• ' OPIC ' is an acronym for 'Op-amP Impedance Converter' •
An operational amplifier (op-amp) with a JFET input can be considered as a functional alternative to a traditional discrete JFET, as the input device for a condenser microphone impedance converter. However, many JFET op-amps are often considered to be too noisy, and/or draw too much current for that task.
Texas based hobby mic builder Jules Ryckebusch has identified Texas Instruments OPA164x series of op-amps as a useful option for impedance converters. - They have low noise, very low distortion, and only require around 1.8mA of standing current per amplifier... Jules has incorporated the OPA1642 into his successful OPA Alice microphone project.
At the time of writing, shipping costs make the assembled project PCBs very expensive for those of us outside the USA, so I looked into the possibility of incorporating the OPA164* devices into 'stripboard' layouts, to create a selection of simple hobby microphones. The resulting project details are outlined in the attached web pages ...
(Just click on any heading at the top of the page to access the associated project notes )