Fostex HP-P1 Portable Amplifier and DAC for iPod/iPhone (Short REVIEW and Impressions Thread) - Page 60

Thanks for your explanation longbowbbs. Unfortunately I don't think the HP-P1 DAC is doing any processing of this signal? The signal in must be digital, analog signals will simply be going through analog processing, no conversion from digital to analog. Possibly a simple way to check is if the digital filter switch changes the sound at all while this setup is running?

I was thinking an app on my iPod Touch could receive digital via WiFi/Bluetooth and pass that to the digital input of the HP-P1 through USB A. 

I can't figure out the difference between a 'Review', 'Impressions', 'Discussion' or 'Appreciation' thread; so I kind of made up a title of my own. 

Intro:

Ever since I first saw one of these a few months back my curiosity about it began to grow.  It seems like most of these have been sold in Japan and are finally starting to creep into the U.S.  So when I saw it being sold domestically here at a good price, I guess you could say curiosity killed the wallet.  It seems we haven't heard a whole lot about this piece, let alone the inevitable showdown between it and the Cypher Labs AlgoRhythm Solo/ RxII.  While I cannot provide the latter (yet?), hopefully this will be the start of a useful resource for both owners and interested Head-Fiers.  I just got mine the other day and I'm still a little high off of the 'new toy' buzz; so I hope I don't come off overly enthusiastic at any moment.  I'm not big on reviews so I'll try to keep this somewhat brief and superficial.  Please keep in mind that theses are initial impressions and I'm just as eager to hear from other owners about their experiences.

Why did I buy it:

I know it's rather expensive for a portable amp (and DAC).  But I am and have always been into my music.  And since my living situation precludes me from having a full-blown speaker setup, this is it!  If you take that into consideration, this portable stuff is actually not that bad of a deal- granted they are not the exact same experiences.  My goal is to have a single portable listening system that I can take from room to room or into my bed.  Of course I want it to be completely free of wires (headphones excluded) and I will not be regularly taking it out of my home.  I'll stick to just the iPod for that in most cases.  So size doesn't really matter as long as I can strap it to my iPod Touch.  I like the fact that the Fostex takes a 'standard' mini-USB plug to charge from.  I have several devices that use this already and I want to keep the number of plugs and adapters to a minimum.


Form:

One of the reasons I chose this amp was the lovely build quality.  I also recently purchased an iQube v2 which has an amazing build quality and finish of its own.  If this is a design competition they are very close.  While the iQube has the dull, bead-blasted finish with smooth rounded edges and a rubbery skin, the Fostex has brushed end caps, sharp (but finished) edges, sculpted curves, and a coarse matte black finish which feels very durable.  They are two very different design approaches and both are well executed.  The switches on the Fostex for 'Gain' and 'Filter' are gray plastic toggles.  They are very short and nearly recessed so they won't catch on anything or break; but they are very easy to use.  The volume knob is not as solid as the iQube's knob but it is easier to turn.  If you apply pressure to it from the side it will wiggle a bit like a loose tooth.  But this does not affect nor is it noticeable throughout its operation.  From a build quality standpoint I prefer the iQube's knob; but from a functional one I like using the Fostex's a little more.  It is smooth with no binding and you don't feel the need to hold onto the unit while turning it.

Function: 

When my Fostex first arrived, it worked straight out of the box without any charging.  While this may not really mean anything, I generally take this as a good sign.  I played with it for about an hour and then I charged it overnight.  To power up, you just turn the volume knob.  There is the very slightest of turn-on clicks and a slightly louder turn-off click.  I want to stress that both are very subtle and of no concern whatsoever.  If you have the iPod connected already, turning on the HP-P1 will put the iPod into LOD mode immediately and the music will start in under a second.  The same thing will happen if you plug the HP-P1 into the iPod when both units are already on.  No glitches, no pops- nothing.  Another neat thing I noticed is that if you turn off the HP-P1 while music is playing, the iPod will act as if the device has been unplugged which will put the music player into pause mode.  I think that's convenient because it makes turning off everything possible with a single action.  The line out jack appears to be completely independent from the headphone jack.  This means that not only does it bypass the volume control, but also you can run both it and the headphone out at the same time if you find the need to do that.  I have not tried the Toslink out yet.

One caveat:  For some reason I expected this to be compatible with all recent iDevices including the iPad.  But after trying it out with my 1G iPad, I heard little random 'clicks' during playback.  I've heard this before in other USB audio chains.  After looking at the manual, website, and brochure, I realized that they never made the claim of iPad compatibility- iPods and iPhones only!  This is not a big deal for me.  But be aware.  The Cypher Labs AlgoRhythm Solo apparently does work with iPads, as it is stated specifically on ALO's website.  I also tried the HP-P1 with my 6G Nano with fine results.  Edit:  At the suggestion of cooperpwc, I went back to the iPad and did a reboot (just normal, not 'hard'), plugged in the HP-P1, and it works just fine!  No clicks or any other noises during playback.  Thank you so much for the tip!  This gives me more options and may come as a relief to others.  Sorry Fostex!  I'm still curious why they didn't list at least the 1G iPad on their compatibility list.

At the end of my first complete battery cycle I got about 8+ hours of playback time.  I was very pleased with this!  Whenever I read the manufacturer's claims of battery life, I usually expect about 60-70% of the stated runtime.  (Apple seems pretty close though.)  This one actually went well over the claimed 7 hours.  In contrast, nobody can seem to get a solid number from Qables for the battery life on the iQube v2.  (I get about 12 hours from mine.)  Oh- and when the battery does die the Fostex just goes silent without the slightest bit of drama.  No clicks or pops (unlike my iQube) and the iPod just acts like the LOD was unplugged.  It will also play and charge at the same time since the USB charging port is separate.  I don't have the guts (yet) to open the Fostex up to see what kind of battery pack it has; so I hope it's something relatively easy to replace in the future.

If there is one impression that I walk away with right now it's that all of the functions of this thing have been well-tested and there are no bugs or 'personality traits' that often come with ground breaking or esoteric devices.  It's how I would imagine the Lexus LF-A: exotic, but with all the quality and 'normalcy' you'd expect from a Toyota.  


Sound:  
DISCLAIMER:  To my ears and in my head the differences between various amps (including iPod headphone outs) on IEMs is relatively small.  Sometimes I can A/B them reliably- sometimes not.  In most cases I doubt I can correctly and reliably identify (actually name) an amp if played on its own.  IEMs and headphones are a different story for me.  So now that you know what you're dealing with and with that out of the way, on to the sound!  This portion of testing was done with my iPod Touch 4G, UE Reference Monitors, and Sennheiser HD580s where noted.

For noise floor testing I ran my Sheffield/Coustic 'All bits Zero' test track and… let's just say I had to skip to the next track to make sure that everything was working.  Is this thing on?  There was nothing.  Zero.  Zilch.  This is with the 'Gain' switch set to minimum and the volume pegged at max.  I would consider my UE RMs to have slightly above average sensitivity for IEMs.  I was incredibly pleased with this absence of noise because one of my goals is to have a set-up that is noise free- a very objective and reasonable goal.  The (analog) LOD on my iPod Touch is not noise free.  It's not bad, but it's not dead silent.  The Fostex is dead silent!

Next, I ran my Alpine Reference CD 'Bruel & Kjaer Installation Sine Sweep' just for kicks.  All went smoothly.  No strange irregularities, pops, noises, or anything else weird.

I would say about 80% of my listening is done with IEMs.  The rest is with headphones.  I used a set of HD580s for this next test to get an idea of how well the HP-P1 can drive headphones.  With the 'Gain' switch at the maximum setting, the vast majority of my listening could be done at around 1-2 o'clock.  To give you an idea of the relative loudness this unit is capable of, here are some popular tracks that you might also have in your library and the volume position needed to get to reasonable listening levels:

- Michael Jackson 'Wanna Be Startin' Somethin' (The Ultimate Collection) Volume position = 12:30
- Dire Straits 'So Far Away' (Brothers In Arms) Volume position = 3:30
- Esperanza Spalding 'Winter Sun' (Chamber Music Society) Volume position = 2:30
- Supertramp 'School' (Crime of the Century) Volume position = 2:30
- Tower of Power 'What Is Hip?' (Direct CD-17) Volume position = 5:00 max**
- U2 'Where the Streets Have No Name' (Joshua Tree) Volume position = 2:00
- James Newton Howard 'E-Minor Shuffle' (James Newton Howard & Friends CD-23) Volume position = 5:00

** wish this could've gone a little bit louder.

As far as volume tracking goes, with the HD580s (maximum volume gain setting) there was only imbalance at the very beginning of the volume travel- just as you can start to hear some sound.  With the UE IEMs (minimum volume gain setting) there was some imbalance and fuzziness at very low levels.  But we're talking about a level so low at which I can't imagine anyone listening to- even for background music.  I hesitate to even bring this up.  I would consider it a non-issue unless you have some special need that would require such listening.

In a brief listening comparison with the iQube:

• iQube has more clear and present upper midrange (~3k).  The Fostex is a little warmer with emphasis around the lower mids (~350hz).
• Fostex has more bass- quite a bit more.  I thought it might have been the overall tonal balance, but I think it has more weight and impact too.
• Fostex seems to reach a little higher in the highs (~10k).  The quantity is similar to the iQube's, but there is a wee bit more sparkle on the Fostex.
• The results of some of these tonal differences are that the iQube has a slightly taller soundstage while the Fostex sounds more grand- think large hall with a lower ceiling.

The above testing was done between the iQube via LOD and the Fostex via digital LOD, both from iPods.  What's interesting is that when I switched the Fostex to using the analog line out from the iPod, the results were pretty much the same.  This tells me that a lot (or most?) of the differences between these two units are coming from the amplifier sections.  I haven't figured out a quick and easy way (yet) to send simultaneous digital streams to these or other outboard DACs to compare just DACs.  Hopefully I'll get around to that later.

As for the 'Filter', I have yet to spend significant time playing with it.  However, my initial impressions are that sometimes I think I can hear a difference between the two settings- and sometimes I can't.  What I can say is that if there is a difference, it's quite subtle.  I'll wait and see what others find and spend some more time with it myself.

Summary:
If you look at my collection of gear you might ask, "Where is he going with this?"  The answer is: I like variety.  So to ask me which amp do I like better- I'd have a hard time answering that.  It depends.  What music am I listening to?  Which recording?  What IEMs?  What is my mood?  And so on.  If pressed, I would say that the iQube does sound a little bit more 'honest' and revealing- perhaps closer to neutral.  All I can say is that for a guy who normally doesn't hear big differences between these things, I'm glad that these two each have a fairly distinct sound of their own and I will gladly use both of them.

Well, that was not a ton of information; but I hope it helps start the conversation!
 

I am not an engineer (I do not even play one on TV... ) However, according the the HP-P1 manual this should work when using the HP-P1 as an external DAC.

I am not an engineer (I do not even play one on TV... ) However, according the the HP-P1 manual this should work when using the HP-P1 as an external DAC.

I just bought an external battery charger for when the HP-P1 runs out of juice and need a few more hours. I am going to use the USB out from the battery and it is asking me is the device I want to charge 9 or 12 volt? I've checked the specs in the manual and cannot find the answer.

Can anyone help please?

This is what I bought

Thanks!

Anyone....please? Boarding the plane in a little while and don't want to blow up me and it 

I thought USB makes these decisions for us. But maybe I'm wrong. I'm only aware of 5V and 12V when computers are involved. My best guess is you can use any of the voltage settings it allows, it will charge faster the more current is available. 

ADD: I have used my USB battery to charge my HP-P1, no problems for me. 

I have been using a Motorola charger that is a 5 volt USB and it has worked just fine with the HP-P1. Sorry I was slow getting the info out. It has been a crazy travel week.