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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Jamin Lynch on April 15, 2014, 11:28:54 am

Title: Neon lights myth
Post by: Jamin Lynch on April 15, 2014, 11:28:54 am
I have often heard that neon lights can cause buzzing in a sound system or a guitar amp. I can't remember it ever being a problem for me anyway. This came up the other day when a band came in for set up and immediately started turning off all the neon lights that have been on this stage for years with no issues. They said they have issues with neons all the time.

Myth or fact?

If a fact, what would cause it and how can it be corrected?

Thanks
Title: Re: Neon lights myth
Post by: Art Welter on April 15, 2014, 12:08:28 pm
They said they have issues with neons all the time.

Myth or fact?

If a fact, what would cause it and how can it be corrected?
Jamin,

No myth, high voltage transformers employed to drive neon signs often radiate lots of RF signals that are readily picked up by high impedance single coil guitar pickups which act as an antenna, the RF is amplified by the high gain compressors, distortion effects, and guitar amps.

Standing with your guitar with the strings and pickups at the correct angle in relation to the "broadcast" transformers can reduce the noise, but when there are several neon sign transformers (as is typical in nightclubs with multiple beer endorsements) there is no angle one can stand at that will avoid the noise radiated by them all.

In those nightclubs, the guitar player and amplifier must be either be enclosed in a Faraday cage to avoid the noise pickup, or use humbucking pickups, an unacceptable solution for a guitar player fond of the tone of his 1962 Stratocaster.

So, the usual solution is to unplug the goddamn transformers.

Art
Title: Re: Neon lights myth
Post by: Nicolas Poisson on April 15, 2014, 01:13:38 pm
It also "works" with dimmed PAR cans: the voltage switching generates high frequencies, which are emitted by the lamp.
Title: Re: Neon lights myth
Post by: Taylor Hall on April 15, 2014, 01:29:00 pm
No myth, here. It can also mess with wireless mic/monitor signals.
Title: Re: Neon lights myth
Post by: Art Welter on April 15, 2014, 02:17:39 pm
It also "works" with dimmed PAR cans: the voltage switching generates high frequencies, which are emitted by the lamp.
The RF from crappy, unfiltered dimmers is radiated from the length of interconnect cable from the dimmer to the lamp.

Crappy dimmers located close to the lamps may cause less noise because their "antenna" are shorter.
Title: Re: Neon lights myth
Post by: Keith Broughton on April 15, 2014, 03:01:39 pm
Jamin,

No myth, high voltage transformers employed to drive neon signs often radiate lots of RF signals that are readily picked up by high impedance single coil guitar pickups which act as an antenna, the RF is amplified by the high gain compressors, distortion effects, and guitar amps.

Standing with your guitar with the strings and pickups at the correct angle in relation to the "broadcast" transformers can reduce the noise, but when there are several neon sign transformers (as is typical in nightclubs with multiple beer endorsements) there is no angle one can stand at that will avoid the noise radiated by them all.

In those nightclubs, the guitar player and amplifier must be either be enclosed in a Faraday cage to avoid the noise pickup, or use humbucking pickups, an unacceptable solution for a guitar player fond of the tone of his 1962 Stratocaster.

So, the usual solution is to unplug the goddamn transformers.

Art
The problem is magnified a lot if there is even a slightly loose connector in the neon cct.
I worked in a bar that has a neon sign along the back of the stage that had to be turned off when the band played.
Title: Re: Neon lights myth
Post by: Jay Barracato on April 15, 2014, 04:37:35 pm
Years ago, I dropped in on some friends band in a Montana bar, some 2000+ miles from where they were used to seeing me. During sound check, their tech got to the two SL instruments and had just a hash of noise. After spending about half an hour double checking their gear he threw up his hands in disgust and looked to me for a long shot solution.

I walked up and unplugged a neon bar sign that was directly behind the amps ( and sharing power) and everything immediately cleared up.

Now that is the first thing I look for when having problems on a new stage.

Sent from my DROID RAZR HD using Tapatalk

Title: Re: Neon lights myth
Post by: Jamin Lynch on April 15, 2014, 06:26:25 pm
Jamin,

No myth, high voltage transformers employed to drive neon signs often radiate lots of RF signals that are readily picked up by high impedance single coil guitar pickups which act as an antenna, the RF is amplified by the high gain compressors, distortion effects, and guitar amps.

Standing with your guitar with the strings and pickups at the correct angle in relation to the "broadcast" transformers can reduce the noise, but when there are several neon sign transformers (as is typical in nightclubs with multiple beer endorsements) there is no angle one can stand at that will avoid the noise radiated by them all.

In those nightclubs, the guitar player and amplifier must be either be enclosed in a Faraday cage to avoid the noise pickup, or use humbucking pickups, an unacceptable solution for a guitar player fond of the tone of his 1962 Stratocaster.

So, the usual solution is to unplug the goddamn transformers.

Art

That makes since for guitars.

I guess I've been lucky so far. I've never had a problem with sound system issues from neon. What could cause that and what would be a cure...other than turning the neon sign off?
Title: Re: Neon lights myth
Post by: Mike Sokol on April 15, 2014, 11:27:32 pm
That makes since for guitars.

I guess I've been lucky so far. I've never had a problem with sound system issues from neon. What could cause that and what would be a cure...other than turning the neon sign off?

A long time ago in a galaxy far away, my band played every month in a bar that had DOZENS of neon beer signs everywhere for "ambiance" which the owner would not turn off. The buzzing through our guitar player's amp was really nasty. So I did some experiments in shielding the pickup and control cavity of this guitar with copper foil to create a Faraday cage. It worked quite well, as I remember. Now, on some guitars this could be a lot of work, but it was worth it to keep my sanity on stage. Also, humbucker pickups should help in this case, but you may need to also shield the interior cavities as well.   
Title: Re: Neon lights myth
Post by: Jeff Bankston on April 18, 2014, 01:06:04 am
Cezar Zuderwijk the drummer for Golden Earring had 2 golden round neon tubes in his clear acrylic bass drums for years. they blinked on and off during concerts. when we played the bar and club circut we never asked for ballasted lights to be turned off. sometimes the amps buzzed and sometimes not bet once the music started you did hear the buzz. maybe the patrons thought the buzzing they heard was from drinking all the liquier or the bad bees in the hive.
Title: Re: Neon lights myth
Post by: Steve M Smith on April 18, 2014, 04:21:11 am
I'm assuming the OP means fluorescent lights rather than neon.

Also, anything on a simple thyristor/triac control will cause some noise as at settings lower than 100% it will switch on when the ac waveform is part way through its positive or negative cycle.

Quote
I walked up and unplugged a neon bar sign that was directly behind the amps ( and sharing power) and everything immediately cleared up.

Things like that are always good.  One of my friends would comment "Now it's your turn to wear the smug hat".


Steve.
Title: Re: Neon lights myth
Post by: TJ (Tom) Cornish on April 18, 2014, 07:28:14 am
I'm assuming the OP means florescent lights rather than neon.

Also, anything on a simple thyristor/triac control will cause some noise as at settings lower than 100% it will switch on when the ac waveform is part way through its positive or negative cycle.

Things like that are always good.  One of my friends would comment "Now it's your turn to wear the smug hat".


Steve.
Nope - neon. http://www.jantecneon.com/Neon-Sculptures.html  Ubiquitous in bars in the states, but slowly being replaced by LED.  I would say we only have about 40 years to go in the transition.

Title: Re: Neon lights myth
Post by: Steve M Smith on April 18, 2014, 12:28:06 pm
O.K. I stand corrected!

I made the assumption because I have lost count of the number of times I have heard fluorescent lights referred to as neon.

Ubiquitous in bars in the states

Over here it's very common to see neon lighting externally but I haven't seen much inside a building.  When I have, it has usually been in a US themed diner!


Steve.
Title: Re: Neon lights myth
Post by: Jamin Lynch on April 18, 2014, 01:23:06 pm
I'm assuming the OP means fluorescent lights rather than neon.

Also, anything on a simple thyristor/triac control will cause some noise as at settings lower than 100% it will switch on when the ac waveform is part way through its positive or negative cycle.

Things like that are always good.  One of my friends would comment "Now it's your turn to wear the smug hat".


Steve.

No, the OP was asking about neon and sound system issues. Everybody jumped over to guitars.
Title: Re: Neon lights myth
Post by: Jeff Bankston on April 18, 2014, 04:57:49 pm
No, the OP was asking about neon and sound system issues. Everybody jumped over to guitars.
we never had an issue with pa system hum around neon lights. Black Sabbath has a song called "Neon Nights".