Group hearing aids

The model 260 was introduced in 1951, a group hearing aid used in schools for the hearing impaired. In 1962 it was redesigned as the 260B shown in this photo. It was a compression amplifier which could be operated with a microphone, phonograph, or external source; it had provisions for connecting a maximum of 12 individual outlets and could generate 135 dB SPL in 12 pairs of dynamic earphones used in the classroom. The frequency response was +-1.5 dB from 150 to 11,000 Hz. with an adjustable low-frequency cut-off point. The model 280A Auditory trainer was a similar type device capable of driving 6 individual outlets and could generate up to 130 dB SPL in 6 pairs of dynamic earphones. It included a speaker for monitoring the phonograph or external source. photo by Dave Fanger: 1965 Shipping and Receiving Subject: 260B Group hearing aid Personnel: Charlie Christian and Bill Wagner

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