Ground to bridge - why?

[scook]

Hey Forum,

This is my first post. I'm building an eight string lap steel and have a few questions, primarily about the electronics. I'll post the design here later today, the model is in the hands of my CNC guy now.

But the question at hand: Why do you typically ground the bridge? Are you in effect grounding the strings as well? Is this necessary? I ask because I'm having the bridge and nut machined out of aluminum. I'd like to have them anodized but am worried because anodization isn't conductive. If the strings need to be grounded through the bridge, anodization seems silly.

Thanks for any advice!

[SwedishLuthier]

You put a ground wire to the bridge, not because the bridge or the strings need to be grounded. What happens is that you, by touching the strings/the bridge act as an extra ground (in lack of the correct word in english) and you are drawing some induced noise to your body, thus lessening the noise level quite a bit. The same effect can be achieved by having a simple metal plate were your wrist (or other bare part of your body) touches the lap steel, and have a ground wire to that plate.

EDIT: Or you can use a ESD Bracelet

and connect that to the signal ground (not really a serious suggestion...)

[Tim37]

Basically he is saying yes it needs to be conductive.

A stroke with a file in the string groove should give you what you need

[SwedishLuthier]

Thanks Tim, much better explained! I tend to lecture a bit too much from time to time

[Tim37]

Naw man I didnt mean anything

Most guys on here are not well versed in electronics so I thought a little simplification might be in order.

[demonx]

Anytime I use a bridge that is painted underneath (Kahler) I file a small area of the paint off so the wire makes contact.

One example on an exception to the bridge earth rule is if you're using actives like EMG's. They do not require an earth.