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Author Topic: help! major RF and noise on guitar rigs  (Read 5597 times)

Keith Broughton

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help! major RF and noise on guitar rigs
« on: June 28, 2011, 11:48:18 am »

We are working a festival at a new location in downtown Toronto and the guitar rigs are getting stomped on by some serious RF and noise.
We usually get a bit of the local multi cultural radio but the "hash" noise is something new.
Tried running power from the genny instead of "shore" but no difference.(Hail Mary pass...)
Also wrapped guitar cables around ferrite discs with some success.
I have never experienced this drastic a problem!
Any suggestions as to some way to address this issue would be most welcome.
Even Voodoo   :)
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Re: help! major RF and noise on guitar rigs
« Reply #1 on: June 28, 2011, 12:05:25 pm »

We are working a festival at a new location in downtown Toronto and the guitar rigs are getting stomped on by some serious RF and noise.
We usually get a bit of the local multi cultural radio but the "hash" noise is something new.
Tried running power from the genny instead of "shore" but no difference.(Hail Mary pass...)
Also wrapped guitar cables around ferrite discs with some success.
I have never experienced this drastic a problem!
Any suggestions as to some way to address this issue would be most welcome.
Even Voodoo   :)

If it's the guitar rigs, then maybe it's the guitars.  Pickups?????
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Chris Hindle

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Re: help! major RF and noise on guitar rigs
« Reply #2 on: June 28, 2011, 12:19:38 pm »

We are working a festival at a new location in downtown Toronto and the guitar rigs are getting stomped on by some serious RF and noise.
Any suggestions as to some way to address this issue would be most welcome.
Even Voodoo   :)
Ask Toronto Island Airport to turn off the RADAR ??
Hey, I never said it would be a good idea.....
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paul bell

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Re: help! major RF and noise on guitar rigs
« Reply #3 on: June 28, 2011, 01:50:29 pm »

Toss a passive DI on the guitar out.
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Brad Ferguson

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Re: help! major RF and noise on guitar rigs
« Reply #4 on: June 28, 2011, 02:01:01 pm »

We are working a festival at a new location in downtown Toronto and the guitar rigs are getting stomped on by some serious RF and noise.
We usually get a bit of the local multi cultural radio but the "hash" noise is something new.
Tried running power from the genny instead of "shore" but no difference.(Hail Mary pass...)
Also wrapped guitar cables around ferrite discs with some success.
I have never experienced this drastic a problem!
Any suggestions as to some way to address this issue would be most welcome.
Even Voodoo   :)

Hi Keith!

Where in Toronto is the site?
Is it happening on all the guitar setups? Only some? Basses too? When the guitar is unplugged does the noise go away?


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Nick Aghababian

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Re: help! major RF and noise on guitar rigs
« Reply #5 on: June 28, 2011, 02:55:21 pm »

Try putting tinfoil over the input jacks of the head. Most of the time when I cant figure it out with the normal tricks I look to the pedal boards, mostly old Ibanez TS-9's and patch cables with shielding problems.
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John Roberts {JR}

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Re: help! major RF and noise on guitar rigs
« Reply #6 on: June 28, 2011, 03:06:42 pm »

Thats a tough one since adding caps to filter RF will roll off HF in the pickups.

rectification of RF is probably from pedals or solid state amps since most tubes will just roll off the RF (I think?).

Putting everybody in tin foil hats, may not work, but if you have the opportunity to experiment, it might be worth a try (shielding guitars, etc).

perhaps experiment with a good active DI that can buffer the guitars at the guitars without decoding the RF itself.

Good luck...

JR
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Bob Leonard

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Re: help! major RF and noise on guitar rigs
« Reply #7 on: June 28, 2011, 07:36:40 pm »

Keith,
before you start to hack cables and put on tin foil hats you need to determine if it's the amplifier(s) or the pedal boards generating the hash. Unplug everything from the amps, except the speakers of course, turn them on and rotate the volume to 10 (11 if you have one of those). If the hum prevails it's the amp and time to isolate the A/C source.

If the amps are quiet then it's on to the pedal boards and guitars. Start by plugging in the board one component at a time until you've found the culprit. Once found you can maybe, and being a guitar player maybe is huge here, maybe re-arrange the stomp boxes.

And you can;
Make sure the pedal boards take power from the same source as the amps, shorten and coil every cable as much as possible, run all the stomp boxes using batteries (changed every 4 hours).

Strats and Tele's will be the biggest offenders in guitar world and there's not much you can do here except look for fixtures or devices that can generate RF. Neon and flourecent lighting is just bad news, especially neon. If there are signs plugged in that are neon, try to unplug them.

Last but not least the little device below works wonders and won't effect tone.

  http://www.ehx.com/browse/noise-gate-suppression

And the last suggestion. If you are using Fender amps (tube type), you can generate a huge amount of hum if the filiment source is not properly grounded. Older fender transformers have a center tap for the filiments that runs to ground. Newer (CBS) Fenders do not. If the hum is severe then go to Radio Shack and buy a half dozen 100 ohm 1/2 watt resistors. Remove the chassis, unplugged of course, and solder a 100 ohm resistor to both sides of the pilot light A/C source. Twist the ends of the resistors together and solder them to ground. Done.
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Gregor Buser

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Re: help! major RF and noise on guitar rigs
« Reply #8 on: June 29, 2011, 08:15:50 am »

Dave Rat had this problem once with the peppers when playing close to a TV transmitter. Was obviously the whole scaffold picking up the RF and reemitting it. They grounded the scaffold better by using salt water and more grounds, then it went away.
You can read it in Dave's blog...
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John Sulek

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Re: help! major RF and noise on guitar rigs
« Reply #9 on: June 29, 2011, 09:40:12 pm »

We are working a festival at a new location in downtown Toronto and the guitar rigs are getting stomped on by some serious RF and noise.
We usually get a bit of the local multi cultural radio but the "hash" noise is something new.
Tried running power from the genny instead of "shore" but no difference.(Hail Mary pass...)
Also wrapped guitar cables around ferrite discs with some success.
I have never experienced this drastic a problem!
Any suggestions as to some way to address this issue would be most welcome.
Even Voodoo   :)

Hi Keith,
This may not be part of your issue, but there is a new transmission source in the downtown Toronto area that effectively shuts down the new Lectrosonics Quadra iem units. 902-928Mhz
This is on top of the changing TV landscape.
Interference was so strong you couldn't get more than 10feet from the transmitter.
The local Lectro office is working on indentifying what this is as it sprang up quite suddenly. They can clearly see it on the analyzer at their shop which is 3 blocks from the evnt.
Quite a drag as they sound great and we were looking forward to using them.
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Keith Broughton

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Re: help! major RF and noise on guitar rigs
« Reply #10 on: June 30, 2011, 08:24:42 am »

Thanks for all the input.
It's not hum but rather RF noise that is being picked up.
It's the single coil pick ups that are the worst and some of the guitar techs are bypassing pedals that cause the most problems. Much cable coiling has been tried as well.
Since I posted the question, I have found that there is a large power substation about 100M from Metro Square.
However, last night, the problem was minimal.
Modifying incoming guitar amps is not an option but I will pass that idea along to the back line guys.
As it turns out, it's unlikely the festival will be back at this location next year and return to Nathan Phillips Square. The radio station is the only problem there.
I am in the process of identifying which local radio broadcast station it is and then can determine the frequency. I suspect either AM 530 or 1050.
At that point, I might be able to design a filter to kill it.
This problem has filtered into the com system as well as an Avalon active DI.
Seems like any unbalanced line is just a big antenna.
Now where did I put that foil hat....
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Re: help! major RF and noise on guitar rigs
« Reply #10 on: June 30, 2011, 08:24:42 am »


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