Fosi Audio V3 Mono Amplifier Review

[tmtomh]

Erin talks a bit more about the fosi's in his latest review on the A07Max.

Where he is coming from is that he simply isn't hearing differences with or without PFFB.
I wonder what the ohms are of the speakers he is using are. I have 8ohm speakers so I will be curious to compare the fosi's with my other 3255 ... but I'll pop that on the user thread here in a few weeks time... https://www.audiosciencereview.com/...v3-mono-user-impressions-owners-thread.54043/

I hope I do hear after all the hype! ... but at least I suppose the reviewer Erin is deflating the hype.

If I were in the market for one of these amps, I would definitely want the load-invariant ones with PFFB. But that said, we're typically talking about frequency response deviations from flat of less than 1dB, and below 15kHz in most cases the deviation less than 0.75dB and often less than 0.5dB. That can be very difficult to detect.

In most cases you're more likely to notice that your speakers' bass response changes slightly depending on temperature and humidity.

 

[Zek]

In most cases you're more likely to notice that your speakers' bass response changes slightly depending on temperature and humidity.

In most cases, the human ear system changes with changes in pressure, temperature and humidity.

 

[drmevo]

Erin talks a bit more about the fosi's in his latest review on the A07Max.

Where he is coming from is that he simply isn't hearing differences with or without PFFB.
I wonder what the ohms are of the speakers he is using are. I have 8ohm speakers so I will be curious to compare the fosi's with my other 3255 ... but I'll pop that on the user thread here in a few weeks time... https://www.audiosciencereview.com/...v3-mono-user-impressions-owners-thread.54043/

I hope I do hear after all the hype! ... but at least I suppose the reviewer Erin is deflating the hype.

I just bought the A07 Max because I needed a power amp until the V3 monos ship. I’m super-impressed - it sounds fantastic and has plenty of power for me. If the V3M is the same with the added benefit of PFFB (even if it’s mostly imperceptible, nice to know it’s there) I’ll be really happy. I could certainly see keeping the A07 but I want the auto on/off that the V3Ms offer since I often power the system on with my preamp remote.

 

[Great Sun Jester]

In most cases, the human ear system changes with changes in pressure, temperature and humidity.

You forgot the yelling grandkids

 

[Joe Smith]

I like that Erin review...a pretty fair assessment of the A07 MAX. I frankly doubt that most people are going to hear a discernable difference with the new PFFB-implemented amps.

 

[MCH]

it is great that the aiyima a07 max exists. Functionality is good, looks are good, i like the volume knob as Erin does + it allows you to switch it on with a smart plug, no pops on turn on/off and i have not read yet any reports of early death. And all this for a little more than 40 euros shipped when on sale or 60 eur with 48V PSU. I have seen it for 39 euros shipped! I have two of them that are perfect for my use case.
That said, looking under the hood, the component selection is very questionable, no PFFB, and no trigger/sense. I don't think it is comparable to the fosi as monoblock, where the vol control doesn't matter. But it is true that the fosi is much more expensive... so it is good that both options exist. Now, at the same price, i would not have any doubts, fosi any day.

 

[tmtomh]

In most cases, the human ear system changes with changes in pressure, temperature and humidity.

Good point! Are you specifically claiming that the human hearing system changes in a corresponding way to speakers so that we don't notice the difference? Or are you just generally pointing out that our hearing apparatus changes with climate conditions?

 

[Negatywny]

I like that Erin review...a pretty fair assessment of the A07 MAX.

I like how he is totally unimpressed by the existence of 70$ transparent 250W amplifiers you can move with your dong
Like, super extra unimpressed.

Oh look at this useless piece of absolutely transparent 250W shit, idk, if you have 70$ to loose, but personally i didn't want it for free.
Oh also in the specs they said it could go to 300W, but it goes only 250W, (or you need a bigger psu i don't give a shit), so that's a robbery and i can't endorse that.

WTF dude?

Seriously, if not amirm, watching erins reviews i would think that fosi and aiyima are only trying to scam and hurt me.

 

[redstang]

I like how he is totally unimpressed by the existence of 70$ transparent 250W amplifiers you can move with your dong
Like, super extra unimpressed.

Oh look at this useless piece of absolutely transparent 250W shit, idk, if you have 70$ to loose, but personally i didn't want it for free.
Oh also in the specs they said it could go to 300W, but it goes only 250W, (or you need a bigger psu i don't give a shit), so that's a robbery and i can't endorse that.

WTF dude?

Seriously, if not amirm, watching erins reviews i would think that fosi and aiyima are only trying to scam and hurt me.

I like the measurements he's been doing, and has basically said he can't hear a difference between these amps when ABX'ing them which is an interesting anecdote, but his lack of interest in them is pretty lame. Transparent high power amps in small packages at low prices is pretty damn cool. I want to see more people putting these up against expensive fat amps and doing some ABX. I mean, I just noticed Marantz's $9000 PM-10. I'd like to know if you can tell a $8700+ difference between that and some of these amps in a blind ABX.

 

[Zek]

Or are you just generally pointing out that our hearing apparatus changes with climate conditions?

Our hearing apparatus changes with everything, even during the same day it reacts differently in the morning or in the evening, this affects the way we hear how the speakers sound.

 

[SMen]

I like the measurements he's been doing, and has basically said he can't hear a difference between these amps when ABX'ing them which is an interesting anecdote, but his lack of interest in them is pretty lame. Transparent high power amps in small packages at low prices is pretty damn cool. I want to see more people putting these up against expensive fat amps and doing some ABX. I mean, I just noticed Marantz's $9000 PM-10. I'd like to know if you can tell a $8700+ difference between that and some of these amps in a blind ABX.

Yes - ABX with his other, I am presuming, much more expensive amps.

 

[DTTOM37]

Hi all, is there - after almost 80 pages - any consideration which of the power supply available
within the Kickstarter project offers the best longevity for the amp chip ?

Context: I am considering to drive 2x 15" bass drivers (15OB350 from SB Acoustics / 4 Ohms per channel
- spec sheet say 98dB sensitivity per driver, but I would think rather think 93-956dB, which seems still high)
with them. x-over is at 250hz, thus they seem to be ideal for that task.

Just being afraid that the 48v/10A powe supply would leave me with a risk of overheating. OTOH, I dont play them in the local stadium, but in a 16sqm environment to usually 80-85 dBa.
Any suggestions / considerations ?
Thanx in advance

 

[Sokel]

Hi all, is there - after almost 80 pages - any consideration which of the power supply available
within the Kickstarter project offers the best longevity for the amp chip ?

Context: I am considering to drive 2x 15" bass drivers (15OB350 from SB Acoustics / 4 Ohms per channel
- spec sheet say 98dB sensitivity per driver, but I would think rather think 93-956dB, which seems still high)
with them. x-over is at 250hz, thus they seem to be ideal for that task.

Just being afraid that the 48v/10A powe supply would leave me with a risk of overheating. OTOH, I dont play them in the local stadium, but in a 16sqm environment to usually 80-85 dBa.
Any suggestions / considerations ?
Thanx in advance

I'm sure most of you had a look at the TPA3255's data sheet but just in case I'll repost this:

(link)

That's with burst signals (so closer to music) and with controlled heatshink temp at 75° C (so close to ideal and far but far from limited cooling conditions as with the small case amp here).

My humble opinion is to run these with lower voltage to be safe and have peace of mind,somewhere in the 35-40V region and no more.
Unpopular opinion,I know but I have learn to respect limits and a little extra that this.

(note that the above charts shows power at 10% THD which is ridiculous,no one will push the amp to such a limit,even if the chip allowed to do so)

 

[Lednek]

Hi all, is there - after almost 80 pages - any consideration which of the power supply available
within the Kickstarter project offers the best longevity for the amp chip ?

Context: I am considering to drive 2x 15" bass drivers (15OB350 from SB Acoustics / 4 Ohms per channel
- spec sheet say 98dB sensitivity per driver, but I would think rather think 93-956dB, which seems still high)
with them. x-over is at 250hz, thus they seem to be ideal for that task.

Just being afraid that the 48v/10A powe supply would leave me with a risk of overheating. OTOH, I dont play them in the local stadium, but in a 16sqm environment to usually 80-85 dBa.
Any suggestions / considerations ?
Thanx in advance

I would think a lower voltage(36V) power supply would be easiest on the chip? But you would loose considerable output unless you were driving low impedance speakers. The higher current powered supply might get you some longevity from the powered supply itself, but wouldn't effect the amp chip. It will only pull what it needs. You could hook that up to a 48v 100A power supply and be fine. Likewise, driving low impedance speakers would be harder on the amp chip because it's pulling more current.
TLDR. both higher voltage and amperage will tax the chip. Only the effect of the voltage is controllable via the power supply providing its not starving the amp of current.

 

[tmtomh]

Our hearing apparatus changes with everything, even during the same day it reacts differently in the morning or in the evening, this affects the way we hear how the speakers sound.

Indeed it does.

 

[Bruce Morgen]

I would think a lower voltage(36V) power supply would be easiest on the chip? But you would loose considerable output unless you were driving low impedance speakers. The higher current powered supply might get you some longevity from the powered supply itself, but wouldn't effect the amp chip. It will only pull what it needs. You could hook that up to a 48v 100A power supply and be fine. Likewise, driving low impedance speakers would be harder on the amp chip because it's pulling more current.
TLDR. both higher voltage and amperage will tax the chip. Only the effect of the voltage is controllable via the power supply providing its not starving the amp of current.

For the umpteenth time, I hereby testify that my two four year old A07s are still performing flawlessly after spending most of those years powered up 24/7 on 48VDC, despite their obviously deficient thermal design and 50V-rated Nichicon filter caps. Real world music listening is a far cry from rigorous bench testing with steady input from a signal generator, and in my particular use case (or others like it) even less-than-optimal little "chip amps" like my now-elderly A07s are likely to thrive long-term.

 

[Lednek]

I don't see it as a problem either. Just trying to answer the question, if for no other reason than theoretical accuracy. I'll be running mine on 48v for sure.

 

[Bruce Morgen]

I don't see it as a problem either. Just trying to answer the question, if for no other reason than theoretical accuracy. I'll be running mine on 48v for sure.

Fair enough -- thanks!

 

[Fosi Audio]

@Fosi Audio 's silence these days and the new measurements have convinced me to change reward from single 48V 10(?)a to double 48v 5a

Sorry, May 1st to 5th are holidays here, so we were unable to respond promptly to your inquiries. Our R&D colleague on duty today sent the test result for the 48V/10A power supply, indicating that it can operate stably at 10A.

Additionally, our supplier Huntkey will provide us with the relevant test report for this power supply after they resume work tomorrow, and we will post update then.

 

[Talisman]

Sorry, May 1st to 5th are holidays here, so we were unable to respond promptly to your inquiries. Our R&D colleague on duty today sent the test result for the 48V/10A power supply, indicating that it can operate stably at 10A.

Additionally, our supplier Huntkey will provide us with the relevant test report for this power supply after they resume work tomorrow, and we will post update then.

View attachment 367686

Thank you for your response and reassurances, always efficient and punctual.
At the moment, for my personal peace of mind, I prefer to maintain the dual power supply configuration, but I really appreciate your availability