"BM-700" is the name used for a number of extremely inexpensive, and extremely low-quality condenser mics sold on Ebay and Amazon. Out of the box, the mics are fairly worthless, but they've become a favorite "donor body" for DIY enthusiasts.
We don't love the BM-700 as a donor mic; the metal parts are the cheapest we've ever seen. The colors are garish (see above). All the internal parts are throw-aways.
Nonetheless, we've developed a series of products that transform the BM-700 into a surprisingly versatile, professional-quality recording device.
First, replace the capsule with our TSB-2555. The capsule includes our custom-designed harness, plus all the screws and wires needed for installation.
(To verify compatibility with your mic, see whether the stock capsule mount uses two screws, front and back, about 1cm apart in the center of the top deck of the chassis.)
Next, replace the mic's circuit with our ETL1. This is a premium implementation of the Schoeps CMC5 design, adapted for use with the TSB capsule. It is uncompromising in its parts selection, and shocking in its performance, thanks to its carefully selected and biased NOS JFET, imported polypropylene signal caps, and low-noise parts throughout.
Read more about the ETL1 circuit kit.
If you haven't already bought the BM-700, consider our S-25 microphone kit instead. These are significantly more robust than the BM-700; the S-25 body sleeve and end cap alone weigh more than twice as much as their BM-700 counterparts.