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Microphonic Wax Potting for Guitar Pickups

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unpotted strat pickups
Guitar pickups contain a coil of very fine wire with thousands of turns. The pickup's job is to convert the moving metal string's vibration into a small electrical current (A/C) and send this to an amplifier however, the string is not all that is "picked up".

It's possible that metal covers and the coil itself can move too which creates an unwanted current - this current results in sounds from your amp.

So what?

Well, at high volume or high gain situations like on stage an un-potted pickup will feed back. There are 2 types of feed back:

Natural feedback

Where the sound looping back from your amp makes the string vibrate and sustain

Microphonic feedback

Where the pickup itself screeches and squeals at you uncontrollably!

The solution? Have your pickups wax potted

The source of the problem is air gaps either in the pickup coil or from a metal pickup cover!

As you can see the wax potted pickup is fully solidified, stopping the pickup cover and coil from moving and creating unwanted sounds

The Potting Process

The wax used is a mixture of Paraffin and Beeswax which is heated to a very specific temperature. At this heat the wax is incredibly runny and can penetrate into the really fine coil winds and replace the air gaps.

Here's an un-potted high-output pickup coil I wound for a P Bass

Bass pickup before wax potting

When the wax has reached just the right temperature I submerge the pickups in the wax

If the pickup has a cover, I dunk the whole assembled pickup in there

Bass pickup wax potting

At first, a small amount of wax cools down and sets on the copper pickup coil. When the coil reaches the same temperature as it's surroundings the wax seeps in

Temperature controlled

The wax and pickup is closely monitored, the wax needs to stay at just the right temperature to remain this viscous but cannot overheat as the plastic work of the pickup may melt. The Paraffin wax is also dangerous at this temperature - the fumes from it can ignite so it's best done in a ventilated area

Air bubbles emerging

This is what I'm looking for: Tiny bubbles coming from the pickup coils.

pickup potting by post
The wax is forcing the air pockets out of the coils all the way into the pickup. When the bubbles stop the pickup is done!

The pickup is then removed from the wax and allowed to cool, then I carefully remove excess wax. When it's dry the wax solidifies and completely secures the coil and any metal covers.

The pickups are then ready to install into the guitar and will now not react to microphonc nasty, squealy feedback!

Book your pickups in for a dunking today! You can post me your pickups, have them wax potted and posted back or book your whole guitar in for the treatment.


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