I was looking for a iPod amp so I got an 1990’s Dictaphone which was unused (record mechanism broken). It didn’t amplify its external input through its built in speaker because in default mode the external input would be a better quality microphone than the built in microphone which suffers motor noise like most Dictaphones of its era, and such use would howl feedback.
So I opened the casing (using jewelers screwdriver) and re powered the unit with 2 x AA batteries. Then with a length of probe wire (about 6″ long bare on both ends) I probed the mic input to the IC of the main amp and got my howling feedback (that I wanted). I probed some more for better points and found increased volume close to the vol pot.
Next I powered in the iPod on a 3.5mm end to end cable. the sound was powerful, a bit high tone but that’s the speaker its coming through, but as the amp unit was face down on the table most sound I was hearing was from the back of the speaker. I slid the unit to the edge of the table and got 30% increase in volume and the tone issue reduced.
I tapped and probed some more to find that the negative voltage point tapped to the positive speaker point gives me all the power I need. So all the wiring is in the battery compartment as the speaker sits under the batts. Volume control is on the iPod and the VOR part of the SONY M-750V pulls up weak signal and re balanced hot audio from the iPod.
Time: 1 hour Cost: FR€€