Vibration and FeedBack...
If you go back to our post about how pickups work,
you will remember that we don't really want anything inside the pickup moving around. Because the entire guitar vibrates when we play, it is inevitable that the parts that make up the pickup will also vibrate.
This can be a blessing and a curse. The downside is that when the larger metal parts vibrate, they can cause uncontrollable feedback.
This usually is heard in the form of a squeal. Bad stuff. It is made worse when we play very loudly or use a lot of gain.
Not all feedback is bad. Some of the vocal, musical qualities that we like about good pickups are a result of the coil wires and other parts moving around a bit or being slightly "microphonic". As long as these qualities are controllable, they can make for a very dynamic pickup. How does wax potting affect and control these extremes?
Why Wax Pot?
When we wax pot a pickup by dipping it in hot wax and allowing the wax to seep into all the little gaps in the pickups construction, we dampen the vibrations and resulting feedback. This is almost always good. It means no more uncontrollable squealing. You have to be careful though. Wax potting for too long, or with too thick a material can dampen the pickup to the point of sounding sterile or bland. Each pickup maker has their own method of doing this to get the results they want.
The good balance is found when the pickup can still sing and sustain, without being out of control. Watch the video for some other ways to control feedback and vibration