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High pitched squeal with some treble in rig while not playing?

Discussion in 'Effects [BG]' started by Travisx2112, Aug 22, 2012.

  1. First off, my rig:
    BOSS LS-2 side 1:
    Sansamp RPM>EHX Bass Big Muff>Digitech Whammy
    BOSS LS-2 side 2:
    Sansamp RBI>Human Gear Animato

    then the bass (either my Geddy, or my American Stanard. I can even replicate it without an instrument plugged in, so that's not the issue either.) and this all goes to a MOTU 828MK3 converter, which goes to my iMac.

    My issue is that it seems that if I have just a bit too much treble (as far as the rig is considered, and not my ears, mind you) if I stop playing, I get a high pitched squeal. It'll go away, or decrease in pitch at the least if I:
    1. Turn down the high end on anything, even slightly.
    2. It will also go away, depending on the nature of whatever else is affecting it, if I turn the tone down on my bass.

    This is most evident if the Big Muff or Animato (especially sensitive, it seems) are on, though I can also have it show up if just the sansamps are cranked.

    I've heard of the LS-2 giving off a squeal, from one reviewer. Could that be it?


    This has always happened, even before the converter was installed, so that's not an issue. I'm also using headphones, so it's not feeding back to any speakers, either.
  2. moles


    Jan 24, 2007
    Winnipeg, MB
    Is your iMac a laptop? It was pointed out to me recently that because laptop power supplies aren't really grounded, (as in, with a three-prong plug) that you can get some serious noise happening with instruments plugged in to it, with the power supply to the laptop plugged in. Running off the battery it's no issue, of course.

    Thought number 2 is that you've just got more treble dialed in than you'd hear through a bass amp...depending on the amp of course...so with that you get more noise, and any noise from power supplies is exaggerated.
  3. No, the iMac is a desktop machine.

    I'm not going through an amp. It all goes directly to the computer.
  4. No other suggestions?

    Should I try different power supplies? I'm using a One Spot for most of the pedals except for the Whammy...
  5. moles


    Jan 24, 2007
    Winnipeg, MB
    Yeah, even just for troubleshooting....I'd try and remove pedals from the chain (both the audio chain, and the One-Spot's daisy chain).

    What happens when you plug the bass straight in to the interface, bypassing the pedals?

    I didn't really explain the amp thing well when I posted last night - what I was getting at was that *maybe* there is some inherent noise in the signal that's always been there, but not noticeable when (at other times) you've run this whole chain through an amp. I was assuming that you've done what I often do, which is take my pedal board, and all the settings that sound great through a bass amp, and try to make it all sound similar through the interface, so I don't have to go change every setting....

    Other thoughts: Have you tried plugging in to a different power source/outlet? Thinking that maybe there are some grounding issues in the mains...or with something else plugged into that circuit that's not playing nice either with the computer PSU or the one spot.

    There is one club I play at regularly - the gear I bring *always* causes terrible noise. No one else that plays there has the same issues, and my gear doesn't do this anywhere else...some times $*** doesn't play nice together....
  6. I'd guess its the ls2 or whammy. I'd start by removing 1 at a time. Next I'd look at the power. The 1 spot should be fine but poor power strips and fluorescent lighting can be a problem unless you're using a Furman or something. A different power supply might help but I'd find the source first rather than start plunking down cash. Heck.. It could even be noisy passive pickups picking up stuff in the room that you don't hear until the effects are engaged or a bad ground. Gotta experiment.
  7. Well I do know that the grounding in my building is awful, as I had a major issue with noise from my Sansamps till I lobbed off the ground loop on the plugs (don't worry, I'll never use those anywehre else.) And I have some other noise in the rig as well, as my power cords for my computer, converters, Sansamps, and pedals, and the cords for the bass rig are all crossing eachother like crazy.

    I'll experiment after I sleep for about a week. I'm tired today!
  8. Bassmike62

    Bassmike62 GAS resistance is utterly futile... Supporting Member

    I'd also look at power issues. I got such a squeal by using a typical Boss adapter with my JamMan. Squeal stopped when I started using the Digitech adapter with the Digitech pedal.
  9. BogeyBass


    Sep 14, 2010
    first remove the LS2 and see if the problem goes away.
    then try to remove sansamp

    poor pedal design, isolate and remove bad one.
    sounds like self oscillation to much gain or strange ground loop
    so distortion or buffered bypass
  10. tech21nyc

    tech21nyc Commercial User

    Aug 17, 2010
    Manufacturer: Tech 21
    My guess is that you probably have a ground loop which will cause this type of problem. It is not recommended to cut the ground on any plug as this is a potential shock hazard. With the RBI and RPM there are instructions in the manual to modify an XLR cable to prevent ground hum. Using good DI's are also very helpful as they allow you to lift the ground safely.

    The One Spot is very likely the problem as it ties the grounds together. If the Digitech is the only pedal that needs AC power, just use the One Spot to power that and try using batteries for everything else and see if that fixes the problem.
  11. I'm using the Digitech adapter with it.

    Will try this!

    I don't use XLR's though :meh: I use just standard TRS cables. I'll try getting rid of the One Spot, and clearing up the jumble of wires beneath my desk..
  12. tech21nyc

    tech21nyc Commercial User

    Aug 17, 2010
    Manufacturer: Tech 21
    The 1/4" outputs on our products are not balanced so using a TRS cable will work but it will not be balanced. TRS cables are balanced cables like XLR's.

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