Fosi Audio V3 Amplifier Review

[Kunti]

I bought a v3 with 32v power and ran it with an ns333. If I buy 48v. Will that fix the problem.?
I played the music I usually play for sound tests. The sound details are correct. But I lost a little bass that wasn't very visible. There is but it's not very clear. Is this the speaker or is there not enough power to move the speaker
?

 

[Djano]

I bought a v3 with 32v power and ran it with an ns333. If I buy 48v. Will that fix the problem.?
I played the music I usually play for sound tests. The sound details are correct. But I lost a little bass that wasn't very visible. There is but it's not very clear. Is this the speaker or is there not enough power to move the speaker
?

NS-333 = 87dB sensitivity
Pretty standard to me
There should not be any problem
At what volume do you listen ?

 

[SuperDerpBro]

Another update: They ended up doing the right thing after a few more emails.

 

[Kunti]

NS-333 = sensitivitas 87dB
Cukup standar bagi saya
Seharusnya tidak ada masalah
Pada volume berapa kamu mendengarkan?

Saya memutar YouTube/musik pasang surut. volume ponsel 80%. Dari amp di 40%, suaranya pas di telinga saya. Belum pernah mencobanya putaran penuh. Terkadang 80% amp. Menurut saya, suaranya sedikit berubah. Suara treblenya sedikit berkurang, hanya bass dan vokalnya saja yang terdengar bagus. Saya penasaran dengan 48v 5v

NS-333 = 87dB sensitivity
Pretty standard to me
There should not be any problem
At what volume do you listen ?

I play YouTube/tidal music. cellphone volume 80%. From the amp at 40%, the sound is just right for my ears. Never tried it full rotation. Sometimes 80% of the amp. The sound changes a bit in my opinion. The treble sound is slightly reduced, only the bass and vocals sound good. I'm curious about 48v 5v

 

[nishamn27]

Well given that this amp has a flat frequency response, low distorition, and can (probably) output more power than you are using when you detect this change AND can maintain that power at low frequency down to 20Hz - what else do you think is going on?

How are you level matching for the comparison? Or are you not comparing at all? Because what you are describing sounds like classic Fletcher Munson. If that is what it is, then it has nothing to do with the amp performance, and everything to do with chosen output level, and with how consequently your ears and brain work together to perceive the bass.

Changed the pot with a reverse log pot which I had remaining from a class A project. Solderd the power switch points togethr after removing the it(which is attached to the stock). To be Frank, a lot of the issue was solved with the simple change of pot.

And no, it is not due to higher gain with less rotation. Level matched it again with the aiyima and now the bass region sounds pretty same, also I found better high mid and treble , which lead to immediate impression of better soundstage.

I donot want to fight over this with the theory, but it definitely made a huge difference to atleast my perception.

 

[Djano]

Changed the pot with a reverse log pot which I had remaining from a class A project. Solderd the power switch points togethr after removing the it(which is attached to the stock). To be Frank, a lot of the issue was solved with the simple change of pot.

And no, it is not due to higher gain with less rotation. Level matched it again with the aiyima and now the bass region sounds pretty same, also I found better high mid and treble , which lead to immediate impression of better soundstage.

I donot want to fight over this with the theory, but it definitely made a huge difference to atleast my perception.

In my understanding, a pot is just an adjustable resistor. You shouldn't be able to change the sound "profile" only with this.

I play YouTube/tidal music. cellphone volume 80%. From the amp at 40%, the sound is just right for my ears. Never tried it full rotation. Sometimes 80% of the amp. The sound changes a bit in my opinion. The treble sound is slightly reduced, only the bass and vocals sound good. I'm curious about 48v 5v

You earlier said it was a bass problem.
Now it is treble. I do not understand what is the issue.

 

[antcollinet]

You should not see any problem at low volume. The issue I show likely only exists when the amp is pushed to its limit, as it is caused by clipping

we are having a subthread where people are complaining of missing bass at low frequencies.

 

[antcollinet]

And no, it is not due to higher gain with less rotation.

Really

The only thing you have changed is a resistive device. The only thing that is chaning is the knob position for the same level of attenuation (volume). It cannot change the frequency response at different levels.

If anything this test confirms that what you are experiencing *is* Fletcher Munson.

 

[Djano]

we are having a subthread where people are complaining of missing bass at low frequencies.

I think you are talking about this thread I opened yesterday
The problem seems now to be well enough explained.

It has to do with:
- Low impedance of the speaker the test was conducted with in the problematic area
- Harder difficulty Fosi has to drive bass than treble
- Need for more W per dB in lower frequencies

It seems that the problem kicks in when the Fosi clips at lower frequencies
S.A. had to push the V3 to its limits to show the problem (100dB). This is not a concern at normal volume levels. Only 6% of ASR members listen to more than 90dB (poll i refered to earlier)

 

[antcollinet]

I think you are talking about this thread I opened yesterday
The problem seems now to be well enough explained.

It has to do with:
- Low impedance of the speaker the test was conducted with in the problematic area
- Harder difficulty Fosi has to drive bass than treble
- Need for more W per dB in lower frequencies

It seems that the problem kicks in when the Fosi clips at lower frequencies
S.A. had to push the V3 to its limits to show the problem (100dB). This is not a concern at normal volume levels. Only 6% of ASR members listen to more than 90dB (poll i refered to earlier)

No, I'm referring to this post from Wednesday in this thread:

https://audiosciencereview.com/foru...-audio-v3-amplifier-review.45757/post-1715161


The post you replied to was a follow on from the subthread here that resulted. Fair enough - it is difficult to follow subthreads if you've not been there from the start.

 

[Juampa1989]

Good afternoon colleagues, let me tell you that today the fosi v3 arrived to replace the tb10d, the voices are heard clearer and the bass is more forceful, it is paired with a klipsch rp-160m and a 32v source, with a dac d03k taishan, I ordered the smsl c100 to be able to control the volume. Very happy with the purchase, thanks to amirm for his recommendation and thanks to you for taking the time to provide your opinions and answer the questions of others.

 

[Djano]

No, I'm referring to this post from Wednesday in this thread:

https://audiosciencereview.com/foru...-audio-v3-amplifier-review.45757/post-1715161

The person specifies that it happends at low volume. So yes, my clipping think doesn't work here.
It could be a loudness thing, but he would feel the same with his A07, which is not the case...

Amir's graphs do not show irregular frequency response in bass region. But I do not know what power was used to test this

 

[Juampa1989]

 

[nishamn27]

Really

The only thing you have changed is a resistive device. The only thing that is chaning is the knob position for the same level of attenuation (volume). It cannot change the frequency response at different levels.

If anything this test confirms that what you are experiencing *is* Fletcher Munson.

Maybe true. Also the better staging maybe a result of a better channel balance (uniform resistance on both channels at a given point) with the new pot.

 

[Mordor]

Well maybe is a false "impression"....also the Debut 6.2 are new for me.....
My "ideal" position power is about 11h:30 position sort of.....if needed i reduce on the DAC

 

[-Jim-]

Another update: They ended up doing the right thing after a few more emails.

Glad to hear it. Are they going to exchange it for a new V3? Or just repair it and send it back?

 

[burkm]

Well given that this amp has a flat frequency response, low distorition, and can (probably) output more power than you are using when you detect this change AND can maintain that power at low frequency down to 20Hz - what else do you think is going on?

How are you level matching for the comparison? Or are you not comparing at all? Because what you are describing sounds like classic Fletcher Munson. If that is what it is, then it has nothing to do with the amp performance, and everything to do with chosen output level, and with how consequently your ears and brain work together to perceive the bass.

Fosi tested the V3 already because of this, if there is a change in frequency response at different volume settings. The result: the frequency response is independend of the used volume, it stays the same at all levels measured. But frequency response of the humen hearing is volume dependend. Thats the reason, why Fletcher-Munson and their current follow ups provided a table of response curves for this (now about 90 years ago, which hat been improved in detail by newer measurements in the meantime). The German ISO organisation had standardized them already (latest incarnation ISO norm 226:2003).
But this is only a generalized and averaged view of what is statistically happening, because indivuals may deveate somewhat from the mean (gauss curve).

Did you measure the frequency response curves of your item yourself to prove your point ?

PS.: I actually responded to the wrong post for whatever reason. Sorry about that...

 

[sylvain.f]

Hello, I apologize for my poor English; I am French. I recently bought a Fosi V3 amplifier with a 36V power supply from Amazon, and I was happy with it. However, I saw that I could get the same thing with a 48V power supply for the same price directly on the Fosi Audio website. So, I returned the Amazon version and purchased the amplifier from Fosi Audio. That's when the problems started: the amplifier causes power outages either when I plug it in or during playback. It even damaged my Mi Box in the process. I am currently in communication with Fosi Audio's customer service and have provided them with videos. I tested the voltage at the power supply's output, and it indeed shows 48V. If I only connect the power supply, I don't experience any outages. Although I'm not sure if that can rule out an issue with it, since I also sometimes have outages during playback. Have others experienced problems with this amplifier? Have others had experiences with Fosi Audio's customer service? Thank you.

 

[sylvain.f]

Automatic Translation...

Is it better now?

 

[antcollinet]

Fosi tested the V3 already because of this, if there is a change in frequency response at different volume settings. The result: the frequency response is independend of the used volume, it stays the same at all levels measured. But frequency response of the humen hearing is volume dependend. Thats the reason, why Fletcher-Munson and their current follow ups provided a table of response curves for this (now about 90 years ago, which hat been improved in detail by newer measurements in the meantime). The German ISO organisation had standardized them already (latest incarnation ISO norm 226:2003).
But this is only a generalized and averaged view of what is statistically happening, because indivuals may deveate somewhat from the mean (gauss curve).

Did you measure the frequency response curves of your item yourself to prove your point ?

It's not my item, and I've been stating in multiple posts that Fletcher Munson is (most likely) at play.