Amplifier for audio magnetic recording playback - compensates for tracking errors in dependence on constant sinusoidal signal recorded with audio signal

摘要

Errosion in tracking of a playback head (1) on a magnetic recording (3) may cause distortion of audio signals amplitude. The present circuit uses a controlled amplifier to compensate for tracking errors. A constant amplitude sinusoidal signal between 20 and 50 Hz is recorded with the audio signal. The input (5) to the amplifier (4) is split by high-(18) and low-(16) pass filters. The high-pass output is fed to the audio amplifier (4) while the amplitude of the low-pass output is compared (8) with a reference voltage. The comparator output controls the amplifier gain. A variant of the circuit can control stereo signals.