I have a jazz bass with stacked bridge and single pickup neck wired like a p bass with master volume and master tone. When I touch my strings the hum goes very quiet but there's noise when I take them off. Is that a bad ground to bridge issue? I've only put copper tape in my cavity and not the pickup routes
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Hum goes away touching strings
- Thread starter jayroc1
- Start date
Assuming we're talking about a "normal" level of buzz:
Touching strings and having a noise reduction is actually good proof that your bridge ground is working fine. Your body is conductive. When you touch the strings, your body becomes part of the circuit - the strings are grounded (via the bridge ground), so your body is now acting like a giant meat shield, stopping noise from reaching your wiring.
The solution is shielding inside the instrument. You mentioned that you shielded the control cavity. Is that shielding grounded? If not, it's going to make the problem worse. Shielding needs to be grounded.
Check that the shielding is grounded. Check that your controls are grounded (i.e. the pots have ground wires soldered to the cases). If your pickups have plain two wire leads, consider swapping to shielded lead wires - or shield the pickup cavities and the wiring channels to the control cavity.
If you're getting really, really bad buzz, there may be another problem. Jack wired backwards, pickups with internal shielding that's on the hot side of the circuit, or even just a bad solder joint somewhere.
Touching strings and having a noise reduction is actually good proof that your bridge ground is working fine. Your body is conductive. When you touch the strings, your body becomes part of the circuit - the strings are grounded (via the bridge ground), so your body is now acting like a giant meat shield, stopping noise from reaching your wiring.
The solution is shielding inside the instrument. You mentioned that you shielded the control cavity. Is that shielding grounded? If not, it's going to make the problem worse. Shielding needs to be grounded.
Check that the shielding is grounded. Check that your controls are grounded (i.e. the pots have ground wires soldered to the cases). If your pickups have plain two wire leads, consider swapping to shielded lead wires - or shield the pickup cavities and the wiring channels to the control cavity.
If you're getting really, really bad buzz, there may be another problem. Jack wired backwards, pickups with internal shielding that's on the hot side of the circuit, or even just a bad solder joint somewhere.
Shield the two pickup cavities as well and run a ground wire from each of them to the back of the volume pot or wherever you have ground wires converging.
Also shield the back of the pickguard and make sure it touches the cavity shielding (run a tab of shielding over a few pickguard screw holes in the body). This might not be necessary but you might as well go all the way.
The pickup pole pieces can also be grounded from below if you can access them - do this in case they make noise when you touch them. A strip of copper tape over them and a ground wire going to the same spot as above.
Also shield the back of the pickguard and make sure it touches the cavity shielding (run a tab of shielding over a few pickguard screw holes in the body). This might not be necessary but you might as well go all the way.
The pickup pole pieces can also be grounded from below if you can access them - do this in case they make noise when you touch them. A strip of copper tape over them and a ground wire going to the same spot as above.
You are getting the hum because you used a singlecoil for the neck pickup but a stacked bridge pickup. If you switch to a stacked neck pickup it should improve significiantly.
That the buzz goes away when you touch the strings, means that the grounding wire is installed correctly.
If you watch pros at gigs, they always have at least one hand touching the strings (even in between songs).
That the buzz goes away when you touch the strings, means that the grounding wire is installed correctly.
If you watch pros at gigs, they always have at least one hand touching the strings (even in between songs).
Single coil hum doesn't go away when you touch metal on the instrument. It's always there. This is a shielding issue.
Agreed. Also, the comment made by @Mushroo about pros "always having at least one hand touching the strings" is news to me. I guess myself and thousands of other professional bass players are no longer professionals?
The interference that shielding is designed to protect your electronics from might be due to a local and preventable source, so it would be worth moving around and facing different directions and/or trying different rooms to see if and where the hum increases or decreases. Common sources are fluorescent lights, dimmer switches, and electronic devices such as computers and even cell phones. If you can identify and eliminate such a source it might reduce the hum enough to not be a bother.
Hi Jay, I (literally) just corrected the same issue on a Vintera JB. I shielded the cavities, pickguard, and control plate. No-touch hum if not completely eliminated, reduced to a point where it is basically indiscernible.
Here is the control cavity without shielding, the two pickup cavities were the same.
While I did not get a pic of the after (kicking myself still) here are the control plate and pickguard:
Be sure to get copper tape WITH CONDUCTIVE ADHESIVE. A hobby knife is nice for trimming but if you have a new, clean single-blade razor, that will work as well.
Good luck, let us know how it comes out.
Thanks. I'm going to look over everything again tonight and upload photos incase I need further help
Look up Puisheen on Youtube. he has a tutorial on shielding. Make sure to check continuity across the whole shielding with a multimeter. Press the pieces of tape down very well. The more the act as one big cage the better.
I noticed my shielding and bridge isn't connected but the control plate touches the copper tape in the control cavity. I have a ground from bridge to pot. Does that mean when I put the control plate back it'll be grounded together?
Shielding and grounding are things Fender does rather inconsistently. Good news is it's an easy fix. You got this.
Thanks to @dwizum for the best new band name of the year!
Thanks to @dwizum for the best new band name of the year!
The shielding and the bridge must both be connected to ground with dedicated wires. They don't have to touch.
If the control plate touches the shielding then it's also grounded
For cavity to cavity grounding I use a bare wire and use copper tape to secure it. Too easy.
A Faraday cage, which is what shielding is, needs a path to ground to work. If there is no path to ground through the jack, through the cable, through the amp, through your wiring to ground then the shielding doesn't work - until you touch the strings or the bridge to provide another path to ground using your body.
I had the same with a PJ. I swapped the J for a Seymour D humbucker J. Still hummed when I wasn't touching the strings. I lined the cavity with metal. Still hummed. It didn't bother me after that. I've since traded it for an SR600E with two Nordstrand Big Breaks.
They do it to mute the strings and to stop feedback and other bad noises. Sometimes us amateurs do it also...Agreed. Also, the comment made by @Mushroo about pros "always having at least one hand touching the strings" is news to me. I guess myself and thousands of other professional bass players are no longer professionals?
I'm not a pro but I roll off the volume when I'm not playing. Sorry, Joe Dart Jr.
I had an almost identical problem which I posted this weekend. The many helpful replies quickly and easily fixed this. Maybe this is completely different though.
Here's how I do my shielding.
I shield both the main cavity and bridge pickup cavity and let the shield tape go over and along the edge. This ties the metal control plate on a Jazz Bass to all the body shielding essentially connecting all grounds togther. All pots when snugged up on the control plate are grounded so it isn't necessary to run ground leads between each pot. The less ground wires means the less chance for ground loops which is usually caused by multiple paths to ground.
The bridge has a stripped of wire under it that sits in a slot that Fender Basses usually have and I put a square piece of copper shield tape over that. I run a ground wire that's soldered to the bridge pickup cavity into the main cavity where this wire and the ground wire coming from bridge are soldered together on the main cavity foil.
The pickguard gets shielding all around the lower section and bridge pickup area. I put a large square block of shield tape in front of the pickup area on both the body and pickguard to ensure a solid connection. All this creates a Faraday cage minimizing the chance for both RFI and ground hum at least from the instrument.
When I take the control plate off and the Bass is still plugged into an amp, it buzzes and hums like crazy. This is what you would expect though. When I set the plate firmly done, the Bass is dead quiet!
Here are some pics of my shield job I do on all of my Basses.
I shield both the main cavity and bridge pickup cavity and let the shield tape go over and along the edge. This ties the metal control plate on a Jazz Bass to all the body shielding essentially connecting all grounds togther. All pots when snugged up on the control plate are grounded so it isn't necessary to run ground leads between each pot. The less ground wires means the less chance for ground loops which is usually caused by multiple paths to ground.
The bridge has a stripped of wire under it that sits in a slot that Fender Basses usually have and I put a square piece of copper shield tape over that. I run a ground wire that's soldered to the bridge pickup cavity into the main cavity where this wire and the ground wire coming from bridge are soldered together on the main cavity foil.
The pickguard gets shielding all around the lower section and bridge pickup area. I put a large square block of shield tape in front of the pickup area on both the body and pickguard to ensure a solid connection. All this creates a Faraday cage minimizing the chance for both RFI and ground hum at least from the instrument.
When I take the control plate off and the Bass is still plugged into an amp, it buzzes and hums like crazy. This is what you would expect though. When I set the plate firmly done, the Bass is dead quiet!
Here are some pics of my shield job I do on all of my Basses.
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