Lo-Cap Front End for SMT MXL 990
Lo-Cap Front End for SMT MXL 990
Lo-Cap Front End for SMT MXL 990
Friday, June 28, 2013
Taking the low capacitance idea to another MXL 990, the little circuit as detailed in the last post is built and wired into a new surface mount mic. Other mods to the mic include tacking 1uF caps across C3 and C4, replacing D3 with a 12V zener and bypassing the electrolytics with 0.1uF ceramic caps, as detailed here.
This pair of mics has Alctron 35mm K67 type capsules. The new first stage increased the sensitivity by about 6dB. Noise is very low, with no hiss or hum audible in headphones at full gain in a quiet office at midnight. Can’t say yet if the mic sounds any “faster” or captures low level detail better. That will come with experience in the field.
Here’s a snapshot with connections for the Drain, Ground, Source, and BackPlate marked:
Wherein the low capacitance first stage concept is applied to the surface mount MXL 990 printed circuit board.
Wired up and a quick test.