quadro in practice

In response to an earlier article on quadrophony (`Ouadro 1-2-3-4 .. .`, December 197 4), we received many requests for the complete circuit of a quadrophony decoder - preferably one which is suitable for all systems. However, the problem here is that the patentees for OS and CD-4 will not consent , to the ICs developed for their systems being supplied by the retail trade*. They are only to be supplied to original equipment manufacturers. As a result, a home-made quadro decoder will have to consist of discrete components, so that it becomes far more complex than would otherwise be necessary. Nippon Columbia has now put such a design at our disposal, so that we can fulfil the wishes of many of our readers. For coma pleteness` sake a survey is first given of the decoder principles of the four different systems: SQ, OS (RM), CD-4 and UD-4.