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.

 

Vacuum Tube Hearing Aids: 1921-1953

Dahlberg Model T-1 "Tonex 1" Vacuum Tube Hearing Aid

 The Dahlberg Model T-1 (Tonex 1) was the very first hearing aid produced by Dahlberg Electronics, Inc. of Minneapolis, MN. It came out in December, 1949.

The next year, in December, 1950, the T-1 (Tonex 1) was renumber as the D-1 and called the "Tru-Sonic".

The Tonex 1 was a one-piece 3-vacuum tube hearing aid. Without the batteries, it weighed 3.3 oz. (94 g). It measured 2 11/16" x 1 13/16" x 13/16" (6.8 x 4.6 x 2.1 cm).

The case was made of sterling silver with a gold-plated? pocket clip.

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Front view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid. The gold-plated? microphone grill dominated the front view.

 


 

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View of the microphone of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid. It was unusual to have the microphone outside the body of the hearing aid as was done here. In this case, the gold-plated? case housed the microphone.
 

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The microphone housing of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid doubled as the pocket clip.

 


 

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Top view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid showing the two controls. The on-off/volume control wheel is in the center and below it is the round knob of unknown function.

The two silver case halves slid in grooves in the black chassis. They no longer fit well hence they come apart (as seen on the right side).
 

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Side view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid showing the round receiver jack.

The receiver cord and receiver are missing.

 

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Rear view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid.

 


 

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Bottom view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid showing the only identifying mark. Very faintly, in the center of the bottom is the word "TONEX". It's so faint it's easy to miss it, even when looking for it.

 

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View of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid with the back cover removed showing the 3 vacuum tubes (upper right). The "A" battery position is the middle left (under the round hole) and the "B" battery position is at the bottom.

 

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Close-up view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid showing the battery compartment.

The 1˝ volt "A" battery was the Mallory RM-1 (or equivalent). The "A" battery was pushed up the left side until the spring clip snapped up to hold it in place. To get the "A" battery out to replace it was a bit tricky. You had to hold the spring clip down and then insert a screwdriver or something in the hole to push the "A" battery out.

With the "A" battery in place, the 15 volt "B" could be inserted across the bottom. This hearing aid used an Eveready No. 504E battery (or equivalent).

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