Copper shielding

[Ou7shined]

So... one thing that's always got me about my S.U.B. is that whenever I play in the house I get a loud hum if I wander within a few feet of my telly. It really bugs me. I've got a bit of copper shielding left over from a previous project and I promised myself that at some point like the next string change I'll whip out the pup and shield out the cavity. My Sadowski Blues arrived the other day so this was my opportunity.
Voilà!
[attachment=14869:SUB_shielding_1.jpg][attachment=14870:SUB_shielding_2.jpg]

As this was more of an experiment than anything, I didn't really expect a vast improvement (if any at all) and in fact I suspected that if I was going to do the job properly I'd have to do under the pup cover and maybe a wee bit under the pickguard too. But no, it totally worked. I can't get it to hum until it is a couple of inches away from the telly - even with the pup side facing the telly. How does that work?

Also, and this might just be Sadowskis (these are my first set so I have no previous experience with them) my bass sounds uber bitchin'. It has never sounded so good, so full and tight after a string change before. Two days later (after resting and resetting the neck due to the different string tension) it still sounds uber bitchin'. I wonder if the shielding has somehow focused the pup?

Anyway either way I'm feckin' glad I tried it and it's a shame that Mr. Ball didn't see fit to do it in the first place.

[Hamster]

I did the same to mine, but I also put an earth connection to the copper shield. Works great

[thisnameistaken]

I should really do that to my Stingray. My house is full of old wiring and dimmer switches and my 'ray fizzes whenever a light is on.

Good work.

[Geek99]

very interesting, where did you get the copper shielding? I know you can get shielding paint from Maplin. My jazz is quite noisy.

[Shaggy]

[quote name='Geek99' post='308330' date='Oct 17 2008, 07:38 AM']very interesting, where did you get the copper shielding? I know you can get shielding paint from Maplin. My jazz is quite noisy.[/quote]
I got mine from Allparts - comes as a self-adhesive sheet or roll; very "Blue Peter"! And like hamster said it should be earthed, the jack socket outer pole or bridge earthing wire is handy to connect to. I couln't get the paint at Maplins except the stuff you repair car rear windscreen heater elements with - that the one?

Edited October 17, 2008 by Shaggy

[OldGit]

[quote name='Geek99' post='308330' date='Oct 17 2008, 07:38 AM']very interesting, where did you get the copper shielding? I know you can get shielding paint from Maplin. My jazz is quite noisy.[/quote]


Well worth it trying ..

[Ou7shined]

[quote name='Hamster' post='308238' date='Oct 16 2008, 10:51 PM']I did the same to mine, but I also put an earth connection to the copper shield. Works great [/quote]
Ooh I never thought about that, I'll look into earthing it soon (got a gig tonight so I don't want to be buggering about with the neck today). Will I have to isolate the springs from the shielding after earthing it seeing as they are connected directly to the poles?

Did you notice a change in tone afterwards?

[Ou7shined]

[quote name='Geek99' post='308330' date='Oct 17 2008, 07:38 AM']very interesting, where did you get the copper shielding? I know you can get shielding paint from Maplin. My jazz is quite noisy.[/quote]
I got mine off ebags. It was an A4 sheet.
I can't remember the exact seller as it was a while ago now but I do remember that their main line of business was copper tape for warding off slugs and snails and as such were more competitively priced to those selling specifically to us musicians.

Edited October 17, 2008 by Ou7shined

[Geek99]

[quote name='Shaggy' post='308335' date='Oct 17 2008, 07:55 AM']I got mine from Allparts - comes as a self-adhesive sheet or roll; very "Blue Peter"! And like hamster said it should be earthed, the jack socket outer pole or bridge earthing wire is handy to connect to. I couln't get the paint at Maplins except the stuff you repair car rear windscreen heater elements with - that the one?[/quote]
No, white can, dark green print. paint comes out dark gray "electrostatic shielding paint" I think - I'll look at the site to see if they still do it.

[Geek99]

they dont sell it any more - try this though

[url="http://www.kookykards.com/shop/index.php?main_page=product_info&products_id=1523"]http://www.kookykards.com/shop/index.php?m...roducts_id=1523[/url]

[Ou7shined]

[quote name='Geek99' post='308424' date='Oct 17 2008, 10:45 AM']they dont sell it any more - try this though

[url="http://www.kookykards.com/shop/index.php?main_page=product_info&products_id=1523"]http://www.kookykards.com/shop/index.php?m...roducts_id=1523[/url][/quote]
I don't think that stuff is self adhesive, like wot I have.

[Prosebass]

This guy sells the best stuff and it usually arrives within 48 hrs sometimes next day. [url="http://cgi.ebay.co.uk/EMI-COPPER-FOIL-SHIELDING-TAPE-LOW-IMPEDANCE-CONNECTION_W0QQitemZ220293313278QQcmdZViewItem?hash=item220293313278&_trkparms=72%3A1301%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14"]Copper Tape[/url]

And if you want to know how it works....[url="http://en.wikipedia.org/wiki/Electromagnetic_shielding"]Read this its easier than explaining it.[/url]
It is also a good idea to run a wire from the pickup shielding to the control cavity and try to make the wire as short as possible otherwise it can act as an aerial.

[obbm]

Garden centres sell self-adhesive copper tape. You find it under slug repellants. You stick it around plant pots and it stops the slugs climbing up but works equally well in a bass.

[Prosebass]

[quote name='obbm' post='308438' date='Oct 17 2008, 11:16 AM']Garden centres sell self-adhesive copper tape. You find it under slug repellants. You stick it around plant pots and it stops the slugs climbing up but works equally well in a bass.

[/quote]


Never really had a slug problem with my basses.....

Seriously though folks, it can be used but is much thinner than shielding tape.

[Ou7shined]

[quote name='Prosebass' post='308450' date='Oct 17 2008, 11:25 AM']Seriously though folks, it can be used but is much thinner than shielding tape.[/quote]
As I said earlier, I'm pretty sure the stuff that I'm using is anti slug (at least it came from a guy that seemed to have it in for them big stylee)... and it works brilliantly.

[Prosebass]

[quote name='Ou7shined' post='308464' date='Oct 17 2008, 11:42 AM']As I said earlier, I'm pretty sure the stuff that I'm using is anti slug (at least it came from a guy that seemed to have it in for them big stylee)... and it works brilliantly.[/quote]

It does the job perfectly and if you are just doing one or two basses it is the easiest to get hold of without recourse to on-line ordering.
I use a lot of it so it makes sense for me to buy in bulk and the stuff from the guy on ebay works out at about 1/2 of the garden center price and its better quality, but you need to buy about 5 rolls which is a little too much for a single bass

[BOD2]

You'll get copper and aluminium sticky-back foil here (just scroll down a bit)

[url="http://www.axesrus.com/axeknobs.htm"]http://www.axesrus.com/axeknobs.htm[/url]


Copper foil shouldn't "focus" the pickups at all as it is not magnetic at all - it will only screen electrical interference without affecting the magnetic properties of the pickup.

[Ou7shined]

[quote name='BOD2' post='308496' date='Oct 17 2008, 12:16 PM']You'll get copper and aluminium sticky-back foil here (just scroll down a bit)[/quote]
Does aluminium work too? I've go a massive roll of alu heat proof tape that I've lovingly hoarded from when I used to work as a heating eng.


[quote name='BOD2' post='308496' date='Oct 17 2008, 12:16 PM']Copper foil shouldn't "focus" the pickups at all as it is not magnetic at all - it will only screen electrical interference without affecting the magnetic properties of the pickup.[/quote]
Ah well, hats off to the Sadowski Blue Lines then. They really are as good as they're supposed to be.

[Prosebass]

[quote name='BOD2' post='308496' date='Oct 17 2008, 12:16 PM']You'll get copper and aluminium sticky-back foil here (just scroll down a bit)

[url="http://www.axesrus.com/axeknobs.htm"]http://www.axesrus.com/axeknobs.htm[/url]


Copper foil shouldn't "focus" the pickups at all as it is not magnetic at all - it will only screen electrical interference without affecting the magnetic properties of the pickup.[/quote]

I have used aluminium tape as it is generally much thicker (5x) than copper so easier to work with. I have also used a combination of the two with copper over the aluminium .
One problem with aluminium tape is that you need a special flux and a high temperature soldering iron to solder to it.
One way round this is to stick a small patch of copper tape on it with a couple of small self tapping screws through both layers for conductivity and then check for this with a meter.
CPC electronics supplies are the least expensive for aluminium tape.

Aluminium Tape

[attachment=14873:Fretless_Shield.JPG]

Then covered with Copper Tape

[attachment=14874:Fretless_Shield01.JPG]

Edited October 17, 2008 by Prosebass

[tauzero]

[quote name='Ou7shined' post='308235' date='Oct 16 2008, 10:49 PM']I can't get it to hum until it is a couple of inches away from the telly - even with the pup side facing the telly. How does that work?[/quote]
Google for "faraday cage" and you'll get the answer.

[~tl]

Looks good, but to finish the job you should add an earth wire (as suggested earlier) and add blobs of solder to connect separate pieces of foil. The glue on the back of the foil acts as a surprisingly effective insulator, so unless you solder across joins you can't guarantee a good electrical connection. The great thing about copper (over aluminium) is that you can solder directly onto it with regular soldering gear. You don't need to worry about covering every seam with solder, as long as there is a blob between each piece the connection should be fine.

Edited October 17, 2008 by ~tl

[Ou7shined]

[quote name='~tl' post='308592' date='Oct 17 2008, 01:44 PM']Looks good, but to finish the job you should add an earth wire (as suggested earlier) and add blobs of solder to connect separate pieces of foil. The glue on the back of the foil acts as a surprisingly effective insulator, so unless you solder across joins you can't guarantee a good electrical connection. The great thing about copper (over aluminium) is that you can solder directly onto it with regular soldering gear. You don't need to worry about covering every seam with solder, as long as there is a blob between each piece the connection should be fine.[/quote]
Cheers. I'm quite chuffed with it actually.
I did it using 3 separate pieces, one for the base and two strips for the sides (no wastage either - I was pretty much on the money with my guestimations - each piece overlaps by about 2-3mm) so I'll be sure to solder them all into one, cheers.

[Hamster]

[quote name='Ou7shined' post='308391' date='Oct 17 2008, 10:01 AM']Ooh I never thought about that, I'll look into earthing it soon (got a gig tonight so I don't want to be buggering about with the neck today). Will I have to isolate the springs from the shielding after earthing it seeing as they are connected directly to the poles?

Did you notice a change in tone afterwards?[/quote]

I didn't bother isolating the springs but I think i did check everything with a multimeter to find any shorts. There are others with better ears than me, but I didn't notice any change in tone - I could just hear the tone clearer because all the background noise disappeared.

[danlea]

- Looking into the physics of a faraday cage won't necessarily answer all your questions given that the conducting enclosure is far from complete.

- I would definitely isolate the springs before connecting to earth (which is something I would definitely do) assuming your bass buzzes if you touch the poles.

- Without a proper A-B test I couldn't tell you if the supposed improvement in tone is real or psychological, but I definitely did think the tone was a lot more defined after I shielded mine. True, it could be the effect removing the noise mask, but in any case I'm happier with the sound now. Oh, and it could have also had something to do with me fixing the earth connection inside my amp!

[Guest]

To avoid all that tedious soldering malarkey get the proper shielding foil, it has conductive adhesive so you just stick one piece on top of the other. It really annoys me that some decent basses come without proper shielding, it can't really cost that much can it?