DIYbanter - View Single Post - Sony SL-2700 Betamax

Cydrome Leader

wrote:
"How were those extra channels added and extracted from the regular two
channel recordings, other than with one of those boxes?
"
By summing the left and right channels and sending them to OP AMPS on the inverting inputs, resuling in the attenuation of the L+R component of both channels. By careful mixing, an audio engineer could do alot with that. A system called SQ came out which standardized the process somewhat and only nulled the mid to high ranges, leavng the bass relatively intact for the rear speakers which were ususally identical to the front speakers, unlike today. Today, usually nothing under 100 Hz is sent to the rear. Those little satellite speakers couldn't reproduce it anyway.

The standardization was simply the time constant of the feedback network and the actual amount of L+R attenuation. It was sort of licensed, and you could buy recording supposedly in "SQ", which meant that they were mixed in a way to take advantage of the standards.

Ah- SQ.

I've always wondered what that was. I seem to think I've seen that on
laserdiscs, and just checked mine, but none have it, not that I'd be able
to play it back correctly anyways.