Fosi Audio V3 Mono Amplifier Review

[MichaelJ]

This is more of a general gain-stage question: But, assuming the DSP in the SHD has sufficient digital headroom built-in, am I correct that I’m better off, from a performance standpoint, using the lower gain V3 mono’s and listening closer to 0.0db on the MiniDSP SHD?

 

[jvdburgt]

Reading all the posts, just a general wondering, but I’m wondering how you all rate the coolness factor.

I come from a decent 5.2 setup with a Marantz SR6010 receiver, a Yamaha AX-892 to power the fronts (Monitor Audio GS10) and the center (Monitor Audio GSLCR) & surrounds (Minitor Audio RX1) via the Marantz, and 2x Monitor Audio RXW12 with their own internal 500W amp. I did away with the Yamaha, and now each speaker has its own V3M to drive it.

Now, to be fair, I haven’t driven the V3Ms to the max (yet) but they sound at least as good as the previous setup. Three things that make me happy at the moment:
1. Each speaker now has its own dedicated amp (and they are thus driven the exact same way)
2. Each speaker now has its own dedicated amp (which just looks fucking cool)
3. The whole “running hot” situation gave me a nice excuse to actively cool my media cabinet and with smart plugs on both ventilators (USB) and amps and automate the whole thing with Home Assistant

Now, with what I’ll get back for the Yamaha on eBay, the V3Ms hardly put a dent in my budget.

No measurements, nothing objective, just a little bit of geek happiness for a few extra bucks.

Just curious about your more subjective experiences with the new setup.

 

[antcollinet]

I just received two V3 Monos. They're replacing two ZA3s that were running in "mono" so that I can repurpose the ZA3s to other smaller systems in the house (and because I couldn't help seeing how the new V3 Monos compare...)

The system is digital and uses XLR connectors: MiniDSP SHD > (2x) Topping D30PRO > (2x) V3 Monos > passive bookshelves (I handle bass management in the SHD and cross over to (2x) powered subs)

First thing I noticed was that the gain on the V3 monos was much less that the ZA3s, which I had previously set to maximum on the volume knob. I ran in-room measurements at my listening position, and the difference is about 10db. I had to dial down the gain on my powered subs to match.

Is this what we'd expect? My assumption was that the ZA3 at full volume would be the same as the set gain on the V3 Mono.

ZA3 gain on XLR is 26dB. On the V3 mono, it is 20dB. You need double the voltage into the Mono to get the same output.

 

[Bleib]

ZA3 gain on XLR is 26dB. On the V3 mono, it is 20dB. You need double the voltage into the Mono to get the same output.

Isn't it ideal for a 4v pre-amp function from a DAC? I seem to recall reading it in this topic

 

[antcollinet]

Isn't it ideal for a 4v pre-amp function from a DAC? I seem to recall reading it in this topic

20dB is x10, so 40V out. This would be enough for 200W at 8 ohm, or 400W at 4 ohm. Both exceed the power rating of this amp - so yes it is more than enough for a 4V output source.

 

[MCH]

This is more of a general gain-stage question: But, assuming the DSP in the SHD has sufficient digital headroom built-in, am I correct that I’m better off, from a performance standpoint, using the lower gain V3 mono’s and listening closer to 0.0db on the MiniDSP SHD?

iI don't remember well but you might want to read minidsp instructions or their forum. iirc, if you use Dirac live, they recommend max of -10dB.

 

[Kimbrough Xu]

It occurs to me that the people here who want to try op amp changes could usefully A/B a mono track, and switch between one mono unit with one set of opamps, and the other with stock NE5532's. Put the speakers next to each other. Get a mate (or suitable relation) to switch so the listener is blind. This ought to settle things for the experimenters (themselves) - could they identify which was which?

A whole new purpose for mono power amps . Think I might give this a go for the hell of it. Rope in my kids.

Dont need to be that complicated, Fosi Audio LC30 is used for comparison.

 

[Kimbrough Xu]

Good to know. FYI I make my case on the basis that my power amps all have line out - suitable for daisy chaining (bi amping), or subs.

How do you set the crossover when bi amping?

 

[seaninbrisbane]

I'm just about to set up LCR speakers for the first time with three Fosi Monos plus a home theatre AVR (+ active sub). Am I correct in thinking that I should invert the red and black connections at the rear of the three mono amps?

 

[JeremyFife]

I'm just about to set up LCR speakers for the first time with three Fosi Monos plus a home theatre AVR (+ active sub). Am I correct in thinking that I should invert the red and black connections at the rear of the three mono amps?

Not necessarily.

#1 are you using balanced or single-ended connections?
#2 do you know what your AVR and sub do to the signal polarity

It seems to depend

My understanding is that the Fosi's maintain signal polarity when you use balanced connections (there is a little debate about that actually, hopefully someone can clarify) whereas the signal polarity is reversed when using single-ended connections.

So: IF you are using balanced connections AND your AVR/Sub also maintain signal polarity THEN connect everything up as normal.
Otherwise you need to work out what's going on and connect accordingly.

You can just wire it all up and listen to it too

 

[Bleib]

I'm just about to set up LCR speakers for the first time with three Fosi Monos plus a home theatre AVR (+ active sub). Am I correct in thinking that I should invert the red and black connections at the rear of the three mono amps?

Well, you have to measure things with the mic anyway right, and if it's a Denon it should check the phase anyway..

 

[seaninbrisbane]

Not necessarily.

#1 are you using balanced or single-ended connections?
#2 do you know what your AVR and sub do to the signal polarity

It seems to depend

My understanding is that the Fosi's maintain signal polarity when you use balanced connections (there is a little debate about that actually, hopefully someone can clarify) whereas the signal polarity is reversed when using single-ended connections.

So: IF you are using balanced connections AND your AVR/Sub also maintain signal polarity THEN connect everything up as normal.
Otherwise you need to work out what's going on and connect accordingly.

You can just wire it all up and listen to it too

Thanks very much for taking the time to reply. I'm using single-ended connections with a Denon X3700H AVR. This is my first time setting up a home theatre.

 

[seaninbrisbane]

Well, you have to measure things with the mic anyway right, and if it's a Denon it should check the phase anyway..

That's good to know, thanks.

 

[korgua]

I am happy with my V3Ms and still not got round to testing the MUSE02 op amps yet. I saw this mod on the Fosi Audio Global Community Facebook and was curious on what others thought of adding / replacing some of the capacitors? https://www.facebook.com/share/p/TUTkPGtb8weheSke/

 

[antcollinet]

I am happy with my V3Ms and still not got round to testing the MUSE02 op amps yet. I saw this mod on the Fosi Audio Global Community Facebook and was curious on what others thought of adding / replacing some of the capacitors? https://www.facebook.com/share/p/TUTkPGtb8weheSke/

No-one can see that unless they join the group. I'm certainly not going to.

However this type of mod is exceptionally unlikely to make any improvement. Far more likely to mess something up.

 

[EddNog]

No-one can see that unless they join the group. I'm certainly not going to.

However this type of mod is exceptionally unlikely to make any improvement. Far more likely to mess something up.

I must admit that I have requested to join that group just purely out of morbid curiosity

-Ed

 

[DavidM1]

The modding fad makes no sense to me. The appeal of the V3m amps is how well they compete with others for test results and price. Mine sound tremendous.

What’s to be gained by second guessing the design just because some paid YouTube influencers puff up their impressions? Show me the data.

 

[Chrispy]

FWIW

 

[antcollinet]

FWIW

Please can people posting youtube videos include a summary of what it is saying. They are a very inefficient way of transferring information, and people shouldn't have to watch the damn thing to find out if it has any interest to them at all.

It would also be useful to know why the poster is posting it. What point (if any) are they trying to make. Do they agree with the content, or not? What are their own thoughts on it. Etc.

 

[Basilderat]

So I have a Topping L70 preamp connected to both a Topping PA7 amp via XLR driving one pair of speakers, and also to two Fosi V3 Monos via RCA driving another pair of speakers. I assume after reading this thread that I should swap red for black speaker wires output from the Fosi?