McIntosh - Performance Indicator MI-3 Control unit

The McIntosh MI-3 is a vintage 'Performance Indicator,' essentially an audiophile oscilloscope launched in 1964, combining five laboratory instruments into one (oscilloscope, FM signal indicator, FM deviation meter, balancing meter, phase indicator) to graphically display the performance of the hi-fi system, helping to optimize FM reception (multipath) and stereo separation, offering a unique visual experience and enhancing sound quality.
Main functions
Audio oscilloscope: Visualize sound waves and radio signals as waveforms, transforming audio into a visual experience.
Multipath Indicator (MI): Detects and displays reflected signals arriving at the antenna, allowing you to adjust the antenna for better FM reception.
Stereo Separation Indicator: Shows the separation between the left and right channels, helping to understand the quality of a disc or broadcast.
FM Balancing Meter and Deviometer: Precision instruments for aligning FM tuners, also used by radio stations.
Features
Produced by McIntosh Laboratory, it is a luxury component for vintage audio (hi-fi) enthusiasts.
It uses tube-based vacuum tubes and offers a uniquely beautiful display, but it also serves practical purposes.
It was considered a top-of-the-line device for its time, offering laboratory-quality performance in the living room.
Bottom line: The MI-3 is not just an “eye”, but a true tuning tool for your FM tuner and preamplifier, designed to achieve professional broadcast listening quality.