Sterling Audio ST77 Mods
The Sterling ST77 is a high-noise FET microphone with what appears to be a variation of the ADK A-51/MXL 2001 circuit.
The mic has relatively high sensitivity, but like most Sterling mics, relatively high noise. The circuit offers insufficient and perhaps even unintentional high-frequency correction: -2dB @ 20kHZ. This results in a slightly over-bright voicing that limits the microphone's utility.
We have two modification options for the Sterling ST77:
#1: Capsule Replacement
The capsule in the ST77 appears to be a standard Chinese 32mm K67, with thin brass shims over plexiglass clamping rings. If you find the microphone to sound thin, harsh, or metallic, blame the capsule.
The RK-47 is a fine replacement/upgrade capsule for the ST77. It is better suited to the stock circuit than is the ST77's original capsule.
The RK-12 is an alternative replacement/upgrade capsule for the ST77. It has a broader, lower amplitude presence boost in the high frequencies than does the original capsule, giving it a much more balanced sound.
Both these capsules should install easily onto the Sterling mic's existing mounting post, using the "supersaddle" enclosed with the RK-47 and RK-12.
#2: Grille Upgrade
The ST77 grille can be easily replaced and upgraded with our custom TLM49-style grille. Our design has no internal parallel surfaces, which can reduce standing-wave reflections within the acoustic cavity.