how to make amp phone jack

[Tone Monster]

i had a amp,small practice amp but i don't have phone jack/line out for the headphone.I need a schematic and how to wire it.I also want the amp speaker turn off after i plug in the phone jack.

[zener]

I also want to know the same thing.

Disconnecting the the amp speaker when using a headphone involves a stereo jack that has an extra lug (total of 4) that shorts with an output lug when there is no plug. When a plug is inserted, the extra lug loose its contact with one of the output lug.

Here's what I want to know:

Heaphones have two channels (stereo) and amps are usually mono, right? Will I just hook both headphone channels to the lone output of the amp or tweak with the amp circuit for it to have two channels (my guess is the first one)?

Thanks for any help :wink:

[petemoore]

Depending on 'how low your amp can go'm yes you could about plug any speaker [at this low volume ohmage isn't so critical but] in, including those in headphones.
 Setting the volume might be very touchy, and blowing the headphone drivers may occur without very judicios volume settings..like I say IF the volume controls low volume real good.
 The 'other' way would be find a preamp tap, and use that into a headphone amp [or some such wiring] and use a fancy jack [I'd use a switch] to disable the output amp, disabling the speaker might not be dangerous, I don't really know what load the amp needs to see, doing all that switching would be the tricky part...yes it could be done, but you'd really be getting just the preamp sound, be about as much or less trouble to make a headphone amp and cab sim and might like that better anyway...I think it might be easier to figure out in the long run, and you don't have to work around high voltages.  Subjectively speaking, [for me at least] the effort would be too great, the outcome couuld be good I guess, maybe...I wouldn't mess with all that.
 I'd but a brand new Behringer Mixer, for like what 50-70 dollars, and have 'that' ...and a lot more..just run the effect into the board, use the headphone out, or get an amp that does that used.
  Sorry for the rains, but seems like a whole lot of messing, possibility of disabling the amp/getting shocked, and there's easier ways to do that.

[Peter Snowberg]

Switching from speaker to headphones involves two things. First, you have to disconnect the speaker, and second you have to supply the headphone output with a series resistor so that you don't blow your headphones. I should also mention that this stuff is for solid state amps only. Never try to use headphones with a tube amp. You want to also have both of the headphone speakers in parallel so that they are in phase.

How you do this depends on your jack to a large amount.

The Marshall style jacks are great for this kind of switching. It is best to use a large jack and then an adapter for your headphones if they use a small jack.

Get a Marshall style jack with stereo and switching contacts. The jack has 6 contacts on it. Connect the amp out power negative to the sleve contact. Connect the speaker negative to the switched sleve contact. Connect the amp positive to the speaker positive and then to a limiting resistor. Maybe something like 220 ohms. That's just a guess. Anyway connect the other end of the resistor to the tip and ring contacts. The switched tip and switched ring contacts get no connection.

This jack will also work as a speaker level direct output.

Take care,
-Peter

[zener]

Oh... how dumb of me to forget that level of the output of an amp can blow up headphones.

Ok, thanks guys. :wink: