Tube Amps / Music Electronics
|For current discussions, please visit Music Electronics Forum.||New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!
|Listen to great tunes streaming live right now!|
|9/22/1997 3:12 PM|
||Shouldn't strings be grounded?|
I noticed that the strings on my newly-aquired '78 Les Paul Standard are not grounded. Is this normal? I thought there should be a wire coming from under the bridge or stop tailpiece into the control cavity where it would be connected to ground, but there is no such wire or hole where a wire would go.
If I short the strings to ground, there is a slight drop in hum (yes, the pickups are grounded propperly). Should I attempt to ground the strings (directly of thru a capacitor for safety)? If so, how would I do this?
|9/23/1997 3:47 PM|
The strings should be connected to ground with a 100K resistor paralleled by a 0.001uF/1Kv ceramic capacitor. This should connect the bridge to the signal ground. The 100K is high enough to not kill you if you touch a live wire (those mike stands!), low enough to bleed away static charges, and the 0.001 cap is an effective ground for RF. This will prevent hum (safely) in all except hard cases.
|9/26/1997 1:38 PM|
How would you suggest getting a wire to the bridge or tailpiece (it's a Les Paul)? I suppose I could try to pull out a threaded bushing , drill a hole from the control cavity, and put a wire thru. Anyone have experience doing this? And why was this not done originally?
|9/28/1997 8:36 PM|
All of them I've seen have a wire to the bridge already. Possibly you have a broken wire.
The stock thing is a drilled hole from the control cavity to the bridge mounting screws, I think.
|10/1/1997 8:19 AM|
A note from EMG installation instructions.
>When installing EMG Pickups, do not
>reconnect the bridge ground wire. This
>wire is usually soldered to a volume or
>tone pot casing and runs to bridge.
>Normally, this grounds the strings to
>use them and your body as a shield to
>reduce hum. This also creates a potential
>shock hazard. Since EMG pickups are
>internally shielded, they do not need
>additional shielding and allow you to
>reduce the possibility of electric shock.
|10/1/1997 9:06 AM|
Well, perhaps I should finish me message before I send it, otherwise I'm just reiterating what Keen has offered already.
In my '72 L.P. Deluxe the ground wire runs does indeed run from the rythym vol. pot through a small hole to the closest bridge stud. I can't beleive that they would cut a corner on a standard that they didn't on a Deluxe.
|10/7/1997 10:26 AM|
You're quite correct; the string earth wire is actually the cheap option when manufacturers can't be bothered to earth/shield guitar pickups & circuits from mains hum and electrostatic interference. The LP Standards of this period (1976-'80 approx) actually enclosed the pots & circuitry in the control cavities in a metal box (a "Faraday" box) which when combined with humbucking pickups is the best solution. Most people tended to throw away the bottom half of the metal box or use it as an ashtray thus destroying the shielding. If you look in the control cavity you will probably see the pots mounted on a metal plate with two threaded holes to locate the "ashtray" cover that has since been discarded. Even the selector switch & jack socket were in small metal cans.
Humbucking pickups by themselves can only cancel mains borne 50 cycle hum. Airborne electrostatic/RF interference can only be eliminated by total shielding of all controls/signal carrying wires. The string earth system is a cop out which lets you do the earthing (and take all the attendant risks).
See previous post regarding resistor/capacitor to reduce the possible current flow through YOU!
|Page 1 of 1|