AEA RPQ503; ribbon microphone preamplifier with 2-band EQ in API 500 format; proven 3rd generation AEA circuitry; ultra-high input impedance: 68 kOhm (phantom power disabled); up to 85 dB gain; Continuously adjustable low and high shelving EQ, ±20 dB; EQ section based on CurveShaper technology; EQ can be switched on separately with center detent for exact neutral position; +48 V phantom power for condenser microphones; Polarity switch for phase correction; switchable between microphone and line input; double concentric potentiometers for precise fine tuning; Design: API Series 500 format, requires a 500 slot