Amplivox Model D8 Vacuum Tube Hearing Aid The Amplivox Model D8 vacuum tube table model hearing aid was produced by Amplivox Ltd. of England in 1938.
The unit measures 4⅞” high by 6⅞” wide and 3⅞” deep. It weighs 1¾ lbs. without batteries. The microphone grill and an on-off switch with volume control are located on the front face. There is what appears to be a tone control knob on the right hand side marked “L M H” although for some reason this is not wired internally. |  | Click picture for larger view | | |  | | | |
| The battery compartment opened downward at the front. Over half of the internal volume of the case was used to house the "A" and "B" batteries (left half). The earphone compartment is at the top right corner.
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| The internal electronics of the Model D8. This hearing aid used three miniature vacuum tubes in its amplifier. |  | Click picture for larger view | | | |
| A close up of the front side of the earphone. The earphone would have been worn with a headband (missing). |  | Click picture for larger view | | | |
| A close up of the back side of the earphone. Also, notice the interesting arrangement of the earphone plug. There was one male pin and one female socket on the plug (right) and a corresponding female socket and male pin on the hearing aid to plug it into. This curious pin arrangement was common on English hearing aids of this period.
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