To Muncybob-Yes! That psychoacoustic affect was patented by a small Maryland company in 81-82 called Psi-coustics. They were friends of mine. They did it with a solid state tape loop device (like an Eq) Within a few years another Maryland company, Polk Audio, patented the circuit at speaker level with their SDA line. My guess is they had one of the early units. Radio Shack bought or leased the IMX patent from Psi-coustics and had it in some of their EQ's as well. I like the last Polk SDA's that did not have the tweeters as part of the circuit. We humans get little or no location cues above 3K. Properly set up they have the biggest and best image possible. This affect is recording dependent of course. It does nothing to a mono signal and can give a bit of a hole in the middle on some recordings. But on the right recording there is nothing better for involvement in the stereo image. I still use a set of their best model: SDA SRSA 1.2 TL. quite often. Lots of fun! Freaks people out when they hear it. They look around for other speakers.
