 
 <prompt> Wetin, between SACD and SQ, bin dey release first? Based on di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: The development of quadraphonic records bin announce for 1971. Dem record four separate sound signals. Dis one dem achieve for di two stereo channels by electronic matrixing, where dem combine di additional channels into di main signal. Wen dem play di records, phase-detection circuits for di amplifiers fit decode di signals into four separate channels. Dem get two main systems of matrixed quadraphonic records wey dem produce, wey dem confuse name as SQ (by CBS) and QS (by Sansui). Dem no too sell well for market, but dem dey important as e be precursor to later surround-sound systems, as we dey see for SACD and home cinema today. 