Meridian America G68 - Manual (Page 50)

Ambisonics
The Ambisonics DSP preset can decode UHJ format, the two-
channel stereo-compatible encoding found on Ambisonically-
recorded discs and broadcasts. This material is specifically encoded
for surround reproduction and can give breathtakingly realistic
sound when replayed using the digital surround controller.
Ambisonics surround sound is quite unlike conventional stereo. A
special microphone technique picks up the sound of the original
performance in all three dimensions, allowing an archive to be
made which describes the soundfield exactly at that position. The
microphone signals are then encoded using a phase-amplitude
matrix to allow the effect to be conveyed on two-channel carriers
(like FM radio, LP, or CD).
The digital surround controller uses accurately matched, frequency-
dependent, phase-amplitude matrices to decode the signal and
construct the signals for each speaker feed.
The fundamental difference between Ambisonics surround sound
and conventional stereo is that the signals from all the speakers
combine to produce a coherent soundfield at the listening position,
giving the illusion that you are sitting inside the recording space
whether you are at the exact central seat or well off to one side.
Of all the signal-processing options, Ambisonics is the one that
requires the greatest attention to speaker choice and positioning.
Super
Super synthesises a signal from a conventional stereo recording
or broadcast so that it can be decoded using the Ambisonic
decoder. The result is especially effective for two particular types of
recordings:
• Those using true coincident microphone techniques.
• Multi-tracked or multi-miked recordings.
Ambisonics and Super DSP preset parameters
Parameter Options What it changes
Width* 0 to 1 The width of the image.
Row† A, C, E, G, I, K, M The seating position; the letters are like rows in a hall.
Channels 7, 6, 5, 4 The number of speakers.
R Filter Off, 3kHz, 7kHz, 9kHz The cutoff of high frequencies from the rear surrounds.
S Filter Off, 3kHz, 7kHz, 9kHz The cutoff of high frequencies from the side surrounds.
*Super only.
†Ambisonics only.
D S P p r e s e t s
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G Series DSP 46 31/10/03, 4:24:39 pm