Description of Different Audio Connectors
 

Balanced vs. Unbalanced Cables

Balanced refers to a “three-legged” type of electrical signal that has two legs independent of ground. One is generally considered positive and the other negative in voltage and current flow with respect to ground. Both legs carry the signal. The benefit is that any noise that gets induced into the line will be common to both the positive and negative sides and is thus canceled when it arrives at its destination, assuming the destination is balanced. This phenomenon is called "Common Mode Rejection” and happens because the receiving device sees the common noise in the signal as being out of phase with itself, and cancels it. Balanced lines are generally best for long cable runs due to their ability to reject induced noises. XLR and TRS type cables are designed to transmit balanced audio from one balanced device to another.

Unbalanced cables are less complicated and less expensive but they have limitations. Any audio signal requires two wires or conductors to function. In an unbalanced situation, one of those conductors is used to carry both the audio signal and ground (shield). Unbalanced cables are much more susceptible to induced noise problems than their balanced counterparts because any induced noise in one conductor is not canceled by similar noise in the other conductor and may be carried with the signal into connected equipment. In general, unbalanced lines should be kept as short as possible (certainly under 25-30' maximum) to minimize potential noise problems.
   
TRS
TRS is the abbreviation for “Tip Ring Sleeve.” This is the accurate term for 1/4" (or 1/8") balanced connectors. A TRS plug can be found at the end of most headphone cords if you want to know what one looks like. It looks like a standard 1/4" plug with an extra “ring” on its shaft. Thus the three sections of the shaft are called the Tip, Ring, and Sleeve. TRS connectors are used wherever you need to have two conductors plus a ground (shield) in one plug. A common use is to connect balanced equipment.
   
XLR
XLR is the trademarked name for circular 3-pin connectors developed by Cannon (later bought by ITT). XLR has since evolved into a generic industry term, and many manufacturers now make this style connector, in which there are positive, negative, and ground connections. In audio, XLR connectors are normally used for transmitting balanced mic and line level signals to mixers or audio to speakers.
   
TS
TS is the abbreviation for Tip Sleeve and refers to a specific type of 1/4" connector that is set up for two-conductor unbalanced operation. An insulator separates the tip and sleeve. The tip is generally considered the "hot," or the carrier of the signal, while the sleeve is where the ground or shield is connected. TS cables are best known as guitar or line-level instrument cables.
   
RCA
RCA connectors are the common name for phono connectors like the ones used to connect most consumer stereo equipment. These were so associated with the RCA Corporation in the early 1900s that they became known as the RCA connector.