Microtone Model T-6 "Lifetime" Vacuum Tube Hearing Aid The Microtone Model T-6 "Lifetime" was produced by Microtone Co. of St. Paul, MN in 1948. It was a 4 vacuum-tube hearing aid measuring 3¾" x 2¼" x 1" thick. It weighed 6¾ oz. without the batteries. The microphone grill (top center) was covered by a cream-colored fabric with the Microtone crest in the center. This attractive hearing aid had a white plastic case with embroidered trim. The Microtone Model T-6 sold for $229.50 in 1950. Here is an original invoice for the T-6. Something must have gone wrong and the hearing aid was replaced under warranty as this warranty card shows a different serial number than the invoice. The pictures here are of this replacement aid as the serial numbers match.
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| Top view of the Microtone Model T-6 "Lifetime" hearing aid showing the receiver plug (right center), and the volume control (bottom left), and on-off/tone control lever (bottom right). "Off" is the upright position. In the middle position both low and high tones are amplified equally (what they call "high fidelity", and in the low position (shown) low tones are suppressed and the higher tones are accentuated. The pocket clips are at the left and right sides (top). |  | Click picture for larger view | | | |
| Rear view of the Microtone Model T-6 "Lifetime" hearing aid showing the manufacturer's name (Microtone) and the model name (Lifetime). You can read the Microtone T-6 manual that came with this hearing aid.
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| The whole back of the case swung down from the top revealing the battery compartment of the Microtone Model T-6 "Lifetime" hearing aid. The round center compartment held an RM-4 1.4 volt mercury "A" battery, and the lower compartment, a size 412E 22½ volt "B" battery. The 4 vacuum tubes are stacked (2 on each side) under the cream housing on each side of the "A" battery. At the very top (center) is the serial number (58650).
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| Inside view of the battery compartment door of Microtone Model T-6 "Lifetime" hearing aid showing the manufacturer, "The Microtone Company/Minneapolis, Minnesota/ U.S.A." (bottom). When the back is closed, the metal assembly in the center makes contact with the back of the "A" battery and transfers power to the internal circuits via the clips in the top left and right corners of this assembly. |  | Click picture for larger view | | | |
| Close up of the battery meter of the Microtone Model T-6 "Lifetime" showing the two meter scales. The upper one ranges from 0 - 2 volts for testing the "A" battery, and the lower one ranges from 0 - 50 volts for testing the "B" battery. To test the batteries, you put them in the appropriate slots (see below picture) then pressed one of the two buttons (right side) labeled "A" (upper) and "B" lower to obtain the reading for the "A" or "B" battery. |  | Click picture for larger view | | | |
| Below the battery meter are two slots for "reconditioning" the batteries. The upper one is for the "A" battery, and the lower one for the "B" battery. The Microtone T-6 "Lifetime" used what they called the "Micro-Mizer" to "recondition" the batteries overnight after you used them all day. By so doing you could extend the effective life of the "A" battery 3 to 4 times, and the "B" battery up to 5 times its normal life. Here is the instruction card on how to use the Micro-Mizer. |  | Click picture for larger view | | | |
| The Microtone T-6 "Lifetime" (right) in its dresser-top case and the battery meter/Micro-mizer (left). There is an interlocking switch in the top left corner that prevents the Micro-mizer from working when the lid is open. |  | Click picture for larger view | | | |
| Outside view of the Microtone T-6 "Lifetime" dresser-top case.
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