Advent Model 100A (1972)

A modular Dolby B-type noise reduction control center designed for home and live recording use.

Overview

The Advent Model 100A is a two-channel noise reduction system manufactured by Advent and produced in 1972. Designed as a control center for Dolby B-type noise reduction, it was intended for use with home tape recorders, prerecorded Dolby cassettes, and FM broadcasting. It was also built with serious live recording in mind, offering flexibility not found in other units of its type. The system requires calibration using a reference tone tape to adjust settings on both the Model 100A and the connected tape deck.

Specifications

Model	100A
Form Factor	Modular
Number of Channels	2
Noise Reduction System	Dolby B-type
Face Color	Silver
Input Sensitivity	100mV
Output Level	1V
S/N Improvement	10dB (Dolby)
Dynamic Range	85dB
Frequency Response	20Hz to 20kHz
Signal to Noise Ratio	70dB
Total Harmonic Distortion	0.1%
Dimensions	11-3/4 x 4-1/8 x 7-1/2 inches

Design

The Model 100A features a modular design and includes a complex setup process requiring a reference tone tape to calibrate multiple controls on both the unit and the tape deck. It was engineered to offer greater flexibility than built-in Dolby systems. An accessory microphone preamplifier, the MPR-1, was available for use with the unit. Tapes recorded with the Model 100A can be played back without a Dolby decoder, resulting in slight treble reduction if desired.

Context

The Model 100A was designed to support the growing use of Dolby B-type noise reduction in consumer audio, particularly with cassette tapes and FM broadcasts. It catered to enthusiasts interested in high-fidelity live recordings and offered a standalone solution for achieving professional-grade noise reduction at home.

Market

Current market prices range from $50 for untested units to $150 for tested, working models. Common issues include the need for recapping and recalibration, though the unit performs well when properly maintained. Service and owner's manuals are available for $29.99 each. A used unit was listed on Reverb four years ago in "Very Good (Used)" condition. Users report reliable performance after recapping and note high-quality internal components.