They say the Devil is in the details. I'm obsessed with details. Some details seem insignificant to some folks- like taking care of your cables. It doesn't matter what kind of cable or where you are using them - if you take care of your cables, they will, in turn, take care of you.
The Story:
I was reminded of this today because an old client of mine called me in to troubleshoot a "buzzing" in their sound system when they used their microphone. I made the 30 minute trip to their dining facility and we set the system up just the way they use it. As is often the case, when they turned on the microphone, all was well. Well, not completely. Upon closer inspection, every time the cable was handled in any way, we could hear crackling and popping from the speakers.
I knew what the problem was instantly.
I had another clue as well. When the client pulled the cable out of the case where they stored the mic. in, it was wrapped up tight in the shape of a dog bone and then the remaining cable tightly wrapped around the center of the bundle. I visibly winced and told them this was bad for the cable.
Uh Oh!
There was no question in my mind. (cue the sinister music) This was a cable gone bad.
To be fair - this cable had no choice. I had seen the signs before. This cable had been forced into a pretzel one too many times and it had finally retaliated. I took the connector apart and one of the wires inside had been broken. The rest of the cable was also in tough shape with many bumps protruding from under the outer jacket showing signs of damaged conductors inside from years of improper handling. This little oversight ended up costing them a pretty penny, not to mention the down time.
Minimum what?
With any kind of cable, there are industry guidelines on minimum bend radii. Thinner cables tend to more flexible and thus have a tighter radius and thicker ones less so. Here's a brief description from wikipedia: http://en.wikipedia.org/wiki/Bend_radius
Tell us why Mr. Wizard!
When coiling up a cable, whether it be a mic. cable or an extension cord, it's important to keep in mind that despite their seeming flexibility, all cables are made up of metal - copper to be exact -and all types of metals experience metal fatigue when bent back and forth repeatedly. So when you take that pain-in-the-tookus extension cord and wrap it tightly around your elbow and then tie it in a knot, you're drastically reducing its overall lifespan. The best illustration of this is to take a piece of metal and bend it back and forth until it snaps. Now imagine a bunch of thin strands of copper taking that kind of abuse. Copper is soft and flexible, but put to the test, it is also very easy to break.
Bones are for dogs.
I see this in field installations a lot too. I have seen many failures of expensive signal cable where the only recourse is to replace the cable. The classic "lazy installer" move is to "dog-bone" the extra cable. They do this by taking the extra, wrapping it up and then putting a tie wrap in the middle so that the result looks like a dog bone. This inevitably leads to the crushing of the internal parts of the cable as well as putting kinks in the wraps. In the case of coaxial video wire, the crushing and kinking of the cable changes the properties of the cable which causes a very poor image quality or even a total loss of signal. I teach all of my technicians how to carefully maintain a proper minimum radius when dressing cables on projectors and also in equipment racks to ensure proper signal flow. I also teach them how to properly coil staging cables so that they last longer. I have mic. cables that I have had for 15 or more years that still work like they were new.
Let's wrap it up then....
So take care of your cables, and they'll take care of you. Wrap them up nicely, and they'll last a long, long time. It'll save you from down time and ultimately, save you money.
Gundy out.
For further reading:
http://www.iewc.com/content.aspx?id=130
This guy does a pretty good demo on how to coil a mic. cable:
http://www.youtube.com/watch?v=0yPcJD7RVuY
