The Bock Audio 47 is a high quality cardioid directivity studio condenser microphone utilizing vacuum tube electronics. Utilizing the U47 format, originally built in the 1950's,this mic takes that platform and expands the electronics bandwidth. It utilizes it's own proprietary cable and power supply. The microphone's audio output is standard male XLR3, with positive excitation of the diaphragm at the front of the mic resulting in a positive voltage at the output XLR's pin 2. Audio output is fully transformer balanced.
The Bock Audio 47 uses classic pentode run as single triode circuitry with no additional negative feedback and high quality through hole components. Through hole components are more mechanically robust than surface mount and allow for worldwide ease of repair. Single triode mic circuits demand excellent capsules before them and excellent transformers after them, with a reward of low noise, simplicity of troubleshooting, and classic sound unachievable otherwise. The Bock 47 departs from the classic U47 of the 1950's in it's expansion of the bandwidth of the electronics, which has had it's low frequency cutoff frequency decreased from 40Hz to 10Hz, without any loss of high frequencies, by use of a larger value grid resistor.