I've seen more than the usual number of ukuleles this month. Nice ones, too. A gentleman contacted me about amplifying his Martin tenor (all koa - a gorgeous instrument). He'd purchased a soundboard transducer from K&K, which I've installed before. Working within the close confines of a mid-size uke presents a step up in the complexity department. The soundholes are too small to allow your whole hand inside, and the scale length is just a little too long to allow one to reach the desired location using fingertips. Well, it's possible to reach, but precise placement requires luck.
There are two options for installation - thin double-stick adhesive can be used, or superglue, which provides better clarity and tone transfer. The owner was looking for nice clear articulation, and as this was to be his stage instrument he like the idea of rock-solid attachment.
The transducers (there are two of them) need a clean, flat bridge plate. I used a small sanding block. (This is really important in older instruments where oxidation and atmospheric oils can prevent proper adhesion, or in guitars with rosewood bridge plates.
After sanding it's important to clean the surface. A towel lightly dampened with alcohol does the trick.
Precision in placement makes a difference! With the glue method you only get one shot, and in the heat of the moment, working upside-down in a mirror it's easy to lose one's bearings. I like to give myself some guidance marks. A set of clamping hemostats and the stub of a pencil suffice.
This way I can measure and place the transducer dots between the 1st and 2nd, and the 3rd and 4th strings for optimum balance and volume. Right under the saddle is the place to be.
I choose to install the jack first, as there's enough play in the wires for me to access the dots through the soundhole. The jack hole is drilled undersize, and a tapered reamer is used to sneak up on the proper diameter. Drills tend to chip out the lacquer, or in really bad cases they can tear out pieces of the side wood. I use a little right-angle probe with masking tape on it to mark the thickness of the end block. I can then set the internal nut and washer for the jack at the correct depth and not have to keep test-fitting it until the proper amount of thread is exposed.
This is the end of a standard 1/4" (6mm) jack glued to a length or thin bamboo dowel. I plug in the jack and fish it through the endpin hole. This is helpful in full-sized guitars, absolutely essential for instruments you can't fit your hand inside. (Electrics with f-holes, etc.)
Here's the real trick. A piece of 1/4" (6mm) by 1/2" (12mm) aluminum bar bent into a funny shape that lets me provide adequate pressure against the bridge pad.
The Aloha has a little lip where the lead wire contacts the disc. I made a cork pad with a recess to accept the wire. The dot is held in place with a little bit of double-stick tape. This releases easily after the glue has cured.
A couple of deep breaths to focus the mind and steel the nerves. I like to use very fresh medium viscosity super-glue. The gel works too, but it's slow to set and you have to hold it in place for a long time. There we have it. Nicely positioned and firmly attached! I like this pickup. It's got a whole lot of output and sounds great, even without a preamp.