The Basics - B&K Reference 20 Plus Owner's Manual

The following is intended to familiarize users with common terms and applications of Home Theater equipment.
Sources - your processor can directly provide audio from its built-in AM/FM tuner. It can also provide limited
video from its on-screen menu system. Typically you will want to connect a number of additional sources (VCR,
DVD player, etc.) to your processor. Your processor is designed to accommodate a wide range of audio and
video signals.
The following table lists the most popular home theater media and how the audio information is stored.
Source Media
Audio Cassette
Video Cassette
Laser disc (LD)
Compact Disc (CD)
Digital Versatile Disc (DVD)
Satellite Broadcast
Digital Audio Tape (DAT)
Digital Compact Cassette
(DCC)
Mini disc (MD)
Analog vs. Digital Audio -
how they are delivered to your processor from the source. Analog signals exactly represent the sound you will
hear through a continuously varying voltage. Audio and video cassettes are analog recordings and are normally
delivered to your processor over a pair of coaxial audio cables.
Digital signals closely approximate the original audio signals with a set of numbers referred to as a bitstream. CDs
and DVDs are sources of digital audio and are normally connected to your processor through a coaxial or optical
digital cable. There are several different bitstream formats available. The simplest format is called Pulse Code
Modulation (PCM). In PCM, the bitstream directly represents the original 2-channel audio. In Dolby Digital and
DTS (see "Surround Formats" below) bitstreams are modified using a process called compression to squeeze
more information into limited space. DTS squeezes 5.1 channels into the space normally required for two
uncompressed channels, while Dolby Digital squeezes 5.1 channels into about ¼ the space required for two
channels. Your processor automatically detects the bitstream currently being provided from the source and
performs the required decompression and surround processing. If no digital signal is present your processor will
automatically switch to analog processing.
All sounds that you hear from your speakers are analog. Digital signals are automatically converted to analog by
your processor before being output to your the speakers.
If analog signals exactly represent the audio, while digital signals only approximate it, why would I want to
use digital?
All analog sources add some amount of noise and distortion to the audio signal. Additional noise can be
picked up through the cables from the source to your processor. It is impossible for the processor to tell
the difference between the desired signal and the added noise and distortion, so it reproduces both of
them. The result is increased background noise and decreased dynamic range and fidelity. Digital signals
are virtually immune to noise and distortion. The processor can, therefore, reproduce the signal with the
greatest possible fidelity. We recommend you use digital signals wherever possible. Also Dolby Digital
and DTS (see "Surround Formats" below) work only with digital signals.
Audio and Surround Formats
Monaural (Mono)
Modern recordings are seldom made in this format, but most older movies and music are available only in
this format. You may get mono from any source - digital or analog. Sound will normally come from the

THE BASICS

Analog
X
X
X
X
This refers to the method used to place audio information on the source material and
- Your source material will be in one of seven possible formats described below.
- This is the oldest format available. It contains a single, full range audio channel.
PCM Dolby Digital
X
X
X
X
X
X (compressed)
X (compressed)
5
DTS
X X
X X
X X
X
X X
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