Published:2009/7/6 5:46:00 Author:May | From:SeekIC
Used when rumble from cheaper turntable or record extends above 100 Hz, causing disconcerting out-of-phase loud-speaker signals, Circuit is based on fact that human ear is not sensitive to directional information below about 400 Hz, making it permissible to remove stereo (L – R) signal at low frequencies and thus remove stereo rumble without losing stereo separation. Emitter-followers feed high-pass filters having 200-Hz breakpoint frequencies and Butterworth characteristics. Attenuation of filter is 12 dB at 100 Hz. Filter circuit can be disabled by placing switch between points P and Q.-M. L. Oldfield, Stereo Rumble Filter, Wireless World, Oct. 1975, p 474.
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