Fosi Audio P4 Preamplifier Review

[Thighsofsteel]

Try a Muses 02 in the P4 if you can. I find the bass on the NE5532 a little ‘loose and flabby’ less defined by comparison in everything.

You could go as far as the opa828 if you want or need specific superior bass control, that op amp hangs onto the bass like a Pit Bull on a Rabbit sandwich!

Superb control from either one of these op amps and don’t let anyone tell you they will not make a difference, they will!

Nonsense.

Op Amps: Myths & Facts

INTRO: The op amp is a fundamental building block of audio gear. Op amps are widely used and, not surprisingly, they’re a popular topic amo...

nwavguy.blogspot.com

 

[RandomEar]

Try a Muses 02 in the P4 if you can. I find the bass on the NE5532 a little ‘loose and flabby’ less defined by comparison in everything.

You could go as far as the opa828 if you want or need specific superior bass control, that op amp hangs onto the bass like a Pit Bull on a Rabbit sandwich!

Superb control from either one of these op amps and don’t let anyone tell you they will not make a difference, they will!

They won't. In addition, the Muses02 and N5532 are very similar in spec: Almost the same noise and bandwidth, similar THD, slightly worse slew rate on the Muses. The idea that these would sound any different at all, especially in the bass region which poses zero challenge frequency wise for any op amp, is just silly.

Ironically, you fail to deliver any proof at all that what you claim to hear has the slightest base in reality for every single claim you make. This is a science-leaning forum. Do better.

 

[Schlippwhip68]

They won't. In addition, the Muses02 and N5532 are very similar in spec: Almost the same noise and bandwidth, similar THD, slightly worse slew rate on the Muses. The idea that these would sound any different at all, especially in the bass region which poses zero challenge frequency wise for any op amp, is just silly.

Ironically, you fail to deliver any proof at all that what you claim to hear has the slightest base in reality for every single claim you make. This is a science-leaning forum. Do better.

Prove to me they don’t!

You can’t and you can’t do better.

You can only prove electrical synergy and similarity with measurements.

You cannot prove anything else, so stop judging people who can obviously tell differences in sound quality of an end product.

Your argument is utterly ridiculous. We already understand the electrical components and common ground such like maybe on.

It’s not even the topic in question.

The truth is there are differences regardless and proof of such is all over the internet but seems to escape some members of ASR!

I have done blind testing and did not fail to spot differences in bass response.

 

[solderdude]

If I knew I would probably be making my own.

How do chip manufacturers and discrete op-amp manufacturers know ?

 

[DSJR]

Prove to me they don’t!

You can’t and you can’t do better.

You can only prove electrical synergy and similarity with measurements.

You cannot prove anything else, so stop judging people who can obviously tell differences in sound quality of an end product.

Your argument is utterly ridiculous. We already understand the electrical components and common ground such like maybe on.

It’s not even the topic in question.

The truth is there are differences regardless and proof of such is all over the internet but seems to escape some members of ASR!

I have done blind testing and did not fail to spot differences in bass response.

Of course, you used all your senses I'm sure, especially eyesight. I don't now refer to this as 'eye-fi' for nothing, as it's amazing how these magical differences disappear when sight (and also touch) is removed in a comparative situation.

Why do I say what I've posted above? Because I've been there in years before my ears failed me and many, many others have also found this to be absolutely true and we've all been down that road in past years or decades. 90% of it is subtle level differences (I didn't believe it either until shown and confirmed for myself).

So forgive us for initially dismissing your own argument as ridiculous here. Many of us have done it at different times in totally different situations and locales and come to the same conclusions. So yes, we CAN prove it and so can you if you're more careful with levels and so on

So maybe you need to prove your findings to us?

 

[RandomEar]

Prove to me they don’t!

That's the beauty of science: You need to prove your claims. The zero hypothesis in this case is trivial: "There is no difference."

You can’t and you can’t do better.

I'm doing pretty good, here. Thanks.

You can only prove electrical synergy and similarity with measurements.

You cannot prove anything else, so stop judging people who can obviously tell differences in sound quality of an end product.

Measurement instruments are orders of magnitude more precise than human hearing in every dimension (magnitude, phase, time resolution, simply everything). The only logical assumption ist that "what measures the same, sounds the same". I have never seen any proof of the opposite. You are welcome to provide such proof.

In extremely stark contrast to most of your claims, audiophiles around the world have repeatedly and reliably failed in well controlled double blind testing of all devices in the audio chain which measure transparent. This includes DACs, preamps, amps, cables, CD transports, you name it. Not speakers though, and measurements also clearly show differences between many of those.

There are also devices which do not measure transparent: Tube amps, some odd transistor amps with drooping frequency response or broken DACs cobbled together by inexperienced EEs. Blind tests have shown differences between such devices and others which are transparent. It always depends on the "level of broken".

Your argument is utterly ridiculous. We already understand the electrical components and common ground such like maybe on.

I don't know what this is supposed to mean.

It’s not even the topic in question.

The truth is there are differences regardless and proof of such is all over the internet but seems to escape some members of ASR!

Feel free to point us to some of that proof. We have repeatedly and openly encouraged you to do so.

I have done blind testing and did not fail to spot differences in bass response.

Closing your eyes while listening is not "blind testing"

We have explained to you on multiple occasions which parameters are essential for reliable tests, including almost perfect level matching and either robust A/B/X or double blind methods. If you want your claims to be taken seriously on ASR, you need to document and share your test protocols so others can understand what you did and where there might be potential pitfalls in your test setup.

 

[Schlippwhip68]

….and prove to me they don’t…no offence but I won’t wait.

You may as well have all of that written on toilet roll as far as I am concerned. So, my suggestion is you enjoy your whatever while you can and I will, as I do, enjoy my system.

Cheers!

 

[Thighsofsteel]

….and prove to me they don’t…no offence but I won’t wait.

You may as well have all of that written on toilet roll as far as I am concerned. So, my suggestion is you enjoy your whatever while you can and I will, as I do, enjoy my system.

Cheers!

You made the claim not us. If you claimed you had fairies at the bottom of your garden, it’s not up to anyone to disprove anything. It’s up to you to offer proof.
We will wait for you to present something. I doubt you will of course.

 

[nvtinh94]

I'm planning to run a Jamo C912 subwoofer with a pair of JBL 306P MKII monitors. The problem is the C912 has no RCA line-level outputs, and the JBLs have no built-in high-pass filter.
The ZP3 would be perfect for this because it has an adjustable high-pass filter, but it's unavailable in my region.
Would the P4 work as a substitute? Specifically, can I use the P4's tone controls (bass cut) to roll off the low end going to the JBLs while still sending the full-range signal to the subwoofer?
I’ve searched everywhere but can’t find any frequency response graphs or specs showing exactly where / how steeply the P4’s bass tone control starts cutting. Does anyone have measurements, graphs, or real-world experience with this?
Any help would be greatly appreciated!

 

[Joe Smith]

Stated spec is Tone Adjustment Gain: ±12dB, but I have not seen any measurement curves from Fosi.

My guess is that it won't work very well for your use case, it would be better to have a preamp or amp with a dedicated HPF function.

 

[Maf]

Hi, long time lurker here... don't have time to reread the entire thread just in case my question was previously answered... can this unit be used to connect to two amplifiers, one via the RCA outputs and one via the preamp output? My use scenario would be two amps powering speakers in different zones of an open plan living space, only one of which would be powered up at any one time.

 

[SnakeLord]

Hi... can this unit be used to connect to two amplifiers, one via the RCA outputs and one via the preamp output? My use scenario would be two amps powering speakers in different zones of an open plan living space, only one of which would be powered up at any one time.

Thats what the pre-out is there for on the P4 according to Fosi:

"What can the pre-out port used for?

Allows for easy connection to external powered subwoofers or additional amplification. It ensures seamless integration with your audio system, enabling enhanced bass response or driving additional speakers for a more immersive listening experience."

Fosi Audio P4 Mini Preamplifier

Mini Control Hub: The P4 supports up to 3 RCA inputs, allowing easy connection to CD players, streamers, DACs, cassette decks, and turntables with built-in phono preamp. Switch between sources with a click for seamless audio control. Practical and User-Friendly: Equipped with volume control...

fosiaudio.com

 

[Maf]

Great thanks, that is what I figured it meant but wasn't 100% sure

 

[Schlippwhip68]

This guy said it degraded the sound................

(1:05+) "Sending the signal from your DAC into the Fuzzy Audio P4 preamp will make it sound worse. Adding the P4 into the signal chain makes the sound stage narrower and flatter. Details or resolution in the music are also noticeably reduced. It's not bad as such, but the idea of a preamp is to be as sonically invisible as possible. We do have to be reasonable given the $100 price tag of the P4….."

It’s decent enough. I doubt it would have the detail retrieval of the Topping Pre90 but unless you are willing to spend 5 x the price then the P4 is an excellent option.

I have one in my chain being fed by an iFi Zen One Signature dac. The P4 feeds my Audiolab M-PWR power amp.

In regards to any degradation of sound quality, it’s a no from me. If anything it brings a little more balance to the sound. For example I connected the iFi Zen One directly to the Audiolab power amp and while there is a slight difference as would naturally be expected, it’s not huge.

For the benefit of extra inputs, remote control for the volume, I kept the P4 in the chain. I also replaced the stock op amp NE5532 with an Audience SX52B with excellent results. A clean ‘non fuzzy’ airy soundstage.

IMO the P4 does an excellent job out of the box but using an low noise power supply like the the iFi Power X or linear power supply and upgrading the op amps takes the Fosi P4 a lot closer to the Topping Pre90 for a lot less money.

 

[RandomEar]

It’s decent enough. I doubt it would have the detail retrieval of the Topping Pre90 but unless you are willing to spend 5 x the price then the P4 is an excellent option.

I have one in my chain being fed by an iFi Zen One Signature dac. The P4 feeds my Audiolab M-PWR power amp.

In regards to any degradation of sound quality, it’s a no from me. If anything it brings a little more balance to the sound. For example I connected the iFi Zen One directly to the Audiolab power amp and while there is a slight difference as would naturally be expected, it’s not huge.

An audible difference is, in fact, not expected based on the published measurements in the OP of this thread.

For the benefit of extra inputs, remote control for the volume, I kept the P4 in the chain. I also replaced the stock op amp NE5532 with an Audience SX52B with excellent results. A clean ‘non fuzzy’ airy soundstage.

IMO the P4 does an excellent job out of the box but using an low noise power supply like the the iFi Power X or linear power supply and upgrading the op amps takes the Fosi P4 a lot closer to the Topping Pre90 for a lot less money.

You replaced the standard op-amps with ones which have three times the distortion according to their datasheet. Naturally, this will not make the P4 perform closer to the pre90. The opposite would be expected, unless measurements are provided which disprove that assumption. As has been explained to you multiple times already, simply swapping a PSU for a linear one will not improve the device by default. In general, it won't have any effect at all.

 

[Joe Smith]

IMO, the P4 is just fine as it comes from Fosi. I use the supplied power supply and the stock op-amps. I do normally switch out the tone control via the switch in the back when I don't need them. I head no audible difference from using a source patched directly into one of my small amps. I'm currently using with the volume control set at 50%, lowest level of gain, and then adjusting volume manually from the amp pot.

 

[SnakeLord]

I also replaced the stock op amp NE5532 with an Audience SX52B with excellent results. A clean ‘non fuzzy’ airy soundstage.

This is an topic which should be addressed. IMHO not every opinion and statement should be tolarated and left like that just there. This is just confusing a bunch of "newbie" people, reading all this nonesense all over the forums and then just making the snowball effect even bigger and bigger.

At first i was thinking you are trolling but even after being proven wrong and shown, that the things you are experiencing have nothing to do with op-rolling and cables or whatever and yet you still keep on writing about your religious fanatism beliefs like those were facts.

You personally can believe in whatever you want, the problem is that you are basically spreading a bunch of false informations on a specific technical topic and make other people who arnt informed into fools. You can do that in a church of your choice but not on an scientific forum where things are measured and proven by facts.

The P4 which we are talking here about has been measured with couple of diffrent op-amps by @amirm already. This are the facts you have to accept or PROVE everybody wrong! And till then i kindly ask you to stop spreading your false informations all around the place and confuse other people.

Sparkos SS3602 Opamp Rolling In Fosi P4

This is a detailed measurements of effect of swapping the stock NE5532P op-amp in Fosi P4 preamplifier with Sparkos SS3602 "discrete" opamp. The SS3602 costs US $79.80 and the NE5532P, US $0.47. Swapping opamps in P4 is more challenging due to back connectors/switches that need to be...

www.audiosciencereview.com

 

[Schlippwhip68]

Yeah anyway guys and gals, as I was saying, a massive difference for the better when swapping out the op amps for the SX52B discreet op amp and upgrading the power supply. Instant likeable sound signature which impressed me a little further than the Muses 02 did in the P4. The SX52B give a notably less congested midrange by comparison, more depth to the soundstage even with the added negligible distortion as pointed out by others that mankind would not be able to discern regardless. The change in sound signature can be clearly identifiable using a resolving dac. I may try the SX35B later.

You hear the proof, not just read it.

Incidentally I never argued against the measurements in the first place or said that anything would change the device itself, just alter the sound quality and imo, for the better.

Enjoy!

 

[mike70]

You hear the proof, not just read it.

With a controlled listening test... or only "listening"?
If it wasn't a controlled test, what you hear isn't a proof, is an opinion. We have scientific proof about the opposite you talk.

So we're waiting for a real proof.

 

[Michou]

With a controlled listening test... or only "listening"?
If it wasn't a controlled test, what you hear isn't a proof, is an opinion. We have scientific proof about the opposite you talk.

So we're waiting for a real proof.