Aiwa AD-6550 (circa 1978)

Little is documented about this model beyond its listing in period equipment directories and a single thorough review.

Audio (December 1978, p.94) published a full set of manufacturer specifications and test results. Frequency response was 20 Hz to 15 kHz with standard tape, and 17 kHz with FeCr or CrO₂ formulations. Signal-to-noise ratio was rated at 65 dB with Dolby NR engaged and FeCr tape. Wow and flutter measured a respectable 0.05% rms. Input sensitivity was 0.3 mV for the microphone input and 50 mV for line. Line output was 775 mV. Fast-forward and rewind times for a C-60 cassette were 90 seconds. The deck measured 16 9/16 inches wide, 5 15/16 inches high and 13 inches deep, and weighed 16.5 pounds.

Surviving information on this model is thin. No production years, original price or circuit details have been confirmed from period sources beyond the Audio review. A brief listing also appeared in HI-Fi-Stereo-Buyers (March 1978, p.23), but that entry held only calibration-level markings and no substantive description.