The Model 111 is a dynamic stage microphone with Lampifier’s unique, phantom-powered, programmable analog audio processing circuit.

The circuit, invented by Gary Osborne, provides compression and noise-gating capabilities. The parameters for the gate and compressor can be modified by repositioning jumpers on the circuit board built into the mic’s handle.

The following parameters can be combined into 308 different “programs,” to tailor the mic for a wide variety of applications — from quiet acoustic instruments to loud guitar cabinets, from spoken word to “extreme” vocals:

• Compression threshold - 7 settings, from low sensitivity (0dB) to high sensitivity (-24dB)
• Noise Gate threshold - 11 settings, from least gating (-55dB) to most (-5dB)
• Noise Gate release - slow or fast
• Output Volume - low or high

The audio-processing circuit consists of a pair of linear amplifiers, a resistor, and a light bulb.

The light bulb is not an optical compressor. Rather, the audio signal from the mic’s dynamic capsule flows through the bulb’s tungsten filament, which heats up with higher-gain signals, increasing the wire’s resistance. As resistance increases, output signal strength from the bulb decreases.

When the lamp is under-driven, the compression effect of the lamp is minimal, Conversely, at higher gains, the compression effect of the lamp is more pronounced. Therefore, the amount of effective compression is adjusted by controlling the output gain of the amplifier at the front of the circuit.

The processing circuit is phantom-powered — unlike most dynamic vocal mics, the Model 111 requires +48V phantom power.

The dynamic capsule in the Model 111 has a supercardioid response, making the mic suitable for applications in which a high degree of feedback rejection is desired. The capsule is tuned to provide a presence peak in the vocal range; the published response curve shows a boost of +4–5dB from 1.2–6kHz, and a secondary +4dB boost centered at 12kHz.