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Author Topic: noise in my guitar rig  (Read 2093 times)

chris mcphee

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noise in my guitar rig
« on: May 17, 2015, 11:21:54 pm »

Hey everyone I've been dealin with this for a long time,we have 500 watt cans in sanctuary with high freq electronic dimmers. so whenever the dimmers are turned on my guitar rig picks up a lot of noise, but when they are off the rig is pretty quiet. tried groud lift , also have power conditioner, put new good quality cables. nothing works. its like my guitar is a giant antenna pickin up the dimmers, any ideas what I can do?
 :-\
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Jonathan Johnson

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Re: noise in my guitar rig
« Reply #1 on: May 17, 2015, 11:51:59 pm »

Might want to make sure that dimmer gear is properly grounded. That means ensuring that you have a good, solid grounding conductor all the way back to the service entrance panel. If your wiring is in conduit and there is NOT a separate grounding conductor in the conduit, a loose conduit connection can turn it from a noise sink into one great big antenna radiating EMF noise everywhere.

You need to start by looking at the problem, not the symptom. The symptom is noise in the guitar rig. The problem is a noisy dimmer circuit. While dimmer circuits are notorious for generating electrical noise, everything in the dimmer circuit from the service panel to the conduit to electrical boxes to the dimmer packs to the lampholders themselves need to be properly grounded in order to minimize the noise that it radiates to the environment.

Once you're satisfied that everything in the dimmer circuit is in proper order, then start looking at the guitar rig. And when you look at the guitar rig, again the prime culprit is grounding: you want to try get everything properly grounded.

NEVER lift the ground on an AC power cord. That is a recipe for electrical shock. The only place a ground lift should be necessary is in the audio signal line between components.
« Last Edit: May 17, 2015, 11:59:55 pm by Jonathan Johnson »
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Stop confusing the issue with facts and logic!

John Roberts {JR}

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Re: noise in my guitar rig
« Reply #2 on: May 18, 2015, 10:55:53 am »

Triac dimmers are noisy... Variac dimmers are quiet, but large, heavy, and expensive.

JR
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Bob Taylor

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Re: noise in my guitar rig
« Reply #3 on: May 18, 2015, 05:49:01 pm »

Triac dimmers are noisy... Variac dimmers are quiet, but large, heavy, and expensive.

JR

Doesn't matter if it's Triac or SCR, it's the Rise Time that transmits all the garbage.
Cheap Dimmers have small or no Chokes to slow down the Delt V / Delta T on the front edge of the dimmer waveform. This can radiate energy into the MHz. Expensive Dimmers have large Chokes to slow down this waveform, some as slow as the 600 microsecond plus area. This helps to keep the Dimmer Hash out of Guitars, Microphones, and stops the Filaments in the fixtures from "Singing".
The ultimate Dimmer is a Variac. They are used in studios mainly for their Low Noise. Expensive and Heavy. Years ago we used them in our Church with Motor Operators to control the light levels.
Not downplaying the grounding, It needs to be in Conduit and Grounded to help control transmitting the Hash and for Safety.

Bob
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Steve M Smith

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Re: noise in my guitar rig
« Reply #4 on: May 18, 2015, 06:57:13 pm »

Lets not forget rheostat dimmers!


Steve.
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chris mcphee

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Re: noise in my guitar rig
« Reply #5 on: May 21, 2015, 10:34:27 pm »

Doesn't matter if it's Triac or SCR, it's the Rise Time that transmits all the garbage.
Cheap Dimmers have small or no Chokes to slow down the Delt V / Delta T on the front edge of the dimmer waveform. This can radiate energy into the MHz. Expensive Dimmers have large Chokes to slow down this waveform, some as slow as the 600 microsecond plus area. This helps to keep the Dimmer Hash out of Guitars, Microphones, and stops the Filaments in the fixtures from "Singing".
The ultimate Dimmer is a Variac. They are used in studios mainly for their Low Noise. Expensive and Heavy. Years ago we used them in our Church with Motor Operators to control the light levels.
Not downplaying the grounding, It needs to be in Conduit and Grounded to help control transmitting the Hash and for Safety.

Bob
does that go for high freq dimmers too?
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Re: noise in my guitar rig
« Reply #5 on: May 21, 2015, 10:34:27 pm »


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