DIY Headphone Amp

[vrom]

I would like to build a box that I can put at the end of my effects chain and that has an in, an out and a headphone out jack (3) total. Perhaps a footswitch to choose between the signal outand headphone out. Maybe a volume knob for the headphone amp section.

I have seen schematics online for something like this, but if anyone here knows of a build, with instructions, that fits this description, do let me know. I am a total noob with regards to reading schematics, and I don't want to go back to school for electronics just to build this unit.

And yes, I realize there are a few effects pedal manufacturers (some I respect highly) that have something like this in their inventory, or who could build it for me, for a hefty price. But where would be the fun in that? Besides, the only ones I'm interested in are several hundred dollars, and/or don't have all the feaures (or too many) that I want.

So, guitar signal in, guitar signal out, headphone out, switchable with volume knob...and instructions on how to do it.

No worries if I can't find an answer. Hours of trolling online has produced nothing useful for me, save a schematic I can't read (might as well be written in Klingon).

Thanks!

[mysteriousj]

I've been really meaning to build one too.. I often used to get banned from playing guitar in my flat when there's exams etc so I really need one .

I actually had like 3 different pcbs made for a few different headphone amps I designed. I only ended up building two of them and of those the best one was a little too noisy for me. I've still got the other design which might work I kind of just forgot about it and have been busy with a few other projects. My design was based on the TDA1308 and has 4 knobs. Volume, Treble, Mid, Bass. (fender style).

Anyway if I get some time this weekend I'll dig them out and see if I can fix them I hardly spent any time on them. If I get something working I can send ya a pcb, but yeah IF I can get something working

[vrom]

Heh, thanks!

Anyone else? TBH, even the prebuilt headphone amps by those manufacturers I love and respect aren't quite what I want, though they look like nice designs. More than I need, or not enough, I guess...

[eatyourguitar]

I think you want this
http://headwize.com/?page_id=707

only I would bridge the inputs of the two opamps to the one guitar signal. you must make your own stripboard layout or etch your own PCB. you might be ok with a mono headphone amp but I would try to avoid it.

[mysteriousj]

I think you want this
http://headwize.com/?page_id=707

only I would bridge the inputs of the two opamps to the one guitar signal. you must make your own stripboard layout or etch your own PCB. you might be ok with a mono headphone amp but I would try to avoid it.

It's more complicated than this as you need to compensate for the pickups mid frequency emphasis as well as low pass anything over ~5kHz. You also need more gain as this is expecting a line out input. BUT if you have some kind of preamp that does this it may work.

[vrom]

ooof... see what I mean? Maybe I should just save the duckets and have [sfx] build me a custom jobber...

I may be in over my head. Soldering wires to jacks and building a BYOC with step by step instructions is easy... this, not so much.

[eatyourguitar]

stick a BS170 pre on it. why would you want to scoop the mids? I'm not comprehending sorry. even if you scoop mids, would it be a different resonant band for every set of pickups? and does the preamp remove any kind of interaction that would cause this mid bump? take me to school please. the 5k LPF is an easy fix with an RC filter. I would go higher like 8k. you might not want to filter out the fizzle of some distortion pedals or octavers.

[mysteriousj]

Have you ever plugged your guitar directly into a keyboard amp/ stereo or any full audio spectrum amplifier? Basically what you'll hear is not good :P.

It's not really scooping mids it's more of a correction. All guitar amps do this. Pickups don't have a flat frequency response. Mid frequencies get picked up much better compared to the bass and high frequencies so all you're doing is really correcting this to give a more natural sounding instrument.

And nope you don't have to change this to suit such and such pickups. That's why different pickups sound different, they will react slightly differently to give you a different tone. But they're all roughly the same so you don't really need to adjust the filters for such and such pickups.

[eatyourguitar]

do you have any simple passive notch filters you would like to share?

[mysteriousj]

Check out, http://www.gmarts.org/index.php?go=212

If you're not wanting to use 3 pots you can just use fixed value resistors. Although having a proper tone control is always nice. Simpler notch filter might work but I haven't looked into it.