So your bass has a hum

[BlueTalon]

It's your bass but I would still recommend learning this yourself. Pots are cheap, for the cost of 30 minutes of shop time you would be able to put in at least two new entire sets of CTS pots.

I concur with this. Dave, you also might consider investing a little money in a better soldering iron.

 

[Big Hoss]

I got it sorted. The shielding on the pickups was grounding them out.. Took the shielding off of the pickups, and problem went away.

The buzzing while not touching strings but gone when touching strings no longer exists. Now I have a buzz that is there whether or not I touch the strings, but is VERY dependent upon which way I am pointed. I suspect it is because the pickup itself is no longer shielded...

I face with the bass sideways to the speakers on the amp in close proximity no problem, but rotate just a bit, and buzz... Move away more than 3 feet no buzz, but close up and not sideways, buzz city...

I am wondering if I could use the shielding paint INSIDE the pickup housing, and use electrical tape to isolate the pickup from the shielding material...

FWIW, the ground is rock solid.

 

[RunBeerRun]

My bass is all hum. The strings barely are heard. I want to be a superstar !

 

[DiabolusInMusic]

I got it sorted. The shielding on the pickups was grounding them out.. Took the shielding off of the pickups, and problem went away.

The buzzing while not touching strings but gone when touching strings no longer exists. Now I have a buzz that is there whether or not I touch the strings, but is VERY dependent upon which way I am pointed. I suspect it is because the pickup itself is no longer shielded...

I face with the bass sideways to the speakers on the amp in close proximity no problem, but rotate just a bit, and buzz... Move away more than 3 feet no buzz, but close up and not sideways, buzz city...

I am wondering if I could use the shielding paint INSIDE the pickup housing, and use electrical tape to isolate the pickup from the shielding material...

FWIW, the ground is rock solid.

If the hum is constant when you touch metal/strings/bridge then it is not shielding related. I was going to suggest looking at the ground wire under the bridge, but you say it is good. Are you favouring one pickup? The hum you described is consistent with 60hz hum, which you would need humbuckers to rectify.

 

[Big Hoss]

If the hum is constant when you touch metal/strings/bridge then it is not shielding related. I was going to suggest looking at the ground wire under the bridge, but you say it is good. Are you favouring one pickup? The hum you described is consistent with 60hz hum, which you would need humbuckers to rectify.

I unplugged all the cables in the signal chain, left the Snark tuner in line, the shorty patch cable and the 20 foot musicians gear cable. Couldn't get it to hum at gun point. Put the Digitech back in with the second MG cable. No hum. No buzz. There was some fuzz in the socket. Figured I picked that up Saturday. New experience. Dirt in a pedal socket...

 

[DiabolusInMusic]

I unplugged all the cables in the signal chain, left the Snark tuner in line, the shorty patch cable and the 20 foot musicians gear cable. Couldn't get it to hum at gun point. Put the Digitech back in with the second MG cable. No hum. No buzz. There was some fuzz in the socket. Figured I picked that up Saturday. New experience. Dirt in a pedal socket...

Your bass is V/V/T, right? If so, try favouring one pickup (either one) by turning the other one back 1/4 turn. Does the hum come in? Does it stop when you balance both pickup controls? If you got hum, this is normal operation for single coil pickups. If you are getting hum with both pickups cranked (or equal) then there is an issue. Mind you, 60hz hum is bad in some places and not noticeable in others. Most of the places I play you do not get hum favouring one pickup but sometimes you get a place that will make your bass hum like crazy.

 

[Big Hoss]

Your bass is V/V/T, right? If so, try favouring one pickup (either one) by turning the other one back 1/4 turn. Does the hum come in? Does it stop when you balance both pickup controls? If you got hum, this is normal operation for single coil pickups. If you are getting hum with both pickups cranked (or equal) then there is an issue. Mind you, 60hz hum is bad in some places and not noticeable in others. Most of the places I play you do not get hum favouring one pickup but sometimes you get a place that will make your bass hum like crazy.

Yes. VVT. Both full on no hum. I haven't favored one pickup more than 50% by rolling the bridge back. If hum was there it was imperceptible. I get a teeny almost white noise low level running ceiling fan... Not acceptable for recording but fine for noodling.

Since the shielding has been done I have been favoring the Jazz over the Ibanez basses...

 

[Scot]

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?

 

[Antisyzygy]

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?

I installed a battery box in my P bass and had a similar problem. The metal shielding paint was flaking off everywhere, but in my case there was background noise coming from somewhere. I think it was because the battery box basically broke the shielding, it was a quiet bass before. Touching the strings did make the noise go away.

I ended up buying copper tape and doing a full shield job myself, covering every square inch of the cavity and then under the pick guard where it covers the cavity as well. I didn't bother shielding the pickup covers. I actually finished that today, it took about an hour. It's back to how it was now, quiet as a mouse--no hum at all even when Im not touching the strings.

 

[DiabolusInMusic]

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?

If the bass isn't humming, I wouldn't fix what isn't broken. My guess is your tech used the Stew-Mac stuff. The Stew-Mac shielding paint is low grade stuff, they just sell it for a premium. If you use MG Chemicals Supershield it is much less prone to flaking off (and much more affordable.) I do not really use the Stew-Mac stuff because it flakes so easily but they do not recommend prepping the surface beforehand from what I recall. I never prep when using the Supershield and it is not a terrible problem. I also do not recommend buying copper tape from Stew-Mac, it is over-priced in my opinion.

 

[Scot]

Thanks DiabolusInMusic. Yeah, I know they use the Stew-Mac shielding paint. Good to know about the MG Chemicals Supershield. The Stew-Mac paint literally comes completely off the finished cavities with a smudge or two with a finger. It's not even something you have to try hard to do. It's pretty ridiculous IMO. I ended up re-shielding the pickup cavities last night with some Stew-Mac copper tape I had left from shielding my Jazz bass. Now I'm kind of worried about the controls cavity. I looked in there (being careful not to touch any of the shielding paint) and can see that there are little black particles of the Stew-Mac paint that have flaked off (although I don't see any exposed white finish like I made with my fingers in the pickup cavities). Now I'm worried that those little black particles will get in to the circuitry of the J-Retro.

Does anyone know of any scientific reason to or not to shield the separate battery compartment on the back? I'm assuming there's no benefit since the tech didn't do it on my Lakland.

 

[SwedenSlapInc.]

Hi! Just a little question someone might be able to answer!

Should you shield the pickup cavity if you have pickups with a grounding plate? If so, is it necessary to connect the cooper paint/foil in the pickup cavity to something or is the connection that you get from the grounding plate and cooper paint/foil in the pickup cavity enough?
I have ordered Fenders Pure Vintage '63 Precision Bass Pickup for a custom build, and don´t want to get any "ground loops" or other problem (I doesn´t know that much about electronics). I've read a bunch of shielding threads but can´t find a straight answer to my question!

Best Regards Joel

 

[DiabolusInMusic]

I'm guessing you are referring to the brass plate underneath the pickups and in the control cavity on vintage basses. That plate is actually just vintage shielding, it doesn't really do anything. The cavities will still require shielding. Those plates are already grounded to the electronics so if you shield the cavities they will ground the shielding. I find you have to remove the plates in order to put shielding underneath though.

The jazz bass picture from post #25, "the Jazz bass supplement" mentioned in post #1, shows my bass with plates. You can see the paint underneath the plates as well as one ground wire connected to the plates, the latter part is kind of hard to see. I get into a little more detail in the post.

I hope that helps.

 

[SwedenSlapInc.]

Thanks for the answer!
Yes I was referring to those plates. The bass is not assembled yet so putting the shielding paint/foil underneath the plate in the pickup cavity won't be a problem!
I was just a bit concerned that I would have to do something different than mentioned in this guide because of the vintage shielding.
But then I´ll just follow your guide!

 

[BlueTalon]

Basically, the grounding plate was a "vintage" half-assed attempt at shielding. What you propose to do by using copper shielding around the entire inside of the cavity is superior by far. If you are wondering whether or not to keep the ground plate, you can go ahead and sell it on ebay or something.

One thing though, don't worry about ground loops. There's not enough "circuit" in your circuit to cause a problem. Assuming everything is properly shielded, and all the shielding is properly grounded, there is really no such thing as "multiple paths to ground" -- it's all the same path.

 

[SwedenSlapInc.]

But it´s possible to keep the pickups as they are, with plate and everything? And use the "connection" between the ground plate and the copper paint in pickup cavity to ground the paint in the pickup cavity?
Good to know about possible ground loop issues, now I don't´t have to think about that. The help i greatly appreciated!

 

[DiabolusInMusic]

But it´s possible to keep the pickups as they are, with plate and everything? And use the "connection" between the ground plate and the copper paint in pickup cavity to ground the paint in the pickup cavity?
Good to know about possible ground loop issues, now I don't´t have to think about that. The help i greatly appreciated!

Your plan is good. @BlueTalon is just suggesting that you can remove them if you want, they really serve no purpose.

 

[SwedenSlapInc.]

Ok then! Thanks alot!

 

[bassman_al]

was going to post a new thread, but I saw this, I'll to try to get an answer here.

I have a Greg Bennett Remington semi-acoustic bass. It has a typical acoustic style bridge (wood/bone), an active 3-band preamp with 9v battery, and the "pickup" type that is the ribbon under the saddles. It is chambered mahogany body, not a full hollow body acoustic. I am running labella deep talking flats, nylon wrapped. I have shielded the cavity the best I can with copper tape. There is a portion of a body cavity that runs under the bridge, and it is impossible to reach with copper tape. It is a relatively small cavity (although I can't see it all) that simply can't be reached. I cannot get rid of some hum present when I'm plugged in. nothing makes it better or worse, no popping. Just mild and annoying. Is this something I have to live with since I can't reach into the small cavity to shield? or is there another trick, possibly shielding under the pickup ribbon? Any help would be appreciated.

Conductive shielding paint from Stew Mac. Works great. Use it all the time in my shop.

 

[bassman_al]

I'll add a little more here. I've started a part time guitar repair and maintenance shop at my house. 44 reviews on my FB page is anyone is curious, all 5-stars. So people like my work a lot. I do a lot of wiring work, as well as quite a bit of shielding work. A couple bits I'll add here, as part of my experience to date with shielding. I'll explain in lay terms because those are the only terms I know since I'm not an engineer. First, to clear up a point here, the point of shielding is to provide a home for unwanted electronic interference. This is done by essentially directing that interference to ground. In order to achieve that, we need an easy pathway for the interference, with as little resistance as possible. Resistance means that the interference would get to ground less effectively. The interference is a type of signal, and we want that particular signal to move to ground quickly and efficiently, without resistance. That is why an ohm-meter (multi-meter) is important. Copper tape will give you a signal of 0 on your ohm-meter, meaning that if the tape is all installed properly with no gaps in connectivity, e.g. the pieces are all touching one another, then you will have a very efficient method to direct those unwanted frequencies to ground. So to clarify, you want to create a connection with as little resistance as possible, so that the unwanted frequencies move easily to ground by way of your shielding work.

I think there are enough of us out there (if you are reading this, you are probably one!) who own, or would be interested in purchasing, a multi-meter. I check all of my work on each shielding job because its critical to know that you have a complete circuit. An incomplete circuit means an incomplete job, and results in a lot of time spent taking apart a completed job to find and fix the break in connectivity.

I find that copper tape yields a 0 reading on my ohm meter, and shielding paint reads .08 or thereabouts. No audible difference in effectiveness, to my ears. Since paint takes a fraction of the time as tape, I typically use paint for most of the shielding, with copper tape for the flat surfaces that are easy to reach. I use tape with conductive adhesive. The combination of tape and paint is most cost effective and people rave about my shielding jobs, including many pro players. I'm working on a shielding job for a bass body now, which was sent to me by a TB-er in Ohio, because he liked what he had read about me. Thanks, TB!

One other nice part of shielding is that any point of the shielding can be used as a ground. If you prefer to solder to the copper tape, have at it. Its way easier than soldering to the backs of the pots. By the way, I suggest soldering to the tape before applying it to the guitar surface. The pots need to be grounded together and to the jack, but mechanically they will also be grounded to your shielding by virtue of the tape on the back of the pickguard, although I also run a ground line from the pots to the shielding for added ground connectivity. You can run your pickup ground wires and or your bridge ground wire to the copper tape if you prefer that over soldering to the pot casing. I personally find star grounding to be unnecessary in a bass or guitar. See other threads on star grounding for more if you are interested.

I never solder the tape joints since I use paint in combo with copper tape. But on the few jobs I did that were just tape with paint for the wire tunnels connecting the pickup cavity to the control cavity, I didn't bother with soldering the joints together. There was more than adequate overlap between the tape pieces, again IMO.

My last thought is in regards to shielding the inside of the plastic pickup covers. Initially I did shield the inside of the covers, then decided it was a lot of work so I began to see if there was a noticeable difference when I opted not to shield the inside of the pickup covers. I could not notice a difference. So I stopped. All of my customers are happy with the results. Thrilled is a more accurate term. "Holy expletive, the bass/guitar is so quiet! Amazing!" is the typical reaction.

As always, take this advice or don't. Your results will not vary if you do a thorough job. But I'm sure some out there may claim that some/all of what I'm saying is bunk. That is why I referenced my reviews on FB, to give my post a little bit of added validity. Good luck and happy shielding! Its been a lot of fun learning how to do it, and helping others as well!