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there were several companies that did that, Acoustic Controls, Phase Linear, and APT are three i can think of that had output devices that had to be below a certain beta, or the amplifier would get unstable (actually the APT amplifier was stable, but too high a beta in their output transistors would cause common conduction if signals over 50khz were applied). keep that in mind when repairing amplifiers. if you have a good channel and a blown channel, check the beta of the good output devices and make sure the new ones are about the same beta. both the Acoustic amps and Phase Linear amps had a tendency to self destruct if output devices with too high a beta were used as replacements.Agree on the tight transistor characteristics requirement.
It was common for high-performance equipment transistorized designs back then, to have commercial transistors selected for certain parameters, and then apply "house numbers" to them.
Or at least a colored dot to facilitate parameter binning.
Heck, even my Zenith Transoceanic radio has selected transistors with Zenith house numbers.
back in the 60s, big consumer manufacturers like RCA and Zenith had "house numbered" transistors, requiring the parts to be ordered from the manufacturer. it was kind of odd to see RCA doing that, because RCA also manufactured and sold transistors with JEDEC 2N series numbers.