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Lots of phony Stereo exist on LP, it's called "Electronically Processed Stereo"

Posted by Teresa on May 25, 2009 at 15:56:51

In Reply to: RE: johnny lee hooker& the hogs might be a mono recording? posted by stevenmbell on May 22, 2009 at 07:25:54:

It's a process where you create a 2 channel stereo signal from a 1 channel mono signal and it usually sounds absolutely horrible.

Once you get a phony stereo signal you could create phony rear channels using the Hafler effect. So yes one could make a surround sound recording from a Mono source, but why?

Hafler circuit

A passive Hafler circuit mimics the effect of "active matrix" decoding but without using costly electronics. It does this by recovering the ambient sound from a stereo recording. Named after its early proponent audio engineer David Hafler, the circuit exploits the high amount of stereo separation in the front speakers. Using the circuit typically reduces this stereo separation by only about 2dB.

The rear sound level in a live performance recorded in stereo is reproduced about 7dB below the front level, but clearly audible. The rear ambient sounds, applause, and coughs from the audience, are sometimes received out of phase by the stereo microphones, while sounds from the musicians mostly are in "synchronous phase". Thus, if rear speakers are fed with the difference between the stereo channels, audience noises and reverberation from the auditorium may be heard from behind the listener. This can be most easily achieved by wiring two similar additional rear speakers in series between the live feeds (positive terminals) from the stereo amplifier. Alternatively, one rear speaker can be used on its own.

Happy Listening,
Teresa

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