Fosi Audio V3 Mono Amplifier Review

[SMen]

Hi,
What are the opamps for? Is this only for creating a balanced signal for the amp chip from rca input and the single ended gain settings or does this also affect the xlr input signal. If so, what is the purpose? An additional buffer?

BR, Moritz

I am not an expert ... but one of you experts out there might like to answer this so + 1 for this question ... The op amps are dual, in a dual mono design (assuming you buy two) ...

 

[surroundman]

It also makes the audiophonics 3e (stereo) implementation look expensive 499 euro...

To some of us it was expensive since the very moment it was released, quite some time before the V3 mono was a thing.

 

[TheHighContemplator]

Superb!

 

[SMen]

The input OPAmp handles balanced <-> single-ended choice

The other two OPAmps:
- one is the pre-amp/buffer for TI IC
- the second one caters for PFFB implementation

Looks like you did @Extreme_Boky ! At the same time as I was asking. Can you expand on this?

I think ... but please correct, that the pre-amp buffer for the TI IC is the one someone might want to swap in when operating with balanced inputs? Leaving the other two alone.

Wondering about how you might improve the PFFB implementation with another op amp? Big difference surely between a buffer swap vs for feedback ...

experts please chip in! Good night all from France! zzz

 

[MvZ]

The input OPAmp handles balanced <-> single-ended choice

The other two OPAmps:
- one is the pre-amp/buffer for TI IC
- the second one caters for PFFB implementation

Thanks,

So does this mean that a balanced (xlr) signal is first converted to single ended then again made balanced (as far as I remember the TI chip uses a balanced input). Seems a little awkward to me. Is this only done for the sake of an easy buffer solution ?

 

[SMen]

To some of us it was expensive since the very moment it was released, quite some time before the V3 mono was a thing.

I agree, but this fosi release might shake the market up here a bit too.

 

[SMen]

Thanks,

So does this mean that a balanced (xlr) signal is first converted to single ended then again made balanced (as far as I remember the TI chip uses a balanced input). Seems a little awkward to me. Is this only done for the sake of an easy buffer solution ?

An answer needed in detail on this please. +1

 

[Golf]

Of course ... At this time, things like the expectable longevity of the finally produced devices, or even less a maybe inhumane working conditions footprint combined to manufacturing them can not be measured at all. But this doesn’t mean they are meaningless.

 

[Extreme_Boky]

Looks like you did @Extreme_Boky ! At the same time as I was asking. Can you expand on this?

I think ... but please correct, that the pre-amp buffer for the TI IC is the one someone might want to swap in when operating with balanced inputs? Leaving the other two alone.

Wondering about how you might improve the PFFB implementation with another op amp? Big difference surely between a buffer swap vs for feedback ...

experts please chip in! Good night all from France! zzz

Thanks,

So does this mean that a balanced (xlr) signal is first converted to single ended then again made balanced (as far as I remember the TI chip uses a balanced input). Seems a little awkward to me. Is this only done for the sake of an easy buffer solution ?

I'd need to check the PCB to be able to answer these questions with 100% accuracy. There are also 3 relays... so Fosi may be using 2 of them as well, to implement gain control and to create the same balanced level signal drive to TI, irrespective of which input is used (RCA / XLR).

 

[Kachda]

I bought a 3e stereo amp board for 134 dollars shipped. Its 6 amp 48 volt power supply was another $40.00. For $174.00 I got 99% of what two of these give me (Not to mention that the 3e has 2 db better SINAD) . If you want to spend $106.00 more to get a bit less than be my guest.

And how about the case and time to assemble it? And nothing to speak of the amount of time it took you to become an expert enough to be able to do that?

If you expect companies to sell at marginal cost, no company would ever launch a commercial product

 

[MvZ]

I'd need to check the PCB to be able to answer these questions with 100% accuracy. There are also 3 relays... so Fosi may be using 2 of them as well, to implement gain control and to create the same balanced level signal drive to TI, irrespective of which input is used (RCA / XLR).

Great… Looking forward to your reply / analysis… would love to understand the circuitry respectively the function of each opamp (have made some great experiences with the use of sparkos labs discrete opamps in the past on other devices).

Greetings from germany

 

[Jhify]

The thing is that IMD can be heard further down in the frequency response. This is one of the reasons why 192khz samples rates is a bad idea.


I've been wondering about this exact thing, how hard and expensive it would be to implement. Hopefully maybe those cheap chinese diy TPA3255 board will start implement them sooner or later, letting us diy:ers building really good and really cheap amps ^^

From what Ive read hearing threshold for IMD is about -70db and this amp has a very large headroom in that regard in the frequency range that matters. It’ll be transparent for 99,999..% of us and the rest will probably hear the issues of their room and speakers first. Let’s be glad we can get transparency as good as it gets for that little money it wasn’t the case 10 years ago.

 

[Golf]

If you expect companies to sell at marginal cost, no company would ever launch a commercial product

I, for one, expect companies to make as much profit as they possibly can ...

Only question with this: Should I go to support them?

 

[Bruce Morgen]

At this time, things like the expectable longevity of the finally produced devices

Not all that much a factor when the product is so inexpensive to replace.

 

[amper42]

Any idea what the longevity of the Fosi Audio V3 Mono amp should be compared to Hypex or Purifi amps? I have always stayed away from external power supplies in the past as they typically have been the weakest link in my experience.

 

[Golf]

Not all that much a factor when the product is so inexpensive to replace.

After 12 months? After 6 months, 4, 2? And how about all that hustle and bustle in order to initiate any replacement?

 

[Jhify]

That kind of spectrum is not going to happen in music. That is the reason I didn't run that test for the longest time. I am running it now only to make it easier to compare to Stereophile tests.

Couldn’t agree more as an amateur musician and producer real world music has little energy in the upper spectrum. I don’t think it could ever be an issue.

 

[SoundsGood2Me]

Has anyone reviewed the TI datasheet for the actual amplifier?
THEY CLAIM IT'S GOOD FOR 600W x 1!!!

TPA3255 data sheet, product information and support | TI.com

TI’s TPA3255 is a 315-W stereo, 600-W mono, 18- to 53.5-V supply, analog input Class-D audio amplifier. Find parameters, ordering and quality information

www.ti.com

 

[Bruce Morgen]

After 12 months? After 6 months, 4, 2? And how about all that hustle and bustle in order to initiate any replacement?

These things are cheap enough that most of us can afford a spare or two. That's why I own four Aiyima A07s -- I bought the two spares after reading of potential thermal management issues with that product, but the first pair are doing just fine after (nearly four!) years in my system, which is more often than not powered up 24/7.

 

[Extreme_Boky]

I think the case and the heat transfer solution are worth $50... plus, the connectors' quality is now better. People are so quick to judge with their eyes closed, from the comfort of their favourite recliner.

They probably have never attempted to DIY such a case, not to mention to implement tight tolerances to get the heat transfer to work as well as Fosi has done while making the overall deign fairly pleasing and easy on the eye.