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Jazz Shielding Pictorial (Big Images Warning)

Discussion in 'Pickups & Electronics [BG]' started by Lyle Caldwell, Jan 5, 2005.


  1. Vic

    Vic There's more music in the nuance than the notes. Supporting Member

    Oct 14, 2002
    Central Illinois
    Staff, Bass Gear Magazine
    amacjazz, with all due respect to I'm sure your solid science, I'm just curious then how you would explain the consistently significant positive results we've achieved by using the method described here? Maybe I can't explain why, but I can very definitely tell you it reduces noise significantly enough to make the work worthwhile.
     
    Rchy7 likes this.
  2. amacjazz

    amacjazz

    Aug 20, 2016
    I am about to try shielding the compartments and around the pickups with MuMetal. My gut says it will help but you obviously can't shield the pickup magnets themselves, and their coils are what's picking up the most hum. (That's why shielded wire will be of no use. The fields in the room are acting just like the strings -- right at the pickups.). I am very dubious of any reports using copper. I have used MuMetal for a studio wall. You might want to wait until I can report my results.
     
    selowitch likes this.
  3. amacjazz

    amacjazz

    Aug 20, 2016
    Yeah, I have no good answer that doesn't insult somebody, but you can find other posters saying exactly what I'm saying. Copper is way cheaper and easier to work with so not much downside to trying it. Added note: I have a bunch of condenser mics which are immune to the EMG fields from my other equipment (their diaphragms are electrically conductive but not magnetic) and one RE20 dynamic. It buzzes like crazy depending which way I point it. Wrapping it in aluminum or copper foil does not stop that and the output is already balanced (differential) and therefore interference cancelling. There's no way around that the element's coil (a magnet) is vibrating with the 60 and 120 cycles. Never mind. We can all get along.
     
  4. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    If one wants to silence their Jazz bass you need to do two things. First, you would need a proper shielding job. This would address RF interference, it would do nothing for 60hz hum. This is the noise you get that stops when you touch metal/strings/bridge. Shielding is recommend regardless of your choice of cable. I have never heard of anybody using coaxial cable in basses for shielding, only home audio, but I am far from a professional tech.

    Second, you will need humbucking pickups. This will address 60hz hum, it will do nothing for RF interference. This is the noise you occasionally get when you favour one single coil pickup. Single coils would work for a "silent" Jazz but only if you like the scooped tone that occurs when you balance two single coils, you cannot solo a pickup with single coils. On that note, a single coil is susceptible to noise, that doesn't mean it will assuredly get additional noise. If you are in a "clean" environment then you will not get hum on a single coil.

    I have no experience with MuMetal but I have achieved equally successful results with aluminum and copper foil as well as conductive paint. My basses could not be any more silent. I have done countless basses using my methods so I am quite confident in its success. I do look forward to the results of the MuMetal though, I am always interested in a new material to work with.
     
    selowitch likes this.
  5. selowitch

    selowitch

    Aug 6, 2005
    Rockville MD
    I'm not sure that's true in all or even most cases. Don't single-coil Jazz pickups cancel each other's hum when they are both at the same volume? Also, I think most people who seek to shield their Jazz Basses want to enjoy the single-coil sound with less of the undesirable noise. Sure, humbucking Jazz pickups are available (e.g., stacked pickups from Seymour Duncan) and they sound good but they surely aren't the only option.
     
    DiabolusInMusic likes this.
  6. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    You are correct. I apologize if I was not clear. I thought I sufficiently explained this with my post but I am not the best with words. You only need humbucking pickups if you want your bass to be silent all the time when you favour one pickup. Two balanced single coils will "buck" hum but they will also scoop out the midrange frequency. You do lose some highs with humbuckers, however, so many folks still swear by single coils. I personally love to favour one pickup and hate hum so I use humbuckers.

    The other available options include a dummy coil, which isn't generally done on basses due to the size and available cavity space, or an Audere Noiseless pre-amp, which will retain the single coil tone but you will require the installation of an active pre-amp. A dummy coils works just like a humbucker would by adding another coil to balance with. The Audere is a great option if you do not mind turning your bass into an active bass and have the space to install the pre-amp. I am passive player so I would rather drop in humbuckers than an Audere. I also do not feel my tone is lacking with humbuckers.

    Just in case I was not clear, shielding will have no impact of 60hz hum and humbuckers will have no impact on RF interference. While they are the same source at a theoretical level (from what I understand, that's all over my paygrade) for our application they are treated as two separate issues with two separate resolutions.

    I hope that clarifies some confusion.
     
    selowitch likes this.
  7. selowitch

    selowitch

    Aug 6, 2005
    Rockville MD
    Sure does! Thanks.
     
  8. jazznut

    jazznut

    Sep 20, 2016
    Before going ahead with sheilding my bass, I should ask: only in some venues I get a noticable hum when using active preamps--even when using both single coils st the same volume. Given that the problem is not chronic, only in particular venues, can it be that electromagnetic interference is exacerbating the hum? Otherwise "noise" isn't an issue, no other symptoms!

    If EMI noise doesnt cause or exacerbate a ground hum, but is significant enough to require sheilding, I have not experienced it at all playing live. (It's easy to see why recording bassist sheild)

    Put in other terms, I am starting to think that the two particular restaurants I play at have significant ground issues thst become increasingly apparent with the active preamp treble boost--level of hum is always commensurate to treble level. Thst's NOT something sheilding will fix, right?
     
    Last edited: Nov 10, 2016
  9. Jmilitsc

    Jmilitsc Supporting Member

    Sep 22, 2013
    Fairfield County, CT
    Hi jazznut, I'm no expert at this so take my answer fwiw... I have a Marcus Miller Jazz and experienced issues with both ground hum and noise from interference, and both symptoms varied significantly in different situations. And I definitely noticed that some rooms were repeatably worse than others. It sounds like your sounds are shielding related if they're still present with volumes matched. Oh, and I've read that some people shield the inside of the plastic pup covers, and removed the redundant ground wires from the pots, etc, but I didn't.

    I recently got a PJB rig and the buzzes, hisses and hums were even more noticeable... yikes!

    So I took to TB and did a ton of reading, including this thread and other very lengthy ones, the "how to" stuff on Stew Mac, and youube, and decided to give the shielding a try.

    Bought the copper tape kit from stewmac and a multimeter... turns out Fender did zero shielding in this bass... zero. Nothing had continuity. Plus the ground cable on the output jack wasn't attached well so I fixed that.

    Spent lots of hours copper taping (and some bleeding - I am not good at this) this thing and holy crap, what a difference! The bass has only a tiny bit of ground hum now when pickup volumes aren't matched, and it is perfectly silent when they're matched. Like perfect.

    I also have to say that the bass sounds so much more articulate in the attack, whether picking or finger style. Such a huge difference. I don't think I'm imagining things... do others notice that after doing shielding?

    Got ambitious with that and decided to upgrade the PUPs to Nordstrand NJ4's.

    I learned a lot, had a blast, and I've never been this happy with the quality and range of sounds I'm getting, it's so much more versatile now.

    Considering the push/pull series wiring mod next maybe!

    Anyway, thank you to everyone who added so much value to this and other threads over the years, great help and education. I hope this post helps others a little too.

    I know many of you other TB'ers need the photo verification :)... So here are some pics of my very not professional shielding job, don't laugh too much at me... it worked!

    First is the non-shielded control cavity, then what I did to it... I didn't take pics after I added a bunch of soldering to tighten up seams, and I also added ground wire from the pup cavities to the main cavity and soldered them to the base.

    IMG_0945.JPG

    IMG_0948.JPG

    IMG_0958.JPG

    And I got the vintage brass foam things too because I had to scrape off the original glued foam to do the shielding fully.

    IMG_0957.JPG
     
    DiabolusInMusic likes this.
  10. Hi jimilitsc - I think your shielding looks pretty good. What is the gauge of the brass piece under the pickup? I have a '56 P knockoff with the old single coil that I shielded, but it's still noisy. Wondering if a piece of brass sheeting might help.
     
  11. Jmilitsc

    Jmilitsc Supporting Member

    Sep 22, 2013
    Fairfield County, CT
    Thx FiveString. Hmm, I don't know the gauge but I ordered the Fender shields from these guys Fender Jazz Bass Bridge Pickup Cavity Shield 0019662000

    Before I installed the NJ4's, I just had the tape (grounded) in the pickup cavities stuck around the glued foam, and it quieted things down quite a bit. I decided to reshield fully and rip out the foam, so I then just needed new foam and thought it'd be cool to set it up that way with the Fender brass.

    - jay
     
  12. jazznut

    jazznut

    Sep 20, 2016
    I greatly appreciate your input. It seems that my tech fixed the hum in the passive mode, but the active hum is not going to go away until the existing "blown up" Fender Active preamp is removed (it's maximum treble output is far less than +18db) & replaved with a real Bartolini TCT. Then I will re-evaluate. Are your active electronics the original stock Fender?
     
  13. Jmilitsc

    Jmilitsc Supporting Member

    Sep 22, 2013
    Fairfield County, CT
    Oh, wow ok, different problem! Curious how that shakes out.

    I did keep the Fender pre, I do like it at this point. Before all this work, and PJB amp, I never even bothered using passive mode, but it really sounds great when I want more old school, so I'm using that about a third of the time... so the pre matters a bit less to me for the moment.
     
  14. Hi Again jimilitsc - Where did you connect the wire attached to the brass plate? Thnx
     
  15. Jmilitsc

    Jmilitsc Supporting Member

    Sep 22, 2013
    Fairfield County, CT
    I soldered ground wire from the brass plates directly to the base of the control cavity copper tape, and soldered the pickup ground wires to the lug screwed into the wall of the control cavity.

    - jay
     
  16. BlueTalon

    BlueTalon Happy Cynic

    Mar 20, 2011
    Spokane, Washington
    Endorsing Artist: Turnstyle Switch
    First of all, congrats on a successful shielding job! The proof is in the end result, especially when the result is as dramatic of a difference as it was in your case. If I may make a couple of suggestions, though, you might find things a lot easier the next time you do it.

    The thing that makes people bleed is not so much a lack of experience working with copper tape (though obviously experience helps) as it is that the copper tape they're using is rather unforgiving. I use copper tape that is thinner, and therefore more pliable. The stuff from StewMac is 1.25 mil thick, the stuff I get on ebay is 1 mil. I can lay down two layers of the thinner stuff in the time it takes to wrestle one layer of the thicker stuff in place, plus the end result looks a lot nicer when you can smooth it out easily and there are no blood stains.

    Not to mention, on ebay you can get twice as much for half the price as what you'd pay at StewMac.

    What I use, and what I recommend, is a 55 yard/50 meter roll of 1/2" tape, available for $12 from an American seller. It's true that you need to lay down four lengths of it to cover the same width that a piece of 2" tape will cover, but there aren't that many large surface areas for it to make a big difference. Plus, if you have wrestled with a piece of cut 2" tape, you know it can be unwieldy, and it doesn't always cooperate with you when you are trying to put it into place. Using 1/2" tape is a lot easier, and will actually cut the time spent shielding quite a bit.

    When I put a piece of tape in place, I smooth it out before putting the next piece in place. I often use the back of a fingernail, but in places that are hard to reach, a small spoon or popcycle stick or something like that will work. It makes the tape look good, but the real reason for doing it is to engage all the adhesive so it sticks better.

    You might have read on here some opinions about adhesive "drying out." I am certain that in any case where tape has not held, it was NOT because the adhesive dried out -- instead, it was either because the surface area was not prepped correctly, or the tape adhesive wasn't sufficiently engaged with the surface. Using a tool (fingernail, popcycle stick, etc.) to flatten out the tape increases your chances of the tape sticking permanently.

    At the end of everything, I go through and solder as many seems as I can easily reach. I totally believe in conductive adhesive, and if I were to skip soldering, I'm confident that my shielding would be just as effective and just as permanent... so why do I do it? Because I believe in overkill. Because soldering is better -- it makes for 100% connectivity, it is permanent, and it adds rigidity to the tape -- in other words, I have form-fitted a bunch of pliable material into a specific shape, and now that shape is reinforced everywhere there's solder.

    And sometimes, after I solder, I put some more tape down just for aesthetics. Yes, it's crazy, but what the hell. I did it with this control cavity. Looks cool, doesn't it?

    BrozTone_zps5a35d94c.
     
    Jmilitsc likes this.
  17. Jmilitsc

    Jmilitsc Supporting Member

    Sep 22, 2013
    Fairfield County, CT
    Ahah, thanks BlueTalon! Your work looks great.

    The stewmac tape was definitely a pain to sort of pre-fold and cut precisely, your suggestion definitely makes sense. I also couldn't smooth it out very well without ripping it. Will remember for next time.
     
  18. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Those brass pieces are just old school shielding, they don't do crap. Does the noise from your bass stop when you touch metal/strings/bridge or is it constant? If it is constant it is likely due to the single coil pickup. If it does actually stop when you touch metal then your shielding job is insufficient.
     
    Duder likes this.
  19. jazznut

    jazznut

    Sep 20, 2016
    Sure looks like a Squire DJAV or DJAV. I have one defretted & it has no ground hum in passive, but with the active Aguilar OBP? Maybe. Gotta see about it in various environments
     
  20. Chad-Chicago

    Chad-Chicago

    Feb 21, 2010
    Just a few tips for those that shield:
    Use paper to make a template for the copper or whatever. This will make application easier.
    Abrade(sand) with 150 then 220 grit sand paper then blow out clean with compressed or canned air
    Work shielding from center out with .5" smooth piece of plastic(cut up old credit card, pick or whatever..)
    Reinstall everything and test
    ??
    Profit!