Developed by Dynaquad, DY was the first commercial attempt to encode four channel sound onto a normal stereo LP. The decoder was not designed to accurately decode the encoded material, with its narrow front separation and its limited rear channel separation of no more than 2db, it was designed more to create an effect of space.
There were only a handful of LP’s released in DY, two of which were by The Beach Boys. Fortunately, owners of the decoder found that EV-4 encoded LP’s decoded just as well as the two systems were very close mathematically.
Hopefully, to quash the misinformed rumours that float around certain groups, one point must be made clear regarding DY, and that it is in no way compatible with QS, or any of the later matrix systems which used 90 degree phase shifting as part of their encoding matrix, namely QS/QX/SQ/BMX/Dolby Surround, as it was devoloped before Peter Schieber announced his work on the 4-2-4 matrix, which was the basis for the systems that followed .