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Re: Conductive Paint

11/12/1997 5:36 PM
Re: Conductive Paint
I was wondering if this might be a good way to connect a guitar to an amp. Please let me know if this has already been tried.  
Wire the guitar with signal common isolated from the cavity shielding system, or maybe tied together with a 0.1 uf capacitor. Use a stereo (3-terminal) jack. Make the guitar cord out of twisted pair with a separate shield (microphone cable?). Wire the Guitar end of a stereo plug: tip to hot, ring to return, and sleeve to shield. Wire the guitar jack to match. At the amplifier end of the cord, use a standard mono plug with hot to tip, and both return & shield to sleeve.  
I haven't tried this, but you got my gears turning.  
11/12/1997 10:28 PM
Austin C

Hi Doc  
Your theory is sound right up to the amp.  
If the signal common is wired to the shield at any point it puts you back to square one. The shield and signal common must be kept isolated from end to end.  
This is where the whole plan falls over. To implement pure grounding theory to a guitar requires any outboard gear to be modified along with the guitar.  
That means pedals, preamps, FX consoles, rack gear and of course power supplies too. Phew!  
Depending on the gear, it can be done but then you end up not compatible with EVERYBODY elses gear. Want to borrow that new pitch shifter? If it doesn't have the fab, shielded pair grounding mod, it's not gonna work.  
So going out on a limb i'll say that guitars are wired the way they are because "That's the way we've always done it", and to change the standard would be a monumental pain in the butt!  
I might E-mail Fender and see what they say.  
Post any ideas you get.  
See Ya  
4/29/1998 4:08 PM
when i shield and rewire my guitars or basses i use copper tape and conductive paint. i remove the string ground wire, single point ground the electronics, make the pickup wires into twisted pair, remove all connecting ground wires from the pot making sure that the pots make contact with the copper shield, apply a piece of copper tape from painted cavity over the edge of the cavity to make contact with the copper tape under the pickguard, solder one wire from the copper tape on the pickguard to the single point ground. you can make the single point ground at a pot or output jack. if i understand correctly the shielding acts as a refective shield.
1/13/1998 6:00 PM
Chuck Smith

This is a little out of date but if its steel you want steel screen should work. Aren't frequencies low enough that the openings would be less than half of the wavelength? That shoud be as effective as a solid sheet if my old physics is correct.  
11/21/1997 7:52 PM

Contrary to popular belief, this shielding stuff is for the birds.  
I contend that most noise introduced into the system by way of the guitar is by nature of the pickup itself.  
Pickups are called Pickups for a reason. They "pickup" a disturbance in the magnetic field they create. If there is any stay noise floating around, the pickup will detect it, and transmit it into the system.  
To prove my point, turn on your TV set. Take your guitar, and move closer to the TV. notice that the closer you get to the TV the more noise you get, particularly if you point the face of the guitar towards the TV.  
This problem is alot greater with single coil pickups. Humbuckers pickups are setup so the noise cancels itself out ( very simple explanation )  
and active pickups have very little noise attributed to them because of the small magnetic field they create.  
A place where noise gets amplified is in the wiring of the controls themselves. Make the ground structure loopless. I've seen Les Pauls with all four pots wired in a connected loop. WRONG!  
About the only thing that would really work well would be the same lead container that protects Superman from Kryptonite. :)  
1/10/1998 3:26 AM

You're almost right. The pickups themselves pick up lots of noise out of the air by electromagnetic radiation from various sources. But LEAD which shields Superman doesn't do much for shielding magnetic fields - try steel or something really good like MU-metal. And copper foil may not stop maagnetic fields, but it does make quite a significant difference when the source of interference (noise) is far enough away from your guitar (5 feet plus) that the coupling to the guitar is primarily electromagnetic radiation, and not magnetic field radiation. Think florescent lights at 25 feet like a video stage has. Paint is OK for smal wierd shapes you can't realistically cover with copper foil.  
2/23/1998 4:45 AM

I'd go with the copper. It's cheaper. In my experience, it works just fine. However, I've only shielded my epi sg with it, and as it has humbuckers and I set it up for single coil switching at the same time I shielded it, I can't say how effective it would be for a primarily single-coil guitar, which is really where the problem is anyway. I get less noise with my sheilded guitar set to a single coil wiring than my friends with unsheilded single coil guitars through the same amp. A friend of mine has a Bluesouth with two custom wound P-90 type pickups (it looks roughly like an early les paul) that appears to have black sheild paint in the control cavity and copper foil on the plastic control cavity cover, and it all seems to be wired correctly, and he gets god-awful hum playing through anything. Part of the problem is that his pickups probably aren't shielded inside the covers, and he can't shield the cavities they sit in. I, on the other hand, sheilded the control cavity and the pickup cavity and the pickguard on which the pickups are mounted. I'm really happy with the shielding, and with the switches set to humbucker, I get no noise at all. With single coil, I do get some, but you really have to listen for it. You have to switch back and forth from humbucker to single to pick up on it. Of course you can make it hum if you sit a foot from a computer screen, but playing directly under a ceiling mounted flourescent light has no effect. To sum it all up, despite all the theory about copper vs steel or the debate about whether or not shielding will have any effect at all, it works great for me, with my guitar, with copper foil, but I know people who have sheilded their guitar with minimal positive effects. Oh, and by the way, no, you can't use aluminum foil and glue, because for shielding to be effective, it has to form a shell around all the wiring and preferably the pickups, and it has to be electrically connected to the ground of the circuit. Because you cannot solder to aluminum, much less aluminum foil, you would have to rely on mechanical connections. To complicate things, the kind of aluminum foil in the kitchen is coated on one side with wax (thus the shiny side and dull side), not the most conductive material. So all the mechanical connections would have to be shiny side to shiny side. I'm not a major fan of mechanical connections, and even though it's not as if in shielding you'd get intermittent signal from faulty connections, I'd rather just use something I can solder, like copper foil. I know I'm long-winded, but hopefully it's helpful.
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