Fostex HP-P1 Portable Amplifier and DAC for iPod/iPhone (Short REVIEW and Impressions Thread) - Page 53

I use the HP-P1(less than 200hrs running time) & Apple Ipod Touch 2G with Grado SR325is(probably less than 200hrs running time). Does anybody know/have ideas whether a particular gain setting would yield greater signal quality? I thought low gain lets me use the pot in a more "open" position, using less resistance in the signal path. High gain may allow better function of some internal part of the circuit? Since I can use any of the 3 gain options maybe it's best to leave it on the same all the time regarding "burning in". So to sum up, what is best practice for the gain selection?

 

I feel the HP-P1 is screaming a bit through the SR325, I use the 2 digital filter position in an effort to ameliorate this. I hoping a thorough "burning in" period yields a discernable result.

 

I'm suspect about what is happening when the Apple iTouch permits alteration of the digital signal via the EQ function. Does anybody have knowledge about what is happening there? I would like as pure digital export as possible to the HP-P1, I'm hoping no conversion between digital and analogue is occurring prior to digital output to the HP-P1.

 

It seems people think the Beyerdynamic DT1350 has good synergy with the HP-P1, maybe the SR325 is not such a positive synergy? I would be interested if anybody has found a great synergy between this amplifier and another headphone. 

 

It would be great is Apple could provide iDevice function with all their computer products. Maybe something for the future.

Edited by AJHeadfi - 12/8/12 at 8:49pm

Any other findings on the soundstage and details? Thanks :)

Hi guys..i would like to ask question about hpp1. Has anyone experience mute sound when using fostex and ipod classic? The mute sound only happend when the first time i turn the fostex on and my ipod classic is playing the music but no sound comes out. Unless i move to the next track or previous track then the sound comes again. Is this normal?

I have never experienced this. I get sound whenever the iPod is playing and the HP-P1 volume is at a listenable level.

yes, same here

 

just connect your iPod while it is OFF, turn the Fostex ON (it will "wake" the iPod) *then* start playing.

Yes. It wakes the ipod. But when i pressed play button still no sound. Unless i press the next button or fwrd button then it plays normal again. It does seems work only that way for me. Btw i checked already with my friend at jaben (also with rudi0504). He told me only to ipod classic we have to give a bit this trick in order to get fostex hpp1 dac locked with ipod classic. But for iphone itouch or ipad..dont have this kind of problem.

Sometimes when I plug in my iTouch and turn on the HP-P1 I get a message to the effect that I cannot connect this device. I simply turn off the HP-P1 and turn it on again to connect to the iTouch. 

 

I must be getting close to 200 hours operating time with the HP-P1. I think it has improved a small increment. I suspect a good 500 hours is necessary for complete sound settling. At the moment the sound is still towards the harsh especially with brass, however piano sounds nice. I probably have expectations that are too high for these portable pieces. 

 

What I want to find is the headphone that has the best synergy with the HP-P1.

Anything 80ohms + is best for the Fostex. The DT-1350 are a popular headphone for it, but not my style.

That output impedance seems very high. Might be time to ask Fostex about it, as it's not straight forward to measure.

I meant 80ohm+ headphones are a best match for it.

 

The Fostex hp_p1 measures at 10.22ohm headphone output according to sonove whose other measurements seem accurate.

http://monoadc.blog64.fc2.com/blog-entry-99.html

 

10.22ohm headphone output impedance x 8 = 81.76. Hence my recommendation of the  80ohm DT-1350.

 

I have emailed Fostex about it in the past, they gave an evasive answer and chose not to honestly tell me (Venturecraft on the other hand was completely honest about their go-dapX).

 

Until they choose to communicate it clearly or until a head-fier with the correct equipment chooses to fully test the hp_p1 we are stuck with the reading of 10.22ohm. 

I value transparency more and more these days from companys and their products.

 

:)

Edited by ExpatinJapan - 12/14/12 at 8:26pm

Thanks for the advice Expat, I'll keep this in mind. The SR325i don't seem to need any additional amplification, which is a good reason for buying them, however they do benefit from the HP-P1 over the usual outputs from iPods/Mac books etc from my experience. I don't think I'll even bother trying the Sennheiser HD600, or any of the full size "ear speakers" with the HP-P1. DT1350 seems like a good candidate but I'm also curious about the PS500.

I'll give the DT1350 a try. I have seen other people praise them for portable use. I should have them around 26 Dec - 1 Jan. The T5P also look interesting, albeit rather large and 32ohm like the SR325i.

 

I have had great success with custom impedance matching an top end Audionote tube preamp to Senn HD650/600. Hopefully this strategy will work well with the HP-P1.

Looks like this thread is close to dead, HP-P1 being old news in the headophile world, close to the first anniversary. I might be the last head-fi user to buy one new.

 

I have at least 250 hours operation on the HP-P1. I can say the nasty bitey edge is much reduced on intense brass, cymbal etc. There is a smoothness to the sound I don't remember enjoying two weeks (long time) ago. I'll take it 500 hours as soon as possible. Has anybody cryo treated their HP-P1 board? Perhaps it's not worthwhile or too risky?

 

I could just keep using the SR325, the sound is satisfying, but I look forward to the DT1350. Seeing as Fostex is/was predominantly a pro gear company maybe the Beyerdynamic DT1350 will pair particularly well with the HP-P1, sound wise as well as electrically. 

 

This unit is looking more like a well thought out product than I expected.

Edited by AJHeadfi - 12/21/12 at 2:15am

 

I'm not so sure. I don't see too much out there that can compete with the HP-P1 as a portable  one-box DAC/head-amp w/ digital iPhone USB in. Do you?

Edited by VandyMan - 12/26/12 at 3:04pm

No. However I expect audiophiles would jump to CypherLabs -db and ALO mk3b using the "balanced" feature throughout, for at least double the cost of a HP-P1. It's audiophile logic.