The Panasonic WM-61A was good in its time... but there are now much better omni electret mic capsules, that will give you better sound with less noise.
Consider the PUI AOM5024L, or the Primo EM272 electret capsules. Electrically similar, but better. Also, on this group, read up on the simpleP48 circuit for using such electret capsules with +48v phantom-powered XLR mic inputs. Easier to build, and better performing than Mr Shin's transformer -equipped design.
