Dumb j-bass single coil grounding question

[UpperBout]

I recently assembled a Jazz Bass. Passive, single-coil, in standard Fender wiring configuration. (Build pix here)

So far when I've played out with it, it's been pretty quiet, but it gets buzzy when conditions are not favorable. I noticed when I play in rooms that have dimmers, it's pretty noisy.

I recently noticed two things:
1) It gets noisier when I touch the strings
2) An ohmmeter does not read 0 when I touch the bridge and the control plate.

I believe the grounding inside the bass is good (see here). I have a bit of copper foil running to one of the plate screws, but I am thinking that perhaps this is insufficient to provide the full loop.

So here are my dumb questions:
1) Should the ohmmeter read 0 when I touch the bridge and the control plate.
2) Any issues with just soldering a wire between the control plate and the same star ground group of wires to ensure a fully grounded config?

 

[Hopkins]

Grounding the bridge to your copper shield should be fine. But from the pictures it looks like your need to take a piece of the copper tape and fold it over to the top of the bass so it makes solid contact with the control plate, so the shield and all components are on the same ground circuit.

 

[line6man]

I'm not sure what you mean by reading 0 Ohms when you touch something. It should read 0 Ohms all the time.

 

[BGF]

Grounding the bridge to your copper shield should be fine. But from the pictures it looks like your need to take a piece of the copper tape and fold it over to the top of the bass so it makes solid contact with the control plate, so the shield and all components are on the same ground circuit.

I'm thinking the same thing. Nice job on shielding the pickups and control area but because the control plate doesn't make contact with the copper in the control area, it's not fully shielded. Here's a good video that shows how the copper tape should done in the control area.



BTW, you've built a very cool bass.

 

[bassbenj]

So far when I've played out with it, it's been pretty quiet, but it gets buzzy when conditions are not favorable. I noticed when I play in rooms that have dimmers, it's pretty noisy.

I recently noticed two things:
1) It gets noisier when I touch the strings
2) An ohmmeter does not read 0 when I touch the bridge and the control plate.

So here are my dumb questions:
1) Should the ohmmeter read 0 when I touch the bridge and the control plate.
2) Any issues with just soldering a wire between the control plate and the same star ground group of wires to ensure a fully grounded config?

1. Ohmmeter should read zero between all metal (bridge, control plate, strings, ANY piece of copper foil and the jack body. And what that means is that the meter should read the same number it reads when you just touch the leads together. The number may or may not be "zero". Your meter has an "ohms adjust" pot to set the meter to zero with leads shorted if it works. It may or may not work. In any case you seem to be using the 10k range but the 1k range would be better for testing shielding connections. Again for shielding to work ALL metal pieces should read "zero" to the jack body including strings, bridge control plate and copper foils.

2. Yes, you can ground the control plate with a wire to jack body tab down into the cavity to the copper foil (and bridge wire) there. The only downside of this is that it gives you one more wire into the cavity when you pull up the control plate. Not a biggie. The tab over the top is just more automatic. Also you need a tab like that to contact the foil on the backof pickguard if there is one.

In any case, if hum level changes when you touch strings that is a pretty good sign that something is not grounded properly in the shielding department. On the other hand, with single coil pickups if you solo one of them you'll usually get some hum. This hum won't change if you touch ground but will change If you alter the orientation of the bass. You really can't fix single coil hum without going to hum cancelling pickups.

 

[UpperBout]

Grounding the bridge to your copper shield should be fine. But from the pictures it looks like your need to take a piece of the copper tape and fold it over to the top of the bass so it makes solid contact with the control plate, so the shield and all components are on the same ground circuit.

I did do this:

But it turned out that this particular piece of foil wasn't conducting (even though it's the conductive backing foil from StewMac)

So I just soldered the tab of foil in there.

Now all is well.

It's quiet now. The same room that was noisy last night (ceiling fan, compact flourescent, and dimmer) is really quiet now. Even with soloed pickups, it's totally tolerable.

Thanks for all the advice and confirmations, everyone!

 

[UpperBout]

I'm thinking the same thing. Nice job on shielding the pickups and control area but because the control plate doesn't make contact with the copper in the control area, it's not fully shielded. Here's a good video that shows how the copper tape should done in the control area.



BTW, you've built a very cool bass.

Thanks! I'm really happy with it. Plays easy, sounds great. Can't go wrong with a Jazz. And the fact that I assembled it myself has made me really comfortable with it right out of the box.

 

[Hopkins]

I did do this:

But it turned out that this particular piece of foil wasn't conducting (even though it's the conductive backing foil from StewMac)

So I just soldered the tab of foil in there.

Now all is well.

It's quiet now. The same room that was noisy last night (ceiling fan, compact flourescent, and dimmer) is really quiet now. Even with soloed pickups, it's totally tolerable.

Thanks for all the advice and confirmations, everyone!

Glad I could be of help. Congrats, sound like you got yourself a great bass now.