The 861 Reference Digital Surround Controller - Meridian 861 User Manual

INTRODUCTION PREFACE
The 861 Reference Digital Surround
Controller
Digital signal processing, or DSP, is a technique pioneered by Meridian in
hi-fi products for achieving extremely accurate reproduction of audio
signals. Unlike conventional analogue systems – which process signals using
electronic circuits based on resistors, capacitors, and inductors – DSP works
by performing exact mathematical calculations on digital versions of the
signals.
The advantage of DSP over analogue circuitry is that the signals are held as
precise numbers, rather than voltages in a circuit. This means that any
number of stages of processing can be performed with high precision, and
without any of the cumulative noise or degradation that inevitably occurs,
even with high-quality analogue circuitry. In addition, several of the
surround-sound decoding techniques and signal improvement techniques
available in the 861 would be virtually impossible to implement in
analogue circuitry.
At Meridian we have taken advantage of the availability of high speed DSP
microprocessors to incorporate DSP in hi-fi products, and the 861 is the
result of over a decade of our research and development in this fi eld.
The 861 takes advantage of DSP for several different functions:
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The 861 converts analogue input signals to digital format, using high-
quality analogue-to-digital converters (ADCs). Digital signals, from CD,
DVD, LaserDisc or digital broadcasting, are already in digital format and do
not need to be converted.
The signals are then retained in digital form throughout the 861 until they
are converted back to analogue form at the analogue outputs, to drive
power amplifi ers. If you are using the 861 with Meridian DSP Loudspeakers,
the signals remain in digital form until the last possible stage.
To de-jitter incoming digital signals and expand the precision of the
signal.
To perform fi ltering or adjustment of the frequency response; eg treble
or bass.
To decode digitally-encoded signals from Dolby Digital (AC-3), DTS, or
MPEG Audio.
To process the audio into a multi-channel signal, and match the source
channels to the confi guration of main loudspeakers and subwoofers in
the system.
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