Frequency analyser type D-669-A No.255341 by Muirhead and Co Ltd, 30Hz to 30kHz in six ranges Frequency analyser type D-669-A No.255341 by Muirhead and Co Ltd 1960-1969
Frequency Analyser, Bruel & Kjaer, Copenhagen, Denmark, type 2105, in fitted carrying case, serial no.24589, circa 1960. (Standard equipment for evaluating audio equipment) Frequency Analyser circa 1960
