I've thought multiple times that a fun little project to build would a simple decoder with complimentary or push/pull control of the blending coefficients. In other words turn the pot to one extreme & you get un-altered stereo in front, full L-R in back. Go the other direction & have full mono blend in front & full stereo in rear. Obviously this could not be used to correctly decode QS/RM because at the mid point the blend would be matched but .5.Years ago I built a decoder similar to this from an article in Canadian Audio Magazine "Electron". It simply used a handful of transistors (4 or 8, I forget). The fronts were blended together via a pot in phase the rear out of phase via another pot. It would properly decode EV-4, Dyna, and even QS (RM actually). Normally I would run it with no blend on the front and maximum blend on the rear, but it was interesting to try different settings. The most amazing thing about it was listening to stereo decoded by this device through quad headphones, as the rear blend was increased the sense of space expanded dramatically. Fixler effect anyone.
You just have to disconnect from ground the negative speaker wires on the back speakers and connect them together, isolated from ground. That's all the adapters did, they would of had an adjustable resistor in series as well to control the surround level. Those passive decoders were never very expensive, you could keep checking eBay to see if one comes up.I've been looking for a small passive decoder for my car such as quatravox or napolex, anyone have better suggestion? (of old passive decoders/adapter that is)
Pretty sure it used the good ol,l wiring trick with a pot....the Hafner Dynaco style and yes that was my first surround system at around 12 years of age, so it was the first Surround Master!!!!!!Here 8s a little passive decoder from Australia, (the first surround master?)
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Groovy little circuit you've got there. As for the AWA unit it appears to go between the amp & speaker like your set up. But the AWA has 2 largeish xfmr's in there. What do you suppose their purpose is?
LOL I can see it coming: Chucky's life story as told by circuitry...And now we are talking the very early "teen age" beginnings of the Surround Master (shameless promotion mode enable). My next attempt at surround was at around the age of 13 in 1971 with an Electronics Australia project (really great magazine died eventually and sorta became the vastly inferior Silicon Chip Magazine) with a simple transistor circuit. This is not exactly it as I would need to dig into my archive of magazines going back to 1969 and I am too lazy. But broadly this is the same sorta thing, I bet this is similar to the circuitry of the Akai SS 1.
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Hmmmm , not sure but I bet your left knacker it was possibly used between the pre and power amp and they were using audio isolation transformers to do the subtraction.........or even if it was speaker level it might be audio isolation transformers as the transformers would not need to handle any bass as that tends to be a common signal and gets cancelledGroovy little circuit you've got there. As for the AWA unit it appears to go between the amp & speaker like your set up. But the AWA has 2 largeish xfmr's in there. What do you suppose their purpose is?