Bock Audio 407
The Bock Audio model 4-0-7 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 407 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 407 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.
It is recommended that the user place the mic in it's shockmount on a stand and connect all the cables before applying power to the unit. Allow a few minutes for the mic to warm up.
The Bock Audio IFET is powered by P48 phantom power.
The Bock 407is a "cardioid only" mic, as the original was used nearly exclusively in cardioid. The 407 comes with a remote power supply and professional spider type shock mount and a special custom 20 foot cable between the mic and power supply.
Frequency Range: 10Hz to 18kHz, +/-2dB
Equivalent Noise: 18dB (“A” weighted) 32dB (unweighted)
Distortion vs.SPL @1kHz:
112dB = 0.5% THD
118dB = 1% THD
129dB = 2% THD
(increasing distortion is non-exponential, nearly linear, and primarily 2nd harmonic)
Impedance: 200 Ohms true transformer balanced
Recommended load: 2k Ohms
S/N (94dB-noise): 76dB “A”, 62dB unweighted
Capsule size: 1” diameter, single backplate K47 type
Tube type: New Old Stock EF814k
Dimensions: 2” dia x 8.5” oal (52x216mm)
Weight: 1lb 9.3oz (1.58lbs) =716g
Shipping weight: 13 lbs
Power Supply: N470 true linear, factory wired 115v or 230v operation