Flightcases
Alesis AM51 professional canrdioid condenser microphone.
The Alesis AM51 is a fixed Cardioid FET condenser with switchable pad and filter and transformer output, and is designed to use as an all-purpose studio condenser. Switches on the AM51 independently enable a pad (-10dB) and high-pass filter (12dB/octave at 75Hz). Requires 48v phantom power.
The AM51 was one of the first microphones released by GT Electronics, the analog product division created when Alesis acquired Groove Tubes. It is a fixed Cardioid FET condenser with switchable pad and filter and transformer output, and was billed as an all-purpose studio condenser.
The capsule is the same as was found in all the Groove Tubes large-diaphragm models, a ~33mm K67 derivative with a resonator disk attached to the active diaphragm to smooth out the high-frequency response.
AM51 PCBThe circuit is a Class A JFET design with an output transformer. It has high gain (32mV/Pa) and relatively high self-noise (22dBA); these characteristics were common to all Groove Tubes and Alesis/GT condensers.
Switches on the mic independently enable a pad (-10dB) and high-pass filter (12dB/octave at 75Hz).
