A-123-2 is a voltage controlled highpass filter with four filter outputs (6, 12, 18 and 24dB slope). It also features voltage control of the resonance.

These controls and in/outputs are available:

• Audio In with attenuator (Lev)
• Manual Frequency control (Frq)
• FCV1: Frequency control input (~ 1V/oct)
• FCV2: Frequency control input with polarizer
• QCV: Resonance control input with attenuator
• Manual Resonance control (Q)
• 6dB Output
• 12dB Output
• 18dB Output
• 24dB Output