Glossary

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ANALOG VS DIGITAL With analog recording and playback, a parameter such as the width of a movie soundtrack, the magnetic field on recording tape, or the side-to-side swings of the groove on a phonograph record varies in a way that is directly analogous to the sound waves of the original sound. These variations are translated to a varying electrical voltage, which ultimately causes the loudspeakers' cones to move back and forth, recreating the original sound. With digital recording and playback, points along the sound waves of the original sound are assigned numeric (or digital) values, which are represented as microscopic pits on CDs, magnetic pulses on tape, or microscopic dots on a digital movie soundtrack. When the recording or soundtrack is played back, the numeric values are converted back to the varying electrical voltage needed to drive the speakers. Digital soundtracks can be of very high quality, but take up much more room than analog. Sophisticated techniques such as Dolby Digital are therefore necessary to make multi-channel digital sound a practical reality.

ATMOSPHERE Background sounds, such as wind or traffic noises, which add to the reality of a scene. These sounds are sometimes recorded right at the shooting location, creating what is called a wild track for mixing into the soundtrack later.

BASS REFLEX Bass reflex is a method of making the bass deeper and at the same time more easily driven. If the bass reflex port is on the rear side of the speaker, it will need a certain amount of space (at least 10 cm) to the back wall in order to sound optimally. If you plan on placing your loudspeakers in a bookshelf, make sure that the speakers don't have a rear-fired bass reflex. If it has it may not perform its best in the shelf. Speakers need air around them to play well. If you choose to place a speaker with rear-fired bass reflex in your bookshelf, make sure that it is at least 10 cm distance between the bookshelf-wall and the rear-side of the speaker.

CENTER The Center speaker is the most important speaker in a home theater system and should be chosen with great care, since almost 70% of the movie sound is reproduced by the center. It is the speaker’s task to reproduce all of the voices and special effects on the screen clearly and with great precision.

CLOSED BOX A speaker with a closed box construction usually gives a lighter, quicker and more precise bass reproduction.

CONSTRUCTION TYPE Construction types 1-way, 2-way and 3-way refer to the number of drivers in the loudspeaker.

1-way construction
In a 1-way construction, a single driver reproduces and transmits the treble, mid-range and bass registers.

2-way construction
In a 2-way construction, a woofer reproduces both bass and mid-range sounds, while a tweeter handles the treble register. The signal is split between bass/mid-range and treble by a so-called crossover filter.

3-way construction
In a 3-way construction, which contains bass, mid-range and treble drivers, the signal is split twice – between treble and mid-range, and between mid-range and bass.

Do not assume that a 3-way speaker will always give you a better result than a 2-way. More signal splits mean less linearity. It is often easier to achieve better sound quality in a 2-way speaker.

CROSSOVER FILTER AND CROSSOVER FREQUENCY A crossover filter directs the signal to respective elements in the loudspeaker. In a 2-way system, the signal is split between the bass and treble elements. The frequency where the signal is split is called the crossover frequency (normally somewhere between 3,000 and 5,000 Hz). In a 3-way system, the signal is divided into bass, mid-range and treble registers. That's why it is easier to make a 2-way system sound better than it is a 3-way system. The crossover filter in an active subwoofer is usually variable. This makes it much easier to adjust the subwoofer and sidespeakers. An active subwoofer usually has both low-level filter (LO-PASS) and a high-level filter (HI-PASS).

DISTORTION Distortions in sound reproduction are most noticeable at high volumes. Turn up the volume to the highest level you intend to listen to your system at, and listen and compare distortions in sound quality and reproduction.

DOLBY 6.1 AND 7.1 Both Dolby and DTS have developed sound systems in which several speakers are used in the home theater system. The 6.1 format thus contains 7 separate channels, which means that the back speakers are joined by a third channel. With the 7.1 format, the entire set-up is shifted and a different sound is created with three front speakers, two speakers to the right and left of the listening area, and two back speakers.

DOLBY AC-3 The name of the multi-channel coding technology used for Dolby Digital film soundtracks, the new Dolby Surround AC-3 laser discs, the upcoming DVD discs and numerous TV, cable and satellite applications.

DOLBY DIGITAL 5.1 As the name indicates, Dolby Digital is a digital sound system. The soundtrack can only be stored in digital media, such as on DVDs. Dolby Digital exists in various formats, but the most common is the 5.1 format which consists of 6 separate channels. Since the channel for deep bass does not have a full frequency range, it is called a ".1" channel.

DOLBY NOISE REDUCTION Complementary (record-play) processing systems developed by Dolby laboratories to reduce the noise inherent in recording media with minimal effect on the recorded. Dolby NR includes the B-type, C-type and S-type systems for consumer formats such as the audiocassette.

DOLBY PRO LOGIC Dolby Pro Logic is a system used primarily for TV broadcasts and VHS because it is an analog system. The system is based on 4 channels that are encoded to a 2-channel stereo signal when recording. Upon playback the same process is repeated, although in reverse, so that 2 channels become 4.

DTS DTS is short for Digital Theater System and is a competitor to Dolby. The company was formed in 1993 and the first film in theaters with DTS sound was Jurassic Park. DTS as a sound format is not as widespread in the home theater market as Dolby Digital in terms of the number of DVD titles available, despite the fact that many people believe DTS provides much better sound.

DVD AUDIO (DVD-A) DVD-A uses a sampling rate up to 24-bit/192 KHz (96 KHz in a multi-channel system) and something called MLP lossless compression. This delivers a sound reproduction quality that is much better than normal CDs, and technically better than normal DVDs. A DVD player must be able to handle DVD-A format. Most DVD-A recordings have a PCM layer (CD format), where the sound is of a CD-quality that all DVD players can read. But even though a DVD-A recording has a PCM layer, a normal CD-player is unable to read or play it.

DYNAMIC RANGE (FREQUENCY RANGE) The dynamic range from the loudest to the softest sounds a sound format or system can properly reproduce. The human ear can hear frequencies from around 20 Hz up to around 20,000 Hz. Within this frequency range, the bass sound is between 20 and 200 Hz, the middle register between 200 and 4,000 Hz and the treble between 4,000 and 20,000 Hz. A good quality loudspeaker system, capable of reproducing the entire frequency range the human ear can hear, allows the listener to hear more details in musical pieces or movie sound.

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