Jazz Shielding Pictorial (Big Images Warning)

[Vic]

1) I searched the site and someone does have the pics in a word document.
2) The term ground should only technicaly be used in refering to AC power or similar systems that have an earth ground reference. Thru sloppy usage a signal shield or common has been called 'ground' but it ain't. The reason I say this is a small effort to try to help us all communicate and think clearly.
3) Moving and cleaning up wiring in a bass cavity is huge. There is a good reason why twisted pair audio cable and network cables have their signal pairs twisted together. When cables are run in way that forms an open look you get an antenna. In a cavity it is a receiving antenna, in a room with a 3 way switch it can be a hum transmitting antenna.

The word document would be me, and technically, you're right, and what we call "ground" should actually be referred to as a "signal return", but in reality, it's tied to ground most often when you factor in the amp connection (not always, but usually), which is also when it does the most good, so it's more of an oversimplification than an inaccuracy... all things considered.

 

[Electrophonic]

I love this thread. It has taught me so much. I followed the copper shielding tips step by step on one of my p basses and now it almost dead quiet. Big difference! I'm no expert and the copper and soldering would probably look even better if a pro had done it, but it was fun and educational to it and it works!

 

[Sliderbass]

I have a Hwy-1 jazz with Dimarzio model-J's. I shielded the bass using copper and tied all the cavities together with copper wire. I left the ground points as they were on the back of the pots and verified that everything was connected correctly, or so I thought.

If the bass is assembeled, only half of the neck pickup works (E & A string). The bridge pickup works fine. When I remove the control cover, the pickup works fine. It does not matter where the controls are set.

I'm going to re-do the ground routing so that everything is to the same physicial point. Also currently, nothing is connected to the ground side of the output jack. Question is, does anyone think that will be the cure?

 

[Vic]

I have a Hwy-1 jazz with Dimarzio model-J's. I shielded the bass using copper and tied all the cavities together with copper wire. I left the ground points as they were on the back of the pots and verified that everything was connected correctly, or so I thought.

If the bass is assembeled, only half of the neck pickup works (E & A string). The bridge pickup works fine. When I remove the control cover, the pickup works fine. It does not matter where the controls are set.

I'm going to re-do the ground routing so that everything is to the same physicial point. Also currently, nothing is connected to the ground side of the output jack. Question is, does anyone think that will be the cure?

Yeah, you've got some part of the signal path shorted to ground somewhere. Just figure out where that is, fix it, and you're good.

 

[vbd]

Nice work!

Quick recommendation, tho. I don't see any tack solder spots on any of the seams. I know you've already put the wiring in there, but I strongly recommend you put a small solder blob across any of the seams you can still get to. A little bit of flux helps the solder flow across the seam and spread onto the tape. The adhesive on the back of the tape is somewhat conductive (by design), but it's not a reliable way to assure a near zero ohm "connection"... especially long term.

I appreciate the recommendation, now I had the opportunity to apply:
P-bass: Shielding, with many, tack solder spots.
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The tapes had a smoother appearance, but I rubbed my finger and left marks ...

 

[Vic]

I appreciate the recommendation, now I had the opportunity to apply:
P-bass: Shielding, with many, tack solder spots.
<pics>
The tapes had a smoother appearance, but I rubbed my finger and left marks ...

Nice work! Don't worry about those marks! That's just the texture of the surface underneath, and really, it probably means the tape is stuck a little better as a result, which is good.

 

[mlopbass]

Can i get help doing this on a deluxe active mim jazz bass?

 

[Black Bart]

Don't know if this has been mentioned before, but when shielding with copper tape using a burnishing tool, specifically a spoon tip such as the one pictured, really helps to get the copper tape into tight corners & spaces, flatten it out and get it to adhere not only to the cavities but to itself as well.

 

[selowitch]

Don't know if this has been mentioned before, but when shielding with copper tape using a burnishing tool, specifically a spoon tip such as the one pictured, really helps to get the copper tape into tight corners & spaces, flatten it out and get it to adhere not only to the cavities but to itself as well.

Can you provide a link to a product page or someplace I can purchase one of these?

 

[Black Bart]

Can you provide a link to a product page or someplace I can purchase one of these?

Try either a Google search for Spoon Tip Burnisher or search for Burnisher in Arts, Crafts & Sewing at Amazon. Alternately, you could try searching art supply and craft resource websites or shops.

Excel and Chartpak are two companies that I found that make a similar tool to the one I have - Pentel doesn't make them anymore.

The image is from Invalid Link Removed that I found during a Google search, but I haven't bought from them so don't know if they're reputable or not.

 

[selowitch]

Would Link Removed work? Cheaper.

 

[Black Bart]

Would Link Removed work? Cheaper.

Yes, the spoon tip would work for the corners and to burnish the seams between strips, but the paddle end is what really helps to smooth out the flatter areas where you want to make sure there aren't any bulges or bubbles like the photos above. This especially is important when you want to shield the underside of pickguards where having a smooth finish is important.

So it's not really cheaper as the one I pointed out is two tools in one, not just one tool for half the price.

 

[Black Bart]

Okay, decided to take a couple of quick photos to show the benefits of using the burnisher. Mind you the only reason I'm so picky about making sure the tape is properly tacked down is to avoid having the tape come in contact with any electronics accidentally.

Nice clean edges and corners and note how flat the tab is coming over the edge.
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You can see that the only bumps in the bottom of the cavity are a result of the wood underneath and any residual paint from production.
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The old Pentel Burnisher - Spoon Tip is for seams and corners and flat end is for larger surfaces.
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[selowitch]

Those are really splendid results. I'm ordering one! Can you link to the appropriate Amazon page? I"m having a hard time locating it under Arts & Crafts.

Is Invalid Link Removed the right thing?

 

[joe5cent]

Just a comment. There is no such a thing as a ground in a guitar or sound system for that fact, it is all, ALL shielding and a common connction. As soon as we all know what to call it and start to think about it we might start dealing with these issues better.

Grounds are for electrical systems that connect to a powerline, or can receive a lightning strike.

 

[joe5cent]

BTW, the sheilding examples are stellar!

 

[selowitch]

Just a comment. There is no such a thing as a ground in a guitar or sound system for that fact, it is all, ALL shielding and a common connction. As soon as we all know what to call it and start to think about it we might start dealing with these issues better.

Grounds are for electrical systems that connect to a powerline, or can receive a lightning strike.

You're correct but people are still going to use the less-precise term "ground" in place of "signal return" because it resembles the setup for such things as grounding an electrical outlet with which many non-electricians are familiar.

 

[Vic]

Just a comment. There is no such a thing as a ground in a guitar or sound system for that fact, it is all, ALL shielding and a common connction. As soon as we all know what to call it and start to think about it we might start dealing with these issues better.

Grounds are for electrical systems that connect to a powerline, or can receive a lightning strike.

You are generally correct, but if a building is wired properly, then the post on a 3-prong plug SHOULD represent "earth ground", which is typically tied to the chassis of, say, an amplifier.

So in essence, by tying the signal returns to the "ground" at some point in the system (typically in the amplifier design in the case of an electric bass/guitar) they essentially become the same thing for practical purposes, so it's not as incorrect as you might think when you consider the big picture.

It's not ideal, of course, they should always be separated for best results, but it's currently the simplified reality we live in.

Ideally, the shielding in our instruments should NOT be tied to the negative (signal return) lines. It should be tied to earth ground, and the signal returns should be paired with the signals inside a braided shield of a three connector cable, which then would also require a different custom plug at the guitar end if it has a preamp in it (or don't rely on ring/shank-shorting to turn the preamp on), and the braid would be tied to the shield can in the guitar and the (isolated) chassis in the amp. In short, ain't gonna' happen.

 

[grobe]

Any consensus of whether star grounding works? The whole purpose is prevent ground loops. And now people say this doesn't cut down the noise? Huh??

 

[Vic]

Any consensus of whether star grounding works? The whole purpose is prevent ground loops. And now people say this doesn't cut down the noise? Huh??

To answer all this in one fell swoop, yes, of course it works, because it's solid electrical policy... BUT... in the case of an electrical guitar/bass, the significance of its benefit is so minute it's insignificant.

Here's the whole story in a nutshell...

Making a bass quiet is, BY FAR, primarily all about two things...

Hum cancelling, and shielding. This thread is about the shielding aspect. There are two aspects to shielding... the electronic cavities and passages, and the pickups themselves.

All we have control over, unless the shell comes off the pickup, is the cavities and wiring pathways. If the pickups are sealed units, and not shielded very well, and the bass still buzzes after a good shielding job, there is NOTHING YOU CAN DO other than swap out the pickups to reduce or eliminate that noise. PERIOD.

Why would a vendor choose to not shield the heck out of a pickup? Simple. Tone. When you encase a pickup with a "shield can", it affects the high end response, and maybe even other tonal aspects. So it's a trade-off. You sacrifice tone for noise reduction. No free lunches.

So for our purposes here, it's both about making sure the instrument we play is shielded very well AND to select the pickups that best meet our needs for the venues and styles of music we play.

Hope this helps.