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CardioidBock Audio 151

Cardioid Tube Condenser Microphone

The Bock 151 is a fixed-cardioid large diaphragm tube condenser. Essentially a budget version of the flagship Bock 251, the 151 was designed for close-miked applications such as vocals.

It uses a proprietary, hand made capsule described as a “dual asymetrical-backplate CK12-type,” a proprietary hand-wound vintage style transformer, a NOS EF732 tube in the mic amplifier and a hand-built custom outboard power supply.

(Note: previous versions of this document identified the tube as a New Old Stock GE5670 triode; this was due to an error in documentation from the distributor for Bock Audio products. The tube in the 151 is an EF732.)

The “brite/normal” switch delivers two sounds in one mic:

  • “Bright” allows unfiltered extended high frequency response that defines a modern high end condenser.
  • “Normal” offers a less bright, more vintage style high frequency response more forgiving to sibilant singers and or voices that need a darker treatment.

The 151 uses US-made metalwork with a relatively utilitarian finish. The mic has been discontinued as of January, 2011, in favor of the new Bock 241, which uses imported metalwork that is closer to the Ela M 251 in appearance.

See also the Soundelux E251C, the original version of this mic design.

The Bock Audio 151 is also known as: Bock 151.

The mic was released in 2007.


Frequency Response - CardioidClick Graph to Compare!
151 Cardioid Frequency Response Chart
Pickup Patterns Pads & Filters
Cardioid (19 mV/Pa; 30 - 18,000 Hz)
Capsule Dimensions Impedance SPL/Noise
Diaphragm diameter: 25mm
200 Ohms (Low) Max SPL: 112 dB
Self-noise: 18.0 dB(A)
Weight Length Max Diameter Interface(s)
694g (24.48oz) 216mm (8.50'') 52mm (2.05'')
  • 3-pin XLR male (1)
Power Specifications
  • Includes tube power supply

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