Wednesday, October 9, 2013
Yet another build of an OPAMP based piezo pickup preamp. The OPAMP again is an OPA2134 (socketed). The single cct. brd. holds both the differential PS, generated by a resistive network and capacitors and the preamp section itself. Control of treble is via a small pot and can be used to "tone-down" surface noise found on most 78 records. There is a battery test point at the front of the preamp to allow easy battery checks without opening the case.
A mustard cap is used on the input and a poly on the output. Internal wiring is solid core copper wire. The case is cast Al and again I have used the hammertone finish which I think is quite attractive. This completes my 78 setup with a new stylus in my Ronnette piezo cartridge. With some reasonable 78s I have managed to get some enjoyment out of the shellacks.