The FAB2010 Mic Input Module is a board that provides an XLR Female Input jack, soft-start phantom power, and -20dB pad in one convenient and small module. Use this in your own DIY project or with other FAB Modules.
RFI Input Protection. Three capacitors protect from RF interference.
-20dB Pad, using 0.1% high precision resistors. This -20dB Pad is controlled by "logic level". Just apply +5V, or V+ voltage to the Pad Control pin. PAD functionality is provided by a high-quality PDIP DPDT Relay, controlled by a switching transistor.
Soft-start Phantom Power. Phantom Power is also controlled by a "logic level." The soft-start circuit applies 48 Volts gradually to your expensive microphones, avoid a loud thump that could destroy your monitor speakers. A PDIP DPDT Relay, controlled by a switching transistor is used for Phantom Power switching.
Phantom Power Blocking Capacitor. Two capacitors (one on each leg of your differential line) is used to block 48Volt Phantom Power from travelling further down the signal chain. Thus, 48Volts can only come out of the XLR input jack, towards your microphone.