Fosi Audio V3 Mono Amplifier Review

[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.

 

[EddNog]

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?

 

[vuittion]

What is the general consensus, buy the fosi v3 mono's with the 10 amp power supply or buy two 5 amp supplies.

 

[ninetylol]

What is the general consensus, buy the fosi v3 mono's with the 10 amp power supply or buy two 5 amp supplies.

2x5a or 2x10a

 

[burkm]

The general consensus seems to be, that 2x 48VDC / 5A is to prefer, because the 1x 10A with a filter and splitter seems to generate some interactions between both mono amps (distortion, noise etc.) plus it produces some additional hum/noise, if only on amp is active. The 2x 48VDC / 5A version uses two power bricks and has therefor no additional intermodulation distortion (=> true mono). Space requirements are almost the same, although the 10A power brick is larger by itself, and an additional filter is provided / needed, on its output side which at least seems to reduce some interactions through the splitter (filter) between both amps.
The 10A power brick does not provide any additonal (output-)advantages as stated by Fosi Audio themself.

Note: Both 48VDC power supplies lead to a "hotter" amp (higher output voltage and power), reaching about 43°C or its equivalent in Fahrenheit in its idle state and about 50°C or 122°F during full use. Higher temperatures shorten the life expectancy of electrolytic capacitors and resistors.

 

[burkm]

I wasn't too concerned about the phase being off, but did a "test" for fun (non measured, and not blind).

Moved the Fosi LC30 amp/speaker switch to my office. Same speakers (Sony SSC-S5), but two amps. The older Fosi V3 stereo vs the V3 monos.

The V3 stereo was louder at the same preamp level on the Wiim Ultra. The V3 stereo seemed to have a tiny bit more treble, but the subwoofer bass sounded better.

I changed the phase switch on the subwoofer and now the bass sounds better with the V3 monos, so I guess I did receive a set with the reversed phase. Expected as each only has one QC sticker.

It doesn't seem right to me for the V3 stereo to be louder than the V3 monos since they have more power on paper, but it is. Other than the slightly increased treble, I do not hear any difference in sound quality. I guess the V3 stereo was actually better than I thought it was.

I recommend the LC30 to anyone that wants to do a simple, quick comparison of amps or speakers or have two setups like my main system (stereo and atmos).

Had to compare the V3 monos vs the ZA3 with the LC30. Again the ZA3 is louder as previously determined. The subwoofer sounded wrong with the ZA3 as expected since I changed the phase for the monos. Switching the phase back corrected that for the ZA3.

Did a compare between the V3 stereo vs the ZA3. ZA3 slightly louder at same preamp level. Not as much difference vs the V3 monos. V3 stereo still seemed to have more treble. Both sounded great. Subwoofer phase needs to be the same for the ZA3 and the V3 stereo. Needs to be switched for the V3 monos.

Knowing what I do now, it doesn't seem like there is really any advantage in my two setups to having the V3 monos vs the ZA3 Stereo or maybe even the V3 stereo. All of them sound great.

I've also "tested" all of them driving my new Klipsch Heresy IV speakers. All sounded equally great as did the Loxjie A40 which seems to have the most power of any of them. Still noticed a slight treble boost with the V3 stereo vs all the others.

It is simple: the gain structure is different. The V3 monos need more voltage at the TRS/XLR input, the RCA/Cinch input might be somewhat adapted, because of that switchable gain (back plate): +21 db is fixed for TRS/XLR and +25db or +31db is for RCA/Cinch input. My impression: The V3 monos are much better sounding (SQ) all around...
But Your personal preferences naturally are determining the final outcome...

 

[imral3]

Email received from Fosi support, regarding V3's phase identification (not sure if already mentioned):

"Here I have enclosed a photo to show the placement of the QC and QR code labels on units where the phase is NOT inverted."

 

[Lux_ury]

Why don't you guys wait for a solution from Fosi, they said they would develop a better DC filter so hopefully one PSU one DC filter, problem solved?
I've got plan B which involves one PSU and two standard DC filters. Not tested it out, as I don't want to buy another filter for the sake of waiting for Fosi to supply me a new improved one, all for waiting an extra half of a month or so.
Either way the argument Fosi gave me was the one 48v 10amp brick is more efficient?
I just need to wait I see they have bundled fans for the heat sayers (LOL emoji) Quick sketch I know it's not tidy, but you hopefully get the idea? Not tested just an idea, don't come back say it doesn't work.

 

[EddNog]

Why don't you guys wait for a solution from Fosi, they said they would develop a better DC filter so hopefully one PSU one DC filter, problem solved?
I've got plan B which involves one PSU and two standard DC filters. Not tested it out, as I don't want to buy another filter for the sake of waiting for Fosi to supply me a new improved one, all for waiting an extra half of a month or so.
Either way the argument Fosi gave me was the one 48v 10amp brick is more efficient?
I just need to wait I see they have bundled fans for the heat sayers (LOL emoji) Quick sketch I know it's not tidy, but you hopefully get the idea? Not tested just an idea, don't come back say it doesn't work.

In case you need the spec, the cable connectors are DC 5.5mm external/2.5mm internal diameter.

-Ed

 

[totti1965]

Thank Amir so much for the measurement! The V3 Mono is another amplifier co-created with members, following the V3 stereo amp. We would particularly like to thank @Toku, @ModDIY , @mike70 , @cyclo, and all the other members who have provided us with invaluable suggestions.

The V3 Mono is our first amp with PFFB implementation. During the period we sent the set to Amir for testing, our R&D team did not stop optimizing the V3 Mono, and we have now further improved its frequency response curve. Below is the chart for your reference.
View attachment 360736


The V3 Mono is currently in production, and it will be launched on Kickstarter on the 20th of this month. There will be very attractive discounts available then, and we hope you'll stay tuned!

@amirm: I would like to ask you whether there will be a re-evaluation one day: Would you like to take another look at the Fosi V3 Mono in the current version, with the further improved linearity and the correct-phase cabling?

You did a re-evaluation with the Benchmark AHB-2 also - and I found it very interesting! Product consistency etc....

A propos consistency: It would be great if it were possible to "work through" a strict, numbered checklist in future amplifier tests. This would prevent certain interesting tests from being forgotten for one device or another and only running for certain devices. For example, it would be great if the 19 kHz/20 kHz intermodulation test was carried out for every device and, for comparability with stereophile, their special test was also always run (even if it is not that informative). It would also be great to always see the broadband up to, say, 200 kHz plotted, as well as the high frequency behavior up to 1 MHz for switching amplifiers - after all, you want to know where the switching frequency is, etc. A fixed checklist would help you not to forget anything.... I am not talking about the test of the Fosi V3 monoblocks here, but generally about some earlier tests.
As an example: You don´t run the stabilitiy "cube" test for each and every amp, but it would be nice to see it on a regular base.

I know, that this all would be extra work and at this time your tests for e. g. amps is by far the best that one can find at the whole internet.
Thank you so much for everything you have done for us music aficionados, even if you found my suggestions inappropriate!

Yours,

thorsten

 

[burkm]

Why don't you guys wait for a solution from Fosi, they said they would develop a better DC filter so hopefully one PSU one DC filter, problem solved?
I've got plan B which involves one PSU and two standard DC filters. Not tested it out, as I don't want to buy another filter for the sake of waiting for Fosi to supply me a new improved one, all for waiting an extra half of a month or so.
Either way the argument Fosi gave me was the one 48v 10amp brick is more efficient?
I just need to wait I see they have bundled fans for the heat sayers (LOL emoji) Quick sketch I know it's not tidy, but you hopefully get the idea? Not tested just an idea, don't come back say it doesn't work.

Are You sure they would supply a 2nd (improved) filter at no further cost ?
You might have to pay for it...

 

[mike70]

Honest question here as I see people very happy about the phono input...
First, I am not a vinyl guy, but why would you want digitize the beloved vinyl/analog output?

You don't have any loses in the process with a decent ADC ... and many things to win in the digital domain with DSP.

I use my vinyl with a MiniDSP Flex and I can't find any difference with the pure analog path.

In other aspect, let me say that I have many (many) records that sounds better than the CD digital version. CD is a better format, yes, and CAN sound better, yes, but ... the awful truth is in the mastering / recording. If the digital version is compressed to death ... that's no way better.

 

[totti1965]

You don't have any loses in the process with a decent ADC ... and many things to win in the digital domain with DSP.

I use my vinyl with a MiniDSP Flex and I can't find any difference with the pure analog path.

In other aspect, let me say that I have many (many) records that sounds better than the CD digital version. CD is a better format, yes, and CAN sound better, yes, but ... the awful truth is in the mastering / recording. If the digital version is compressed to death ... that's no way better.

You are right by 1.000.000%! Today there is often more compression in the CD Format - without any need!
And: Linn did a lot of research in digitize or don’t digitize the LP 12 analogue music signal.
They decided to digitize the signal in their most expensive chains years ago! It simply sounds better with 192 kHz 24 bit and a bit of equalizing.