Wax-Potting Pickups to Eliminate Microphonic Feedback

When I was working on a 1967 Telestar T2 Teardrop recently, I noticed that that both pickups had become microphonic. What does that mean? The pickups had become ultra-sensitive, squealing with feedback and creating sounds at the smallest tap on the guitar. The sensitivity is caused by windings coming loose, so that they can slide up and down on the polepieces. Each shift in winding position causes sound and/or feedback by induction, just as the magnetic coil inside a cardioid microphone does.

In an extreme case, a microphonic pickup becomes a rudimentary microphone, so that you can speak into the pickup and hear your distorted voice come through the amp. Kind of cool, but after the novelty of Darth Vader impressions wears off, you might want to fix it.

Wax-potting the pickups is the guitar hacker’s solution. (And it’s more than a hack; high-quality pickups are often wax-potted at the factory). Here’s how it works:

  1. Telestar_Pickups_PottingMelt 20% beeswax and 80% paraffin, using a hot plate or crock pot set to “Low.” (You’re shooting for 160-180 degrees fahrenheit, and you shouldn’t do this on a gas range or with flame nearby as wax vapors are flammable). I use a cheap crock pot lined with aluminum foil. You can get the beeswax and paraffin at a Michael’s or other hobby store, and groceries sell paraffin for canning, too.
  2. Lower each pickup into the melted wax for 15-20 minutes, suspending it so that it doesn’t touch the bottom or sides. Rock it from time to time so that it emits bubbles – this lets you know that the wax is penetrating all cavities.
  3. Pull back out and clean off the excess wax. Reinstall the pickup. In most cases you’ll find that the microphonics are gone, leaving a great single-coil tone!

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