How to install knobs on your bass guitar
BBG tech Max takes us through the tricks and traps of installing new knobs on a bass guitar.
What you'll need
- Slotted screw driver
- Dremel (if you need to adjust the potentiometer)
We are going to look at how to install knobs on our P bass guitar we’ve been working on. In a previous tutorial we installed a preamp with a single master volume control and a stacked bass and treble control.
Adjusting a loose volume knob
Now the bass was previously set-up with just a volume and a tone control. We saved the volume knob to reuse with our new preamp. However, we can tell that it is going on a bit soft. You can feel that it is not grabbing it entirely. We don’t want it to fall off at some point in the future, so it’s best to deal with that now.
Using a slotted screwdriver we spread the split in the shaft. This will help it better engage the knob, which should keep the knob from flying off and getting lost.
Installing the concentric Knob
Now for our concentric knob. For this we are going to have to do a bit of custom fitting.
Because the lower knob has recesses on both sides it can be used reversibly. Whichever side you put down, the bottom recess will cover the control nut and the top recess will allow for the top knob to nest into it.
While pre-fitting it we see that the lower knob goes on nicely. It’s a good fit, and it sits low to the bass. However when we put on the top knob there is a little bit of a gap between the two knobs, which just doesn’t look how we want it to.
We could raise the lower knob to try and cover that gap, but what I’m going to do is just drop that high knob.
Grinding down the potentiometer
Now if we were building this bass from scratch and we had the foresight to do it, we’d just take the potentiometer over to the belt sander and take a little material off the top. But since it’s already built into the instrument we are going to use a Dremel rotary tool instead. Using a coarse bit we’re just going to grind it down a bit.
As you’re doing it work in slow increments, checking the fit constantly, to make sure you get it just as you’d like it.
Aligning the knobs and potentiometer
Now, before we start to tighten the set screws on the side of these I’m going to find the center dent position for each knob. With these particular noble stacked pots that means lining the notch on the lower brass sleeve with the notch in the aluminum post.
The lower concentric goes on first. Then we line up the set screws with the slot of the post. We want to adjust it so that it’s is down low enough so that it looks tight to the bass, but no so low that it rubs against the body.
Now you might be wondering why we have to be so particular with the position and orientation of these. It is so that when we put on the top knob the set screw will drive into the slot, making the two havles expand and holding the knob nicely in place. If we were to put incorrectly, say by rotating it 90 degrees, the set screw would actually be collapsing the split, making the knob sit askew, and it just always looks a little off.
We fit it just like the lower knob – enough to make it look right, but without it scrapping against anything.
Give them all a test to make sure everything is turning smoothly, everything looks straight, and the knobs are held on solidly.