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Is this a shielding issue?

Discussion in 'Pickups & Electronics [BG]' started by complexprocess, Jan 7, 2013.

  1. complexprocess

    complexprocess

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    I have an Ibanez SR505 that has been buzzing pretty badly at my house. I believe it's RF interference because ground lifting and completely isolating from the power grid make no difference. Also, changing the way that I'm facing can limit or almost totally remove the buzzing. Sounds like classic RF interference to me. It doesn't go away when I touch the strings, which again, makes me think it's RF and not grounding. Does that sound right?

    Here are some other facts about my situation:
    * In other locations the bass is pretty near dead quiet
    * Brand new battery didn't help.
    * Other basses with near-identical Ibanez electronics are much quieter in the same space
    * The bass in question didn't always buzz like this

    Maybe a connection to the shielding paint dislodged? The electronics still function as expected and when I take it out of the house they sound as good as ever. But I don't want to show up at a venue with RF issues and have it buzz like this.

    So my question: Does this sound like a shielding issue? If I bring it to a pro and have a really good shielding job done, should that protect me from any RF-noisy spaces?

    Thanks!
  2. uOpt

    uOpt Supporting Member

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    Most passive basses have no shielding to speak of anyway.

    Does the noise get better when you touch the strings and worse when not touching the strings?
  3. stepswork4me

    stepswork4me Supporting Member

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    You really didn't read his post, did you? :D
  4. complexprocess

    complexprocess

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    This is an active bass, 9 volt electronics. Touching the strings makes no difference. That's part of why I suspect it's shielding and not grounding, but I really don't know for sure.
  5. uOpt

    uOpt Supporting Member

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    Well no difference between passive and normal active basses here.

    Unless you have more shielding elsewhere it is expected that you act as a shield by grounding yourself via the strings.
  6. stepswork4me

    stepswork4me Supporting Member

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    The 505 is a well made bass. It's got Bartolinli (licensed) pups that are well made and quiet. The pre is well made and quiet. The cavity is sheilded.
  7. JoeWPgh

    JoeWPgh

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    Do you use the same cable in your house as when you're out? I just ran into this and using a differnt cable did the trick.
  8. complexprocess

    complexprocess

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    I usually do use the same cable, but I tried a number of cables to debug the issue and it didn't seem to make a difference.

    Perhaps I'll just bring it to a shop and have it shielded really well, even though there's some shielding paint already in the cavity from the factory. If that doesn't solve it, at least I'll have one more data point to work with. :)
  9. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

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    If the buzz gets louder when you touch metal/strings/bridge you have a grounding issue.

    If the buzz goes away when you touch metal/strings/bridge you have a shielding issue. If your buzz is persistent it is not a shielding issue.

    The SR-505 is active, active pickups do not buzz. If you have a shielding issue it means the pickups are passive and the pre-amp is active which is definitely a possibility. I was quite sure the SR-505 is actually active pickups but I didn't own mine (506) for long. I got rid of it for a BTB 676 and I was quite sure they had the same pickups (Those cheap Bart Mk-1's).

    If it is a shielding issue, you can source copper foil tape locally from stained glass supply shops, but as I stated earlier I do not think that is your issue. But just in case:


    DO NOT PAY SOMEBODY FOR SHIELDING!!! Two reasons.

    A)Most techs think you cannot remove it (seriously, probably 4/5 it is shocking)

    B)You are going to pay over $100 so somebody can put tape in your bass and solder maybe 3 wires. Talk about getting hosed. The job costs less than $20 in parts, and that is assuming you need to pay a soldering iron and solder.
  10. uOpt

    uOpt Supporting Member

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    Can you be more specific about the "same cable" you used? You need to use shielded wire outside the shielded cavity, unless you want to go all Fendereske.

    The shielding paint will only serve as a shield if it is grounded.

    You said that the noise does not get better when you touch the strings. That means the strings and bridge are not grounded. That is only OK if you have complete shielding otherwise (the guitar manufacturer uses you as a shield via the grounded strings).
  11. ics1974

    ics1974

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    Just shield it yourself. It dosn't take long, it's easy to do and it's dosn't cost much at all.
    You have really nothing to loose trying it yourself.
  12. Technotitclan

    Technotitclan Lurking TB from work Supporting Member

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    First I want to correct everyone, The SR505 is passive with active EQ. so unless all three bands are turned up all the time it qualifies as passive.

    Second I have a SR500. I run into the same problem as you. personally I don't let it get to me as my usual practice spaces don't have this issue, just some odd spots in my house. I'd recommend buying the copper tape and tape it up. Do the pup cavities, wire holes and control cavity. heck do the batt cavity too if you can.
  13. uOpt

    uOpt Supporting Member

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    I think it is time to step back a little and wait for the OP to pass over more information.

    If the thing already has shielding paint in the cavities there's no point adding copper tape.
  14. JoeWPgh

    JoeWPgh

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    Yes and no. Different environments might require more aggressive shielding. I live in sight of a TV broadcast tower, with a major train yard in between. If that's not enough, there's tall hills behind me to bounce it back. For where I live, there's no such thing as too much shielding. If you live out in the boonies, 20 miles from anything, you might not need any shielding.
  15. uOpt

    uOpt Supporting Member

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    No, that's not how it works. Any conductor, no matter how thin, will do the trick, as long as it doesn't have holes larger than the wavelength. Think Faraday cage. You can roll gold so thin you can see through it and it would do a complete job as a shield against electrostatic interference - as long as it is properly grounded.

    There is a possibility here that the conductive paint doesn't have even amounts of the conductor in it. But given that the OP is so sluggish in answering any questions in a coherent manner it is far more likely that he screwed something up and that is why his guitar hums and he'll be unable to fix it.

    As long as answers aren't forthcoming I'm outta here.
  16. Stealth

    Stealth Supporting Member

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    I have to make a small correction there - unless the preamp is completely bypassed, it qualifies as active as the pickup signal is still going through the preamp, whether or not you fiddled with the EQ.

    As far as shielding paint goes, I prefer shielding with copper foil, because that way I'm absolutely certain how well it conducts.
  17. complexprocess

    complexprocess

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    I typically use a 6 foot Monster cable when recording, and a 15 foot Monster cable when playing through an amp. Neither are particularly fancy, but they've always been quiet in the past.

    Thanks! I think this may be the key to my issue. My suspicion is that the wire grounding the cavity or maybe the scrap of tape connecting the cover to the cavity may have become dislodged. That would be consistent with the following facts:

    * Touching the strings has no impact on the buzz.
    * The problem seems to have developed somewhat suddenly. I have have a recording from a month ago with the same bass which doesn't exhibit the issue.
    * I have two other basses with essentially identical electronics and construction which don't exhibit the issue when playing through the same setups.
    * Changing the instrument cable has no discernible effect.

    So if I understand correctly, the buzz is introduced to the circuit because ungrounded shielding doesn't do its job. The reason I heard no buzz when I took the bass out of the house is that there was just less interference there, not because the problem went away.

    I'll follow this up by digging around in the electronics and see if I can find anything that I missed before. I can post back here when I've had a chance to do so.

    Thanks for all of your input, everyone!
  18. uOpt

    uOpt Supporting Member

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    Oh I was more asking what wire you use between the pickups and the cavity.

    The first thing you need to find out is this: was the manufacturer's intention when making this bass to have complete shielding (via conductive paint and foil) or did they intend to ground the strings to use your body as a shield as it is normally done.

    One way to find out is whether the is any wire (trying to) connect the bridge to ground, which might have failed.

    It's also unclear to me what "cover" you mean.
  19. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

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    Read my post above. This rule always works.


    If you touch the strings/metal/bridge and the noise goes away it is a shielding issue. (Your body creates the shield when you touch the metal)

    If you touch the strings/metal/bridge and the noise gets louder you have a grounding issue.

    You probably do not have a shielding issue, it doesn't appear as such. Are you %100 certain you used a new battery or was it one you found around the house? Is there a gain control on your pre-amp that got cranked? I think something is happening with your pre-amp personally.
  20. SGD Lutherie

    SGD Lutherie Supporting Member

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    Disclosures:
    Owner, SGD Music Products
    That's not necessarily true. EMGs are very quiet because of the way they are made and the differential circuit they use. But even EMG has had noisy pickups, like the EMG-58. The replaced that with the EMG-85 because of the noise.

    I have an '87 Ibanez SE-885LE which I bought new. When I got it it had Ibanez "Regulated Low-Z" active pickups, and a preamp. The pickups used a dummy coil under each pickup. The dummy coil was one half of a guitar humbucker with no poles.

    The pickups sounded very nice, but they were noisy. So at the time I replaced them with EMG Js. Later I installed my own pickups.

    So active pickups can buzz and hum.

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