Updated with pics and new content 20/10/2019
The first step is to rig up a pickup to a jack and test it out in different positions in front of the guitar to see what tones you like. Try getting a friend to hold it over the 12th fret, and right down by the bridge. Electric strings are recommended but not strictly necessary.
Now for the build:
I start by picking a spot to mount the pickup, then checking the underside of the top for braces (I don't like cutting through those, they're there for a reason). Then I mark the hole to cut, take the strings off, and get cutting with the dremel. I recommend using masking tape for doing the markings; that way you can move it around if need be and you don't mark the instrument itself.
Mounting it on the south edge (toward the bridge) of the soundhole is my favourite spot. I love stratocaster middle pickups and it's less cutting to do. The pickup is then test-fitted in the hole, and then the screw-holes are marked and drilled.
The first step is to rig up a pickup to a jack and test it out in different positions in front of the guitar to see what tones you like. Try getting a friend to hold it over the 12th fret, and right down by the bridge. Electric strings are recommended but not strictly necessary.
Now for the build:
I start by picking a spot to mount the pickup, then checking the underside of the top for braces (I don't like cutting through those, they're there for a reason). Then I mark the hole to cut, take the strings off, and get cutting with the dremel. I recommend using masking tape for doing the markings; that way you can move it around if need be and you don't mark the instrument itself.
Mounting it on the south edge (toward the bridge) of the soundhole is my favourite spot. I love stratocaster middle pickups and it's less cutting to do. The pickup is then test-fitted in the hole, and then the screw-holes are marked and drilled.
I often leave out all controls just for the sake of simplicity (it's nice just controlling volume with fingers and the amp, but whatever works for you). Continuity between the pole-pieces (or just the largest bit of metal on the pickup) and the ends of the coil are tested, and whichever side is connected to the most metal bits goes to the ground on the output jack.
This is the tricky part: you'll find that there's a hum, unless you're putting a really expensive pickup in your acoustic. This is especially apparent with single coil pickups.
This is because your strings aren't grounded and they're acting like some sort of antenna. There are many other causes for hums but this is the biggest one.
In my guitars, two holes are put in the saddle between the bridge and the pins (or tailpiece/stoptail whatever). A piece of nice copper (or literally anything that'll contact the strings) is bent to fit into the holes. One holes goes all the way through the top and the other is just to make it comfy for the player (the copper is bent into it).
The end of the copper wire that goes into the guitar is soldered to a thinner wire which goes to the ground on the output jack (or the volume knob, if it has one). Slap some electric strings on it and you're good to go.
This is because your strings aren't grounded and they're acting like some sort of antenna. There are many other causes for hums but this is the biggest one.
In my guitars, two holes are put in the saddle between the bridge and the pins (or tailpiece/stoptail whatever). A piece of nice copper (or literally anything that'll contact the strings) is bent to fit into the holes. One holes goes all the way through the top and the other is just to make it comfy for the player (the copper is bent into it).
The end of the copper wire that goes into the guitar is soldered to a thinner wire which goes to the ground on the output jack (or the volume knob, if it has one). Slap some electric strings on it and you're good to go.
Sometimes you'll need to wrap the copper piece with more wire to bring it up to thickness so that all the strings are contacting this grounding rod properly. See the pictures below of some of the modifications I've done. The only other thing to consider with installing a grounding piece like this is the break angle of the strings behind the bridge (this affects tone and sustain, with a sharper angle generally providing more sustain). I try to minimise the height of the copper so that the original string geometry of the guitar is maintained.
Obviously a better, cleaner way to ground an acoustic is to make a new bridge for it out of metal, and then hide the hole for the ground wire underneath the bridge itself. I've done it before, but getting the geometry right for a completely new bridge is difficult.
Especially when all you wanted was just to put a pickup into your guitar. The other downside to this is that changing the material of the bridge can change the natural tone of the instrument. Denser bridges and nuts tend to be better, but generally by putting a pickup in I'm trying to capture the tone that's there rather than altering it completely.
Next project: Finishing the big S H O E G A Z E acoustic you see above (the maroon one with the two pickguards). It needs a low profile roller bridge and maybe some more pickups.
Thanks for reading, and I hope this guide helps with your sonic endeavours :)
