DSF-2 Digital Broadcast Microphone System
The DSF-2 Broadcast Microphone System has been specifically developed to simultaneously provide both the surround and stereo soundscape at large scale outside broadcast events such as football stadiums and concert hall venues. Its advantage over alternative methods is that the multichannel audio it generates from a ‘single point’ source is completely phase coherent. This enables the broadcaster to collapse the surround to stereo or mono for TV and radio feeds without loss of information, frequency imbalance or any of the other phase problems associated with spaced microphones or multi capsule ‘dummy head’ arrangements.
All processing is in the digital domain and the 1U controller is equipped with digital 750 ohm AES 3-id outputs on BNC connectors capable of driving up to 1000m of coaxial cable (subject to correct cable specification). When used is conjunction with the 250m SoundField mic cable, the microphone head can be situated up to 1.25 Kilometres from the DSF-2 controller. This can be a major benefit in situations where the OB vehicles have to be sited some distance away from the venue or performance.
The DSF-2 outputs stereo Left/Right (digital and analogue), stereo M/S (digital only) and four channels of SoundField B-Format called W, X, Y and Z (digital only) which is the surround sound information. A single lightweight multiway cable is used to connect the microphone to the DSF-2 controller which as well as carrying the individual capsule signals also supplies the necessary power to the microphone allowing unrestricted use in OB and ENG applications as well as in the studio. All microphone parameters can be remotely adjusted from the DSF-2 controller’s front panel whilst monitoring the results on the provided headphone monitoring.
The DSF-2 is designed to function as either a variable pattern single (mono) microphone, a variable pattern, variable width, coincident stereo microphone array or to generate full surround from the four B-Format outputs which will then be decoded into 5.1 by the SP451 Surround Processor or Surround Zone software. This is achieved using four sub-cardioid capsules set in a regular tetrahedron, and by adding or subtracting the outputs from these four capsules in different proportions, it is possible to derive all possible polar patterns from omni, through cardioids to figure-of-eights.
For surround recording applications the engineer should use the four B-Format output signals. These contain the three dimensional information (Height, Width, Depth and Sub Bass LFE) required for all current and future surround sound formats. In live broadcast applications the B-Format outputs of the DSF-2 should be connected to the B-Format inputs of the SP451 (after D/A conversion) which will output full 5.1 surround on six discrete channels (Left, Centre, Right, Surround Left, Surround Right and Sub-Bass). In addition to 5.1 the SP451 also outputs Left/Right stereo. If the surround and stereo mixing will be done at a later time in post production the B-Format signals should be recorded on four tracks and introduced to the SP451 or Surround Zone software in a studio environment.