A simple circuit used for enhancement of space or stereo width in recording. The shuffler, (first described by Blumlein) is the basis for MS microphone decoding to stereo, as well as the circuit used to create FM signals. The shuffler takes the left and right signals of the stereo pair and mixes them into two separate signals, one being the sum of the signals (A+B), the other being the difference (A-B). While they are in this format, we can apply processing to either signal (A+B or A-B), and then convert them back into stereo. A mixing console with polarity invert switches on the channel strips can be used to create a shuffler. The A+B signal is easy to create (it’s just the sum of the two); the A-B signal is created by combining the two while the polarity is reversed on B.