March 26, 2008: There is currently a three to four week backlog. We are still accepting deposits to reserve a place in the shipment queue. Please see the On-line Ordering page.

At the Audio Engineering Society Convention in San Francisco (AES-2006), Core Sound was proud to introduce its groundbreaking TetraMic, the first portable, single point, stereo & surround sound Ambisonic microphone to be available for under $1000.

Based on the principles of Ambisonic recording developed by Michael Gerzon and Peter Craven during the 1970's, TetraMic allows you to place a single exceedingly accurate tetrahedral microphone in a sound field, record four channels of audio in "A" format, transform them using software into "B" format (W, X, Y and Z), and later interpret those four channels to essentially any single-point configuration of microphones:

• omni
• sub-cardioid
• cardioid
• super-cardioid
• hyper-cardioid
• figure-8
• multiple combinations of those including:
  • Blumlein (two crossed figure-8 microphones in the azimuth plane))
  • Height-enabled Blumlein (three orthogonal figure-8 microphones)
  • M/S (Mid/Side)
  • XY (two crossed cardioids) separated by any arbitrary angle
  • binaural, using HRTF information
  • Three hypercardioids facing forward and two cardioids facing rearward (for 5.1 surround)
  • any combination and arrangement of microphones for surround sound or other effects

The apparent orientation can be rotated, tilted, tumbled or zoomed at will.

The four channels of "B" format can also be interpreted into almost any playback format, including:

• mono (without "sum to mono" phase cancellation issues)
• stereo
• binaural, using HRTF information
• four speakers arranged as a square or rectangle
• six speakers arranged as a regular or irregular hexagon
• 5.1 (ITU)
• 7.1
• 10.1
• any of the above plus height information (e.g., two hexagonal arrays of speakers, one above the listener and one below)
• and many, many more.

This process allows your audio projects to have unparalleled flexibility in post-production.

How good a microphone is TetraMic? We believe TetraMic has the flattest and most extended fig-8 response of any commercially available microphone, bar none; so it's among the best Blumlein arrays in the world. Its free-field omni response is not quite as good as a Bruel & Kjaer 4133 1/2-inch measurement microphone; it's only as good as the wonderful DPA 4003 that we use for calibration -- i.e., sensational! However its diffuse-field response is better than the 4003. This combination of capabilities makes TetraMic one of the world's finest microphones.

Until now, a tetrahedral Ambisonic microphone and its associated electronics cost over $4000 and sometimes as much as $7000. TetraMic is priced under $1000 including its processing software.

TetraMic is more than four microphone capsules on a tetrahedral mount. Building a TetraMic starts with a large batch of carefully assembled microphone capsules, pre-selected for sensitivity and frequency response. Each capsule is then exhaustively tested for sensitivity, frequency response, directivity pattern and other parameters. We select four well-matched capsules and confirm their compatibility. Then another round of exhaustive testing begins, this time for the complete tetrahedral assembly. All in all, each TetraMic undergoes more than seven hours of testing and calibration. Each TetraMic exits the test phase with its own calibration and correction files, used with "VVMic for TetraMic" and VVTetraVST to ensure that each TetraMic is a fine example of one of the best sounding microphones in the world.

When TetraMic is combined with our new 4Mic portable battery-powered four-channel microphone pre-amp/A-to-D converter and a two-channel (yes, two channel!) digital audio recorder they become the first completely portable, stereo & surround sound, high-resolution (24-bit) Ambisonic digital audio recording system. And the total system price, including the recorder will be around $2000!

"VVMic for TetraMic", VVTetraVST and VVMicVST

To ensure that TetraMic is the finest sounding Ambisonic microphone in the world, it is supported by a custom version of David McGriffy's fine "VVMic for TetraMic" post-processing software. With design assistance from some of the world's experts in Ambisonic microphone design and testing (including those involved with the original commercial Ambisonic microphones), VVMic performs detailed equalization based on both individual capsule-level and fully integrated TetraMic-level calibrations. It includes functions for shelf filtering for improved localization cues, "A" to "B" format transformation, and decoding for playback in many playback configurations (e.g., mono, stereo, ITU 5.1, hexagon, square and many others).

For real-time processing you would use the VVTetraVST and VVMicVST VST plugins with your recording software. VVTetraVST performs A- to B-format transformation using the calibration data for your TetraMic. VVMicVST controls virtual microphone and playback configurations. On PCs, both plugins should work with any recording application that can use VST plugins (e.g., SONAR, AudioMulch, Bidule,Wavelab, Cakewalk, Cubase, Samplitude, Ableton Live, Reason, FL Studio, Sound Forge, Nuendo, REAPER). They may also be able to be used with programs that require RTAS plugins (e.g., ProTools) by use of a translation layer like FXpansion.

"VVMic for TetraMic" runs on Windows PCs. VVMicVST and VVTetraVST VST plugins are available for both PCs and Macs.

Mac

As of April 2008, both VST plugins work fine with Bidule running on PPC Macs. VVTetraVST also runs fine on Intel Macs. Next to come is an Intel Mac version of VVMicVST.

At the moment, we can't recommend using Nuendo 3 or 4. They enforce rigid speaker playback assumptions that are incompatible with Ambisonic's flexible speaker routing.

Linux

Other software developers are developing applications independently for Linux. See Fons Adriaenson's powerful and great sounding Linux-based TetraProc and TetraCal applications here.

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