Shielding a Hollowbody Bass

[micguy]

hm, interesting, I might revisit one bass that's still picky to some EMI, probably the one from high voltage lines.

if I have a separate battery box, should I shield the wires in between it and control cavity?

It might not be necessary, but it won't hurt.

 

[edwinhurwitz]

My Starfire in my profile pic has a big door in the back and the entire lower section is shielded. It was the only way to tame the Alembic wiring in there.

 

[matthewbrown]

One of the most bizarre things I ever experienced was an active guitar I built that, at one point, had radio frequency interference issues. I lived rather close to a huge AM radio antenna farm, and one day, I had AM radio coming out of my (previously silent) guitar. Oddly, it was far better sounding than most AM radios - very good fidelity of the unwanted signal. The thing didn't have too many components, but at one point I had changed them all, and the AM radio persisted in coming through.

So I tried (in desperation) a different battery. Silence. Swapped the battery back and forth a couple times so be certain, but yes, somewhere in that battery was a poor contact acting as an RF detector. If you're trying to shield against interference (electrostatic and.or RF), yes, even the battery should be shielded. Another takeaway is that and active bass has to be done right, or someday you may have RF issues - active electronics (and batteries) can be RF detectors, passive circuits don't do that.

This is very helpful. I have a noisy archtop bass with piezo pups, and it's had problems with RF interference. Now I have another avenue to pursue. None of the techs can help , it seems.

 

[slowburnaz]

For a dummy coil to work well, it needs to be matched in terms of hum pickup and impedance to the pickup. There is a way of doing this that gets a you an essentially perfect match:

View attachment 7312746View attachment 7312747

Those older PRS Curly basses that had the three pickups did just that... put a fourth one on the back: