sub is the best way to go instead of using speaker level connections.
Yes I am using MJ Acoustics, and have for years. They were fine with both the Ayima A07 and A08 attached solely with one or other connection but not both (obviously I did not try both having read this). I agree about the line level being safer, but I'm geared up with Speakon cables.

This is their warning that I have kept.
 

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Lednek

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Yes I am using MJ Acoustics, and have for years. They were fine with both the Ayima A07 and A08 attached solely with one or other connection but not both (obviously I did not try both having read this). I agree about the line level being safer, but I'm geared up with Speakon cables.

This is their warning that I have kept.
Is this not specifically for connecting LFE(line level sub out) and speaker connections simultaneously? Do you even have a line level sub output? Under what circumstance would someone want both LFE and speaker level inputs hooked up simuopiniously. Obviously the manufacture saw a case, but I don't. Can someone help me understand how a bridged load amplifier cares about grounding at the soeaker level. Isn't it just a red and black wire going to the speaker? In other words, if you switch them does something other than a 180 degree phase shift happen?
 

SMen

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Is this not specifically for connecting LFE(line level sub out) and speaker connections simultaneously? Do you even have a line level sub output? Under what circumstance would someone want both LFE and speaker level inputs hooked up simuopiniously. Obviously the manufacture saw a case, but I don't. Can someone help me understand how a bridged load amplifier cares about grounding at the soeaker level. Isn't it just a red and black wire going to the speaker? In other words, if you switch them does something other than a 180 degree phase shift happen?
Yes it has both. It can be useful for combining a stereo set up with an audio visual set up. You can optimize the volume and response levels differently for each and then whichever is 'in play' works through the subs.

I'm also interested in your question though, as to why exactly something as simple as a speaker level connection causes problems. I understand the alert from MJ Acoustics not to connect line level and speaker at the same time but this conflicts completely with REL's suggestion to do the exact opposite! In other words MJ Acoustics just say don't run a dual input system - just one or the other.
 

rvsixer

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Is this not specifically for connecting LFE(line level sub out) and speaker connections simultaneously? ... Under what circumstance would someone want both LFE and speaker level inputs hooked up simuopiniously.
I suppose it would be possible to route LFE via line level sub out to a dedicated sub(s), and to run bass managed channels to a separate dedicated sub(s) via speaker level. I personally would never use speaker level input into a sub (I've not met a sub amp having enough flexibility for full manual integration, and question the quality of their speaker-to-line level converters).

I just run the normal setup (preamp line level sub output is used for both bass managed channels and the LFE channel). And a simple HT bypass to integrate stereo 2.x/HT systems (will be even easier using Fosi with its switchable dual input).
 
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Lednek

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Yes it has both. It can be useful for combining a stereo set up with an audio visual set up. You can optimize the volume and response levels differently for each and then whichever is 'in play' works through the subs.

I'm also interested in your question though, as to why exactly something as simple as a speaker level connection causes problems. I understand the alert from MJ Acoustics not to connect line level and speaker at the same time but this conflicts completely with REL's suggestion to do the exact opposite! In other words MJ Acoustics just say don't run a dual input system - just one or the other.
In my theater setup(Denon x3400) I crossover everything at 80hz as I have some decent subs(Monolith 12's) and want to take as much load off the amplifier. I will be using three v3 monos for the front stage. My plan is to continue to use the crossed over sub outs for everything. I will also run a balanced input from my DAC for a pure 2 channel experience for the fun of it. If I were to run both line and speaker level inputs to the subs, not only would I have to flip a switch on the subwoofers. The V3 Monos will have enough power to run full frequency to my towers for the occasional 2 channel listen in the theater. I do have a dedicated 2 channel system with subs as well, so I haven't realy considered dual inputs to my theater subs.
 

EddNog

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Cal_Cobra

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Yes it has both. It can be useful for combining a stereo set up with an audio visual set up. You can optimize the volume and response levels differently for each and then whichever is 'in play' works through the subs.
I run a separate dedicated stereo system from my home theater system, and have thought about sharing the subs from my home theater system with the dedicated stereo system.
 

Lednek

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I run a separate dedicated stereo system from my home theater system, and have thought about sharing the subs from my home theater system with the dedicated stereo system.
I guess you could adjust the sub output to match your 2 channel, and let the avr processor do the equalization for the multichannel. Just a flip of the switch between sub inputs.
 

rgruber

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My experience going from a well reviewed at the time class A/B Rotel 1520 to first a Crown XLS 1002 and then an XTZ-Edge A2 300 (both class D) was a profound improvement in sound.

The clarity and general oomph of the system was not subtle. It could have just been that more power woke up my speakers (the Rotel was rated at 60 watts per channel) versus the Crown and the XTZ being more like 300 watts per channel (depending on how much you trust these power ratings) but I would say if the Fosi is anywhere near it's rated power, you could have a really significant improvement. For me it was like going from having the sound coming from down the hall to having the sound be in front of my face. I've since brought another more powerful class A/B (Denon PMA 1700 NE) but still prefer the sound the XTZ . The detail in the midrange and treble and the control and power of the bass is just better to my ears. I think some people have a preference for the warmer sound of class A/B but for me I prefer the clarity, dark background and punchier bass of class D.

Hello everyone,
I plan to purchase these monoblocks as a replacement for my oldschool AV-Receiver onkyo TX-SR700 (from 2002 at original price around 800$). I'm currently running it (in stereo mode) as a temporary replacement for my original power amp (same price range and even slightly older than the onkyo), which has definitely gone to silicon heaven.

Based on the parameters and amirm measurements, it should be a significant improvement for me. Unfortunately, I don't have personal experience with any D-Class amplifier yet. Is there a chance that even with these "cheap" boxes I will really move up in sound quality?
 

Doodski

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The clarity and general oomph of the system was not subtle. It could have just been that more power woke up my speakers (the Rotel was rated at 60 watts per channel) versus the Crown and the XTZ being more like 300 watts per channel (depending on how much you trust these power ratings) but I would say if the Fosi is anywhere near it's rated power, you could have a really significant improvement. For me it was like going from having the sound coming from down the hall to having the sound be in front of my face. I've since brought another more powerful class A/B (Denon PMA 1700 NE) but still prefer the sound the XTZ . The detail in the midrange and treble and the control and power of the bass is just better to my ears.
That sounds about right when using a very high power amp on difficult loads/speakers.
I think some people have a preference for the warmer sound of class A/B but for me I prefer the clarity, dark background and punchier bass of class D.
I'm not so sure about this claim though. But you did go from a 60W/ch amp to hundreds of watts. Have you been able to do a A/B blind listening test with a switchbox to compare the amps?
 

gwing

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Is this not specifically for connecting LFE(line level sub out) and speaker connections simultaneously? Do you even have a line level sub output? Under what circumstance would someone want both LFE and speaker level inputs hooked up simuopiniously. Obviously the manufacture saw a case, but I don't. Can someone help me understand how a bridged load amplifier cares about grounding at the soeaker level. Isn't it just a red and black wire going to the speaker? In other words, if you switch them does something other than a 180 degree phase shift happen?

With RCA red carries the signal and black is ground.

With a bridged amplifier the red and black can carry + and - signals with neither being tied to ground.
 
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