ImageI originally posted this article on the OzBass forums a few months ago. ‘Debbie’ (as in Harry, from Blondie) & I didn’t see eye to eye, so she  has since gone to a more appreciative home. I’d have loved to keep her, just to gaze lovingly at, but I’m a player, not a collector!

ImageThis was the stock wiring; random pots with 6mm shafts, and a .1 uF capacitor (versus the more typical .047 uF used in Precision basses). The pots were okay, but the .1 uF capacitor is just a bit too woolly for my tastes – you don’t get a lot of signal left over 400 Hz when you roll the tone back all the way.

ImageFirst of all, thoroughly clean all the dust and buffing compound out of the cavities – this helps the tape stick. Before cutting out random shapes, rub the foil over a control or pickup cavity to get the perfect fit. Cut outside the line, so there’s a bit of overlap.

ImageI don’t try to get the sides done in one piece as you can never keep the alignment through the corners. Cut the foil slightly deeper than you need, and cut some slits in the bottom edge so it doesn’t bunch up. Watch out that you don’t go over the top to the extent that the foil will peek out from under the pickguard/bridge plate/control plate etc. Finally, run a strip up the side to one of the control plate screw holes to ensure a good tight connection.

ImageA digression: on the left we have an Electrosocket jack system of random Asian manufacture. On the right is the standard cup & jack arrangement used by Fender. One of these will slip at a random moment on a gig, and will be a huge pain to fix. Note that I’ve used a stereo jack (it’s a fairly accurate clone of the Switchcraft ones, but costs about 1/4 the price) – this prevents the plug becoming loose once the jack wears out over time. Can’t remember where I picked up this little tip, but it’s a keeper.

ImageSandwiching the bridge ground lead between a strip of foil & the bridge itself ensures a good connection – if you’re paranoid, you could tape over the wire too.

ImageIt’s important to electrically connect all the cavities together – normally I use the shielding braid from some good quality coaxial antenna cable; it’s great as you can run at least two wires through it to shield them, so long as the hole is straight. I got a little creative this time and went under the pickguard. Needless to say, a multimeter (even a cheap one)  is essential to check continuity – try and get one with an audio tone so you’re not always watching a display.

ImageNote that I shielded the entire pickup cavity – the copper foil reflects the black of the pickup cover, so it looks stock. I then ran a foil tab up and over to where the pickup cover was going to be installed – I decided I might as well make it functional & help to shield the pickup from interference.

ImageHere we can see the finished wiring – I’m not sure if the twisted wire actually ‘rejects’ EMF noise, but it’s worth a shot, especially as I didn’t shield the jack cavity or the connection between pickup and control cavities.

ImageI like to be as economical as I can with my wiring, while leaving just enough wire to re-do the job easily later. Of note is the .047 uF paper-in-oil capacitor – it doesn’t do much to the tone, but it looks cool. You’ll see I used one leg to ground it to the volume pot, via the volume ground lug. The bridge, jack and pickup grounds are all hooked up to the wire between the volume ground lug and the pot casing – just loop them over and crimp them tight with a set of needle-nose pliers, and you can solder the whole lot in rapid succession. Always make a good mechanical connection before you pick up the soldering iron if you can!

ImageAs an example of a bass where the pickup is surrounded by the pickguard, here’s my Aria Pro II. It is shielded with my older batch of foil without the conductive adhesive. Note the tack soldering; it’s a major pain in the ass. I went a little over-the-top with this one, you need just enough solder to make an electrical connection.

ImageDon’t forget to shield the underside of the pickguard too – I’ve used conductive foil again here. You’ll only get the full benefit of the shielding once every screw is in place to hold down the pickguard & controls plates. I was chasing a bad connection for half an hour when I shielded my Jazz bass, before I thought to install every screw. Doing so immediately put the clamp-down on the buzz as well!

Points to note:
– hookup wire &  shileding foil in small amounts is usually cheapest on eBay.
– I love vintage style cloth covered wire – it’s a piece of cake to work with, no wire stripping required. Rub it in some dirt or ash if you want it reliced.
– if you shield the jack cavity, make sure the jack doesn’t touch the sides when you plug in. It’s far better to have some EMF noise than to short-circuit the bass entirely – if in doubt, give it a miss.
– CTS pots are overrated in this case, as they are a 1/4″ shaft, slightly over 6mm. The original MIJ ‘chrome dome’ knobs won’t fit, nor will any other metric (6.0mm) knob. Although purists may sneer at using anything other than CTS pots, Alpha pots are metric (and smaller) and practically as good in terms of quality. I’ll be using them from now on – since most of the time I’m replacing 16mm pots with metric shafts, I may as well re-use the knobs.

As I mentioned in my long-winded post about ‘Miss Blue’, my old Jazz bass, shielding is one modification with no discernible downside. It can make a P.O.S. instrument gig-worthy, and a good player just that little bit more special!

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