Fosi Audio P3 Preamplifier & Headphone Amplifier Discussion

[Clmrt]

I've been using a P3 for about 10 tracks so far. It displaced an Outlaw 975, drives a Crown PS-400 into my Snell D7s and is pretty much spectacular on well recorded jazzy stuff.

Live music sounds great. 80s studio stuff not so much so far. Older 60s and 70s tracks sound better. Definitely bringing through the recording and mastering techniques if that makes sense.

With the 975 everything sounds equally good. With the P3, things stand out and truly fill space with body and energy if it was recorded in a way to allow it. Interesting and pleasing effect.

Currently Bluetooth from a Samsung S22, Tidal max res, P3 volume at 12 o'clock and controlling volume with the phone.

I'll wire it to my Wiim mini analog out tomorrow to see what it can really do.

 

[Deckard71]

This one looks much better, and it seems to be as transparent as the Schiit Loki

 

[timiambeing]

Hi folks

After my Line Magnetic LM34ia went pop the other day (well more like 'snap, crackle and pop! UK breakfast cereal joke - but surprisingly accurate! ) I am looking at weeks of waiting for repair - so in a crazy moment I ordered a Black Friday deal on the Fosi Audio V3 from Amazon. After hooking it up in my main system (it looks tiny and massively overshadowed by the Pontus II DAC and the Lumin streamer!!) I am slightly unbelieving of the power and transparent nature of this amazing little device feeding my full range single driver floorstanders! After room correction measurements were done again just in case there was a change (there wasn't much) I implemented a very small PEQ of four bands in Roon to loose a couple of bass humps and one always present rise around the 2Khz mark I always have - result is this little amp is not disgracing itself at all, far from it!! I am rapidly becoming a Class D fan (I can feel a DIY project coming on this winter! ) .

Ayways, why am I telling you this in the Fosi Audio P3 thread I hear you say - well as it was still Black Friday yesterday so I ordered the P3 to go with the V3 and act as a preamp. Actually, I'm thinking of it as more like a tube input buffer, a few people are making good noises about the effect.

So, what I really want to know, being a bit OCD about this sort of thing, is how you guys are setting the two volume controls of the respective P3 and V3? I would have thought max volume on the V3 as it is now taking the role of a power amp and adjust volume with the P3 but I have seen other ideas and now I am confused?

Because we don't have a remote with the Fosi gear I am also playing around with Lumin's LeedH digital volume control, the idea would be to set the Fosi P3 hardware volume pot at a level that is just above what would be comfortable listening (presuming V3 is set at max), then use LeedH to slightly reduce this by a small percentage as required. Playing with the V3 alone seems to show no reduction in SQ (isn't it daft to be talking about this stuff in relation to a £100 amp!!) using LeedH so this looks like it might be the way to go.

So... what knobs in what position do you think, any reasons why maxing out the V3 isn't a good idea?

 

[NoMoFoNo]

When I stream the volume controls are set so that V3 is at roughly 11:00 to noon and the P3 winds up somewhere around 11:00 as well. I've tried the V3 set to max but that leaves too little travel for the P3. Just shy of noon on the V3 gives me good range of P3 control.

 

[Clmrt]

Aux out from the Wiim mini, record out from the 975 to the P3. Volume knob is barely cracked open and we have music just a bit too loud for conversation. A less sensitive travel would be appreciated. But it sounds really goood.

 

[Clmrt]

Knocking the Wiim output down to 500mv gave me another 5 minutes of travel on the pot. Not much. Sounds thinner...back to 1v.

 

[timiambeing]

Knocking the Wiim output down to 500mv gave me another 5 minutes of travel on the pot. Not much. Sounds thinner...back to 1v.

Its all about that weird 'unity gain' things isn't it, when you have more than one volume control in the chain! If manufacturers actually provided accurate output voltages and input sensitivities we might stand a better chance (I wonder if those are available anywhere, haven't looked really) - anyway the P3 arrived and after a few hours playing to itself in the bedroom its in the main system this morning. So far it seems the ideal spot for slightly above comfortable listening levels on loud recordings (using both volume pots together) is 12 and 12 for me, I can then lower the volume by 10-20% digitally using LeedH to get somewhere within normal listening levels.

Incidentally, it nearly went straight back as getting those valve in was a bloody nightmare! I'm well used to tube amps but either these sockets are out of spec or the tubes are... I bent the legs more than once and was about to open the damn thing up to insert them!! Not a good design - no tube rolling for me I don't reckon!!

Also, just to engage the ASR trolls, this thing sounded absolutely awful out of the box, the bass was overblown and drowned out everything else. I didn't listen for more than five minutes and had to take it out of the main system and leave the little V3 to its own devices - much more natural and sweet. I left the P3 playing to itself in the bedroom headfi setup, only to realise later that I was probably only burning in the cheap headphone amp chip! Anyway the tubes must have benefited as it a different beast this morning - but we will see, I just wanted a tube buffer not a preamp that exhibited all that's wrong with tubes, but let's see how it pans out...

 

[timiambeing]

Knocking the Wiim output down to 500mv gave me another 5 minutes of travel on the pot. Not much. Sounds thinner...back to 1v.

I did just answer you, but I mentioned a word which put it into moderation... I mentioned 'burn in'!

Edit... ah its been let through

 

[NoMoFoNo]

Knocking the Wiim output down to 500mv gave me another 5 minutes of travel on the pot. Not much. Sounds thinner...back to 1v.

You remind me of trying to match an Audio Research LS-1 line stage/preamp with power amps that had no gain control on them. I had almost no usable volume control because the LS-1 provides 29db of gain. In order to use it I have to acquire a power amp with gain control or insert a passive between the LS-1 and the power amp. It sounds like you have a similar mismatch between gain on the P3 and your power amp. Sounds ridiculous I know but to use them together you may need to add a passive preamp (something like a Schiit Sys) between the P3 and power amp.

 

[Clmrt]

I'm resisting dialing down the PS-400 because I have my 3.1 running through it. I don't want to mess up my perfect trim. LOL. Tonight it'll be back to 2V and trimming back the Crown so I can get it to 12 o'clock. That was the sweet spot at work in a much nastier setup.

 

[timiambeing]

When I stream the volume controls are set so that V3 is at roughly 11:00 to noon and the P3 winds up somewhere around 11:00 as well. I've tried the V3 set to max but that leaves too little travel for the P3. Just shy of noon on the V3 gives me good range of P3 control.

I’m doing some research here at Timiambeing hifi headquarters! So, if I have the V3 at 12 and the P3 at 12 I reach just over normal listening levels which I can adjust down with LUMIN LeedH volume… but what about if to get the same volume I try…

V3 @ 3 o’clock/P3 @ 9 - do I get less P3 tubeyness more flat V3 goodness
V3 @ 9 o’clock/P3 @ 3 - do I get more P3 tubeyness less flat V3 goodness

Dont ask me, by the time I’ve sat down to listen I’ve forgotten what the previous setting sounds like!! ‍

 

[Guddu]

V3 @ 3 o’clock/P3 @ 9 - do I get less P3 tubeyness more flat V3 goodness
V3 @ 9 o’clock/P3 @ 3 - do I get more P3 tubeyness less flat V3 goodness

What exactly is this "tubeyness"??

 

[timiambeing]

What exactly is this "tubeyness"??

Tubeyness, oh perhaps it’s called tubiness? Well I would say it’s that (slight in this case) euphonic effect of tubes… a kind of liquidity, sweetness. You might say it could be an antidote to the crystalline (and sometimes described as sterile) output of typically extraordinarily well measuring audio equipment. A sort of gentle embrace of encouragement, for the silicon, helping it output music along with that perfect sine wave?

Hows that?

 

[-Jim-]

Tubeyness, oh perhaps it’s called tubiness? Well I would say it’s that (slight in this case) euphonic effect of tubes… a kind of liquidity, sweetness. You might say it could be an antidote to the crystalline (and sometimes described as sterile) output of typically extraordinarily well measuring audio equipment. A sort of gentle embrace of encouragement, for the silicon, helping it output music along with that perfect sine wave?

Hows that?

 

[Guddu]

Tubeyness, oh perhaps it’s called tubiness? Well I would say it’s that (slight in this case) euphonic effect of tubes… a kind of liquidity, sweetness. You might say it could be an antidote to the crystalline (and sometimes described as sterile) output of typically extraordinarily well measuring audio equipment. A sort of gentle embrace of encouragement, for the silicon, helping it output music along with that perfect sine wave?

Hows that?

I would say “too technical” for my appetite.
Sometimes I underestimate the participation in this forum

 

[timiambeing]

I would say “too technical” for my appetite.
Sometimes I underestimate the participation in this forum

 

[Clmrt]

Welp, using the WIIM at 2v fixed, I had to cut the Crown by 20db to get the P3 volume control at noon with room volume louder than conversation level. Sounded great but it was time to get the system back in the hands of the kids.

Off to work with it, into an old BK amp driving Altec E-waves.

Seems like a hot linear pot. I might mess around with some in-line attenuators vs dropping the input level from the PC analog feed. Gasp.

 

[GGroch]

How to install tubes in the P3....the orange rings unscrew. It looks a good bit easier knowing that:

 

[timiambeing]

How to install tubes in the P3....the orange rings unscrew. It looks a good bit easier knowing that:

Yes wish they had released this before - took me 30 mins of struggling!!

 

[John in CH]

Yes wish they had released this before - took me 30 mins of struggling!!

Same here. And that was even after removing the orange rings. After 3 weeks I decided to re-purchase the P1 which I had previously returned. In side-by-side comparison and with the same 5654W tubes installed, the P1 sounds much better than the P3 IMHO. And provides a bit more volume to boot. P3 will go. PM me if you are in EU and have interest. Rgds... -John