Modding a Stage Piano to add audio outputs

[The Piano Man]

Has anyone had any success adding proper right and left standard jack audio outputs to a keyboard. I am keen on a low cost, simple piano with built in speakers as a backup for gigging but quite a few models only have a headphone output. This means that if you need to amplify the piano further, you lose the onboard speakers.

 

Is anyone aware of any online guides as to how I might go about doing this? I know I would need to drill a couple of holes and add the physical sockets but quite how I"d hook them up, and where I"d get parts from, I am not so sure!

 

Any help much appreciated!

[Reezekeys]

There are a few ways to do this that don't involve drilling holes. First, you're sure that you want to keep the onboard speakers when you plug into external amplification? My reasoning is that if the gig requires external amps, the onboard speakers aren't gonna be much use anyway.

 

The first thing I would do is research, because unless I'm misremembering, some boards have a setting that will keep the speakers sounding when a cable is plugged into the headphone jack.

 

There may be a way to avoid drilling and keep the simplicity of a single cable like this one, if the headphone output jack is a simple switch-type that breaks the connection to the speakers when a plug is inserted. I would want to see a schematic, but by shorting the switches you can permanently have the headphone jack and speakers active at the same time â not what I would do, but again, simpler than drilling holes & installing jacks. Also, what you're proposing to do would in effect be the same (speakers always active).

 

To answer your specific question, no I have not seen an online guide on how to do this. But in theory it's not a hard mod to do â just solder some shielded wires from the headphone jack L&R connection points to the 1/4" jacks. The devil is usually in the details. Finding safe spots to drill with adequate room for the jacks and access for the wiring, along with some possibly delicate soldering work near sensitive components. Not to mention a very obvious voiding of the warranty!

 

[EDIT - Doing a little more reading on this subject, it's possible that a keyboard or other device that turns speakers off when a cable is inserted into a jack may not be using a simple switching jack. It can be indirectly controlled by circuitry that senses whether a device is plugged into a jack or not. I suspect this is not the case with a simple keyboard and onboard speakers though I would definitely want to see a schematic to make sure.]

[Jazz+]

Would like a mod to keep speakers on and use line out on Casio ctx700

[The Piano Man]

Thanks Reezekeys! A very helpful and insightful response. I"ll do a bit of checking on the settings in the first instance. I am sure the Kawai ES100 has this feature and, indeed, the successor ES110 has the proper outputs.

 

The Korg B2, for example, just has a single 3.5mm headphone/line output.

[Reezekeys]

LOL, well I'm an amateur electronics wonk (with the emphasis on amateur!). I started out building Heathkit amps when I was a kid and haven't shied away from trying to fix my own gear (with help from a lot of folks here).

 

Good luck on your quest. Best bet is to find a keyboard that gives you this feature without having to do anything at all!