These comments are from a “newbie". I am trying to get satisfactory volume from a rod piezo pickup inserted in the bridge of a licence plate CBG. The bridge is the outer shell of a barrel bolt. I have the piezo just lying in the channel; I get no where the volume as I get with a disc piezo placed within the sound box. Should the rod be fixed in the channel with something like a two pot epoxy?
Also I seem to get better results with disc piezo's when I have them connected straight thru, i.e. no volume or tone pot. The above is based on very few observations
I cut one down for this 2 string build i did. The rod was cut down to a 1 1/4" length to work in the carved bone skull bridge. What i made up was a tester to make sure the rod is still in working order after i cut it. 2 alligator clips soldered on an input jack. I started using the 2" uke rods on my 1x2 neck width bridges. But now and then i still have to cut one for custom orders. I use a pair of sidecutters and snip the rod off on the side of it, sometimes it is necessary to take a pair of pliers and resquare the end of the rod after cutting. But i always test the rod after cutting or removing the 1/8" plug off the end of the wire. Better to make sure it`s working before sticking it in the bridge base and stringing up the build.
I have tried both solutions too. The rod piezo in far weaker than the disc.
Today I tried an other solution. I cut my bridge in two.
Strings//// 0.0787 inches of wood//// the rod piezo//// then the rest of the bridge.
The volume is higher but and that's where this piezo is not usable at all, the volume is not the same for all the strings. I would say that the middle string has some volume and the other strings are weak.
It's a lap steel guitar, the tension is high, the tail is tight, the vibration very good. So, what's wrong when it is written on the add that it's a good piezo ? !
You need very hard wood to transfer the vibration to the rod. Randys' method of using bone would be very effective as it is very hard/dense material. I've used bamboo skewers.....not as good as bone or steel, but does provide a reasonable transference of vibration/sound to the rod piezo. Average density hardwood, will dampen the vibrations to some extent.
I tried the rod piezo in the channel of a barrel bolt. It did not work even when the rod was cemented in with very dense plaster cement. I got a great result by boring a 1/8 hole down the centre of a 10 mm brass rod and inserting the piezo. It fitted very snugly. With this arrangement the piezo was about 4 mm below the strings with a full metal connection
The whole basis of a rod piezo is it has to have pressure on it to work correctly. Unlike a disc piezo that works off vibration. So when your using the rod in a slotted bridge you need a dense material for the saddle, be it bone, exotic woods, even a brass rod. It works from string pressure on the saddle transferring the pressure to the rod. Can`t explain it any easier....lol. just look at my photo`s i`ve made alot.
Ok, I have checked. The rod although it's brand new doesn't work. Only the middle ceramic bump reacts.
So I took an other one. It works but as the strings of my lap steel don't correspond to all the bumps, some strings have a weak volume. As the difference in volume is too big, I can't use this rod for this kind of guitar.
The wood I use is a dry, very good rose wood.
When I put the rod piezo inside the brass threaded rod bridge I didn't (couldn't) line up strings and bumps unless accidentally. It worked fine. I did not shorten the rod for a 3 string CBG. It was a licence plate resonator CBG.
You can get flexible/bendable piezo rods that have a continuous pickup surface rather than set wafers along the length like these
and so you don't have the problem of lining up the strings.
These give you an idea of how flexible they are
Piezo cable is available in the USA from "Experimental Musucal Instruments". It is sold by the inch