Alesis AM51
Cardioid Condenser Microphone
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.
The 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).
The AM51 circuit is extremely similar to the GT55, ST55, and M-Audio Nova circuits that we’ve seen.
Permalink: Alesis AM51
The mic was released in 1999.
Specifications
Pickup Patterns | Pads & Filters |
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Cardioid
(32 mV/Pa; 20 - 18,000 Hz) |
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Capsule Dimensions | Impedance | SPL/Noise |
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Diaphragm diameter: 25mm Capsule diameter: 32mm Diaphragm gauge: 3 microns |
200 Ohms (Low) | Self-noise: 22.0 dB(A) |
Weight | Length | Max Diameter | Interface(s) |
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n/a | n/a | n/a |
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Power Specifications |
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