So your bass has a hum

[bassman_al]

One other thing, re: Stew Mac shielding paint. Its got graphite in it, lots of it. So its going to be a little like a pencil in that it will indeed come off if you rub it, but not that much. I've been using it for a few years, and if you apply 3 coats, it will do the job superbly. It won't come off, although you will get some on your fingers if you rub it. But its mostly going to soak into the grain of the wood. And I never prep the surface other than to make sure the surface is clean of that white chalky residue that a lot of cavities seem to have, and of any other dirt or grime. That's it. I have not counted how many shielding jobs I've done but I would guess about 30. Again, no complaints from anyone. As to how it lasts over a prolonged time, I can't attest to anything past the 8 years or so that I would guess I've been using it.

 

[DiabolusInMusic]

@bassman_al excellent post, thanks so much for sharing. I would not recommend using Stew Mac shielding paint though. As you have noticed, it doesn't have very good conductivity and rubs off easily. It is also quite expensive. I use MG Chemicals Supershield, it is a far superior product in every single way. I source the paint locally from my electronics part supplier but I know some Americans source it off of Amazon. It costs me about $50 CDN for a can but a can will do multiple basses. You can get it in a brush on liquid but you need to make a very large order. I recommend giving it a try because I don't imagine you go back.

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[bassman_al]

Great guide and thanks for posting.

I did a very novice shielding job very much like you describe on my MIM Deluxe Jazz bass with a J-Retro Deluxe some years ago. Before I did it I was getting crazy buzzing in certain rooms that would stop when I touched the strings. I was also sometimes getting the ol' static shock on my mouth from the mic. All of this went away after I did the shielding job. I shielded the separate battery cavity as well. I used the copper tape you can get from Steward MacDonald.

A few months ago I decided to have my Lakland Skyline DJ4 professionally shielded while at the same time installing a J-Retro and Aero JB4 Type 1 pickups (single coil). I had them route a battery cavity in the back of the bass and install a battery compartment. The work seemed pretty quality although last night I removed the pickups and noticed some things. I rubbed a bunch of the shielding paint off while in there. It appears that they sprayed right over the existing finish in the cavities. The shielding paint seems to easily rub right off so now there are spots with no shielding paint. I still had some copper tape from StewMac so put a couple of strips in each pickup cavity on the bottom to try to remedy the situation. In doing that I also rubbed off some spots on the sides in the pickup cavities. I also noticed that they didn't shield the battery compartment at all.

It seems like you have to remove the finish inside the cavities before applying the StewMac shielding paint. Is this correct?

My OCD is seriously going off! Should I just move on and not worry about it if I don't have any buzzing issues? I don't play the one room that used to give me serious problems anymore. Or should I take the bass back and have them remove the paint in the cavities and re-do the shielding job?

Ok one last response re Stew Mac paint. It adheres to any surface. It has excellent conductive properties (not sure why Diablo thinks I said it has poor conductance), and I've shielded many guitars and basses using it. Many. Works great, one can will cover many jobs and if used properly will more than suffice. I offer a lifetime warranty in my shop because I believe in this product. You need to apply 3 coats and wait 24 hours between coats. That's it. I'm all done with this topic.

 

[bassman_al]

I did find the mg brand paint on Amazon. A supply of one liter of graphite paint is $100 and nickel gallon is $163.

 

[DiabolusInMusic]

Ok one last response re Stew Mac paint. It adheres to any surface. It has excellent conductive properties (not sure why Diablo thinks I said it has poor conductance), and I've shielded many guitars and basses using it. Many. Works great, one can will cover many jobs and if used properly will more than suffice. I offer a lifetime warranty in my shop because I believe in this product. You need to apply 3 coats and wait 24 hours between coats. That's it. I'm all done with this topic.

It does have acceptable conductive properties but note the numbers of MG's site, the MG Chemicals paint performs better. I probably should have said "doesn't have as good conductivity" for better clarity. The MG Chemicals paint is also far more durable, it will not flake off as easily. I agree that any material will perform just as well for our application. I have experience with the Stew-Mac stuff as well, it is an inferior and more expensive product. This is especially true for people outside of the United States. If you want to spend your money on Stew-Mac paint you are welcome to do so but I don't know anybody who has used both products and stuck with Stew-Mac's paint. I highly recommend giving Supershield a try.

 

[finetops]

It does have acceptable conductive properties but note the numbers of MG's site, the MG Chemicals paint performs better. I probably should have said "doesn't have as good conductivity" for better clarity. The MG Chemicals paint is also far more durable, it will not flake off as easily. I agree that any material will perform just as well for our application. I have experience with the Stew-Mac stuff as well, it is an inferior and more expensive product. This is especially true for people outside of the United States. If you want to spend your money on Stew-Mac paint you are welcome to do so but I don't know anybody who has used both products and stuck with Stew-Mac's paint. I highly recommend giving Supershield a try.

I've tried various graphite paints and typically after 2 coats you'd still have ard. 200-300 ohms whereas 2 coats of Supershield are said to bring the DCR reading down to 2-3 ohms... So I will try Supershield on the next P and J, but how about effect on sound? Does such a tight shield affect output or anything? (Considering also closing the shield from above by foil on pickguard and also taking into consideration that supershield has ferromagnetic properties acc. to their technical data sheet.)

 

[Scot]

I've tried various graphite paints and typically after 2 coats you'd still have ard. 200-300 ohms whereas 2 coats of Supershield are said to bring the DCR reading down to 2-3 ohms... So I will try Supershield on the next P and J, but how about effect on sound? Does such a tight shield affect output or anything? (Considering also closing the shield from above by foil on pickguard and also taking into consideration that supershield has ferromagnetic properties acc. to their technical data sheet.)

Yeah, I'm now noticing buzzing issues with my Lakland bass that was professionally shielded with the Stew Mac spray on stuff. I plan to use some of the copper tape myself and do the same job I did for my Jazz bass. I'm definitely NOT a fan of the Stew Mac spray on stuff.

I've read that shielding can lower output of high-end frequencies or otherwise affect the high-end. I haven't really been able to hear that, at least not with the J-Retro preamps I have installed in both of my basses.

 

[DiabolusInMusic]

I've tried various graphite paints and typically after 2 coats you'd still have ard. 200-300 ohms whereas 2 coats of Supershield are said to bring the DCR reading down to 2-3 ohms... So I will try Supershield on the next P and J, but how about effect on sound? Does such a tight shield affect output or anything? (Considering also closing the shield from above by foil on pickguard and also taking into consideration that supershield has ferromagnetic properties acc. to their technical data sheet.)

I would imagine there is an argument that shielding impacts your tone. I know plenty of cats will not shield the pickup surrounds as they feel it impacts the tone. I personally do not find any significant impact to the tone. If there is an impact it isn't nearly as noticeable as the lack of hum.

@Scot do not let Stew-Mac's crappy paint turn you off of paint. Check out MG Chemicals Supershield, it is a fantastic product that I, obviously, cannot say enough good things about.

 

[cellkirk74]

Since this here seems to be a place with mor knowledge about noisy basses I will try to get an answer from you guys.

I have a Gibson Midtown bass that I modded with a EB-BS (huge single coil) pickup by Curtis Novak. I also exchanged the toggle switch for a Bourns blend pot and swapped the stock bridge for a hipshot supertone.

So far so good, blend to the stock bridge pickup leaves the bass totally quiet. With the neck pickup mixed in I get hum that goes away when I touch the strings. It gets louder the more I blend in the neck. When I touch just the metal cover over the pickup, the noise gets significantly louder (which is bad because I like to anchor my thumb there for playing), but again goes away when I touch the strings. I also get a static plop when touching the pickup cover.

My gues is I will at least have to connect the cover to ground, but how? The Cover is crewed directely into the wood without any grounding plate like the old EB-basses used to have.

Should I also try to shield the cover from the inside?

 

[DiabolusInMusic]

Since this here seems to be a place with mor knowledge about noisy basses I will try to get an answer from you guys.

I have a Gibson Midtown bass that I modded with a EB-BS (huge single coil) pickup by Curtis Novak. I also exchanged the toggle switch for a Bourns blend pot and swapped the stock bridge for a hipshot supertone.

So far so good, blend to the stock bridge pickup leaves the bass totally quiet. With the neck pickup mixed in I get hum that goes away when I touch the strings. It gets louder the more I blend in the neck. When I touch just the metal cover over the pickup, the noise gets significantly louder (which is bad because I like to anchor my thumb there for playing), but again goes away when I touch the strings. I also get a static plop when touching the pickup cover.

My gues is I will at least have to connect the cover to ground, but how? The Cover is crewed directely into the wood without any grounding plate like the old EB-basses used to have.

Should I also try to shield the cover from the inside?

I should say first and foremost, I am not familiar with your bass or pickup.

You could try grounding the pickup cover through contact. I'm guessing the bass needs some shielding as well (to deal with the hum that stops when you touch the strings as well as the static). When you screw the cover down the screws should touch the cover and pierce the grounded cavity shielding, similar to what you see in the guide. This will ground the cover. Ensure that the pickup does not touch the ground. I would also double check your ground wire connection under the bridge.

You will want to have double-sided conductive (conductive adhesive) copper foil tape to accomplish this. I would recommend getting some from Ebay or Amazon.

 

[cellkirk74]

Thanks for the answer! i already ordered some tape and also got a reply from Curtis who told me to grund the pickup cover with a wire to one of the srewholes. Will try this and report.

 

[DiabolusInMusic]

Thanks for the answer! i already ordered some tape and also got a reply from Curtis who told me to grund the pickup cover with a wire to one of the srewholes. Will try this and report.

Best of luck with your project.

 

[exiii]

I thought I had bought a well-shielded bass, added coated strings and suddenly there was a nasty hum. I have some experience with shielding, but this thread served as a great set of additional ideas - foil behind the bridge, for example.

In this case, there was no shielding around my pickups - that was the problem. I had copper tape on hand, so I surrounded the pups, added a shield-ground between the pup and main cavities, and the bass is silent once again.

Oh, finally, I prefer copper foil to paint. I've heard different opinions on how well different paints work. With foil, there's no question in the conductivity - it works. I've also used it to wrap unshielded wires running into other cavities.

Thanks for the resource.

 

[DiabolusInMusic]

I thought I had bought a well-shielded bass, added coated strings and suddenly there was a nasty hum. I have some experience with shielding, but this thread served as a great set of additional ideas - foil behind the bridge, for example.

In this case, there was no shielding around my pickups - that was the problem. I had copper tape on hand, so I surrounded the pups, added a shield-ground between the pup and main cavities, and the bass is silent once again.

Oh, finally, I prefer copper foil to paint. I've heard different opinions on how well different paints work. With foil, there's no question in the conductivity - it works. I've also used it to wrap unshielded wires running into other cavities.

Thanks for the resource.

Glad to help boss. I hate hum so I love to hear about a well shielded/properly functioning bass. I have found some basses let me get away without wrapping the pickups but I have always done the pickups for years now. If there is a difference in tone I do not appreciate it as much as I do the silent operation.

 

[Cider]

Thank you so much for the post @DiabolusInMusic. The (lovely) AJB in my avatar unfortunately suffers from a loud nasty hum, so I think it'll be my upcoming project to shield it before I do any electronics upgrades.

I live somewhere I can't spray paint though - so I was wondering if conductive paint that can be applied with a brush (like this stuff MG Chemicals Nickel Print (Conductive Paint): Amazon.com: Industrial & Scientific) could be an alternative?

 

[DiabolusInMusic]

Thank you so much for the post @DiabolusInMusic. The (lovely) AJB in my avatar unfortunately suffers from a loud nasty hum, so I think it'll be my upcoming project to shield it before I do any electronics upgrades.

I live somewhere I can't spray paint though - so I was wondering if conductive paint that can be applied with a brush (like this stuff MG Chemicals Nickel Print (Conductive Paint): Amazon.com: Industrial & Scientific) could be an alternative?

That would be exactly what you want to use. It looks like you can now buy a reasonable size of MG for the brush on stuff. They used to only sell aerosol unless you bought a bunch, far more than any hobbyist would require. You can brush on the aerosol too, I just spray some in a cup. You can always use copper tape too.

 

[Cider]

That would be exactly what you want to use. It looks like you can now buy a reasonable size of MG for the brush on stuff. They used to only sell aerosol unless you bought a bunch, far more than any hobbyist would require. You can brush on the aerosol too, I just spray some in a cup. You can always use copper tape too.

Thank you! My biggest concern is the bridge, really. Do I need to take it off?

 

[DiabolusInMusic]

Thank you! My biggest concern is the bridge, really. Do I need to take it off?

You don't have to but I would recommend it. I like to remove the bridge so that I can add some copper tape to ensure a solid connection between the ground wire and the bridge, they occasionally come loose.

 

[Big Hoss]

That would be exactly what you want to use. It looks like you can now buy a reasonable size of MG for the brush on stuff. They used to only sell aerosol unless you bought a bunch, far more than any hobbyist would require. You can brush on the aerosol too, I just spray some in a cup. You can always use copper tape too.

The brushing on after spraying into a cup is how I do it

 

[Trieu Duong]

I have a Precision bass. My bass has 2 hums. The first hum is loud and goes away when i touch the metal parts. According to you it'll be shielding issue. I havent fix it yet.
But there is another hum occuring at the same time. At first i didnt realize it but when I turn up the amp volume at max, it becomes apparent. As I touch the metal parts, the main hum goes away but the bass does not go quiet. The 2nd hum is still there, and it seems to get louder when i pluck the strings. I tested to pluck and mute the string right away, the hum keeps on and then fade away until it reduce to the initial loudness. My bass is P bass, and this is not 60 cycle hum.
Is there anyone experiencing the same problem. The 2nd hum is very strange and I havent found any information about it.
I havent done any big changes to my bass. Just one time, i put a tiny piece of cloth under the trebble pu to raise it up, because it cant be raised by adjust the screw.
The 2nd hum is much quieter in comparison to the first hum. But it is still make me frustrated, that even if I shield up everything my bass will still have hum. Can anyone help me out?