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[Alex Donkle]

Has anyone here ever run Clear-com / RTS TW cables next loudspeaker and/or lighting cables during a show? The comm noise issues I've had in the past are always from grounding issues, but I haven't run next to speaker and lighting before. There's limited cable paths in a venue so I'm curious if anyone's tried it before.

[Jordan Wolf]

Alex,

Are you referring to AC power for lighting (Socapex, feeder, etc.) or DMX control?


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[Keith Broughton]

Has anyone here ever run Clear-com / RTS TW cables next loudspeaker and/or lighting cables during a show? The comm noise issues I've had in the past are always from grounding issues, but I haven't run next to speaker and lighting before. There's limited cable paths in a venue so I'm curious if anyone's tried it before.

Clear Com type system cable is not balanced audio and may be subject to noise from adjacent power cables.

[Riley Casey]

This :

Clear Com type system cable is not balanced audio and may be subject to noise from adjacent power cables.

Both Clearcom and RTS run at line level but only RTS is a balanced line.  CCom should be run at least a foot away from AC power cables

[Henry Cohen]

Both Clearcom and RTS run at line level but only RTS is a balanced line.  CCom should be run at least a foot away from AC power cables

Telex's "RTS" branded TW intercom is also UNbalanced. It's architecture is that it's two channels of [unbalanced] audio whereas CC is only one. However, Telex's "AudioCom" branded intercom IS balanced, but only a single channel.

[Alex Donkle]

Alex,

Are you referring to AC power for lighting (Socapex, feeder, etc.) or DMX control?


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Power, it's Socapex power cables out to light fixtures with adjacent DMX cabling.

And yes, I'm aware that Clear-Com and RTS TW are unbalanced and should be run away from power cables. I'm just looking for real world experience from anyone that may have done this before. The Clear Com beltpack headphone amps low end is 150Hz, above the primary 60Hz and 1st Harmonic frequencies of the power cables.

[Mac Kerr]

Power, it's Socapex power cables out to light fixtures with adjacent DMX cabling.

And yes, I'm aware that Clear-Com and RTS TW are unbalanced and should be run away from power cables. I'm just looking for real world experience from anyone that may have done this before. The Clear Com beltpack headphone amps low end is 150Hz, above the primary 60Hz and 1st Harmonic frequencies of the power cables.

I would not expect big problems from running adjacent to Socapex. Yes, TW comm is unbalanced, but it's also line level, and as you say, limited bandwidth. It is very common to have to run all types of cable via a single path. I have done it countless times. If you find you are picking up unacceptable levels of hum you can try to separate the cables, but whoever finds the hum unacceptable has to understand the solution may involve extra labor costs to find a new path for either comm or power cables.

Mac

[Pete Erskine]

Has anyone here ever run Clear-com / RTS TW cables next loudspeaker and/or lighting cables during a show? The comm noise issues I've had in the past are always from grounding issues, but I haven't run next to speaker and lighting before. There's limited cable paths in a venue so I'm curious if anyone's tried it before.

if you must run next to power cables and the number of cables is small, use an audio only box to split your channels into balanced audio and add a power supply (with termination OFF) at the far end.  You will still pickup some hum but much less.  Keeping your comms at least a foot or more from lighting and power is the best way.  crossing cables at right angles will not induce noise.

[Matthew Knischewsky]

Has anyone here ever run Clear-com / RTS TW cables next loudspeaker and/or lighting cables during a show? The comm noise issues I've had in the past are always from grounding issues, but I haven't run next to speaker and lighting before. There's limited cable paths in a venue so I'm curious if anyone's tried it before.

As has been mentioned both types of coms are un-balanced. Running com lines near AC cable is going to cause some degree of hum. Generally the longer the com and AC cables are run together the louder the hum will be. Running near speaker cables would be less of an issue, there may be some crosstalk but I would not expect hum from running near speaker cables.

One event in particular years ago I remember the TD of the show was very discerning about coms. It was a product launch with multiple worldwide locations connected by satellite trucks plus telephone interfaces. We had 30 something stations locally plus however many were at the half dozen other sites. The TD wanted the coms to be dead quiet clean (or so he said) so as A3 I was tasked with sorting out the noise problem. I learned a lot that afternoon about just how much hum can be picked up by unbalanced lines when in proximity with AC cables, even crossing at 90 degree angles. The main culprit was feeder cables and socas run across a truss arch being used as a cable bridge so I had to make a new cable path to avoid all of that at which point the hum was much better but still there. I used mic stands to make up some mini cable bridges to separate the com cable from feeders in a few areas where they had to cross. Even better now. I asked the TD to have a listen, barely puts his headset on says hardy anything then tells me "oh yeah, it's fine".

Show went well but the product flopped.
Matt

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