Need Help with Buzz advice; not 60 hz hum

[indigo7us]

Hi There,

I have a buzz issue and would appreciate some suggestions to solve it. I am the sound tech for an Indian casino.

When we have bands play, anytime we have a player using single coil pick-ups, there is a loud buzz.

The buzz occurs according to orientation. When the musician turns in place the buzz lessens but is still audible. This leads me to believe that it is the guitar at fault picking up electromagnetic interference.

The buzz sounds more like a higher frequency buzz than a 60Hz hum. If they switch the pickup selector to a middle position (selecting two pickups at once) then the buzz is also reduced. Obviously a single coil situation here. We have tried a optical isolator which helped but does not solve the problem.

Being a casino there is obviously a lot of power being routed in many different directions for many purposes.

Any ideas for how to solve this issue? I can have the casino electricians fix the problem, but I would need to give them a direction to go in.

Thanks!

 

[Footer]

What amp is the guitarist playing through? Is it house backline or does this happen with multiple setups? Have you tried switching off lighting fixtures? Are you on isolated power for your "band power"?

I would get a hold of a guitar that does this. Unplug/power down EVERYTHING onstage except the guitar's amp. If you still have the noise you have issues in the wall. If you don't, one by one power each circuit up. That will help you get zeroed... then you can divide and conquer.

 

[DuckJordan]

It is the pickups they're called humbuckers for a reason.

Sent from my XT1060 using Tapatalk

 

[indigo7us]

Hi There,

I have a buzz issue and would appreciate some suggestions to solve it. I am the sound tech for an Indian casino.

When we have bands play, anytime we have a player using single coil pick-ups, there is a loud buzz.

The buzz occurs according to orientation. When the musician turns in place the buzz lessens but is still audible. This leads me to believe that it is the guitar at fault picking up electromagnetic interference.

The buzz sounds more like a higher frequency buzz than a 60Hz hum. If they switch the pickup selector to a middle position (selecting two pickups at once) then the buzz is also reduced. Obviously a single coil situation here. We have tried a optical isolator which helped but does not solve the problem.

Being a casino there is obviously a lot of power being routed in many different directions for many purposes.

Any ideas for how to solve this issue? I can have the casino electricians fix the problem, but I would need to give them a direction to go in.

Thanks!

It seems to happen with every set-up with single coils. Not our back line, all bands provide their own.

Different guitar/amp combos, same problem when they go DI.

No problem with hum buckers.

Thanks Kyle, I'll try powering everything off and starting up one by one, we've tried with no lights on and same buzz.

Some hum is expected, but this is pretty outrageous. I am fairly sure its in the walls, where would I have the electricians start?

 

[WooferHound]

Guitar pickups are directional, it gets the signal best when it is directly in front (or behind) of the pickup. Reorient the guitar till you get the loudest buzzz, it will be facing directly toward (or away) from your problem.
Do you have the big loop inductive Hearing Impaired system ?

 

[FMEng]

I'm going to predict the stage is wired with romex or plastic pipe. Rewire it in EMT or MC.

 

[JD]

Although shielding the wiring in conduit or MC will help, it is important to know why and what is going on. You said it sounds like a higher pitch than 60Hz. This is both correct and incorrect, I will explain:
Lighting dimmers produce a square chop to the waveform, sometimes referred to as a saw-tooth waveform. A square wave is defined as a sine wave with every possible harmonic added. The square portion of the saw tooth is radiating many harmonics well above 60Hz but occurring at a rate of 120 times per second. Your dimmer system is probably three phase, so if the guitar pickups are seeing chops from each of the three phases, then your occurrence rate is 360 per second. Bottom line is that it is coming from your lighting system and being magnetically picked up by the single coil (not humbucking) pickups. You may also notice the characteristics of the sound change as you change lighting settings. The problem will show up the least when all the lights are up full, or all off. It will show up the worst when your lights are at about 50%. You will hear some of it even when all your lights are off. This is because they are never completely off, they just idle at a very low, not visible level.
So, how to work with it?
Well, short of rewiring the place in metal conduit, which will help but not eliminate the problem, you can give the acts that play there a warning notice that they will have problems if their instruments use single coil pickups. Well, we know how that will work Now, I have had to deal with this on shows and about the only proactive thing you can do is design scenes that leave your channels at 0 or 100% but limit any channels from having half-settings like 50%. (Especially in quiet numbers!) The second thing you can do is try to maintain a good distance between any extension cables that feed lights and where the person playing the offending instrument will stand. It's a Rubik's Cube solution, but you can usually find a tolerable compromise!

 

[MrX]

http://www.stewmac.com/How-To/Onlin...hy_and_how_of_electric_guitar_shielding_.html