FM 133 Linearizer

About the FM 133 Linearizer

The FM Acoustics LTD FM 133 Linearizer is a high-level, single-ended harmonic/constant-phase linearizer intended for insertion in a preamplifier tape loop or between a line preamplifier and power amplifier. It uses five adjustable frequency bands centered at 50 Hz, 200 Hz, 800 Hz, 3.2 kHz, and 12.8 kHz. The circuit is designed to pass the signal transparently while permitting controlled addition or subtraction around these bands to correct tonal or recording-related problems. It includes main and tape-monitor signal paths, bypass operation, and a ground-lift arrangement. The FM 133 is the unbalanced counterpart to the balanced FM 233. Available manufacturer and distributor material confirms the model and its technical data, but does not clearly establish whether production has permanently ended; it should therefore be treated as a legacy or possibly discontinued model rather than definitively declared discontinued.