Aux in and/or Headphone Out pedal?

[Octavian]

So I'm aware adding an aux in to an amp can be a bad thing for the speaker. I'm also aware that adding a headphone out to a tube amp can be a bad thing. This is neither of those things.

I'm thinking of a pedal that goes right before the amp, that's basically an aux-in / headphone out pedal. If the pedal is on, the signal is cut from going to the amp, and instead goes through a built in little mini amp (maybe a LM386 or something like that) and to the headphone out jack. This also connects the aux in. The point is to be able to run your guitar through your pedals and out to headphones to play at night without having to unplug a bunch of stuff.

Thoughts?

[MaxPower]

Search for A/B box. I think that's basically what you're talking about (with a headphone amp added to one of the outputs).

[Octavian]

Ha! You're totally right MaxPower - I didn't think of that. Maybe I'll do something like an A/B box plus this. So, I guess my revised question is: How do I add the aux in to that? Can I just wire the switch to connect the aux in left and right to the headphone out left and right? Do I need any additional circuitry in there?

MaxPower - just noticed the latest member is MaxxxPower. Is that your pornstar alias? 

[GibsonGM]

Sounds like, if you want to use your pedal chain, you don't need 'aux IN' so much as 'aux OUT', right?

You could just run your last pedal into a headphone amp, a stand-alone thing you can use anywhere rather than 'build in' to something existing; easy enough to make the levels work with a simple volume/gain control.   Maybe you'd want to incorporate a cab sim, too?   They won't sound the same just 'going direct' like that - speakers work wonders on tone  

[R.G.]

The Workhorse amps had headphone outs, CD mix inputs, and a 9V dc output for running pedals as part of the amp itself.

[Octavian]

Sounds like, if you want to use your pedal chain, you don't need 'aux IN' so much as 'aux OUT', right?

I guess a statement of goals would be good.

I'd like to be able to - without having to plug and unplug much (if anything) - be able to play along with some music through headphones and have access to my pedals. Getting the sound from my amp would be great, but if that's not possible then I'm ok with using something else. This is more for practicing than rocking out. And of course, I'd prefer to build rather than buy - what forum are we on anyway?!? 

[GibsonGM]

Hmm...I made a (stereo) headphone amp from one of the MANY designs you can find on the net.  I believe I actually  just passively mixed the 2 sources (computer out and multi-effects pedal out) thru 1k resistors, and sent them to their respective LM386's.   Each channel has its own level control.   How they mix together is set by the pedal/comp. output levels.

This was to take my computer's audio out and allow me to mix my pedal's output into it, so I could monitor when recording into the computer.   Something like this could probably work for you.     Now - adding a line out to an amp isn't (generally) that big a deal (2 resistors, depending on the amp)...how complicated would you like this to be?

A STEREO headphone amp like this would let you use any of your stuff, and also have a line in to monitor audio at the same time.  A cab sim, if used, would just be part of the pedal chain rather than something you need to worry about building in....

[GibsonGM]

I built something based on this: http://www.minidisc.org/schem.gif

For what you want to do, I'd keep the basic setup but possibly would also buffer the inputs so your guitar will play will with your audio source (my outputs are already buffered by comp. & pedal)....and mix the resultant 386 outputs either thru a summing amplifier or a couple of 1k resistors direct to an output jack....DON'T just connect the 2 outputs to a jack without something in the path, tho, or it will probably destroy the chip!

1 dual opamp, 2 386's, and you'd have a sweet headphone practice amp

[PRR]

> play along with some music through headphones

This means a Mixer. Mono guitar, stereo CD, knobs on each, two outputs L and R.

Follow that with some gain and power to drive headphones.



This does NOT mix CD into the guitar amp. That does not seem to your need(?). Adding that frill would need more parts, and I am too tired this week to be so clever.

The guitar input probably wants to be buffered against the mix network impedance.

"CD" may of course be WalkMan, iPod, etc.... any hot stereo line level.

As the "CD" is likely much stronger than guitar, I've used larger mix resistors on the CD side.

Pots may be 50K, and probably Audio taper.

The hi-gain output stage may be LM386 with about 180 Ohms between pins 1 and 8. Do not omit bypass cap on Pin 7. Somewhere recently I posted a detailed LM386 headphone-amp plan.

I have shown the Amp Out coming from the guitar buffer because it seemed convenient. If you are adverse to an extra buffer in your amp-chain, take amp signal before the buffer with an either/or switch. (Could be a switched jack?)

[MaxPower]

MaxPower - just noticed the latest member is MaxxxPower. Is that your pornstar alias? 

wth? Someone must have a really powerful hair dryer.