Maico Model M "Precisioneer" Vacuum Tube Hearing Aid
The Maico Model M, also known as the "Precisioneer",
was produced by Maico Electronics, Inc. of Minneapolis, MN in 1944. The name "Maico" was derived from the initials of the Medical
Acoustic Instrument Company.
This hearing aid was a two-piece body worn aid. It measured 4˝"
x 2⅜" x ⅞" (11.5 x 6.1 x 2.4 cm) and weighed 6˝ oz
(184 g) without the batteries. It was worn in
a man's shirt pocket or carried in a purse by a lady. |
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Top view of the Maico Model M "Precisioneer" vacuum tube hearing
aid showing the combined volume/on-off control.
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Bottom view of the Maico Model M "Precisioneer" vacuum tube hearing
aid showing the design on the bottom front of the aid and the 4-pin
battery/receiver jack (bottom center). |
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Close-up of the battery/receiver plug of the Maico Model M "Precisioneer"
vacuum tube hearing aid. It plugged into the bottom of the aid. Since
it connected two batteries and the receiver to the hearing aid,
obviously one pin was for the 1˝ volt positive "A" battery current, one
pin was for the 33 volt positive "B" battery current, one pin was for
the receiver plus signal and the final pin was a common ground.
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Rear view of the Maico Model M "Precisioneer" vacuum tube hearing
aid showing the model and serial number (center) and the 4-hole "adjusting
bar"
(bottom center). |
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Close-up of the bottom left corner of the Maico Model M "Precisioneer"
vacuum tube hearing aid showing the 4-hole "adjusting bar". Only hole
number 3 contains an adjusting screw. It seems likely that this was
actually a four position filter. When a screw was screwed into one of
the holes, it switched in one of the high or low pass filters, thus
giving different sound characteristics. |
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The picture at the right shows in inside view of the Maico Model M
"Precisioneer". It used three vacuum tubes and had a single volume
control.
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A close-up of the rear (interior) view of the microphone showing
various patent numbers for the US, Great Britain and Canada, 1931-1941.
The crystal microphone was manufactured by
the Brush Development Company. |
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Close-up of the receiver and ear mold of the Maico Model M "Precisioneer"
vacuum tube hearing aid.
This Brush Development Co. crystal type receiver was commonly
used on many of the hearing aids of the early 1940s rather than the more
usual dynamic receiver used later on.
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Close-up view of the Maico Model M "Precisioneer" vacuum tube
hearing aid battery cable plugs. The two-pronged plug (left) plugged
into the "A" battery and the 3-pronged plug (right) plugged into the "B"
battery. |
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Close-up of the "A" battery plug of the Maico Model M "Precisioneer"
vacuum tube hearing aid. Since both the plug (right) and the larger
adapter (left) had the same size pins, one wonders what the adapter was
really for. It doesn't appear to be needed. |
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The Maico Model M "Precisioneer" hooked up to its "A" (right) and "B" (left)
batteries. The earphone is at the extreme right.
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