How to Disable Headphones-Speaker Mute of a Guitar Amp?


See, we have a nice digital guitar combo amp with a headphones/record out jack. We'd like to connect the amp to the PA system. The thing is, it automatically kills the speaker once you insert something on it like a headphones.  We swish to use the jack as a direct line out without killing the speaker.

In addition to this, I also wish to do the same thing on our electric piano with built-in speakers. It does the same thing of muting every time you plug it to the PA.

1. How do you tweak and bypass this mute function on some combo amps/instruments?
2. Does the same principle/switching applies to these situations?

Hope to see your post soon! Thanks!

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orksecurity6 years ago
They're using a switching jack for the headphones. The amp has only one output, and plugging in the headphones "steals" that output.

To change this, you would have to rewire the headphone jack so it is in parallel with the normal output path. HOWEVER, that additional load could have unpleasant effects on the circuitry, so you might wind up needing a to add a high-input-impedance amplifier between the box and the headphones before it would work as intended.

Another solution, of course, is to just have whoever's running the PA put the keyboard and guitar output in the stage monitors. Which is probably what the folks who designed this equipment assumed would be done. Of course that only works if the PA *has* stage monitors and the guy running the sound equipment has at least a vague clue.
ervzman (author) 5 years ago

So, is it possible to JUST disable that switching device? I imagine it is a normally 'on' mechanism that changes when in contact with the plug, so I can just 'jump' it?
JackC167 ervzman5 months ago

Did you try the above, ervzman? I'd really like to be able to do this to a bunch of Casio keyboards, and am hoping its a simple case of jumping the switching jack.

dentsinger1 year ago

Those jacks are usually 6 pin board mount 1/4" jacks (AKA stereo). Since the signal is actually mono from the amp, it's using 2 of the jack pins to act as a disconnect. Figure out which pins they're using for the disconnect and solder a jumper across the 2 leads.

I've just done this on a Roland Cube 30x.

The Cube 30x mutes the speaker when you plug in a cable to the recording out socket. Modern amps use complex plugs and complex switching circuits from the logic boards, rather than simple jack switches.

Unless you know exactly how they work, or your amp is very simple, you should not interfere with the socket or logic boards.

All is not lost, though.

I installed an additional jack socket to my Cube amp and, following the simple circuit diagram shown in the link below, I wired up a patch from my speaker to the additional jack socket.


So I could get a variable output level I installed a 1k variable potentiometer instead of a fixed 1k resistor.

If I get time, I will write an instrucable article detailing how to do this.