Friday, 27 September 2013

Siena's Stratocaster - Shielding the Pickguard

Today I shielded the back of the new perloid pickguard I bought for Siena's stratocaster. For this I used adhesive copper foil purchased from eBay. I gotta say, I love this stuff! It's awesome to shield both flat surfaces like this, and pickup/control cavities. If you are buying this stuff from eBay or whereever, it is very important that you make sure it uses conductive adhesive. If you don't, the overlapping strips of foil won't form an electrical connection and your shielding will be useless. The whole surface you create must be one large ground conductor!

The secret to effective shielding is to create a complete Faraday cage around your hot (signal) wiring. The faraday cage is grounded so that any estraneous EM radiation in the playing environent is collected by the cage and directed to ground rather than being accepted and transmitted as noise by your guitar wiring.

To create an effective faraday cage, a good conductive surface must be created above, below and encasing the whole cavity, with as few gaps as possible. This means that the shielding from the walls of cavity must overlap the edge to make sure the top shielding (ie on the back of the pickguard) is electrically joined to it. Also, the shielding must be electircally connected to your circuit's ground (along with the grounded bridge, output jack, and control casings). What I love most about this copper foil though, is that it makes this job much easier by allowing ground wires to be soldered directly to it!

The next job I need to do is to work on shielding the walls and floor of the cavity itself. In the next few days I'm going to trial some Stewmac Conductive Shielding Paint to see whether this can do as good a job as the foil. With a cavity as big as the one on this strat, it's pretty expensive to foil the entire thing. The question I have though, is just how many coats of conductive paint do I need to create a good shielding surface? If it's more than 3 coats, then I'm not sure the paint will be an effective solution.

I will attempt to answer this question before deciding whether to use the paint or not, so stay tuned for trial results!