Fosi Audio V3 Mono Amplifier Review

[Bleib]

The v3 mono’s don’t have the load dependency the others two models have. If your speakers have an impedance tending to be higher than 4 Ohm, the treble in both stereo units will be enhanced a bit.

It's still not quite neutral

Erin's audio corner measurements
But sure, it's better than ZA3 for instance

 

[antcollinet]

Thanks. presumably for optimum SINAD I'd run the Ultra at highest output and the Fosi at lower gain setting?

Yes.

 

[antcollinet]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

What are the different lines in your chart?

 

[burkm]

Different speaker Ohms / Impedance.
The PFFB type V3 mono has less variability at higher frequencies than i.e. a ZA3 or other Non-PFFB class D amps. Distortion etc might be affected too.
It depends on Your hearing (and age) if that is hearable or not.
There is a White Paper from TI about the PFFB technique...

 

[Deleted member 72219]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

Is that graph in Stereo mode? Or is it in Mono mode? Would changing between Stereo and Mono modes change that graph?

-Ed

 

[Endibol]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

True, but practically inaudible I would say.

 

[burkm]

True, but practically inaudible I would say.

it is not known to me, if other consequences exist, because the judgement considering "sound quality etc." seems to be at least inconsequential ...

 

[Sokel]

Is that graph in Stereo mode? Or is it in Mono mode? Would changing between Stereo and Mono modes change that graph?

-Ed

Don't take the above chart as a law,this (really) small deviation with the simulated speaker (complex load) applies only to that particular load.
Other complex loads (speakers) may have none or a greater effect.

There's a thread about the load depended cousin,same calcs apply to this one or any other more or less load depended amp.

 

[Bernard23]

Mine arrived today, set them up worked fine, got a bit hot. They came with the DC filter but I noticed still a buzz if you turn off one of the pair and leave the other on
Ultimately didn't sound any different to my Yamaha so they're back in the box ready to be returned tomorrow.
It's been a fun ride.

 

[Freezak]

I'm just wondering what's the consensus on using fans (like 120mm AC Infinity) under these monos? I've read conflicting posts on whether the SINAD effect mentioned earlier would be audible or not in a normal daily music listening scenario.

 

[Sokel]

I'm just wondering what's the consensus on using fans (like 120mm AC Infinity) under these monos? I've read conflicting posts on whether the SINAD effect mentioned earlier would be audible or not in a normal daily music listening scenario.

As far as I have seen measuring various ones,the result can be measurable but it's highly unlikely to be audible.

 

[burkm]

There seem to be reports about some of the commutation frequencies showing up in the distortion and else graphs.
Sorry, I am, too, not familiar with this...

 

[Sokel]

There seem to be reports about some of the commutation frequencies showing up in the distortion and else graphs.
Sorry, I am, too, not familiar with this...

I have posted such in another thread:

Strange polarity issue with new amplifier (Topping PA5 II Plus)

Due to improper encapsulation, heat death will catch up to it eventually. You will probably lose one channel first. Maybe I'm just lucky, but enjoying my ~2 year old PA5 original used almost daily. Ampguy conveniently didn't mention that he already had one PA5 replaced, and is one of the...

www.audiosciencereview.com

Note that the level is way-way low.

 

[Down South]

Thank you for your reply. ADC's have improved over the last 40 years I believe, but we were told that digital measured perfectly and so was perfect back in the day.

My ADC is not expensive but very good. The 'anything else' you refer to is probably more measurable with phono stages than any (most) other piece(s) of gear these days.

To quote the wisest of members here (approximately) - why not do a blind test to be sure, with all these phono preamps!

No, what interests me most about these V3 monos, and a couple of other devices I am trying, is in fact related to your statement ... what is the point at which the measurements don't count because even the cheapest devices measure and perform so well? x distortion vs slightly worse distortion? The point of zero returns.

Historically measurements (it seems to me) have often been abused, and amazingly the equipment has got better (when it was of all perfect before). But these days, it does seem to be a very good time to be buying 'value' gear because it performs so well.

Very good post, chock full of ironic truth that many will miss or ignore (doesn't suit their belief system). In the 70s the Japanese made amps that measured perfectly but sounded like shite. It used to be heresy to have bass and treble adjustment, which completely ignores the fact that a lot of listening rooms are made of crap material - single plasterboard walls and ceilings (USA) or hard clay blocks (France,Spain, Italy,Portugal) finished with a hard plaster finish. Just loved the comment - and amazingly the equipment has got better when it was all 'perfect' before .

Re. phono stages - in 2010 I bought at half price because the whole financial system was at the point of meltdown an MC3 Talk Electronics two box phono stage. Adjustable loading and gain via two banks, one for each channel so the jumpers should mirror each other, a warp filter and true mono replay. Not unusual in good phono stages, it caters for virtually all cartridges both MM and MC. So comments made about analogue and digital should be made with details of actual phono stages used. As Parks Audio Puffin and Waxwing are said to neither add or subtract from the analogue signal it should be interesting to do an A/B using one or both to see the digital outcome.

 

[Down South]

But non subjectively - why on earth would that be. Dire Straits Brothers in Arms was recorded fully digitally in 1985 - with audio quality (including noise floor) vastly exceeding that possible on vinyl. So absolutely the ADCs used for that are easily capable of recording anything on vinyl without any audible degradation whatsoever.

Many other fully digital recordings were made much earlier, as mentioned above.


None of which has anything to do with the straight capture of a vinyl recording to digital and subsequent playback without any degradation.

You do know that Mark Knopfler built two studios, one digital and one all analogue. He was hacked off that he didn't build the analogue studio earlier as it cost a lot more than if he had built it earlier.

 

[Deleted member 72219]

You do know that Mark Knopfler built two studios, one digital and one all analogue. He was hacked off that he didn't build the analogue studio earlier as it cost a lot more than if he had built it earlier.

Wait, so which studio did he prefer and get better results from?

-Ed

 

[theREALdotnet]

As far as I have seen measuring various ones,the result can be measurable but it's highly unlikely to be audible.

Probably less audible than the fans.

 

[antcollinet]

You do know that Mark Knopfler built two studios, one digital and one all analogue. He was hacked off that he didn't build the analogue studio earlier as it cost a lot more than if he had built it earlier.

None of which says anything about the relative quality capabilities of the analogue studio vs the digital one. Nor does it say anything about the point being discussed in this subthread** - which is about the capability of an ADC (even - most likely - one from the 80s) being able to fully transparently digitise a vinyl record.

**And seeing as we are at least a dozen posts into this off topic subthread, I'm going to leave it there.

 

[Bernard23]

Thank you for your reply. ADC's have improved over the last 40 years I believe, but we were told that digital measured perfectly and so was perfect back in the day.

My ADC is not expensive but very good. The 'anything else' you refer to is probably more measurable with phono stages than any (most) other piece(s) of gear these days.

To quote the wisest of members here (approximately) - why not do a blind test to be sure, with all these phono preamps!

No, what interests me most about these V3 monos, and a couple of other devices I am trying, is in fact related to your statement ... what is the point at which the measurements don't count because even the cheapest devices measure and perform so well? x distortion vs slightly worse distortion? The point of zero returns.

Historically measurements (it seems to me) have often been abused, and amazingly the equipment has got better (when it was of all perfect before). But these days, it does seem to be a very good time to be buying 'value' gear because it performs so well.

I can't test them as I don't own them, it's merely a hypothesis.

Agree with your latter points - there is a point at which we can't hear the measurable differences (hence placebo), though perhaps if you use the price of a device as some form of measure of it's capability you might find a very strong correlation!

 

[Bernard23]

Very good post, chock full of ironic truth that many will miss or ignore (doesn't suit their belief system). In the 70s the Japanese made amps that measured perfectly but sounded like shite.

So in the 70s we had golden ears that could hear things we couldn't measure? Really? What exactly is "shite" as a measure of a device? Surely what you mean is that at that time, they were not measuring the important characteristics that influenced SQ; so what is measured today that is, but wasn't back then?