Universal Audio UA Bock 251 User manual

Introduction Getting Started
The UA Bock 251 microphone continues Universal Audio’s proud
tradition of timeless craftsmanship. Lovingly handbuilt at the
UA Custom Shop in Santa Cruz, California, your new microphone
is designed to deliver uncompromising quality and a lifetime of
musical inspiration.
This microphone is a multi-pattern tube design of the highest quality.
Offering Omni, Cardioid, and Figure-8 polar patterns, extended
low-frequency response, and high sound pressure level tolerance,
we trust this microphone will become an indispensable part of your
recording studio.
Engineered by David Bock and inspired by the iconic 251, the
UA Bock 251 is ideal for capturing vocals and musical instruments.
Place the UA Bock 251 microphone in its included shockmount on a
stable mic stand. Connect the power supply to AC, then connect the
included six-pin XLR cable from power supply to microphone.
Note that the power supply should be powered off before connecting
or disconnecting the microphone. After switching on the power supply,
allow the tube several minutes to warm up before use.
To adjust the microphone polar response pattern, slide the switch until
the desired setting is visible.
For customer support, visit help.uaudio.com
UA Bock 251 comes with convenient Apollo Channel
Strip Presets. These downloadable settings for UA’s
Apollo audio interfaces give you professional results on
a wide range of sources, instantly. To get your presets,
download UA Connect by scanning the QR code or visit
uaudio.com/mics/presets
Universal Audio, Inc. 4585 Scotts Valley Drive, Scotts Valley, CA 95066
UA Bock 251 Microphone
Get Apollo Interface Presets
User Guide
www.uaudio.com

Universal Audio, Inc. 4585 Scotts Valley Drive, Scotts Valley, CA 95066www.uaudio.com
Safety
UA Bock 251 Specifications
Before using this unit, be sure to carefully read the applicable items of these operating
instructions and the safety suggestions. Afterwards, keep them for future reference. Take
care to follow the warnings indicated on the unit, as well as in the operating instructions.
Important Safety Instructions:
Read and follow all instructions. Heed all warnings. Keep these instructions.
Do not use this apparatus near water.
Clean only with dry cloth.
Do not block any ventilation openings. Install in accordance with the manufacturer’s
instructions.
Do not install near any heat source such as radiators, heat registers, stoves, or other
apparatus (including amplifiers) that produce heat.
Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug
has two blades with one wider than the other.
Polar Patterns
Cardioid, Omnidirectional, Figure-8
Frequency Range
10 Hz — 18 kHz, ±2 dB
Sensitivity
-34 dB (19 mV) ref 1V at 1 Pa, 1 kHz
Self-Noise
18 dBA
Distortion versus SPL @ 1 kHz
(Increasing distortion is non-exponential,
nearly linear, and primarily 2nd harmonic)
112 dB = 0.5% THD
118 dB = 1% THD
129 dB = 2% THD
Output Impedance
150 Ohms
Recommended Load Impedance
> 1.2K Ohms
Maximum SPL
118 dB SPL, 1% THD
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
Case
Audio (-)
Audio (+)
No connection
Heater (5VDC)
B+ (130VDC)
Ground
Shield
Dynamic Range
100 dB
Signal-to-Noise Ratio
76 dB
Capsule
1” diameter
Dual asymmetrical backplate
Dual diaphragm CK12 type
Tube
New Old Stock ECC85
Connectors
Tuchel (mic)
3-Pin XLR (power supply)
Microphone Weight
1.58 lbs (716 g)
Shipping Weight
12 lbs (5.4 kg)
Dimensions
8.5” (216 mm) length
2” (52 mm) diameter
Safety Standards
UL 62368-2, EN 62368-1
Microphone input power:
From UA BOCK 251 PSU
Power Supply
UA Bock 251 PSU
Input: 100VAC, 115VAC, or 230VAC
Output: 130VDC @ 0.55mA, 5.1VDC @ 332mA
Maximum operating temperature 40°C
Power Rating = 11.5W
Power Supply Pinouts
Used electrical and electronic equipment should not be mixed with general
household waste. Please dispose in accordance with local regulations.
Hazardous voltage enclosed. Do not open, will cause shock or burn. If servicing
is needed, disconnect power and contact Universal Audio customer support.
Protect the power cord from being walked on or pinched particularly at plugs, convenience
receptacles, and the point where they exit from the apparatus.
Only use with attachments/accessories specified by the manufacturer.
Refer all servicing to qualified service personnel. Servicing is required when the apparatus
has been damaged in any way, such as power-supply cord or plug is damaged, liquid has
been spilled or objects have fallen into the apparatus, the apparatus has been exposed to
rain or moisture, does not operate normally, or has been dropped.
UA BOCK 251 does not contain a fuse or any other user-replaceable parts.
For the UA Bock 251 Power Supply Guide, visit help.uaudio.com
UA Bock 251 Microphone
User Guide
10004924REV12