Hugh Hetherington Hearing Aid Museum
Hugh Hetherington Hearing Aid Museum

The Hearing Aid Museum

Hearing Aids of all types—Ear Trumpets, Carbon Hearing Aids, Vacuum Tube Hearing Aids, Transistor Hearing Aids, Body Hearing Aids, Eyeglass Hearing Aids and much more!

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Click on the "General Information" button (top button above) for an overview and general information on this category of hearing aid.

 

Hybrid Vacuum Tube/Transistor Hearing Aids

Acousticon Model A-310 Hybrid Hearing Aid

The Acousticon Model A-310 was produced by Dictograph Products Corporation in 1953 and is a sample of the early use of a transistor in a hearing aid.

This second Acousticon vacuum tube-transistor hybrid hearing aid was much smaller than it’s A-300 predecessor. It had a gold anodized aluminum case and weighed only 4 oz. with batteries. The A-310 measured 2½” by 1¾” by ⅞”.

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Internal view of the Model A-310 from the front.

Notice the t-coil (coil of wire at the bottom).

 

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Internal view of the Model A-310 from the rear. This hearing aid used two CK549DX miniature hearing aid vacuum tubes (top center) with a single CK718 transistor (top left) for the output stage.
 

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This model included a telecoil that was activated by rotating the (blue) receiver plug on the top of the hearing aid. The oval cutout to the left of the blue switch is the microphone opening. For some reason, the microphone was placed here instead of the normal place on the front of the hearing aid.

 

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Read the manual for the Acousticon Model A-310 hybrid vacuum tube/transistor hearing aid.

 

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The Acousticon A-310 used a 15 volt 504E "B" battery (bottom) and an 1.4 volt RM-1 mercury "A" battery (top right).

Note: by substituting a transistor for one of the vacuum tubes, filament current drain was reduced by 1/3 resulting in a slightly longer battery life and reduced cost to the user. Hybrid hearing aids were only produced for about a year as fully transistorized hearing aids quickly took over the market.

 

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