Shielding a telecaster - a test and a review
Niels M. Nielsen
A controlled test
The human ear is deceptive. So is the mind. Often people find that they don't hear the difference between a guitar before it was shielded, and after. It may be because we simply don't remember sound very well, compared to eg. visual input. And it may be because subconsciously you gain the amp right op to the level where the noise becomes offensive, in which case you might erroneously think that the shielding didn't really reduce the noise, while in fact your gain level is now much higher than before shielding. This problem is widely acknowledged, and is also mentioned on the GuitarNuts homepage (http://www.guitarnuts.com/wiring/shielding/tele.php), which is my primary reference.
While preparing to shield my tele, I decided to try to work around the problem of the subjectivity in recognizing the impact of shielding. I decided to make a test of the results of shielding in a controlled environment in order to demonstrate the (possible) difference.
On these audio clips you can be the judge of the difference. The procedure was as follows: First I adjusted and noted recording levels on my mixer, sound card and software, then recorded a track directly into the sound card of my PC. Then I routed that audio through two different presets in Amplitube. The resulting three recordings are named 'pre-shielding direct in', 'pre-shielding clean' and 'pre-shielding dirty', respectively. After the shielding operation I did exactly the same thing with exactly the same levels and settings so that there are three corresponding 'post-shielding' clips. The point here is that the recordings are made on the same guitar, same equipment, same electric and acoustic environment (a very noisy one - in front of a PC), same settings, levels and presets. The only source of error could be the fact that I put on a fresh set of strings when reassembling the tele (but the first set was also brand new). In any case, you should be able to make rather exact comparisons between 'before' and 'after' with this setup.
Pre-shielding direct in
Post-shielding direct in
Pre-shielding clean
Post-shielding clean
Pre-shielding dirty
Post-shielding dirty
On all sound clips you hear the three PU settings consecutively, and for each one I eventually let go of the strings so that you can hear the hum of the guitar when not grounded by the touch.
Guitar, hardware and software used for the test:
2002 Fender Standard Telecaster fitted with Fender Vintage Noiseless PU's. First unshielded, then shielded with copper sheets in cavities and on the back of the pickguard.
The guitar is connected through a Behringer Eurorack MX 602A into an M-audio Delta 44 Sound Card running on a 2.8 GhZ Pentium 4 PC.
Recorded with Cubase VST32, and - for four out of six clips - routed through the IK Multimedia Amplitube amp simulator.
All sound clips are compressed in the mp3 format.
Review of the shielding process
I followed the instructions that you can find on the GuitarNuts homepage (http://www.guitarnuts.com/wiring/shielding/tele.php), please refer to that site for the details of the shielding process. However, I had to deviate slightly from their recommendations. I couldn't get hold of spray adhesive and copper self-stick shielding tape. So I used some superglue for the adhesive, and instead of the tape I ordered some heavy 12" x 12" copper sheets and a tele copper pickguard shield from Superior Sound Designs (http://www.monteallums.com). Otherwise I followed closely the instructions given by GuitarNuts. So those are the premises for the review.
The materials from SSD arrived quickly and safely from the US to where I live in Denmark (northern Europe, you know). The sheets are really thick, more like light metal plates than foil. The pickguard shield is the same material and fitted perfectly on the back of the pickguard.
So was it a piece of cake? Not really, no. In fact it's kind of awkward. In my tele the cavities are in fact very complex, for instance, the neck PU cavity has two extra little cavities at the bottom allowing the PU screws to go all the way down. That made it extremely complicated. You need to form a small model of each cavity or curve out of copper foil, then put it into the cavity, and then meticulously press it onto the bottom and sides, making sure that there are no lapses, and no pieces of copper not firmly glued to the wood. There isn't a lot of spare room, mind you, and you don't want the copper touching anything like PU's or pots or anything electrically connected to them (maybe I should come right out and admit at this point that I know next to nothing about electricity, wiring, grounding etc. So please don't take me for an expert on that!).
You might say that my choice of materials is open for discussion. For one thing, I would highly recommend not using superglue instead of spray adhesive. One thing which is just not cool for a guitar player is having the thumb and index fingers glued firmly together :o) (no it didn't happen, but almost!).
As for the copper sheets I'm more in doubt. Frankly, it is not the easiest thing to work with, but it can be done. I used a sharp hobby knife to cut out pieces. I also used a lot of patience. The pick guard shield, on the other hand, was very easy to fit. You have to grant that the copper does reduce hum significantly, but it might have been easier using the self-sticking copper tape recommended by GuitarNuts, though that is surely not as thick and consequently probably less effective in terms of noise reduction. If anyone has tried it, I'd be happy to hear about it.
One last note about grounding. Instructions that came with the copper sheets from SSD recommended to ground everything to one common point, i.e. solder a small wire from the shielding to the back of one of the pots. GuitarNuts on the other hand had no mention of this. Like I've mentioned, I followed the GN instructions, so I did not apply the grounding wire, I only - as instructed - made sure that all copper foil was electrically connected (which involves soldering a wire from the neck PU cavity shielding to the control cavity shielding). But apart from that I didn't apply any extra wiring. I wouldn't know the importance of this. But my shielding seems to work. I'm happy.