Overviewε27 ("epsilon 27") is a volume control mounting board for the Alps RK27 series ("blue velvet") stereo potentiometers (also compatible with the Noble AP25 series). It is recommended for DIY pre-amplifier and headphone amplifier projects, where the potentiometer is not soldered directly to the amplifier board. The use of this board avoids the messy task of soldering wires to the thin potentiometer pins, and makes the wiring look neater and more attractive. Clearly-labeled input and output pads virtually eliminate the chance of wiring errors. The use of Molex connectors allow the potentiometer assembly to be easily removed, enhancing serviceability.
The following is a photo of the top and bottom sides of the ε27 circuit board, and a photo of an assembled board.
Parts listThe following is the parts list to populate the ε27 board.
Note: The Molex headers and crimp terminals specified in the list above are tin-plated. Gold plated versions are also available under separate part numbers for a higher price.
The circuit boardThe ε27 board is made of high quality FR-4 glass epoxy, single copper layer with top-side silkscreen and bottom-side soldermask. The dimensions of the board is 2.0" x 1.0" (50.8mm x 25.4mm). The thickness of the board is 0.062" (1.58mm). There are two screw holes which can optionally be used with a bracket to further secure the potentiometer/ε27 assembly. The following image shows the board layout:
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