Polk Audio SDA-CRS (1984)
Not much is documented about the Polk SDA-CRS, and some of what circulates online gets it wrong. The period record shows it was a speaker system, not a processor or outboard correction box. HiFI-Stereo (November 1984, p.40) ran a Hirsch-Houck Laboratories test report. It described the SDA Compact Reference System as Polk’s latest use of its Stereo Dimension Array (SDA) technique at the time: a pair of compact “bookshelf” speakers, meant for near-wall placement or for use on optional free-standing pedestals. SDA was aimed at a basic problem of stereo playback. Each ear hears sound from both speakers, and that affects channel separation and the stereo image. The report also noted that the four speaker subsystems making up the SDA-CRS stay active during operation.
Polk’s own advertising in Audio (May 1986, p.2) listed the SDA CRS at $395.00 each, below the SDA-1A at $875.00 each. Later Audio advertising (October 1988, p.19), using the SDA CRS+ badge, quoted Stereo Review saying the SDA-CRS was an impressive achievement and that listeners tended to forget they were hearing speakers at all - just the music remained. The Archive’s files don’t document how the original SDA-CRS relates to the “+” badge used later.
No complete factory spec sheet has surfaced here, so don’t trust frequency response, impedance or crossover points from random online listings. What is confirmed: the SDA-CRS was a real, moderately priced compact Polk SDA loudspeaker of the mid-1980s.
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