Akai SS-1 Universal Synthesizer

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From:
https://www.quadraphonicquad.com/forums/threads/sq-sony-sqd-2020-sq-decoder.15154/page-6#post-603463
Thanks! I only had one design for the decoder I built (switchable DynaQuad + one of the Pioneer Quadralizer decoding modes):
LF=L,RF=R,LB=L-R,RB=R-L
and Quadralizer
LF=L+0.5R,RF=R+0.5L,LB=L-0.5R,RB=R-0.5L

The Pioneer Quadralizer decoding equations are in a Pioneer QA-800 brochure I picked up in 1971 at the CMC Stereo store here.

I may post my schematic (if I can find it).


Kirk Bayne

 

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Found my DIY decoder materials, apparently, I didn't make a complete schematic, just some sketches as a guide to make the wire wrap decoder.

All I did was use 2 resistors in parallel in the feedback part of opamps, a CMOS switch (IIRC, controlled by 1 hardware switch, it switched one of the in parallel resistors in/out of the feedback part, thus changing the gain of the opamp)

The rest is a standard opamp based system to provide 180 degree phase shifts for both L and R, then a switchable gain adjustment opamp system (described above) and then a summing opamp system for the 4 outputs.

It turns out that my design provides:
LF=L+0.5/0.25R,RF=R+0.5/0.25L,LB=L-0.5/0.25R,RB=R-0.5/0.25L
(not using the decoded LF and RF mimics the Quadralizer front output)


Kirk Bayne