Electric humm & buzz. . .

[WesW]

Okay, at my church we play in a theater - a movie theater. The sound is great due to the natural acoustics of the place, and we have great gear (some powered subs that we run at about 25%!!!!) - so that's not an issue.

Power is.

Whenever I plug in, I get a horrible hum as soon as I turn up. I end up turning my treble down all the way - which is not my preference, at all - to kill some of it. But it's horrible! I have tried using the ground lift - but that is not the issue, as it only makes the issue worse.

Any suggestions on killing this noise in a poor-power theater?

Thanks!!

 

[bassman1185]

Is the noise audible when you're playing, or is it just an issue between songs?

If it's not THAT big of a problem, you might be able to get rid of the buzz with a noise supressor pedal, like the BOSS NS-2 (I use this one and I love it) or the ISP Noise Decimator.

 

[mrokern]

Question(s):

1) Are you running direct?
2) Is your bass rig plugged into the same ground path as the PA?

-Mark

 

[WesW]

Well - I turn my vol off between songs - cause it would be an issue if I didn't.

1 - yes - running direct out of my GB Shuttle.
2 - hmmmm - good question. I'd like to think no - but not sure. I just plug into the extension cord they lay out for me!

I'll check on that next time I play - not this weekend. . . nat'l guard.

 

[mrokern]

Well - I turn my vol off between songs - cause it would be an issue if I didn't.

1 - yes - running direct out of my GB Shuttle.
2 - hmmmm - good question. I'd like to think no - but not sure. I just plug into the extension cord they lay out for me!

I'll check on that next time I play - not this weekend. . . nat'l guard.

Start by seeing if the buzz is there when the Shuttle isn't connected to the XLR line. If your rig is quiet on its own and the buzz only appears when you plug the XLR into the Shuttle, you've got yourself a ground loop.

If that's the case, plug into the same power circuit as the sound board and it should go away. DON'T do the the dangerous fix, which is lifting the AC ground.

-Mark

 

[Parabolic Box]

On some amps, though, the ground lift just lifts the XLR. Hopefully, GB has that design. (I know GK does.)

But it does sounds like a ground loop issue.

Unless there's a large power transformer somewhere nearby.

 

[WesW]

The buzz is still there whether I'm connected direct or not - that doesn't seem to matter.

I can't plug into the same circuit as the board - as it's a hundred feet away at the back of the theater.

Thanks for the assistance guys. . .

 

[mrokern]

The buzz is still there whether I'm connected direct or not - that doesn't seem to matter.

I can't plug into the same circuit as the board - as it's a hundred feet away at the back of the theater.

Thanks for the assistance guys. . .

Same grounding path, I should have said.

Are your guitarists experiencing any of this in their amps?

-Mark

 

[WesW]

Oh yes - it seems to be everywhere. . . there are some things built into the board that assist there so its not in the mains. . . but the power at this place is. . . well, old.

 

[Vinny D]

If it is a place you will be using all the time I would hire someone to just run a new dedicated line to use for stage power.
More then likely if it's an old theater there are probably plenty of miss wired outlets where grounds and neutrals and even hot legs have been swapped around on outlets or have broken off from age.
It could be a bunch of issues and the only way to fix it easy is too run a new circuit.

 

[MX21]

Had the same problem in a theatre. The electric guitar was putting out a huge buzz. It went away if you held your hand on the strings. We also found if you rotated the guitar 90°, it diminished. We did everything we could to fix it assuming it was a power problem. It turned out to be the lights. The dimmer packs were apparently radiating a lot of electromagnetic interference through the air and the strings were picking it up. Wasn't much we could do about it except turn off the bank of lights that were causing it. Other lights weren't a problem, so we just went with those.

 

[sonicnuance]

I find this topic very interesting as I'm currently having a similar issue with my Shuttle in our church.

I find the hum is only through the xlr di and doesn't go away when lifting the ground on the back of the shuttle. I was using line level and someone suggested using mic level... I'll give that a go next time.

I even tried tying a passive DI in series with the input of the shuttle and it still buzzed through the passive DI. If I unplugged the shuttle it went away (using the passive DI only)

 

[Bob Lee (QSC)]

Turn the volume knob(s) up and down on your bass. Does the volume of the buzz change when you do that? If you turn the volume knob(s) all the way down, does the buzz disappear? Does the buzz volume change when you orient the bass in different directions?

If all these are "yes", the culprit(s) is/are your pickup(s). This is a fairly common problem. If you have a dual-single coil-PU bass, like a J-bass, the pickups might be wired in opposing polarity so that they act as a big humbucker when you balance their volumes. You might also benefit from switching to actual humbucking pickups.

In the meantime, keep your distance from power transformers, including wall warts, in your gear or anyone elses. Stay away from fluorescent or neon lights as well as AC motors.

Some will try to sell you a power "conditioner." That will lighten your wallet but won't help your situation.

 

[WesW]

Bob - thanks for that. I was indeed using single coils. I'll have to try with an active bass and see what happensa.

Vinnie - grat idea, but we are renters - rewiring isn't in the agreement .

Thanks!!