Stereo Shuffling
- explanations and demos

Despite being discussed since the earliest days of stereophony, there remains much confusion about the term Stereo Shuffling. This is not surprising because the term actually refers to two, quite separate and different techniques.

1. Simply put, the earliest use of the term (coined by no less than Alan Blumlein himself), refers to the processing of near-spaced omni' microphone signals so that they reproduce correctly on loudspeakers.

2. The second Shuffler was invented some twenty years later for the processing standard stereo signals to give better realism.

Why use the same name?

Well the later "Shuffler" was invented by the team who had worked with Alan Blumlein before he was killed in WW2. Perhaps they sought to honour him in adopting the term which derived from him?

In any case, the Phædrus Audio SHUpHLER incorporates both type of historical Shuffler, plus some newer shuffling (or matrix) processes, so that you can experiment and use these amazing techniques on your own recordings.

Read Hugh Robjohns explanation of the problems with intensity-coded (pan-pot) stereo from the Sound on Sound review of the Phædrus Audio SHUpHLER.

Shuffling demonstration files

Some brief musical extracts of the various Shuffling techniques are given below:

The shuffling technique selected when the SHUpHLER is set here is an entirely new technique and is intended to compensate for various shortcomings in crossed-cardioid recordings which are usually accused of lacking "spaciousness". We call it "Phædrus Crossed Fours" or "Rectified Cosine microphone technique" and you can read more here. Musical examples as a FLAC file are here. The first part of each musical extract (taken from rehersal tapes) is the signal direct from the microphones and the reprise is treated with the "crossed four" process. Beware.. this is a 42MByte file; FLAC is great but the file sizes are appreciable! An alternative 192kbps mp3 file is here.

Blumlein δ The greater part of Alan Blumlein's (1933) patent is concerned with a binaural stereophonic microphone arrangement in which two omnidirectional microphones are spaced about 8 inches apart (like the ears). Signals from microphones so arranged tend to produce excellent stereo on headphones, but disappointing results on loudspeakers. Blumlein contrived a theoretically sound and practical system for treating these signals for loudspeaker replay. The Phædrus Audio SHUpHLER has a modern implementation of Blumlein's original "shuffler" when the switch is set in the Blumlein δ position.

An example of the process is given here as a FLAC file. Once again, The first part of the musical extract is the signal direct from near-spaced omni microphones and the reprise is treated with the Blumlein δ process. Beware.. FLAC is great but the file sizes are appreciable! An alternative 192kbps mp3 file is here.

Stereosonic - The SHUpHLER incorporates a modern (yet still completely passive) implementation of the Stereosonic Shuffler in which the uneven frequency-response and group-delay problems of the original implementation have been entirely resolved.

An example of the Stereosonic Shuffler process is given here as a FLAC file. Once again, The first part of the musical extract is the signal direct from crossed-cardioid microphones and the reprise is treated with the Stereosonic Shuffler process. Beware.. FLAC is great but the file sizes are appreciable! An alternative 192kbps mp3 file is here.


BoF - The Stereosonic Shuffler actually over-compensates for the theoretical correction required for pure, "pan-poted" stereo, multi-track recordings. This is possibly because the original filter was intended only for stereo recordings made with stereo microphone arrays. This is the motivation for another, completely new, Shuffling process called Bride of FRANCINSTIEN (or BoF). All the theory behind this is given here.

An example of the BoF Shuffler process is given here as a FLAC file. Once again, The first part of the musical extract is the signal direct from the mixer and the reprise is treated with the Bride of FRANCINSTIEN Shuffler process. Beware.. FLAC is great but the file sizes are appreciable! An alternative 192kbps mp3 file is here.



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