Studio Projects B1 Mods
The B1 uses a linear circuit based on the Schoeps transformerless design. It was implemented by Brent Casey of PMI, and is a very sound design built with excellent components.
We see no value in attempting to "upgrade" this circuit. It is unlikely that you'd hear any sonic benefit from changing components. Note, too, that we've seen no published schematics for the microphone, so any DIY upgrade attempt would have to begin by manually tracing the circuit.
All that said, we hear from B1 owners frequently, asking how to make the mic sound less sibilant, less bright, less peaky. If your B1 is giving you more high-frequency content than you need, we do have a fix for you.
The fix is easy: change the B1's K67-style capsule to a K47 type, such as our RK-47. This will give the microphone a broad, rich midrange boost, with a neutral top end. The result is great on male vocals, voiceover, strings and percussion.