Bock 507

Common name: Bock Audio 507

Production Status: Discontinued / Vintage

The Bock Audio model 5-ZERO-7 is a high quality cardioid directivity studio condenser microphone utilizing vacuum tube electronics and a unique elliptical capsule developed by George Cardas and David Bock. The new Bock/Cardas elliptical capsule design strives to resolve the chronic in-band resonance issues of both large and small diaphragm microphones. Round capsules have a relatively low frequency in band resonance, typically around 1K. Small diaphragm mics usually have a much higher in band resonance, typically about 15K or higher. The elliptical capsule offers the best of both, avoiding the constant distance “edge to center” of round capsules, reducing in band resonances dramatically and expanding the application possibilities. The ZERO capsule also has many conventional attributes such as the time tested 6 micron gold sputtered diaphragm used in the Bock 251 and edge termination design. The capsule is hand built in very small quantities in Germany. Utilizing the U47 format, originally built in the 1950’s, this microphone takes that platform and expands the electronics and capsule bandwidth. It utilizes it’s own proprietary cable and power supply. The Bock Audio 5-ZERO-7 uses classic pentode run as single triode circuitry with no additional negative feedback and high quality through hole components. In addition the microphone utilizes fixed cathode bias derived from the heater, as the original U47 did. The Bock 507 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 40 Hz to 10 Hz, without any loss of high frequencies, by use of a larger value grid resistor.