DIY Bass Hum Busting-Part II


I’ve got a pretty new-old-stock Behringer 4-string I call my Death Valley Test Mule bass.

A $75 flea market find, a new replacement Chinese Kmise $48 Canadian maple neck with bright maple fretboard made it playable. But the humming was bad. And the frets need smoothing.
Inspection revealed the Behringer had almost zero radio frequency shielding (Faraday cage) in the form of tape or special metal paint.

StewMac sells the pricey paint and copper tape with the conductive adhesive, $22USD.dsc06974(2)
But as I’m a notorious tightwad I used random Nashua brand aluminum tape I found in the garage.

Because the adhesive was very likely non-conductive, I needed to fold back edges of each new piece of sticky foil to make sure conductive surfaces contact each other. Or so I figured.
I tried to ensure tape overlapped the top of the cavity to meet the conductive tape I stuck to the pickguard bottom. I scotch-taped all the pieces together.
I finally just put back on the new D’Addario XL nickels, bright as new pennies, and the hum was gone. Wow! I was surprised this actually worked so well without buying musical foil with conductive adhesive.

Good result for only a few hours work. Now it sounds nice and thumpy and I can hear all my awful finger scrapes.

If I can figure out fret smoothing the Behringer Death Valley Mule will not be so sharp on the fingers. My next project for the plague time.

[I cross-posted this to, the social media site and forum for bassists and got this comment: “Long term you might start having problems again because one of the things about aluminum is that it oxidizes very quickly, and the oxide layer is a very good insulator. This will cause all the connections and overlaps to become intermittent leaving the shielding connected to nothing. Thin copper sheet is superior because it doesn’t oxidize as quickly, and it can be soldered together at the joins, making for a good low impedance shield”.

I replied: “Thanks for the tip byacey, if it starts humming again I’ll know to try it again using legit materials. But its working for now.”]

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