Effective 1/1/2010

SF-24V pin-out

Pin 1 Common – Lower element
Pin 2 output – upper element
Pin 3 output – lower element
Pin 4 B+ (high voltage)
Pin 5 Heater supply – upper element
Pin 6 Common – Upper element
Pin 7 Heater supply – lower element

Effective 10/19/05

R-121, R-122, SF-1
Standard 3-Pin XLR
Pin 1 Ground
Pin 2 Signal Hot (+)
Pin 3 Signal Cold (-)

SF-12, SF-24
Standard 5-pin XLR
Pin 1 Ground
Pin 2 Upper transducer: Signal Hot (+)
Pin 3 Upper transducer: Signal Cold (-)
Pin 4 Lower Transducer: Signal Hot (+)
Pin 5 Lower Transducer: Signal Cold (-)

R-122V
7-Pin XLR
Pin 1 Ground
Pin 2 Signal Hot (+) (unbalanced)
Pin 3 No Connection (open)
Pin 4 High DC Plate Supply Voltage (approximately 135-VDC)
Pin 5 Heater supply (6-Volts DC)
Pin 6 Ground
Pin 7 No Connection (open)