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.

 

Body Type Transistor Hearing Aids

Unknown Make (XX1) Transistor (Body) Hearing Aid

The manufacturer of this 3-transistor hearing aid is unknown, but it is almost certainly of European origin, perhaps Audium B.V. of the Netherlands (here referred to as the Unknown Model XX1.)

It was made between 1954 and 1957, most likely in 1955.

 The Model XX1 hearing aid measured 2⅝" x 1 11/16" x 1" (6.6 x 4.2 x 2.5 cm) and weighed 3.2 oz (90 g) without the battery. It used three transistors.

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Back

 

Front view of the Model XX1 transistor hearing aid showing its unique elegant guilloche enameled front. Since enamel was often done over silver, the front half of the case is made of silver, while the back half is chrome.

 

 

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Close-up view of the upper front of the Model XX1 transistor hearing aid showing the intricate guilloche pattern on this hearing aid.

 

 

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Top view of the Model XX1 transistor hearing aid showing the 2-hole receiver cord jack (left), the battery compartment latching clip (center) and the on-off/volume control wheel (right).

Note: this aid does not have a  microphone grill or microphone port. As near as we can tell, the sound reached the microphone via the space around the volume control wheel.
 

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View of the top left corner of the Model XX1 transistor hearing aid showing the unusual rotary switch shown here in the "1" position (lower left).

 

 

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View of the top left corner of the Model XX1 transistor hearing aid showing the rotary switch in the "2" position (lower left). It is not known what this switch was for.

 

 

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View of the left side of the Model XX1 transistor hearing aid showing the "1-2" switch (left) and the word "Silver" (upper center). The upper half of the case is silver and the lower part is covered in chrome.

 

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View of the right side of the Model XX1 transistor hearing aid showing the volume control wheel (left).

 

 

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View of the back of the Model XX1 transistor hearing aid showing the pocket clip (upper center). The whole back of this aid swung down to reveal the battery compartment.

 

 

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Bottom view of the Model XX1 transistor hearing aid showing the hinge for the swing-down battery door.


 

 

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View of the back of the Model XX1 transistor hearing aid with the battery compartment door swung down showing the empty battery compartment (bottom left) and the serial number (17367) above it.

 

 

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View of the inside of the battery compartment lid of the Model XX1 transistor hearing aid showing how to correctly place the RM1 battery in the battery compartment.

 

 

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Close-up view of the empty battery compartment of the Model XX1 transistor hearing aid. The plastic tab (bottom) made it easy to pull out the battery.

 

 

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Close-up view of the battery compartment of the Model XX1 transistor hearing aid showing the 1.4 volt mercury RM1 battery in place such as this Mallory RM1 battery.

 

 

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Inside view of the Model XX1 transistor hearing aid showing the microphone (round disc center) and the 3 tube-shaped transistors—one upper right and two lower left.

 

 

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Close-up of the inside of the Model XX1 transistor hearing aid showing the Mullard OC70 transistor (above) and the OC71 transistor (below).

The OC71 transistor has "Made in Holland" on its back side. Thus this hearing aid may have been made in Holland. Most Mullard transistors were made in England.

Both of these transistors were developed by Mullard in 1954.

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Close-up of the top right inside corner of the Model XX1 transistor hearing aid showing the Mullard OC70 transistor placed there.

 

 

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Inside view of the case of the Model XX1 transistor hearing aid showing its repair history with two sets of repairs done in 1964.

 

 

 


 

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