| Author |
Topic: Bridge grounding |
Peter Jacobs
From:
Northern Virginia
|
Posted 2 Dec 2016 8:19 am |
|
I have a 1964 Supro Jet Airliner which has amazing clean and dirty tone, but in some rooms, I'm getting some mains hum. The string through pickup should be very quiet, and I can cut the hum considerably by touching the pickup, bridge or metal shell of the cord.
The pots and jack are on a plastic plate, so they are not connected to the pickup or bridge except by the pickup wires. There doesn't appear to be a ground wire going from the pots to the bridge -- is this normal on these guitars? Any thoughts on the best place to attach one to the bridge? Thx, all.
_________________
Peter
---------
www.splinterville.com
YouTube: https://www.youtube.com/@splinterville6278/videos |
|
|
|
Larry Carlson
From:
My Computer
|
Posted 2 Dec 2016 9:17 am
|
|
I have a lap steel with a steel bridge.
I soldered a grounding wire to the volume pot and routed it so it lays under the bridge.
I stripped about 1/2 inch of insulation from the wire and flattened it out for contact to the bottom of the bridge.
It shut my guitar up completely.
You said you are getting a hum in some rooms only.
Is there a ceiling fan or fluorescent lights in those particular rooms?
I have heard of ceiling fans doing weird things.
_________________
I have stuff.
I try to make music with it.
Sometimes it works.
Sometimes it doesn't.
But I keep on trying. |
|
|
|
Erv Niehaus
From:
Litchfield, MN, USA
|
Posted 2 Dec 2016 9:28 am
|
|
| A dimmer switch will do the same thing. |
|
|
|
Jack Hanson
From:
San Luis Valley, USA
|
Posted 2 Dec 2016 9:38 am Re: Bridge grounding
|
|
| Peter Jacobs wrote: |
| Any thoughts on the best place to attach one to the bridge? |
Simply wedge the ground wire between the wood body and the metal bridge stamping.
When playing instruments equipped with single-coil pickups, in certain rooms an EH HumDebugger can be nearly indispensable:
 |
|
|
|
Peter Jacobs
From:
Northern Virginia
|
Posted 2 Dec 2016 11:34 am
|
|
Thanks, all -- Unfortunately it's a crap shoot as to whether the room will be noisy - most clubs have at least a few dimmers, fluorescents or some other noisy stuff causing mains hum. I'll try wedging a wire from the pot to under the bridge.
_________________
Peter
---------
www.splinterville.com
YouTube: https://www.youtube.com/@splinterville6278/videos |
|
|
|
Jim Kennedy
From:
Brentwood California, USA
|
Posted 12 Dec 2016 4:22 pm
|
|
Sooner or later the wire wedged under the bridge will sink into the wood, you will get a little corrosion, and yo will get buzzing. I usually put a square of foil 4 layers thick under the wire. Distributes the force pressing it into the wood. So far I have not had one buzz after that. If that doesn't work try star grounding. Google it and you will find plenty of articles on how to do it.
_________________
ShoBud Pro 1, 75 Tele, 85 Yamaha SA 2000, Fender Cybertwin, |
|
|
|
Peter Jacobs
From:
Northern Virginia
|
Posted 13 Dec 2016 6:29 am
|
|
Guys, I appreciate all the suggestions. I'm talking specifically about the Supro stringthrough pickup, though, which is very different from most arrangments, as the pickup is actually built onto the bridgeplate.
Here's a photo of how it looks -- the hot wire (thin yellow wire connected to the red wire) comes from the pickup to the pots. The ground wire (black) connects from the pots to the baseplate, so adding another ground wire would be redundant (or could cause a ground loop).
It's just strange that I haven't had hum issues before, at least not that I've noticed. It might just be that RF interference is getting worse nowadays...
_________________
Peter
---------
www.splinterville.com
YouTube: https://www.youtube.com/@splinterville6278/videos |
|
|
|
Tom Pettingill
From:
California, USA (deceased)
|
Posted 13 Dec 2016 4:55 pm
|
|
Most likely its fine, but if you have a multimeter it would not hurt to double check that you have ground continuity between the ground on the jack to the pots and bridge plate.
Some shielding of the control cavity and back of the control plate would help with any RFI / EMI noise. If properly applied, any of the shielding paints and or copper tape will do the job. For a one off simple cavity like that, the copper tape might be the cheapest and easiest.
_________________
Some misc pics of my hand crafted steels
Follow me on Facebook here |
|
|
|
Peter Jacobs
From:
Northern Virginia
|
Posted 14 Dec 2016 7:57 am
|
|
Thanks, Tom - I'll definitely check for continuity. The more I think about it, the more it seems like RF and EM issues, rather than 60Hz hum. I just need to decide if it's enough of a problem to shield a 50 year old instrument.
_________________
Peter
---------
www.splinterville.com
YouTube: https://www.youtube.com/@splinterville6278/videos |
|
|
|
Tom Pettingill
From:
California, USA (deceased)
|
Posted 15 Dec 2016 8:25 am
|
|
| Quote: |
| It's just strange that I haven't had hum issues before, at least not that I've noticed. |
Chasing down the source of noise can be tough. I had an issue once where the transformer mounted in the garage for the doorbell went south and was causing all kinds of line noise. Those style transformers can be found on furnaces too. Fluorescent lights, including those compact CFL's can be troublesome too. The way I found it was to kill all the breakers and turned them back on one at a time to isolate the offending circuit.
Checking out your wiring with one of these cheap testers is not a bad idea either.
_________________
Some misc pics of my hand crafted steels
Follow me on Facebook here |
|
|
|
Peter Jacobs
From:
Northern Virginia
|
Posted 15 Dec 2016 9:11 am
|
|
Thanks, Tom - wow, a doorbell transformer -- that's one I haven't heard before. I actually bring one of those testers to gigs to make sure the "grounded" circuits are actually grounded. It's hard to get a bar owner to turn off the neon or the fluorescents, though! We just need to play louder to cover up any buzz -- it's all part of the fun...
_________________
Peter
---------
www.splinterville.com
YouTube: https://www.youtube.com/@splinterville6278/videos |
|
|
|
David M Brown
From:
California, USA
|
Posted 15 Dec 2016 11:13 am
|
|
| Peter Jacobs wrote: |
| It's hard to get a bar owner to turn off the neon or the fluorescents, though! |
Man, that is so true! |
|
|
|
