Fosi Audio V3 Amplifier Review

[sarumbear]

I did say atmos so 4 speakers in my case, I didn't mention bed layer

Atmos is a superset of surround with the edition of height speakers. The 7 surround, 2 heights and the LFE channels are called the bed layer. On top of that you have the objects that can be positioned within the 2pi sphere.

Atmos playback requires each bed channel at minimum to have its own speaker. Otherwise, sounds on bed channels are created with phantom method, like the phantom centre speaker. If your setup doesn’t have side or rear speakers it is not possible to create phantoms of them. Anything less than 5.1.2 is a limited solution. Even that is only acceptable if your listening environment is 1pi, i.e. you sit with your back to the back wall.

I hope I was clear.

 

[GabrielPhoto]

Atmos is a superset of surround with the edition of height speakers. The 7 surround, 2 heights and the LFE channels are called the bed layer. On top of that you have the objects that can be positioned within the 2pi sphere.

Atmos playback requires each bed channel at minimum to have its own speaker. Otherwise, sounds on bed channels are created with phantom method, like the phantom centre speaker. If your setup doesn’t have side or rear speakers it is not possible to create phantoms of them. That is why anything less than 5.1.2 is a limited solution that is only acceptable if your listening environment is 1pi, I.e. you sit with your back to the wall.

I hope I was clear.

You REALLY like to "hear" yourself talk, dont you? You know VERY well that by ATMOS we always refer to the top speakers but I guess you love to be pedantic (Ted Mosby much?) for ZERO reason.
I sure hope your other 7280 posts are more useful.
But yes, you were very clear...you gave me a clear reason to add you to my ignored list.
Regards

 

[DavidMcRoy]

I received one with a 48VDC power supply the other day. So far it’s great in my highly specific application, dedicated to driving a pair of planar magnetic mid-tweeters from 2-6kHz in a DIY active 5-way system (including subs in the count.) I’ll try to put it on a conventional passive speaker. Maybe something tricky like my c. 1991 Acoustat Spectra 1100s. (Where did I put that hand truck?)

EDIT: forgot to mention the silky-smooth volume control. I imagine it must be very unusual in this class, for those who care. Most of them feel like there’s sand in them.

 

[grogi.giant]

So, you are adjusting the "volume range" from your preamp or source, not the volume knob on the amp.


ADD off topic: I'm confused about the attention paid here to the Impedance dependence graph. It looks nasty because the steps are small, but can anyone really hear a +/- .5dB variance above 10K? Perhap we just feel better about our gear when we see straight lines?

There are speakers that have high frequency impedance much higher than 8Ohm... The setup is very bright then...

Below graph for the Elacs... Impedance doesn't get below 10 Ohm from 1kHz...

 

[ObjectAudio]

To all comparing the Fosi V3 to the Aiyima A07 , please pay attention to the max gain difference between them.
The Fosi V3 max gain is 20 and the A07 max gain is 40. This fact can explain the few dB advantage that the Fosi V3 has on the A07 with the THD+N results.
No other magic.

​

 

[MCH]

To all comparing the Fosi V3 to the Aiyima A07 , please pay attention to the max gain difference between them.
The Fosi V3 max gain is 20 and the A07 max gain is 40. This fact can explain the few dB advantage that the Fosi V3 has on the A07 with the THD+N results.
No other magic.

​

?

 

[vbutani]

Hi folks.

I'm using an Aiyima A07, with the stock 32v PSU.

Just bought the Fosi V3, without the PSU, to use the one I already have on the Aiyima.

I listen in near field, low volume level, so I don't need too much power.

Could I get a better sound quality with another PSU or would be the same as the Aiyima 32v I already have?

Thanks!

I have two 32v power supply from Aiyima and Fosi, I tried both on Fosi V3 and Fosi PSU sounds more clean to me.

 

[ObjectAudio]

?
View attachment 297461

I meant ratio not in dB. So in dB it will be 26dB for the Fosi V3 and 32dB for the A07.
Amir measured around 26dB for the Fosi V3 and 29dB for the A07.I have few A07, and they all measured gain are 32dB.
Still there are few dB gain difference between them that can explain the few dB THD+N difference.
By the way all my A07 measured THD+N are better than the one Amir measured. They all come aground 87dB.
As I see it the biggest Fosi V3 advantage on the A07 is the heat dissipation capability.

 

[grogi.giant]

I have two 32v power supply from Aiyima and Fosi, I tried both on Fosi V3 and Fosi PSU sounds more clean to me.

Oh c'mon...

 

[Lux_ury]

You guys should get a buddy to switch out power supplies blind see which ones you likes, do it a few times and average it out.
I don't have expensive equipment so I do it old skool.
I definitely see hear a difference in outboard PSU not just reliying on logic that I expect the higher the volts the more distortions to come through if AC mains is noisy to begin with.
I would love to buy a load of linear supply's and dedicated PSUs, but they cost more than my AMP itself!

 

[GGroch]

......By the way all my A07 measured THD+N are better than the one Amir measured. They all come aground 87dB.
As I see it the biggest Fosi V3 advantage on the A07 is the heat dissipation capability.

I had not considered how Gain and THD=N are related. After Googling, I see gain is a factor but I am still confused as to why.

Amir measures THD+N at 5w. Intuitively that specification would not change regardless of what gain the amp employs internally to reach that 5w. How does this work?

I agree that the THD+N measurements on the Aiyima A07 Pro and V3 would be indistinguishable in use. I would argue that heat dissipation difference would matter primarily on a test bench, a tiny minority of owners will tax the dynamic output of either one.

More likely the A07 Pro's channel imbalance and lack of center detent tone controls could be audible in blind tests.

But 98% of owners do not do blind tests. The audiophile friendly design choices Fosi made in the V3 will assure that it produces more endorphins than similarly priced competitors in ASR readers.

 

[vbutani]

Oh c'mon...

Sorry, I didn't get it.

 

[Jeromeof]

Sorry, I didn't get it.

One power supply seemingly cleaner than another seems very subjective

 

[ObjectAudio]

I had not considered how Gain and THD=N are related. After Googling, I see gain is a factor but I am still confused as to why.

Amir measures THD+N at 5w. Intuitively that specification would not change regardless of what gain the amp employs internally to reach that 5w. How does this work?

I agree that the THD+N measurements on the Aiyima A07 Pro and V3 would be indistinguishable in use. I would argue that heat dissipation difference would matter primarily on a test bench, a tiny minority of owners will tax the dynamic output of either one.

More likely the A07 Pro's channel imbalance and lack of center detent tone controls could be audible in blind tests.

But 98% of owners do not do blind tests. The audiophile friendly design choices Fosi made in the V3 will assure that it produces more endorphins than similarly priced competitors in ASR readers.

The gain of these amplifiers are defined by combing the gain from the input op-amp gain and the TPA3255 chip gain. In both amplifiers the TPA3255 gain will be the same.
The difference in the gain between them will be the resistors ratio on the input op-amp. for the A07 the ratio is 20K/10K that will multiply the input signal.
For the Fosi V3 it looks like the ratio is one. So the gain is set no matter what is the volume control position. The volume control is only playing as signal attenuator before the op-amp stage.
The gain is also amplifying the noise. So higher gain higher noise. but to get the same power output the volume control on the A07 is set lower than the volume control on the Fosi.So the actual input signal to the op-amp is half for the A07 compare to the Fosi , reducing the actual signal to noise ratio.
I hope my explanation is clear enough.

 

[ClassicGuy]

I meant ratio not in dB. So in dB it will be 26dB for the Fosi V3 and 32dB for the A07.
Amir measured around 26dB for the Fosi V3 and 29dB for the A07.I have few A07, and they all measured gain are 32dB.
Still there are few dB gain difference between them that can explain the few dB THD+N difference.
By the way all my A07 measured THD+N are better than the one Amir measured. They all come aground 87dB.
As I see it the biggest Fosi V3 advantage on the A07 is the heat dissipation capability.

I'd rather have the slightly lower gain to achieve higher THD+N. Also, I don't think you can achieve the SINAD difference between Aiyima A7 (83) and Fosi V3 (88) by simply lowering the gain.

 

[Lux_ury]

But 98% of owners do not do blind tests. The audiophile friendly design choices Fosi made in the V3 will assure that it produces more endorphins than similarly priced competitors in ASR readers.

I thought that was a pre-requisite or disclaimer!
Sometimes I help out, even if it's a hammer in a glass shop.
That sounds fun in itself!
One thing I'm only buying outboard power units from Aiyima or Fosi, as I would hope they had done the quality control in the first place (Rub chin Emoji)

 

[ObjectAudio]

I'd rather have the slightly lower gain to achieve higher THD+N. Also, I don't think you can achieve the SINAD difference between Aiyima A7 (83) and Fosi V3 (88) by simply lowering the gain.

I think it actually feasible if you want to mod the A07 by replacing the 20K feedback resistor on the A07 input op-amp to 10K.
See my explanation above.

 

[Lux_ury]

I've dug out this old beast of a active sub.
I don't use subs, but own a couple of logitech z906. So this sub has added the extra lower frequency to the B&Ws and sounds good. Looks like it's got a Active D amp already? SA-W2500 Sony.
Questions:
I've set it up via two pole 3.5mm to two rca then female rca to coaxial to sub.
It's the only cables I own to do this.
This sub is not mine it's my fathers.
is this the cable mgm OK or is there something like coaxial to stereo 3.5mm?
Would there be an audio difference? How would you set up the sub as there are volume and frequency dials which I've had to set low cut off where my ears say ok. But I can hear other Frequencies without any amp volume on?

 

[Doodski]

I've set it up via two pole 3.5mm

What are you using that has two pole RCA?

is there something like coaxial to stereo 3.5mm?

That requires mixing/summing the left and right channels into a mono form for the sub. Hence I asked the previous question.

How would you set up the sub as there are volume and frequency dials which I've had to set low cut off where my ears say ok.

Usually around 85 Hz to 120 Hz for a cutoff is a nice lean bass that is not bloated or too fat and boomy. I tend to lean towards that 85 Hz but it is room and sub dependent.

 

[vbutani]

One power supply seemingly cleaner than another seems very subjective

Right, I forgot to mention it was my subjective experience. There is no day and night difference, but slight improvement observed in vocals. Btw, it was my first post on ASR, will keep it in mind. Thanks.