[Matt]

Hello, all.

I KNOW (!) this is only somewhat head-fi oriented, but think of this as helping a fellow listen to good jazz at work where he otherwise could not...

I have a plantronics headset and a problem!

I need someone with some EE or general tinkering background to help me out, if you can.

I would like to buy a project box and accomplish the following:

Plug my headset into the project box (this is a 1/16" miniplug with three contact points, the same jack as you plug into your cellphone with a wired headset: one contact for mic, one for speaker and a common ground)...

Plug my music source (stereo miniplug) into the project box...

and have it mix the music into the voice I hear, however, where the other person cannot hear it.

I have a radio shack unit meant for recording cellphone calls, but the other person hears my jazz music.

I would also like to put a slide "pot" on there to reduce or increase the volume of the mix-in.

Finally, this should all be passive.

Can anyone give me a few pointers or a diagram?

Thank you!

- Matt

 

[tangent]

You can make a primitive sort of mixer with just passives. Basically a pot plus some balancing resistors. You avoid sending music to the caller just by passing the mic signal straight through; the mixer operates only on the line going the other way.

But I wouldn't. An active mixer will perform a whole lot better, and it can be as simple as the above circuit plus a CMoy type amp. Google for "DIY mixer" or something obvious like that. That's what you want.

 

[heatmizer]

Something a bit different. Used a relay with comparator circuit for my motorcycle. You could change it to a latching relay and use a push button to switch the relay back to music.

more info:
http://www.head-fi.org/forums/showth...ght=motorcycle