Version: July 17, 2004

Rob Lomas

The cutting shack


This is a brief presentation of two recorders, each driven by a small Radio Shack speaker, hence the title of this page. The first one is the more elaborate, using an Ediphone reproducer as its base. To this reproducer, Rob made a new cutter bar from a piece of circuit board, and glued a new sapphire cutter to it. The other end of the bar connects to the loudspeaker by a piece of soft wire that is glued to the center of the speaker's diaphragm. The hingeblock that carries the arm is fixed so that it will not move laterally.

Underside of the cutter head. Detail showing the sapphire cutter on its circuit bord bar.


The pictures below show a simpler solution, where Rob has done away with the original reproducer, and simply cemented a glass cutter directly to the speaker diaphragm. This unit requires quite some adjustment before it produces a groove of the desired depth.

To make a recording with either of these cutters, the signal fed to the speaker needs some filtering. The high and low frequencies need to be removed, and the remaining frequency curve further tweaked by trial and error. Rob reports that both units work well, and that the volume is about the same as on period recordings.

Christer Hamp, 2004

The speaker is mounted directly in the Edison's ring.

The cutter is cemented to the speaker diaphragm.

All pictures provided by Rob Lomas

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