The microphone signal is fed to a XLR 3 M connector. The modulation output is balanced. The N 149 A supplies the bias voltages for the microphone capsule, the filament voltage controlled by a sensor circuit, and a further voltage to generate the plate voltage and other necessary operating voltages within the microphone itself.
The unit produces constant current effecting a soft start of the tube. The KT 8 cable between microphone and power supply can be up to 100 m long. Modulation cable lengths up to approx. 300 m are allowed.
The three available versions of the N 149 A just differ in their enclosed mains power cable.