So your bass has a hum

[bassman_al]

For a J bass one could use either copper tape or shielding paint on the bridge pup lead wire as long as that shielding job was connected to the other shielding paint/tape, correct? This would be an alternative to trying to shield the drilled channel/route between bridge pup and control cavity. Thanks, Blue, for your contribution to this thread.

 

[bassbenj]

So I'm getting ready to start my foray into this mod, and I'm excited. I'm no electrician, but I have a very basic understanding of the science involved here. From what I can gather, there is no such thing as a partial shilding job. Its either done right, or it will sound the same as pre-shield. If RF can find a way to the cavity, it doesnt matter how small the gap or lack of seal, the RF will get in and cause the same amount of disturbance as pre-shield?

I'm excited to get to use my multi-meter for a new use. Not sure most guys on TB don't own one. A lot of us are pretty handy and tend to carry an electricians worth of gear to gigs, just in case.

Yeah, there is such a thing as partial shielding, in fact it's what you ALWAYS get! Why? Here's the electrical scoop. Shielding works like this: If you have a bunch of wires and stuff connected to an amplifier it picks up hum usually from the power wiring in the room. To stop that pickup, the ideal is to enclose all that wiring in conductive grounded water-tight box. Note if the box is not grounded it won't shield a thing. "ground" on a bass is the outside of the output jack. So if the jack is mounted through the conductive box, the box is automatically grounded. For example the jack through a Jazz bass control plate where the control plate is connected to the box shield (either with a wire or by pressing down on the conductor up over the lip where the plate screws down (soldered wire is best)) makes the ground.

I say "water-tight" because to really be effective, the metal (say copper) must be that sealed. And if the conductor isn't as good as copper, like say conductive paint that isn't working well, then hum can "leak" right through the shield! This is why I prefer copper foil to paint. All the things said about paint and convenience are all true, but paint can be quite variable as to resistance depending on type and manufacturer. Copper ALWAYS works PLUS it's a snap to connect to (solder). But yes, copper is harder to use and glue may come loose over time. Anyway, you can NEVER get a true water-tight shield because typically the tops of the pickups (or at least the poles) have to stick out. But even with the "leak" it will work pretty darn good! Typically I run copper foil also into bottoms of pickup cavities and sometimes also up the sides. It may not be needed there.

Also I would caution about putting foil INSIDE a pickup cover. Too much low resistance metal (copper) close to a pickup coil can change the tone! Now I've never noticed a tone change if the copper foil is OUTSIDE the pickup, lining the cavity, even if close to pickup.

Note that the top of pickup cavity is often shielded (neck pickup) by foil on the back of pickguard. This ALSO must be grounded to work and is usually grounded mechanically by running pickguard foil over to a screw hole where the cavity shielding (paint or copper) is extended to surround that hole. The screw pressure makes a decent mechanical connection between the guard foil and the cavity shielding. Note that the same thing can be done to ground conductive paint although the standard paint ground is a wood screw with a wire lug (wire runs to jack body) and a lockwasher that "bites" into paint to make a good connection.

So to recap: You want to enclose all wiring inside a box that is a "watertight" as possible and as conductive as possible (copper or best paint you can buy) and that box is grounded to the output jack body. That's it.

One final note. You can buy copper foil with "conductive glue" that isn't supposed to need soldering. I don't use it because of the expense and I don't trust the glue to not dry out in a few years and lose conductivity (develops resistance). As you learned above, if EVERY piece of your shield "box" is not grounded it will not shield against hum! So even if you use conductive glue, I'd put a gob of solder "tack" connecting all separate pieces of your shield box.

That's it. Note that shielding only stops hum that changes when you touch ground (usually strings or jack body) If only the bass ORIENTATION changes the hum then that is single coil hum which is only fixed with a humbucking pickup.

Note that shielding theoretically also stops RF pickup (you hear a radio station on your bass) but usually your shield is not "water-tight" enough to really do that and other measures are often necessary (100 pf cap across the output jack).

Finally don't be scared of a digital meter! Harbor Freight often gives them away FREE! And even full price are just a couple of dollars. Not professional, but way good enough! Also when using aluminum or copper foil, the ground connections can also be tested with the simple automotive continuity checker (looks like a screwdriver but has a battery and light bulb and a wire). The light lights up if there is a good connection. But the meter is best. Since it measures voltage as well as ohms, you can use it to test batteries, AC outlets, as well as shielding and even speakers. Very handy for the 'emergency" box.

 

[DiabolusInMusic]

For a J bass one could use either copper tape or shielding paint on the bridge pup lead wire as long as that shielding job was connected to the other shielding paint/tape, correct? This would be an alternative to trying to shield the drilled channel/route between bridge pup and control cavity. Thanks, Blue, for your contribution to this thread.

If you were going to shield the wire routes I would recommend just spraying some paint in a cup and use a pipe cleaner. There are copper tubes and shielded wire as other viable options, but those would be more difficult options. I do not like to change pickups leads, but that is just me. There is no audible difference from my amp or in studio in my basses being plugged in or not and I have never bothered with wire channels. My passive basses are all just as quiet as my active basses. This is why I do not see the point in this added step, but I respect that some do, it so I included the info in the guide. I wouldn't recommend wrapping the lead wire in copper tape, you may end up connecting the hot to the shielding.

BlueTalon, while I respect your opinion, I disagree with it. Every sealed passive pickup I have used is shielded internally, unless it has some kind of flaw no shielding should be required in the rest of the bass. Theoretically you might get RF interference but I have never experienced noise issues on a bass with shielded sealed pickups that did not have cavity shielding. I have better things to do with my life than redundant work and saving time by not doing unnecessary tasks is hardly short-sighted. To each their own.

 

[bassman_al]

I bought Stew Mac paint which comes in a can. It gets rave reviews for its effectiveness and although it's pricey, I think it will overall be less expensive than tape. But I got tape as well. Did a little bit of taping on my pickguard tonight. Pretty easy to use although I can see how it's going to be time consuming. I'm pretty obsessive so I'm sure I'll be thorough. And so far my multi-meter says I have a continuous seal! 0 resistance!

 

[BlueTalon]

One final note. You can buy copper foil with "conductive glue" that isn't supposed to need soldering. I don't use it because of the expense and I don't trust the glue to not dry out in a few years and lose conductivity (develops resistance). As you learned above, if EVERY piece of your shield "box" is not grounded it will not shield against hum! So even if you use conductive glue, I'd put a gob of solder "tack" connecting all separate pieces of your shield box.

You made a lot of good points, but I gotta ask -- have you ever had an instance where the conductive adhesive on copper shielding tape has dried out or lost conductivity? I have never had that happen. If you have experienced it, then I suggest it was probably because you didn't fully engage the adhesive to the wood when you first put it on.

I use multiple layers of thin (0.6mm) copper tape with conductive adhesive, and I press down hard on every bit of the tape with the back of my fingernail or spoon or something. That seats the adhesive firmly onto the wood, and after that it isn't going anywhere. It also smoothes out any wrinkles that might have arisen when I laid down the tape. That said, I also use solder. But solder isn't going to make the adhesive stick to the wood any better, and I don't use a "gob" of solder anywhere.

Oh, and copper tape with conductive adhesive is not expensive. You'll pay a lot more than you have to if you buy it from StewMac, where it is expensive, but if you get it from ebay, it's probably cheaper than you can find in a hardware store with non-conductive adhesive (seriously, $6 for a 100' roll!).

One more thing -- since the purpose of shielding is to conduct unwanted energy to ground, you want it to conduct as best as it possibly can. Therefore, it is silly to intentionally use copper foil that has non-conductive adhesive. If cost isn't an issue, and it's not, then there isn't any reason to prefer using non-conductive adhesive over conductive adhesive.

For a J bass one could use either copper tape or shielding paint on the bridge pup lead wire as long as that shielding job was connected to the other shielding paint/tape, correct? This would be an alternative to trying to shield the drilled channel/route between bridge pup and control cavity. Thanks, Blue, for your contribution to this thread.

I wouldn't put any kind of shielding on the pickup wires themselves. The only thing I put on wires is some heat-shrink, to protect them from chafing anywhere on the sidewalls. I only recommend shielding the wire channel, not the wire itself.

I personally use copper tubing, like what you can get at a hardware store for plumbing. You can just as easily use copper tape -- just find a straw or dowel or something that will fit through the drilled channel, wrap some tape around it adhesive side out, and slide it in. Leave a roughly equal amount of copper tape exposed on both ends of the channel. Cut a few slits length-wise, and then fold the tape outward so it sticks to the shielding on the cavity walls. Easy peasy.

You can even use shielding paint to do it, if that's what you are using for the rest of your shielding job. Q-tips work great for that. If you're using copper for the rest of your job, then stick with copper for the channel shielding.

 

[BlueTalon]

BlueTalon, while I respect your opinion, I disagree with it. Every sealed passive pickup I have used is shielded internally, unless it has some kind of flaw no shielding should be required in the rest of the bass. Theoretically you might get RF interference but I have never experienced noise issues on a bass with shielded sealed pickups that did not have cavity shielding. I have better things to do with my life than redundant work and saving time by not doing unnecessary tasks is hardly short-sighted. To each their own.

????? If that's what you think, then why go to the bother of making a shielding guide thread? Why not just recommend people use sealed passive pickups?



Telling people that shielding a bass is unnecessary, in a bass shielding thread, that you started. Unbelievable.



Regarding better things to do with your life: all of that is entirely your choice. I don't begrudge you the right to do whatever you want with your bass or your time, and I apologize if I came across that way. I said...

"If you enter into a shielding job with the priority being "how much time can I save", your priority is in the wrong place.
The priority must be to do a complete and perfect shielding job, however long it takes."

I meant you in the generic sense, not you as in 2nd person singular. You can take whatever shortcuts you want, you can try to break records for world's fastest shielding job, whatever. Your time, your bass.



Everything else I said was regarding your advice for other people.

"For a person doing their first shielding job, it doesn't matter if it takes all day, or even two or three days, as long as the end result is complete and perfect. It's a learning experience, and the person will learn what steps are necessary, and how to do them quicker, and that person's third or fourth shielding job will take a lot less time.

100% of the time taken to do a shielding job is an investment of time, no part of it is a waste of time. The first few jobs might be just as much an investment in one's own education as it is an investment in actually shielding the bass. Even though there might be a lot of "wasted motion" or "wasted time" in the sense the shielding job could have been done more quickly be a more experienced person, that time is still a worthy investment. Recommending that someone might not need to shield a bass, in order to save them an hour of their life, is very short sighted."

People who are not very experienced at shielding will come to threads like this to learn and to get advice. Such people obviously do not already have their own shielding routine. Their first few shielding jobs are going to be an educational process, and that includes going slowly and being careful, making some mistakes along the way, inefficient use of time, etc. So it will take a lot more time than it otherwise would.

Every single bit of that time is an investment in a person's own education and experience base, and therefore it is time worth spending. Don't you understand that? They should be encouraged to spend as much time as they need on their first few shielding jobs, the speed and efficiency will come with experience.

 

[Fat Steve]

I bought Stew Mac paint which comes in a can. It gets rave reviews for its effectiveness and although it's pricey, I think it will overall be less expensive than tape. But I got tape as well. Did a little bit of taping on my pickguard tonight. Pretty easy to use although I can see how it's going to be time consuming. I'm pretty obsessive so I'm sure I'll be thorough. And so far my multi-meter says I have a continuous seal! 0 resistance!

As far as copper tape goes, I buy it at Home Depot in the pest control section. For $7.49, I get 15' of 1" tape. It's called "Snail Barrier Tape". Way cheaper than any online source I've found.

 

[bassman_al]

Good tip! Conductive adhesive?

 

[Fat Steve]

I'm not sure. My bass is dead quiet now though, so it may be.

 

[scuzzy]

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.

 

[bassman_al]

I found it on the HD website and also on Amazon. 15' for same price that just got me 10' on E-bay.

http://www.amazon.com/gp/aw/d/B000QD3BPW?vs=1

 

[bassman_al]

One reviewer tested for adhesive conductivity. Conducts! Score!

 

[BlueTalon]

As far as copper tape goes, I buy it at Home Depot in the pest control section. For $7.49, I get 15' of 1" tape. It's called "Snail Barrier Tape". Way cheaper than any online source I've found.

I get my copper tape on ebay. With conductive adhesive.

$18.95 gets you 165' of 1/2" tape. (One hundred and sixty five feet.)
$29.95 gets you Invalid Link Removed.
$8.81 gets you 100' of 20mm tape.
$15.99 gets you Invalid Link Removed.*


* Ships from China. All others ship out of Los Angeles.

 

[bassman_al]

To Diab and to Blue,
FWIW I think there is benefit to hearing both of your perspectives. I'm learning a lot from both of your points of view, and I'm impressed that the debate has stayed north of "rude and disrespectful," unlike a lot of other threads on TB. Thank you for that.

 

[bassman_al]

Blue, I searched eBay and couldn't find deals this good. Would you mind posting links to these sellers?

 

[bassman_al]

Oh snap, you already linked! Thanks and sorry for my stupidity!

 

[BlueTalon]

Two steps ahead of ya!

 

[BlueTalon]

Here's another one. 100' roll of 10mm for $6.06. Ships from Los Angeles.

I include this one specifically because it is handy to have a roll of narrower tape. It makes doing pickup route side walls and other tight spaces much easier.

 

[Fat Steve]

I get my copper tape on ebay. With conductive adhesive.

$18.95 gets you 165' of 1/2" tape. (One hundred and sixty five feet.)
$29.95 gets you Invalid Link Removed.
$8.81 gets you 100' of 20mm tape.
$15.99 gets you Invalid Link Removed.*


* Ships from China. All others ship out of Los Angeles.

Nice. Should I ever have a need for that much tape I'll go that route. In my case, I had two basses to do at once, and I was able to get the tape locally.

 

[DiabolusInMusic]

????? If that's what you think, then why go to the bother of making a shielding guide thread? Why not just recommend people use sealed passive pickups?



Telling people that shielding a bass is unnecessary, in a bass shielding thread, that you started. Unbelievable.



Regarding better things to do with your life: all of that is entirely your choice. I don't begrudge you the right to do whatever you want with your bass or your time, and I apologize if I came across that way. I said...

"If you enter into a shielding job with the priority being "how much time can I save", your priority is in the wrong place.
The priority must be to do a complete and perfect shielding job, however long it takes."

I meant you in the generic sense, not you as in 2nd person singular. You can take whatever shortcuts you want, you can try to break records for world's fastest shielding job, whatever. Your time, your bass.



Everything else I said was regarding your advice for other people.

"For a person doing their first shielding job, it doesn't matter if it takes all day, or even two or three days, as long as the end result is complete and perfect. It's a learning experience, and the person will learn what steps are necessary, and how to do them quicker, and that person's third or fourth shielding job will take a lot less time.

100% of the time taken to do a shielding job is an investment of time, no part of it is a waste of time. The first few jobs might be just as much an investment in one's own education as it is an investment in actually shielding the bass. Even though there might be a lot of "wasted motion" or "wasted time" in the sense the shielding job could have been done more quickly be a more experienced person, that time is still a worthy investment. Recommending that someone might not need to shield a bass, in order to save them an hour of their life, is very short sighted."

People who are not very experienced at shielding will come to threads like this to learn and to get advice. Such people obviously do not already have their own shielding routine. Their first few shielding jobs are going to be an educational process, and that includes going slowly and being careful, making some mistakes along the way, inefficient use of time, etc. So it will take a lot more time than it otherwise would.

Every single bit of that time is an investment in a person's own education and experience base, and therefore it is time worth spending. Don't you understand that? They should be encouraged to spend as much time as they need on their first few shielding jobs, the speed and efficiency will come with experience.

If I said "I think you like to argue," you would counter with a post telling me about how you don't like to argue. Once again, I am not interested in useless bickering and I am not interested in changing your opinion, please stop attempting to change mine. Both opinions are equally valid and I am getting a little bit tired of your "I am better than you" posts. There are different perspectives all around the world, just because they differ from yours does not make them incorrect.