Phono Preamp Ki.

The cct. brd was assemble and the ABS plastic case drilled ready for assemble. ABS is a very hard plastic to drill. Before assembly the lid, base and sides were lined with heavy tar and foil stick-on shielding. This helps with case dampening also. All gold RCA connections were kept to the rear (see other photos). The chips are the LM833s but the Burr-Brown OPA2134 high performance chip can be directly substituted. The on-board +/- 12V regulated PS is shielded from the rest of the sensitive cct. Additional snubbing was added to the line caps to remove PS noise and chip RF decoupling. Though three different compensation can be selected from the cct. brd by moving two jumpers the lid must be removed to do this. A double pole rotating three position switch could be added to provide this facility externally. The cct. includes a gain control which is accessed from the front and allows easy and silent level adjustment. The sound is natural with no hiss or hum. Easy to build.