Fosi Audio P3 Preamplifier & Headphone Amplifier Discussion

[-Jim-]

At it's price, and with the higher voltage power supply, I was impressed by the Fosi V3 Amplifier. I think it's a good buy. Now for this pre-amp, I'd be more impressed if it didn't have tubes, and maybe more inputs. Like most here there are better ways to EQ than tubes, and good pre-amps should be clean and not inherently add their own sound to the signal. I think in Fosi's urgency to cash in on the V3 they missed the mark here.

I know this seems to be ready for distribution and I get they want to generate income from it. I expect they'll get some sales but not what they could have achieved. They should take another swing at a solid state unit with a Sub out as well.

 

[GGroch]

.......They should take another swing at a solid state unit with a Sub out as well.

So, perhaps something like the new RSL Integrated, but with a pair of RCA Pre-Outs instead of the built in amp. I agree that would more directly target V3 buyers in the U.S.

This is interesting; a new update on the P3 Kickstarter shows a change from the common GE Branded 5725 tube to a very uncommon 6m2 tube (brand not specified). This indicates continuing engineering, as I can't find 6m2 tubes used in any tube electronics currently sold. The only reference I see to 6m2 are long discontinued magic eye tubes used for tuning. I am pretty sure this is not what the P3 will use.

My Guess: Its a typo. The P3 will actually use 6J2 tubes which are 5725 equivalents. There are internet rumors that most all GE branded tubes are fakes, that would not go well with Fosi V3 fans.

 

[-Jim-]

So, perhaps something like the new RSL Integrated, but with a pair of RCA Pre-Outs instead of the built in amp. I agree that would more directly target V3 buyers in the U.S.

This is interesting; a new update on the P3 Kickstarter shows a change from the common GE Branded 5725 tube to a very uncommon 6m2 tube (brand not specified). This indicates continuing engineering, as I can't find 6m2 tubes used in any tube electronics currently sold. The only references I see are to a magic eye tube used for tuning.

Thanks @GGroch for the link to the RSL iA255.1. Another interesting Class D amp but this time an integrated unit. Fosi should take notes.

 

[Kimbrough Xu]

Why using tubes?

I'd like a well priced preamp that measures very well, not using any tubes and with XLR... my feedback 2c.


JSmith

I would like the XLR input and output.

 

[Kimbrough Xu]

I would be interested in monoblocks but maybe with some other TI chip like TPA3221 which requires less voltage 24v vs 48v for 3225 an can deliver up to 200w. Much easier to supply it with 24v/10A integrated or external power supply

If use TPA3221, you can just get 100W power.

 

[Joey]

hi bro

Why using tubes?

I'd like a well priced preamp that measures very well, not using any tubes and with XLR... my feedback 2c.


JSmith

I would like to know What parameters and specifications belong to a better product

 

[JSmith]

Sure, we'll turn to our R&D team for the preliminary test measurements and share them with you.

Any news on that yet, or too soon to release?


JSmith

 

[Kimbrough Xu]

The terminology and usage of the noun preamplifier seems to be a sticking point. For many decades, audio consumers have understood this to be a control center for one's audio system, a component which accepts multiple audio inputs and outputs, allows switching between those inputs and outputs, as well as providing customizable features such as tone controls, balance control, tape recorder output, headphone output etc. In the classic 20th-century definition, a preamplifier also includes a subsidiary phono stage (or "phono preamplifier").

I regret that the industry's terminology for this type of device has changed in recent times, hence some disappointment about this specific Fosi Audio product which may be a superb performer for its intended purpose (tonality enhancement using vacuum tube technology), but which omits the typical control functionality found in a preamplifier from the late 20th century. Many of us would really, really like a compact control-type preamplifier to complement the brilliant Fosi Audio power amplifiers: two or three RCA input jacks, possibly an RCA output jack for recording (maybe), a dedicated subwoofer output, tone and balance controls, a DAC and headphone jack.

Yes, I hope FOSI can see this @Fosi Audio

 

[Fosi Audio]

separate 3.5mm pre out, hopefully tied to the volume control

Yes, the pre-out is tied to the volume control and power switch

 

[Fosi Audio]

Now for this pre-amp, I'd be more impressed if it didn't have tubes, and maybe more inputs

Actually, we have planned a pre-amp/selector w/o tubes but w/ more inputs in our development list.

 

[Fosi Audio]

So, perhaps something like the new RSL Integrated, but with a pair of RCA Pre-Outs instead of the built in amp. I agree that would more directly target V3 buyers in the U.S.

This is interesting; a new update on the P3 Kickstarter shows a change from the common GE Branded 5725 tube to a very uncommon 6m2 tube (brand not specified). This indicates continuing engineering, as I can't find 6m2 tubes used in any tube electronics currently sold. The only reference I see to 6m2 are long discontinued magic eye tubes used for tuning. I am pretty sure this is not what the P3 will use.

My Guess: Its a typo. The P3 will actually use 6J2 tubes which are 5725 equivalents. There are internet rumors that most all GE branded tubes are fakes, that would not go well with Fosi V3 fans.

Sorry, the tubes should be 6ж2 instead of 6m2.


Our team tested and found 6ж2 can provide better sound than 5725.

 

[Fosi Audio]

The terminology and usage of the noun preamplifier seems to be a sticking point. For many decades, audio consumers have understood this to be a control center for one's audio system, a component which accepts multiple audio inputs and outputs, allows switching between those inputs and outputs, as well as providing customizable features such as tone controls, balance control, tape recorder output, headphone output etc. In the classic 20th-century definition, a preamplifier also includes a subsidiary phono stage (or "phono preamplifier").

I regret that the industry's terminology for this type of device has changed in recent times, hence some disappointment about this specific Fosi Audio product which may be a superb performer for its intended purpose (tonality enhancement using vacuum tube technology), but which omits the typical control functionality found in a preamplifier from the late 20th century. Many of us would really, really like a compact control-type preamplifier to complement the brilliant Fosi Audio power amplifiers: two or three RCA input jacks, possibly an RCA output jack for recording (maybe), a dedicated subwoofer output, tone and balance controls, a DAC and headphone jack.

We're trying to make things smaller. So we may develop the gears separately as a series.

 

[-Jim-]

Actually, we have planned a pre-amp/selector w/o tubes but w/ more inputs in our development list.

Thank you for the response. Glad to see that you have this on the drawing board. I'll look forward to it.

 

[JLGF1]

Tubes are great for guitar amps for their signature sound. For audio pre-amps, not so much, imo. For one thing, they burn out. And there are ways to get tube distortion (if one really wants that, I don't) without using real tubes, at least for HiFi usage cases (not guitar amps).

 

[Jeromeof]

Actually, we have planned a pre-amp/selector w/o tubes but w/ more inputs in our development list.

This is great - IMO if you include a headphone amplifier ideally include the power rating at different impedance levels e.g. start at 16Ohm, 32Ohm at least up to 300Ohms - would be a definite buy from me if it had the same styling of the V3 but with decent headphone support (too many 'cheap' pre-amps with poor headphone compatibility IMO - especially for Planar headphones).

 

[Kimbrough Xu]

This is great - IMO if you include a headphone amplifier ideally include the power rating at different impedance levels e.g. start at 16Ohm, 32Ohm at least up to 300Ohms - would be a definite buy from me if it had the same styling of the V3 but with decent headphone support (too many 'cheap' pre-amps with poor headphone compatibility IMO - especially for Planar headphones).

I will need such a headphone amplifier too, and with roll op amps.

 

[Sava]

After the successful launch of our previous mini stereo amplifier, V3, we received significant attention and recognition from members. Thank you all!

As a brand committed to designing and developing products based on user feedback and demands, Fosi Audio swiftly responded to customer suggestions and feedback. We promptly assembled our team of engineers to embark on the development of our next-generation vacuum tube preamplifier and also a headphone amplifier, the P3, which belongs to the same series of V3. We'll reveal the development process information about it and collect your suggestions!

First, we'd like to share the concept map of this new preamplifier.

View attachment 295751

What I would personally like to see, that would pair well with V3, is a decent DAC/Preamplifier with tone control(treble, mid and bass - with bypass) in one unit at a reasonable price. Remote would be nice but not necessary. No headphone amp(that can be a separate unit). No Bluetooth either.

 

[GGroch]

My P3 Arrived today from Kickstarter. I have attached some photos and a couple of observations from a very brief evaluation.

The tubes it shipped with are GE 5654w JAN tubes, exactly like the ones sold on their site. As you can see, they are shorter than the original artist renderings but look and work fine and have soft white LED illumination from below in addition to their own glow. The front power LED is blue.

Exactly the same size as the V3 (but for to tube bump). The cosmetics are a good match, except the text/logos front and back are in gray, not white like the V3. This makes them difficult to read, but also not visually similar to the V3. The top tube rings are orange, but a redder shade than the orange knob of the V3. I hope they can change both of these things in later runs if it is supposed to pair with the V3.

The 3.5mm "Aux Out" on the back duplicates the RCA OUTs, so it is controlled by the volume knob and the tone controls. It should be fine to send to a powered sub or a 2nd amp or set of powered speakers.

I hear no popping at all when it is powered up or down, and when the tubes warm up/sound starts (a few seconds later).

The headphone output sounds good on a brief listening.

The volume knob seems to have a lot of gain in the 1st quarter turn, so not a Taper A I think. Overall there seems to be a lot of gain available, so if your DAC does not put out a full 2V this could help.

I will not get to listen more til tomorrow, but wanted to get the photos out.

 

[JimFarrell29]

My P3 also arrived today, but unfortunately I have issues. Terminal ones. Firstly when I connected my powered sub to the Aux out I got a loud, painful noise from the sub despite the Fosi volume pot being at 0. Removing the sub I listened for a while and was very impressed. For the price it sounded warm and balanced with the V3 into Revel Performa M106 speakers in my study.
Leaving the sub issue for later I went out for the afternoon, came back, switched it on , and....dead as a doornail. No power LED, no valves lighting up, no music. I switched out the wall wart for another 12v psu but no dice.
Looks like my P3 has bit the dust. Very disappointing indeed, especially as it really sounds very good indeed.
I have contacted Fosi for their thoughts.

 

[GGroch]

That is terrible news Jim. I did not test the Aux Out with a sub, just briefly with a pair of headphones to confirm it worked and was controlled by the volume/tone controls. Please keep us informed on what you find, and good luck.