Maximum length of XLR cables

[Graham Archard]

I have recently started using prosumer gear and currently use Canon XH A1. The handbook states that I should not use longer than 3 metre XLR cabling to a microphone but I want to record good stereo sound of a choir perhaps 50 feet away from the camera. Is the 3 metre length just if I use on-board mic power or will longer lengths need microphone independent power or pre amp etc? Thanks for your help.

[kimco52]

XLR is a type of connector. Nothing more, nothing less. It basically has nothing to do with the cable inside of it. If Canon tells you to limit the length to 3 meters, it must have something to do with the way they have it connected internally or whether they are running power through it.

Generally speaking, the length of cable depends on how it is connected and the impedance used. Do not run high impedance microphone cables for long distances and do not lay them across the stage floor. Microphone cables should all be configured at balanced low impedance. Then you can run them anywhere for reasonable lengths. We have many microphone cables that run 200+ feet (60-70 meters).

If you purchase cables with XLR connectors, they should be 3 conductor twisted within a shield (ground). Whether you connect them balanced or unbalanced or high or low impedance is dependant on what you connect them to at the ends of the cable.
Need to determine why they say to limit the distance to 10 feet. Other than power, it doesn't make much sense.

[jctruth1]

Kimco is correct !

I have ran XLR shielded cables for over 300 feet with very limited signal loss. I am guessing that Canon is using a high impedance microphone (typical 2 wire with no shielding and no ground wire in use).

Any UNSHIELDED cable longer than 10 feet begins to act as an antennae of sorts and just like AM radio, it will receive the strongest signal in the area: whether you want to or not. This is called RI or radio interference.

If you want to record a choir at the distance you mentioned, I suggest getting the best XLR mics that you can afford and wire them to TRUE XLR cables, and possibly a mixer and then running a cable from the mixer directly into your Canon Video camera.

OR better yet, invest in some wireless mics and all but eliminate the long cable runs. It all depends on your budget !

A simple test to make sure that it is a TRUE XLR cable is to run a continuity tester to make sure that all 3 posts are truly independent of each other. Each post is labeled as : 1 - 2 - and 3. Connect #1 post with # 1 pot and it should buzz. If you get a buzz when connecting # 1 post into # 1 pot and # 2 pot, it's a good chance that you don't have a TRUE XLR cable.

A cheaper cable that is not shielded, will result in 2 wires being connected together (as I described above) and also allows for "hum" and "buzz" to be carried through the wires. Plus also, all kinds of other RI.

If you can only afford 1/4 inch mics, but want to run cable lengths greater than 10 feet, use them but plug them directly from the mic cable into a "Direct Box" 1/4 inch female plug and then run the XLR cable out from the Direct Box to your camera area. A Direct Box "converts" the signal.

At your camera area, you will need to convert the signal back to what your mic input is on your camera -- it is usually a 1/8 inch stereo jack. There are a lot of small mixers that will accept both 1/4 inch male plugs and XLR mic inputs. If you want suggestions on name brands etc. PLEASE ask.

Hope this helps unravel the mystery of a low impendence cable ( XLR ) and a high impedence cable ( 1 / 4 inch and 1/8 inch).