Fosi Audio V3 Mono Amplifier Review

[jvdburgt]

RE bi-amping (thanks for all the feedback) I belive that the receiver does not have an active cross-over option for bi-amping, so I think I'll go with the skeptics on this one.

This does open up another question, given that surround channels often are less used than fronts and center (in terms of both sound volume and frequentness of sounds being played over these channels) will the auto on/off (triggered by 55db sounds if I remember correctly) work properly for the V3Ms driving the surrounds?

If this is not the case, I could still go with a smart plug setup for the surround-amps, but I'm not sure if that will result in the infamous "pops" of class D-amplifiers when turned on/off at the socket. Any insights on these two points?

 

[Rafaille]

RE bi-amping (thanks for all the feedback) I belive that the receiver does not have an active cross-over option for bi-amping, so I think I'll go with the skeptics on this one.

This does open up another question, given that surround channels often are less used than fronts and center (in terms of both sound volume and frequentness of sounds being played over these channels) will the auto on/off (triggered by 55db sounds if I remember correctly) work properly for the V3Ms driving the surrounds?

If this is not the case, I could still go with a smart plug setup for the surround-amps, but I'm not sure if that will result in the infamous "pops" of class D-amplifiers when turned on/off at the socket. Any insights on these two points?

According to @amirm measurements, there may be some pop when turning them on. Look at page 1.

 

[mike70]

but I'm not sure if that will result in the infamous "pops" of class D-amplifiers when turned on/off at the socket.

i have a well regarded british class AB amplifier (class "A" in Stereophile if that matters ) and have that noise at power on / off ... and i can say, very loud at power on.
we need to forget urban myths about "classes" and begin to think in the amplifier project / design

 

[quocheiser]

Or you go with a proper analog cross over in the speaker and feed channels with separate amps, hence my question about amount of existing crosstalk when only using one amp.
I actually read too fast I thought that is what @quocheiser had in mind.
Although I agree doing this upstream and in the digital realm (+ some DSP) is preferable and offer more control.

What I already have is a 31-band analog EQ between the source and amp, aka "upstream", which when used with a careful touch hopefully is reducing induced phase issues.
In the future if I bi-amp with these V3Ms I'd have to consider if getting an active crossover or even another EQ unit would be practical and cost-effective. If I can't hear the difference with any reduction in IMD distortion then it will be a costly part of the quest, but enjoyable nonetheless .
Luckily these V3Ms make it so cheap and easy to build/stack upstream components in a system as we go along.

 

[quocheiser]

But there isn't more power reaching each driver, unless the amp is being driven into clipping (the edge case I mentioned above). In which case the correct solution is to use an amp with enough power, rather than bi-amping.

In your case you already (will) have an amp with enough power. Don't waste them by using two per speaker.

Ah somehow forgot to reply to that.
Yeah you make a great point!
What I wrote was terribly worded, replace "more power reaching" with "more power available for" aka "headroom".
From what I understand, the closer you get to an amplifier clipping, the more likely distortion (from the amplifier) will increase.
I'd still prefer to stack amp power via these V3Ms than getting one bigger amp which offers way less flexibility AND costs more.

 

[Lednek]

RE bi-amping (thanks for all the feedback) I belive that the receiver does not have an active cross-over option for bi-amping, so I think I'll go with the skeptics on this one.

This does open up another question, given that surround channels often are less used than fronts and center (in terms of both sound volume and frequentness of sounds being played over these channels) will the auto on/off (triggered by 55db sounds if I remember correctly) work properly for the V3Ms driving the surrounds?

If this is not the case, I could still go with a smart plug setup for the surround-amps, but I'm not sure if that will result in the infamous "pops" of class D-amplifiers when turned on/off at the socket. Any insights on these two points?

Driving the front LCR stage of a home theater is an ideal use for the V3 mono. I've got three coming for just that purpose. My older Denon AVR-3400 will be more than adequate for driving the four surrounds. It shouldn't even break a sweat at very loud levels.

 

[Kayshot]

Driving the front LCR stage of a home theater is an ideal use for the V3 mono. I've got three coming for just that purpose. My older Denon AVR-3400 will be more than adequate for driving the four surrounds. It shouldn't even break a sweat at very loud levels.

I'd love to do this, but only have two balanced outputs on my DAC (as well as two RCA outs). How can I get balanced output into three V3 monos? Would I need a DAC with at least 3 outputs?

 

[quocheiser]

I'd love to do this, but only have two balanced outputs on my DAC (as well as two RCA outs). How can I get balanced output into three V3 monos? Would I need a DAC with at least 3 outputs?

You can do what I've done and use an XLR splitter.
I used something like this: https://www.thomann.de/intl/cordial_ey_03_fmm_elements.htm

 

[Kayshot]

You can do what I've done and use an XLR splitter.
I used something like this: https://www.thomann.de/intl/cordial_ey_03_fmm_elements.htm

Would the goal be to connect a splitter each on my DAC's left and right channel outputs, with one half of each splitter going into my L/R, and the other halves getting combined and sent into the V3 Mono that will feed my center channel?

 

[Rafaille]

I'd love to do this, but only have two balanced outputs on my DAC (as well as two RCA outs). How can I get balanced output into three V3 monos? Would I need a DAC with at least 3 outputs?

What would be the point of the center channel?

With a 5.1 (or more) receiver you would get most dialogues on the center speaker in movies, which makes sense. However, if you just merge left and right channels into the center speaker you would just get, well, a mix of both.

Applied to music, you would likely lose stereo spatialisation to some extent.

 

[gwing]

You can do what I've done and use an XLR splitter.
I used something like this: https://www.thomann.de/intl/cordial_ey_03_fmm_elements.htm

How would an XLR splitter help? If I understand the requirement correctly our user needs three separate channels, left right and centre. Which output from the DAC would you split and to which pair of speakers would you route that signal?

 

[Kayshot]

What would be the point of the center channel?

With a 5.1 (or more) receiver you would get most dialogues on the center speaker in movies, which makes sense. However, if you just merge left and right channels into the center speaker you would just get, well, a mix of both.

Applied to music, you would likely lose stereo spatialisation to some extent.

You're right, the point of the center channel is that it should carry different information than the left and right (like dialogue).
I understand how to go about 5.1 via a 5.1 AVR, just quite the novice and can't figure out how you'd go about sending 5.1 info to the LCR with the V3 Mono driving those 3 channels. Maybe the best approach is using a 5.1 receiver to split the channels, and send those separate signals out to the V3 monos for amplification? The AVR would be more of a pre-amp I suppose?

 

[antcollinet]

"more power available for" aka "headroom".

Read the passive bi amping section of the article you linked to. It explains why you won't even get more power.

From what I understand, the closer you get to an amplifier clipping, the more likely distortion (from the amplifier) will increase.

Generally distortion is fairly constant until clipping hits, and then it shoots up very quickly. This particular amp does have a distortion characteristic that gently increases from a minimum at about 20W, then it hit clipping and shoots up.

But even just before clipping the distortion is still basically inaudible.

 

[gwing]

You're right, the point of the center channel is that it should carry different information than the left and right (like dialogue).
I understand how to go about 5.1 via a 5.1 AVR, just quite the novice and can't figure out how you'd go about sending 5.1 info to the LCR with the V3 Mono driving those 3 channels. Maybe the best approach is using a 5.1 receiver to split the channels, and send those separate signals out to the V3 monos for amplification? The AVR would be more of a pre-amp I suppose?

Yes, if your receiver has pre-outs for each channel you could connect as many of those as you like to V3s and use them instead of their power amp sections in the receiver- so you are indeed then using the receiver as a pre-amp.

I'd guess your receiver doesn't have balanced pre-amp connections though? In which case just use RCA or, if you are dealing with intractable hum problems, convert RCA to balanced as has been discussed here quite a lot and isn't that simple to do properly.

 

[quocheiser]

How would an XLR splitter help? If I understand the requirement correctly our user needs three separate channels, left right and centre. Which output from the DAC would you split and to which pair of speakers would you route that signal?

Oh that's right, somehow I thought Kayshot was referring to bi-amping and not an LCR setup.
Different conversations in my head

 

[Kayshot]

Yes, if your receiver has pre-outs for each channel you could connect as many of those as you like to V3s and use them instead of their power amp sections in the receiver- so you are indeed then using the receiver as a pre-amp.

I'd guess your receiver doesn't have balanced pre-amp connections though? In which case just use RCA or, if you are dealing with intractable hum problems, convert RCA to balanced as has been discussed here quite a lot and isn't that simple to do properly.

Thank you! Pre-outs are definitely what I need to be looking for. Just didn't know the term. "Luckily" I have no AVR yet, and I'm not exactly bound to the idea of using balanced connections. Still in need of a center channel and AVR before I have 5.2 up and running.

 

[SMen]

Thank you! Pre-outs are definitely what I need to be looking for. Just didn't know the term. "Luckily" I have no AVR yet, and I'm not exactly bound to the idea of using balanced connections. Still in need of a center channel and AVR before I have 5.2 up and running.

Need Your Advice on Developing a 5.1 Channel DAC

Hi all! Our team is now developing a 5.1 channel DAC for home theater and desktop setup. Again, we want to hear your voices and hope to collect valuable advice here on ASR. Let's make amazing gear together! The picture below shows the concept design of this DAC. Besides the I/O, it will also...

www.audiosciencereview.com

Funnily Fosi put out a thread asking about possibly developing a 5.1 pre. And then it had power amps added to it with a change of use case.
Lots of people think you seem to need to go straight to 7.1 (or however many).

But there is a "use case" for a 2 channel or more balanced pre-amp that is for sure, with these monos.

Me, I'd quite like to just set up a center channel for dialogue, and not have to get a big bulky receiver for this.

 

[Rafaille]

Need Your Advice on Developing a 5.1 Channel DAC

Hi all! Our team is now developing a 5.1 channel DAC for home theater and desktop setup. Again, we want to hear your voices and hope to collect valuable advice here on ASR. Let's make amazing gear together! The picture below shows the concept design of this DAC. Besides the I/O, it will also...

www.audiosciencereview.com

Funnily Fosi put out a thread asking about possibly developing a 5.1 pre. And then it had power amps added to it with a change of use case.
Lots of people think you seem to need to go straight to 7.1 (or however many).

But there is a "use case" for a 2 channel or more balanced pre-amp that is for sure, with these monos.

Me, I'd quite like to just set up a center channel for dialogue, and not have to get a big bulky receiver for this.

I am planning to go 3.1 as well. I cannot be bothered with surround speakers and they are not very WAF.
Best option seems to downmix from 5.1 or else directly at the source, which for me is Kodi running on a Nvidia shield. Then, 'demultiplexing' on a USB receiver (Raspberry Pi running CamillaDSP) and add some room correction while at it for both music and movies.

I just need to sort out CamillaDSP first, find myself a decent but compact center speaker and order a third Fosi

 

[SMen]

I am planning to go 3.1 as well. I cannot be bothered with surround speakers and they are not very WAF.
Best option seems to downmix from 5.1 or else directly at the source, which for me is Kodi running on a Nvidia shield. Then, 'demultiplexing' on a USB receiver (Raspberry Pi running CamillaDSP) and add some room correction while at it for both music and movies.

I just need to sort out CamillaDSP first, find myself a decent but compact center speaker and order a third Fosi

Jeez!

I use Kodi too and adjust using their settings with a stereo set up to 'fill in' the center channel effect on the stereo.

It works pretty well, but for Fosi, that won't sell a third mono ...
The thing is that there is a center channel in the cinema n.1 mix and it is pre-mixed for dialogue. Probably (definitely) the most important for dialogue.

A good use for monoblocks.

 

[Lednek]

I'd love to do this, but only have two balanced outputs on my DAC (as well as two RCA outs). How can I get balanced output into three V3 monos? Would I need a DAC with at least 3 outputs?

For a home theater you need a reciever with pre-outs.

I'd love to do this, but only have two balanced outputs on my DAC (as well as two RCA outs). How can I get balanced output into three V3 monos? Would I need a DAC with at least 3 outputs?

You need an avr with pre-outs. Other wise you would be running a right, mono center, left configuration. I am guessing it would sound horrible. My set up will be the avr processing all multichannel content. My dac handles teo channel, with the DAC rca outs will gong into the avr input for when I want to have 2.2 channel with bass management handled by the avr. The pre-outs are used for multi channel content. LCR pre outs will go into the rca of the three v3 monos. Additionally I will will run balanced xlr outputs from the dac straight to the l and R v3 monos to allow for strict two channel listening without subwoofers. Hope this helps.