Universal Audio Bock 251 Tube Microphone

Universal AudioSKU: MIC-UA251

Price On Application


Reach sonic nirvana.

The UA Bock 251 is Universal Audio’s flagship multi-pattern tube condenser microphone, handbuilt at the UA Custom Shop in Santa Cruz. 

Going beyond the famed ELAM 251,* considered by many to be the greatest vocal mic ever made, this David Bock-designed masterpiece features hand-sourced components for rich vintage sound with enhancements for performance and consistency. 
Key Features

  • Large-diaphragm tube studio condenser mic, lovingly handmade at the UA Custom Shop in Santa Cruz, California
  • Iconic, "golden unit" mic sounds with modern enhancements by David Bock
  • Switchable omnidirectional, cardioid, and figure-8 polar patterns 
  • German-made CK12 capsule and Cinemag transformer

Add Handmade Magic to your Studio
The UA Bock 251 is David Bock's loving interpretation of the classic 251 microphones he studied and maintained as chief technical engineer of the world's top recording studios for two decades. Hand built at UA’s Custom Shop in Santa Cruz, California, the UA Bock 251 mic puts "golden unit" sound at the heart of your recordings.

Rich Tube Mic Sounds, with Updated Sonics
With its German-made CK12 capsule and large output transformer, the UA Bock 251 gives you extended low-frequency response down to 10 Hz and higher SPL capabilities versus vintage 251 microphones. 

Built for a Lifetime of Harmonious Recording

Handwired using premium components, each UA Bock 251 is built and tested to David Bock's exacting specifications. With its vintage-inspired case, robust shock mount and accessories, this mic spares no expense to last a lifetime. 

*The UA Bock 251 product is not affiliated with, sponsored, nor endorsed by any other company. The "251" name is used solely to identify the classic mic design that Universal Audio's product is based on. All other trademarks are property of their respective owners. 


Microphone Type

Tube Condenser

Polar Pattern


Frequency Range

10 Hz - 18 kHz, ± 2dB


-34 dB (19 mV) ref 1V at 1 Pa, 1 kHz


118 dB SPL, 1% THD

Output Impedance

150 Ohms

Recommended Load Impedance

Greater than 1.2K Ohms

Adjustable Controls

Polar pattern selector for Cardioid, Omni, Figure-8


Tuchel (mic), 3-Pin XLR (power supply)

Included Accessory

  • UA Bock 251 power supply, 100V, 115V (default), or 230V operation
  • Premium vintage-style suitcase


8.5” (216 mm) length, 2” (52 mm) diameter


1.58 lbs (716 g)

Shipping Weight

12 lbs (5.4 kg)

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