Nicer headphone/travel amp design?

[grisezd]

I've been doing more traveling for work than I like to and that's cutting into my practice time. I have a few half-assed solutions for being able to hear my bass, like plugging into my Zoom recorder, small headphone booster, old compressor pedal, etc. but none have been very satisfactory. I've also tried some of the newer headphone amps (Vox amplug, etc) and I've had a Rockman, a guitar model, which has come the closest to working for me. But it's still not a "really nice" solution.

But I've got a bug to play with building one, sort of a boutique pedal-ish amp. I saw that EH has one, but I want to be able to mix recorded music with the instrument sound and the EH doesn't have an input for that.

So, what I've got in mind is a 9V powered Ruby amp (schematics and description here: http://www.runoffgroove.com/ruby.html)
with either just a mix pot or maybe a second amp for the mp3 output. I'd want to have mp3 and instrument in both ears.

So, first question: If I just run the mp3 signal straight to a blend pot, or even just straight through to the headphone jack on the Ruby amp will I run into problems? I don't expect so, since I assume the mp3 player's output and the output of the Ruby are both buffered/isolated. If so any easy solutions, like diodes before the headphone jack?

Second question, do you think it would be worth the complexity to amplify the mp3 signal a second time for a good volume boost? I guess I can try it without and add later, but any suggestions?

Third, I expect that I can modify the Ruby design to better emphasize the low end. Anybody see anything obvious in the schematic or have any experience with this?

Lastly, I think, if it's not ghastly complicated, I'd like to add a bit of compression to the instrument signal, maybe just switchable. Is this a pretty simple circuit? Yea, I know I should look it up and will. I thought about adding some other simple effects, but mission creep always kills my projects while they sleep. I can always bring an outboard pedal if I have to have that.

If I have success with this I'd be happy to share what I come up with or possibly build for those who'd like one. It just really bugs me that there isn't a really good headphone amp. Honestly, rather than buy a $50 POS, I think I'd happily pay another hundred or so for something really nice.

Thanks,
Dennis

[HertzWhenIPlay]

comments, anyone...?
i am also interested in a setup along the lines of what is described above.

[grisezd]

Since I posted this I found that General Guitar Gadgets has kits for the MXR and EH clean boost pedals. I think this might be a good starting point. Still thinking about it...

I also had a thought that there was something called Jam Hub advertized in the magazines a while ago, for multiple players to practice through headphones. Haven't seen one though.

[ian_s]

I know that the Flecktones use Jamhubs on the bus. They look nice but are pricy.

If your MP3 player is an iPhone, have you looked at iRig?

[grisezd]

I just had a look at Jamhub. It does look like a nice device, but it is pricey and larger than I want to carry around. I could use my old 4-track tape recorder if size didn't matter much.

I'm not an iPhone user, unfortunately. That does look like a cool option.