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[Brad Weber]

Jim Brown, Pat Brown and Dale Shirk have all performed testing of various cable types and separations to different EMI sources including a parallel power run and a simulated localized higher energy EMI source (I blieve that Dale used a bulk tape eraser).  They found that the physical separation is definitely a significant factor but as already noted, so were the cable and even the devices to which it connects.  I look at it this way, if you could insure the the interfering source affects each conductor of a balanced circuit equally and you can properly address SCIN and Pin 1 issues, then a high quality differential input would cancel whatever noise is induced.  Those factors are cable and device dependent and the further they deviate from the ideal, the more you have to depend on physical separation.  Add in the aspect of what is an acceptable result varying by application and there unfortunately is no broadly encompassing answer.

[Justice C. Bigler]

I live sound, particularly in touring shows, pretty much everything is taped together, or in groups going to the same places. Often times you have no choice but to run power feeder and cross stage bundles along the same path. Separate them if you can, but sometimes it is what it is. It you are using well made cables and the shields are all intact, you should have only minimal problems. Other times if there is a bad problem, you may have to carry an extra 150 foot mult or feeder bundle to reroute things.

[Andre Vare]

Thanks everyone so far.  Most have have gone where it is irrelevant to my question.  Let me do the introduction again.

I am amongst other hats, a studio designer.  I am involved in a discussion on a studio design forum where John Brandt (another studio designer) and I are trying to explain "zero loop area" design.  Several people have written that power and signal lines can not be adjacent to each other.  I have referenced work by Dan Brown on line separation requirements in conduit and given the example of power/signal lines together in live sound.  To help get across the point of what works, how much do you separate the power and signal lines when doing outdoor events?

Andre

[Art Welter]

Thanks everyone so far.  Most have have gone where it is irrelevant to my question.  Let me do the introduction again.

I am amongst other hats, a studio designer.  I am involved in a discussion on a studio design forum where John Brandt (another studio designer) and I are trying to explain "zero loop area" design.  Several people have written that power and signal lines can not be adjacent to each other.  I have referenced work by Dan Brown on line separation requirements in conduit and given the example of power/signal lines together in live sound.  To help get across the point of what works, how much do you separate the power and signal lines when doing outdoor events?

Andre

I have taped the AC to the snake since 1974, my first snake was 50 feet, later snakes were 250 feet.
I have audio tapes and CDs of shows going back to that same time period, any audible 60 Hz and harmonic noise is always from the stage (guitar, bass, keys) amps.

The only time that the induced noise of the AC line has ever been the slightest problem has been on shows using low gain lavaliere microphones worn on the chest by soft talking individuals. In that case, with the input pre amps wide open, some AC hum harmonics were noticeable, but that noise was swamped by dimmer noise.

At the level of input given by any usual pop performance, any 60 cycle induced noise from taping the AC to the snake is so far below ambient noise as to be a total non issue if decent wire and consoles are used.

Which is why I have never seen a touring company run separate AC and snake runs.
Anyway, that would be well over 200 votes for "T", and none for any of the rest in my experience with touring "rock and roll" productions.

[Mac Kerr]

Thanks everyone so far.  Most have have gone where it is irrelevant to my question.  Let me do the introduction again.

I am amongst other hats, a studio designer.  I am involved in a discussion on a studio design forum where John Brandt (another studio designer) and I are trying to explain "zero loop area" design.  Several people have written that power and signal lines can not be adjacent to each other.  I have referenced work by Dan Brown on line separation requirements in conduit and given the example of power/signal lines together in live sound.  To help get across the point of what works, how much do you separate the power and signal lines when doing outdoor events?

Andre

Your question is still a little unclear. Most of your message talks about studios, but then seems to swerve to live concert sound. If you are inquiring about how to deal with power and signal lines in an outdoor live concert situation, it is fine to bundle power with the mic multi and the line level return snake. If you have to run mic level signals with high power, like hundreds of amps of worth of feeder cable you should try to get as much separation as you can. Unlike a studio installation you will often have little control over where cable is able to be run. With the exception of running with alongside feeder cable you should be fine.

Mac

[Andre Vare]

Your question is still a little unclear. Most of your message talks about studios, but then seems to swerve to live concert sound. If you are inquiring about how to deal with power and signal lines in an outdoor live concert situation, it is fine to bundle power with the mic multi and the line level return snake. If you have to run mic level signals with high power, like hundreds of amps of worth of feeder cable you should try to get as much separation as you can. Unlike a studio installation you will often have little control over where cable is able to be run. With the exception of running with alongside feeder cable you should be fine.

Thanks Mac. You did answer my question. 

There seems to be an ongoing misperception that I am asking how to run power in studios.  I am not.  I am looking for and slowly recieving here, the practices used by LABsters on outside sound to show the people on the othere thread that adjacent lines are used all the time in live sound. 

Baring all*,
Andre

*Ethan, who did the acoustics 101 video is friend.  The closing is tip of the hat to him.

[Tim McCulloch]

Thanks Mac. You did answer my question. 

There seems to be an ongoing misperception that I am asking how to run power in studios.  I am not.  I am looking for and slowly recieving here, the practices used by LABsters on outside sound to show the people on the othere thread that adjacent lines are used all the time in live sound. 

Baring all*,
Andre

*Ethan, who did the acoustics 101 video is friend.  The closing is tip of the hat to him.

Hi Andre

We've been taping 8/5 to the 80 meter drive snake for a long time and runs directly adjacent to the mic snake... and in 1 venue that bundle is on top of about 10 meters of the feeder run, too.  No problems.

As a stagehand I can recall one show running power to FOH that was physically separated from the mic snake, Mannheim Steamroller's Christmas show.  That was because the delay ring hangs were above FOH and their power was part of the FOH run.  High current, bigger magnetic field...  Tell your recording friends that we appreciate their commitment to input integrity, but live needs are more tolerant of miniscule noise than they are accustomed to.

Have fun, good luck.

Tim Mc

[Andre Vare]

Hi Andre

We've been taping 8/5 to the 80 meter drive snake for a long time and runs directly adjacent to the mic snake... and in 1 venue that bundle is on top of about 10 meters of the feeder run, too.  No problems.

Tell your recording friends that we appreciate their commitment to input integrity, but live needs are more tolerant of miniscule noise than they are accustomed to.

Have fun, good luck.

Thanks for the info I am exactly looking for.  People seem to think that I am looking for "good enough".  I am not.  Good practices have to be followed throughout. 

The (huge) block that John Brandt and I are running into is people not understanding, much less accepting the "zero loop area" concept developed by Neil Muncy.  They just follow blind dogma expecting one or the other, not understanding how to use both.  This is interesting, and somewhat understandable considering how long it has taken Neil's "pin 1 problem" to be understood and mostly accepted.  That is consistent with traditional engineering.  The loop area" flies in the face of traditional engineering at first glance.

Andre

[JonathanSmith]

When doing stage to FOH cable runs how close do you have the audio snake to the power lines?

T Taped together
0 0-2"
2 2-4"
4 4-8"
8 8-16"
M More than 16"
S Separate runs

Thanks.

Andre

Touring, 4-5 shows/week, 2k-5k seat arenas

300' input snake, power, and drive snake taped together. No noise problems.

With any touring I do, it is extremely rare for me to not have all of my FOH audio cables loomed together. With local one-off or corporate shows, I deal with whatever is given to me. Usually, lower channel count (<24 ch) snakes are not loomed together. Higher channel count snakes (48+ channels) are almost always loomed with power since I generally use a larger desk if I have a snake that size.

[Brad Weber]

There seems to be an ongoing misperception that I am asking how to run power in studios.  I am not.  I am looking for and slowly recieving here, the practices used by LABsters on outside sound to show the people on the othere thread that adjacent lines are used all the time in live sound.

I think that a critical aspect of this is addressing temporary runs not in conduit versus installed runs in conduit.  Whether studio or live sound, with the latter there can be practical factors and code requirements that relate to physically separating different signal types.

[ProSoundWeb Community]