Some Fundamental Information Regarding XLR Microphone Connectors

http://www.amazon.com/XLR-Male-Female-Microphone-Cable/dp/B00CTHNM52/
Some Fundamental Information Regarding XLR Microphone Connectors
XLR cables are used in audio applications ranging from live shows to professional recording sessions. XLR cables have 3 pins, a circular connector and are accustomed to deliver balanced microphone and line-level signals over long distances. An XLR cable's ability to deliver a balanced signal means that the final audio signal will have less unwanted noise from outside electrical interferences. This preserves the original audio signal, even over long distances and near other electronic devices. Learn how XLR cables are able to accomplish this.

When two balanced devices are connected, the shielded XLR mic cable from http://www.amazon.com delivers a positive audio signal, a negative audio signal along with a ground signal. The positive audio signal and the negative audio signal are identical, except that they are inverted. If electrical interference is encountered (such as from nearby electronic devices), that noise enters both the positive audio signal and the negative audio signal.. When the positive and negative signals reach the balanced device at the end of the chain, one of the two audio signals is inverted. Now the two audio signals are identical in every way. However, the noise that was about the audio signal has now been inverted. When the inverted noise is combined with the original noise, they cancel each other out. All that is left is the original audio signal.

XLR cables can only deliver a balanced signal if both devices on either end of the signal are also balanced. If any audio device in the chain is unbalanced it will cause all signal chain to be unbalanced. Also, always check with the manufacturer to ensure that a device is balanced.