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How does DTS work?
DTS stands for “Digital Theater System.” DTS Digital Surround is a 5.1-channel surround sound format, similar to Dolby Digital. As such, it is a competing format to Dolby Digital. The “5.1” designation means that the format features up to five discrete (independent) channels (front-center, front-left, front-right, surround-left, surround-right) of full frequency sound (with respect to the range of human hearing, which ideally ranges from 20 Hz to 20,000 Hz), plus a sixth channel for low-frequency effects (LFE). The LFE signal is usually reserved for the subwoofer speaker(s), or those speakers capable of reproducing low frequency ranges. The low-frequency effects channel gives DTS the “.1” designation. The “.1” signifies that the sixth channel is not full frequency, as it contains only deep bass frequencies (3 Hz to 120 Hz).
Keep in mind that “DTS” does not always equate to “DTS 5.1.” “DTS” generically refers to the encoding scheme. Though the vast majority of DTS digital surround soundtracks consist of 5.1 channels, some may be composed of less than 5.1 discrete channels. For example, DTS 4.0 soundtracks have discrete audio signals for the center, left, and right channels, plus a mono audio signal that is common for the surround channels. DTS 4.1 is like DTS 4.0, but adds the “.1” low-frequency effects channel. DTS 5.0 is like DTS 5.1, but lacks a discrete audio signal for the low-frequency effects channel. Only when the packaging explicitly says “DTS 5.1” can you be sure that the soundtrack consists of 5.1 discrete channels. Fortunately, the vast majority of DTS-encoded DVDs are in fact DTS 5.1.
DTS uses data-encoding rates that are two to four times faster than Dolby Digital — 1.5 Mbit/sec or 754 kbit/sec, compared to Dolby’s 448 kbit/sec or 384 kbit/sec. These numbers, theoretically, indicate a higher quality of sound, and have prompted many home-theater enthusiasts and industry experts to claim that DTS is superior to Dolby Digital.
However, DTS surround-sound encoded DVDs are far fewer in number than their Dolby Digital counterparts, and until recently were released months after their Dolby Digital counterparts. This was because DTS soundtracks, when encoded at the full data rate of 1.5Mbit/sec, took up so much space on the DVD that little room was left for other audio formats or special features. Thanks to the new lower DTS data rate (754 kbit/sec), some studios (e.g., Buena Vista, DreamWorks, Fox, New Line and to a lesser extent Columbia TriStar and Artisan) have begun to release DVD titles that feature both Dolby Digital 5.1 and DTS 5.1 (at the lower data-rate).
To take advantage of DTS digital surround, you must have one of two configurations:
Configuration A: “Preferred Configuration”
* This configuration requires a receiver or preamplifier with built-in DTS decoding. When shopping, look for the “DTS” logo on the faceplate.
* You will also need a DVD player with DTS digital output. Again, look for the “DTS” or “DTS digital out” logo on the faceplate. Alternatively, you can use a DVD player with DTS decoding built-in with its digital output (in which case you’re not really using the decoder in the DVD player).
* You’ll also need an optical or coaxial digital audio cable to connect the DVD player to the receiver or preamplifier
Configuration B: “DVD player with built-in DTS decoder”
* This configuration requires a DVD player with built-in DTS decoding. Look for the “DTS digital surround” logo on the faceplate and a set of 5.1-channel analog outputs on the back panel.
* You’ll also need a “5.1-channel ready” receiver or preamplifier (with no DTS decoding) that has a set of 5.1-channel analog inputs.
* You’ll use six analog audio cables (i.e., three stereo RCA pairs) between the DVD player and the receiver or preamplifier
Dolby Digital is a competing format that also supports up to “5.1” discrete channels.
Glossary of Terms
- Anamorphic
- Process that condenses the image in the source material to be expanded by the display device. With DVD, the anamorphic recording preserves a vertical detail that would otherwise be lost on a widescreen film that is cropped, or letterboxed, to fit the 4:3 reading image space.
- Ohm
- A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.
- Preamplifier
- A control and switching component that may include equalization functions. The preamp comes in the signal chain before the amplifiers.
- Spider
- The part of the loudspeaker that holds the diaphragm in place, and allows it to move when activated. Also called suspension.
- Woofer
- A speaker driver designed to reproduce low frequencies.
