Fosi Audio P4 Preamplifier Review

[Carl-Fosi Audio]

This is a remotely operated, standard motorized potentiometer. You understand this, correct?
The operation really can't be improved upon, significantly.

Also, I don't think Carl-Fosi is really a member of their team. I think maybe this is an AI bot.

I am a real person from Fosi Audio, and any suggestions or ideas please let me know.

 

[olds1959special]

Thank you for your feedback, we will try to improve it.

I realize that it’s also because my power amps are more powerful and so it means I use less of the range of the knob. My average listening volume was at 9 o clock.

 

[Davey]

I am a real person from Fosi Audio, and any suggestions or ideas please let me know.

I suggest to not post any misinformation as you did in Post #290.

 

[Madesu]

Hi, I am wondering if there is any scientific approach to determine/measure soundstage of a device? Is this even a thing that is possible for different electronics to influence the soundstage?
I am asking because I have watched/read some reviews of this device and the one thing some reviewers mentioned was that the soundstage gets slightly reduced by the P4.

 

[mike70]

Hi, I am wondering if there is any scientific approach to determine/measure soundstage of a device? Is this even a thing that is possible for different electronics to influence the soundstage?
I am asking because I have watched/read some reviews of this device and the one thing some reviewers mentioned was that the soundstage gets slightly reduced by the P4.

soundstage is an acoustic effect created by the speaker / room interaction. The End.

if you want the long answer, well, i can add a little more, but you also can read the miriad of scientific information available.
soundstage is a brain interpretation based on the differences between phase, volume, direction, etc in the acoustic information (vibrations over the air).
in the music production, engineers use that "instruments" to create different soundstage effects, but they are totally electrical efects in the signal that needs to be exactly reproduced by your speakers / room, something that not always happens. I mean, if you sit on one side of the speakers, at 1 feet ... you won´t have any soundstage at all, even with the recorded "tricks" in the music. Room acoustics is the first evil ... and in second position, speaker quality (distortion, high energy difraction, etc)

Regarding the preamp, as you can see, if it's transparent to the signal ... how the preamp can affect the soundstage? Think by yourself ... you have the answer.

 

[Madesu]

Thanks @mike70
I guess I am just questioning how so many people say that something like the soundstage could be affected. In case of the reviewers I could think that it is to "justify" recommending the ZP3. "If you want a bigger soundstage, you should upgrade to the ZP3". Probably it is all nonsense.
In my case I want to use it in my headphone setup to connect three sources to my headphone amp without always having to switch cables. I ordered one for 67€ new from Amazon with discount code that worked while it was already on an offer price.

 

[mike70]

Thanks @mike70
I guess I am just questioning how so many people say that something like the soundstage could be affected. In case of the reviewers I could think that it is to "justify" recommending the ZP3. "If you want a bigger soundstage, you should upgrade to the ZP3". Probably it is all nonsense.
In my case I want to use it in my headphone setup to connect three sources to my headphone amp without always having to switch cables. I ordered one for 67€ new from Amazon with discount code that worked while it was already on an offer price.

Even the Bible says that narrow is the path of those who have the truth

 

[Smithg97]

If I wanted to use this unit purely as a remote controlled RCA switch for 2 subwoofers for 3 different amps/AVRs would this work and still allow me to EQ each sub independently for each of the 3 different sources?

 

[gino1961]

soundstage is an acoustic effect created by the speaker / room interaction. The End. ...

Hi i wonder if speakers and room impact the soundstage in the same way
I am asking because i have listened in the same room with the same system two bookshelves One was good at 3D the other very poor
Imho a really great speaker will throw a decent soundstage almost in any room
this is an important point for who cannot treat the room for various reason Waf the usual one

 

[mike70]

Hi i wonder if speakers and room impact the soundstage in the same way
I am asking because i have listened in the same room with the same system two bookshelves One was good at 3D the other very poor
Imho a really great speaker will throw a decent soundstage almost in any room
this is an important point for who cannot treat the room for various reason Waf the usual one

Generally (generally ) speakers are good at "pinpoint " positioning of the instruments or at creating a big scenario, is more difficult to play both effects well.

In the first case you need little interaction with the room (single point speakers, as coaxials speakers) and in the other case you need high interaction with the room (dipole speakers ).

So, choose your poison or buy a (good) many thousands speaker.

 

[gino1961]

Generally (generally ) speakers are good at "pinpoint " positioning of the instruments or at creating a big scenario, is more difficult to play both effects well.
In the first case you need little interaction with the room (single point speakers, as coaxials speakers) and in the other case you need high interaction with the room (dipole speakers ).
So, choose your poison or buy a (good) many thousands speaker.

Hi thanks a lot for the very kind and valuable advice
With really good speakers, and a warm, thermally stabilized system, what's impressive is that they seem completely disconnected from the system. It's a truly surprising sensation.
They make the surrounding space resonate.
I believe the secret lies in the cabinet design and construction.
Heavy ones usually sound better.
A stereo that isn't 3D is a failed stereo, imho.

 

[mike70]

Hi thanks a lot for the very kind and valuable advice
With really good speakers, and a warm, thermally stabilized system, what's impressive is that they seem completely disconnected from the system. It's a truly surprising sensation.
They make the surrounding space resonate.
I believe the secret lies in the cabinet design and construction.
Heavy ones usually sound better.
A stereo that isn't 3D is a failed stereo, imho.

Well, you have the spinorama measurements to check for very good speakers ... i mean, anechoic room flat response, good dispersion, etc.
Bass response is what i don't care too much, i use a subwoofer for bass.

 

[gino1961]

Well, you have the spinorama measurements to check for very good speakers ... i mean, anechoic room flat response, good dispersion, etc

Hi thank you very much again for the precious advice
Sorry for the belated reply but i am moving to another flat a disaster
Anyway ... I have learned something on speakers cabinets
To put together woofer mid and tweeter in the same box is more challenging than using two separated boxes one for the woofer and one for the M and T
This is my preferred concept
And i have learned another thing
I compared two mini speakers with similar drivers but very different enclosure One aluminum and the other plastic
The sound from the plastic speaker was ridiculous
Instead i could get a much better sound from the metal speakers
It was even 3d at the point that i am thinking to add a woofer and use it as satellite
The speaker is a Teac ls-x5
I have 5 pairs now
It's the enclosure that captured me

Bass response is what i don't care too much, i use a subwoofer for bass.

Very interesting but this complicate the system
A prefer a passive speaker with one stereo amp

 

[mike70]

Very interesting but this complicate the system
A prefer a passive speaker with one stereo amp

Yes, more complicated. But, better results indeed.
Not any tower speaker have the energy and extension for flat response on bass (and not any amp can drive that ).

It's not a question of "words"... Once you listen to a good integrated sub... There's no coming back.

 

[gino1961]

Yes, more complicated. But, better results indeed.
Not any tower speaker have the energy and extension for flat response on bass (and not any amp can drive that ).

It's not a question of "words"... Once you listen to a good integrated sub... There's no coming back.

Very interesting
I agree that many speakers have weak bass
I usually use pipe organ music to test it like the famous Bach Toccata e fuga
The weak speakers shake
The good speakers shake the room
Thanks again and kind regards Gino

 

[narutofan]

I have am in need of a preamp to multiple RCA inputs and the P4 looks ideal. However, I have the option to get the Schiit Saga S second hand from someone close for whatever I would have spend buying a P4 brand new.

I don't need the extra inputs but obviously will come in handy maybe sometime in the future. All things equal and just basing it on quality alone, would you take a new Fosi P4 or a second hand schiit S (I assume these things rarely go wrong as it's just a preamp?)

 

[gino1961]

Hi an interesting video about the effects of changing power supply

After watching this i would like to try a sealed lead acid battery
But i don't have a clue about the current draw of the P4 to get an idea of the time needed between two recharges
Or at least a very good linear power supply

 

[redjr]

I've been using one of these for a few months off and on in various setups, and it sound very, very good indeed. It is interesting that with a 12V battery you can shave a couple more dB off an otherwise inaudible noise floor. I wonder if I could hear the results?

 

[gino1961]

I am not an expert but batteries provide a complete isolation from the grid
These units use dc dc converters that can pass some upstream noise coming from the grid
And this noise is not always the same during the day
Maybe the converters are just fine noise wise but they could have a so so rejection of incoming noise?

 

[norman bates]

In the end, we are listening to the power supply……..

Subjectively, I thought a battery pack sounded better than the cpu brick on a diy 3116 chip amplifier on a 110db compression driver……

Incoming noise ?
perhaps separate the power wires and twist them ?