Earthworks CTB30 Boundary Microphone (30kHz)

Low-profile tabletop boundary microphone for temporary or permanent installations


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The Earthworks CTB30 high-definition, tabletop boundary mics are next-level microphones for critical conferencing and speech, designed for fixed installation in tabletops or ceilings

The advantage of boundary mics is the elimination of comb filtering, since rear reflections off walls and tables are non-existent. Already a leap in intelligibility, the proprietary technology of the Earthworks CTB30 takes it several steps further, with their True Semisphere™ omni polar pickup response, which has the same high intelligibility at virtually any point around a conference table or other surface. Complementing that is a flat 60Hz to 30kHz frequency response optimized for voice—and of course, Earthworks’ trademark ultra-fast impulse response and diaphragm settling time. Not prone to the same problems as other boundary mics, the CTB30 also features a unique filter that significantly reduces the low-frequency thumping of shoes against table legs and HVAC noise. Since we’re talking meetings and copious note taking (or scribbling and faking it), the CTB30 also delivers an impressive reduction of unwanted sounds from paper, pens, and computer keypads. And, because no executive worth their MBA can live without a Smartphone, the CTB30 is completely immune to RF interference from mobile phones and other RF sources.

Earthworks CTB30 tabletop boundary microphone in one take:

  • Low-profile, small footprint design
  • Unique low-frequency filter minimizes noise from table thumping and HVAC
  • Reduced pickup of paper shuffling
  • Flat Frequency Response from 60Hz to 30kHz
  • Ultra-high intelligibility
  • More gain before feedback
  • Near perfect polar pattern
  • True Semisphere Polar Response (near-perfect frequency response at 45 degrees incident to the surface in a hemispherical pattern)
  • Immune to RF interference
  • Rubber, shock absorbing pads eliminate vibration noise
  • Designed to allow cable to exit from the rear or bottom of the microphone
  • Only 4-3/16″ (10.4cm) in diameter
  • Available in black, white, silver or Nextel® Dark Black finish
  • Primary applications include teleconferencing, distance learning, surveillance, boardrooms, government facilities, worship facilities and ambient room miking

In-table design for conference tables, lecterns, and alters

Engineered to deliver crystal clear, highly intelligible reproduction of the human voice at any point around a conference table or other flat surface, the in-table design and near-perfect polar pattern also means that attendees at meetings won’t be unnecessarily leaning into microphones or tapping them to see “is this thing on.” The result is a more natural speaking and listening posture, making conferences more enjoyable (especially if there’s food involved).

This wider coverage also means that fewer Earthworks microphones are required to properly cover a conference room, cutting down on the number of channels of DSP, cables and other ancillary equipment required for the system. Compatible with all DSP systems that provide 24-48V phantom power, Earthworks TableComm™ series microphones can easily integrate into existing system designs or new installations. 


Measuring a mere 4-3/16″ in diameter, the CTB30’s sleek design fits seamlessly into any room. It comes with a 10′ (3.04m) low-profile cable with XLR-3M attached, which is designed to exit from the side or bottom of the microphone. The XLR can be removed, allowing the cable to run through a small hole in the table surface for permanent installation. Two 6-32 screw holes and a keyhole are found on the bottom of the microphone for secure mounting. 

The Earthworks CTB30 delivers the highest level of speech intelligibility and articulation, which means less straining to understand the words and time better spent understanding the message. For more information, call or chat online with your Westlake Pro Sales Consultant today.


Earthworks CTB30 specifications:

  • Frequency Response:60Hz to 30kHz -3dB @ 1′ (30cm)
  • Low Frequency Rolloff:60Hz, 15dB/octave
  • Polar Pattern:Omni Semisphere
  • Sensitivity:-25dB
  • Power Requirements:48V Phantom, 10mA
  • Max Acoustic Input:136dB SPL
  • Dynamic Range:116dB @ 1kHz
  • Output:XLR-3 (pin 2+)
  • Output Impedance:65 ohm balanced
  • Min Output Load:1k ohm between pins 2 & 3
  • Noise:5dBA (Typical)
  • Microphone Color:Black, White, Silver or Nextel® Dark Black
  • Dimensions:4-3/32″ x 4-3/32″ x 7/16″ (104.1 x 104.1 x 11.4 mm)
  • Cable Length:10″ (3.04 m) with installed XLR-3M
  • Connector Type:Low-profile cable terminated into a 3-pin XLR-M
  • Weight:36 lbs. (162g)

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