This is based on the article that appeared in tape-op magazine a couple
of years ago. (See http://www.mojaveaudio.com for a download of the article
and a kit if you need one
I initially did this on perf-board and didn't buy the kit. I used a
regulated power supply for the heater filament. Later I etched a PCB for
the mic circuit and made a few changes.
Some pictures of the modded MXL2001 are below.
The transformer is a sowter model no.4935. I had to shave off some of the metal from the can cap to fit the trannie. Hot melt glue stops it moving around.
The mic sounds good, impressive even - quite warm and tubey. It's seen
a lot of action in our studio as a vocal mic for both male and female voices.
I mades some further modifications to the initial '"Royer" design, adding
B+ voltage stabilisation capacitor and a cathode bypas cap (470 uF).
The big fat 'mustard' cap is the output cap - salvaged from an old temperature
controller.
Some tips: When gutting the mic, make sure you don't throw away everything:
there are some useful bits in there. Grab the two 1 gig resistors and the
PTFE mounts.
I used the PTFE mounts for wiring the capsule leads and connecting the Hi-Z parts of the circuit. This is to prevent leakage across the circuit board.
Here's the re-assembled mic in a home-made shockmount. Two rings of
copper (these are used vacuum gaskets but you could use anything),
a broom handle, and some rubber bands. Total cost: nothing
I have also built a dual capsule cathode follower mic into an MXL body:
more on this if you click on this
link.