Fosi Audio P4 Preamplifier Review

[MGJ]

on this type of machine...without balance...

Yes, this would be even better if the large outer rim on the volume control knob was instead a balance control.

 

[Hipster Doofus]

Excellent! ... now, the balanced version, please

I not sure people will be willing to pay the extra $1.47 it would cost Fosi to add balanced features.

 

[morillon]

Yes, this would be even better if the large outer rim on the volume control knob was instead a balance control.

a "balance" is essentially useful, coupled with a mono function...
(I'm afraid that in recent decades it has been a bit forgotten balance/mono (or the funny forgotten function of the Denon 70s...."null balance"..useful))

 

[Joe Smith]

Glad to see this review, and nice to see that the measurements do support what my old ears were hearing with their demo unit. It's a very nice product for the money, I'm enjoying mine.

 

[solderdude]

@amirm This pre-amp is all about the tone controls (and its circuit) but no measurements of that feature ... only with the tone control bypassed vs center position?

Does distortion increase ? What is the range and contour of the tone controls (I assume standard Baxandall) ?

Would buy one if I needed it.

 

[Millo_jp]

¿Preamplificador vs amplificador?

El preamplificador es más bien un interruptor de entrada con control de volumen y un poco de ganancia, por si la entrada es débil y lo necesitas. No tiene potencia suficiente para controlar los altavoces. Así que podrías conectar, por ejemplo, un DAC, un preamplificador de phono y la salida de una radio al BT30D, y conmutar la entrada y controlar el volumen con un solo control remoto.

El BT30D controla los altavoces. Existe una buena superposición de funciones. El P4 sería más práctico para quienes tienen un amplificador de potencia sin controles. Por ejemplo, un par de amplificadores mono Fosi V3 . Aunque, como ya se mencionó, no admite disparadores, lo cual habría sido una ventaja.

En mi ejemplo, un amplificador mono P4 + Fosi V3 te permitiría controlar el volumen del sistema. (Otras opciones incluyen, por ejemplo, si un DAC o DSP permite controlarlo por software).

What you wrote makes sense to me, but thank you for your response. I'm new here and not sure where to ask the Fosi guys. I have a BT30D PRO, which I believe is the V1.2 version. However, Williston Audio Labs tested one, and it turns out to be the V1.7 version, which now supports 48V.


Right now, I have my phone and a Jcally JM20 Max USB adapter connected via RCA to the Fosi BT30D Pro. The difference compared to using Bluetooth is incredible.

 

[teched58]

This preamp (Fosi Audio P4) does NOT appear to be available from (US) Amazon.

 

[Bruce Morgen]

Would buy one if I needed it.

Exactly. The smaller and even cheaper Fosi SK01, although not nearly as good an overall performer, is actually better suited for my particular use case due to its feature set, e.g. midrange knob, headphone amp, (quasi)loudness control.

 

[PlasticDoc]

Thank Amir for the great measurement and review!

This is a well-designed, well-built preamplifier. This is a winner.

It would be nice to see a FOSI V4 PFFB stereo amplifier, with that same orange motorized volume control (and companion remote control).
Nothing complex and no attempt at being too clever, just:

- plain well-designed and well-built TPA3255 PFFB amplifier board,
- balanced and unbalaced inputs,
- external PSU (48V/5 ~ 48V/7A),

And no other gimmicks: no 12v triggers, no hdmi arc, no gain buttons, no sub out, etc.

 

[ssashton]

Sorry if this was asked already, but how is the channel matching? Worth consideration given a physical volume control (I.e. not digital or IC based stepped resistor)

 

[DSJR]

Agreed. I’ve tried comparing my turntable’s phono preamp connected to the WiiM’s line-in versus going straight into my Naim amp, and I’m struggling to hear a difference. Granted, it takes me about seven seconds to switch, by which time any nuances are lost on me, but aside from a difference in gain, I’m hard-pressed to notice any variation. Plus, with the ability to EQ a 65Hz room node, the WiiM is a win for me.

The Naim is from an era where amps really *could* 'sound' different to each other. Maybe the latest models are a bit better?

 

[DSJR]

This preamp (Fosi Audio P4) does NOT appear to be available from (US) Amazon.

Neither Amazon UK currently. It'd be nice to get one here from a collection point rather than direct to my front door, as per direct from Fosi as the DS2 was.

The blasted things we have to do for domestic bliss...

 

[JSmith]

Neither Amazon UK currently.

Strange... is available on Amazon AU. Without going into it too much, I gather this could be something to do with current/pending international trade dramas.

eBay, seems to be available in general, US, AU, UK, DE etc.


JSmith

 

[FFR]

Hello,
I'm new to this forum and I thank all the participants who do a fantastic job of evaluating and providing feedback.
Perhaps this type of device is aimed at people like me who aren't looking for perfection, especially at US$80.
I currently have a FOSI V3 STEREO ((48 V/5A), which I enjoy enormously. I listen to classical music (95%) at moderate volumes in a small 15 m² living room. Passive speakers, no subwoofer, no headphone and to make matters worse, all this with 64-year-old ears.
The only problem with the V3: only one input, while I have three sources: a CD player, a DAC streamer, and a tuner. If I want to switch between them, I have to change RCA cables.
Would the P4 be a good solution in my case? I don't know anything about technology, but I read somewhere that it is not recommended to put a preamp and an integrated device in series. I will end up with two devices each with a volume controller.
I also read that it was possible to set the V3 amp at the 3:00 position, then turn up the preamp controls to the desired listening level or turn the V3 volume to maximum and use the P4 volume to control the sound level. Will this work properly without degrading sound quality ?
In France :
Incoming restock
04 - 11 April

 

[CedarX]

I noticed that Fosi has toned down their opamp rolling feature as compared to the ZD3: no more opamp recommendation by musical genre !!!

I could only find this mention of the feature in their website (I have zero problem with the feature itself):

More verbiage on their AliExpress store, but still reasonable IMO:

 

[Mart68]

The only problem with the V3: only one input, while I have three sources: a CD player, a DAC streamer, and a tuner. If I want to switch between them, I have to change RCA cables.
Would the P4 be a good solution in my case? I don't know anything about technology, but I read somewhere that it is not recommended to put a preamp and an integrated device in series. I will end up with two devices each with a volume controller.

You can't use this pre with your V3 as you say but a switching box will solve your issue and is cheaper

Something like this

https://www.amazon.co.uk/Switcher-BolAAzuL-Stereo-Selector-Passive/dp/B0CW5BJPKT/ref=asc_df_B0CW5BJPKT?tag=bingshoppinga-21&linkCode=df0&hvadid=80333258031350&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583932725391814&psc=1

 

[FFR]

You can't use this pre with your V3 as you say but a switching box will solve your issue and is cheaper

Something like this

https://www.amazon.co.uk/Switcher-BolAAzuL-Stereo-Selector-Passive/dp/B0CW5BJPKT/ref=asc_df_B0CW5BJPKT?tag=bingshoppinga-21&linkCode=df0&hvadid=80333258031350&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583932725391814&psc=1

Thanks for the idea and the link. It's a good solution and cheaper too. But if it works with the P4, I'd prefer that solution; the price difference isn't huge (in France, the P4 is available for €99 including tax). That way, I'll have a real preamp.
Now I just have to wait for it to be available. The audiophonics website had announced a preliminary availability date, but that date has been changed; now it's announced April. I've noticed this is the case for a lot of equipment coming from China.

 

[Bruce Morgen]

switching box will solve your issue and is cheaper

Something like this

I still have one of these from back in the day.

 

[Miley_B]

I read somewhere that it is not recommended to put a preamp and an integrated device in series

The Fosi v3 isn't an integrated amplifier (at least not to my knowledge) so this seems like a great complimentary device for the Fosi V3, it's even listed as a bundle pairing on their website, am I misunderstanding something?

Regarding stocking on Amazon, from the Fosi P4 webpage:

• Pre-order Shipping: Shipping is expected to begin in April.
  ​

 

[DWPress]

I'll chime in for wanting a balanced version. This would be perfect to replace my active DI Box and have more control over gains.