Overview:
'OPIC' is an acronym for 'Operational-amPlifier Impedance Converter'....
Operational Amplifiers ('Op-amps') have been used as alternatives to discrete FETs in condenser mic impedance converters for some time, but many op-amps suffer from being too noisy for the task - or they draw too much current to be effectively operated from phantom power - or both!
In addition, the requirement for a very high impedance JFET input can limit the available choices.
Texas based hobby mic builder Jules Ryckebusch has identified the TI OPA1642 op-amp as a useful option for the task... It has low noise, and only requires around 1.8mA per amp.
Jules has incorporated the OPA1642 into his 'OPA Alice' microphone project, and you can find details of ready built project PCBs using these devices -
HERE
At the time of writing, shipping costs make those PCBs very expensive for those outside the USA, so I looked into the possibilty of incorporating the OPA1641 (single amp) and the OPA1642 (dual amp) devices into stripboard layouts, for a selection of different mic options.
The resulting project details are outlined in the attached web pages ...
(Just click on any of the 4 buttons at the top or bottom of this page to access the desired project)