Farralane.com - Shure 545SD Classic Unidyne® Instrument Microphone

The predecessor to the SM57, The 545SD Classic Unidyne® Instrument Microphone is a dual-impedance, unidirectional, dynamic microphone.

Shipped connected for low-impedance operation, the 545SD features a silent magnetic reed on/off switch with lock-on option. A favorite for instrument pickup and recording, the 545SD can also be used on lecterns in public address systems.

Exceptionally uniform cardioid pattern minimizes feedback
Selectable dual-impedance operation
Silent magnetic reed on/off switch with lock option
Cardioid, dynamic
Frequency response: 50 to 15,000 Hz

Type: Dynamic
Frequency Response: 50 to 15,000 Hz; View Larger
Polar Pattern: Cardioid (unidirectional)--uniform with frequency, symmetrical about axis
Impedance: Dual. Microphone rating impedance is 150 ohms (250 ohms actual) for connection to microphone inputs rated at 19 to 300 ohms and "High" for connection to high-impedance microphone inputs. Wired for low impedance as supplied. To change impedance, see sections on lmpedance Selection and Connections in User Guide.
Output Level (at 1,000 Hz): LOW: Open Circuit Voltage* -58.0 dB (1.3 mV); HIGH: Open Circuit Voltage* -35.0 dB (17.6 mV); *0 dB = 1 volt per Pascal (1 Pa = 94 dB SPL)

Polarity: Positive pressure on diaphragm produces positive voltage on pin 2 (with respect to pin 3).
Switch: Built-in magnetic reed on/off switch with lockplate.
Cartridge Shock Mount: Internal rubber vibration-isolator