Digital Audio Formats
“By The Numbers”
There are a lot of letters and numbers associated with modern digital surround sound for home theater systems. The associated designations and their abbreviations for different digital audio formats can be confusing to newcomers to home theater and also to the casual HT fan. In this section we will de-mystify all of the associated abbreviations for the many different digital surround sound formats. First we will examine the different brands/types of digital audio and then further down the page you will find an explanation of the number designations associated with different speaker set-ups and their placements.
DPL, DD, DTS, THX, etc. — The “Alphabet Soup” Clarified
Digital sound has come a LONG way since the early history of sound days of mono, stereo and then Quadrophonic sound. Modern digital audio formats accurately reproduce audio virtually identically to the original source. Dolby Laboratories were the pioneers of the digital revolution. Sprouting from the widely popular Dolby ProLogic (or Dolby Surround) format – Dolby Digital is the most common format currently available and is used on virtually every DVD produced since the inception of the DVD format. Dolby TrueHD is their format for Blu-ray and is the Dolby “lossless” format. Note that in order to discern the difference and advantages of any format you must have quality equipment. Most “WalMart type” of equipment won’t show much difference between formats.
DTS is a relative newcomer to the digital audio scene and is a competitor to Dolby while developed in part from Dolby technology. DTS HD is their latest format that is on many Blu-ray discs. DTS is a fine format in its own right – no edge given to either Dolby nor DTS with average equipment. Yet there are some who swear by DTS due to its claim of lower compression ratios and signal-to-noise ratio. However you must have a receiver capable of decoding the format utilized by your source. You may want to be sure your prospective receiver can decode all current digital audio formats.
THX is not a format – contrary to popular belief. THX is merely a “stamp of approval” from Lucas Films that the equipment or component is up to their strict standards for accurate sound reproduction.
5.1, 6.1, 7.1 — “By the Numbers”
The numbers you see associated with different formats or mainly receivers correspond to available decoded and amplified audio channels/speaker channels and their placement. Originally there was monophonic, or mono sound which essentially had one speaker or sound source. Then along came stereophonic sound which had two speakers or sound sources. Stereo more accurately reflected the way humans hear sound and it was great in its day. Then along came Quadrophonic sound – which sported four sound sources. It was not quite as popular as stereo and was not widely adapted by home consumers – saving the esoteric audiophiles who had to have the latest and greatest of everything.
Dolby ProLogic made the leap into surround sound with five channels of synthesized sound information – center, left, right, rear surround fill and subwoofer channels. Modern digital surround sound now incorporates encoded information which has up to eight independent audio information channels. Capable of having information for center, right, left, right-side, left-side, right-rear, left-rear, and subwoofer information (the subwoofer LFE/Low Frequency Effects channel accounts for the “.1” designation). BTW – if you see a “.2” receiver — that simply means it has two subwoofer output jacks … some folks prefer having that option for larger rooms.
The not quite so popular 6.1 format has C, R, L, right-rear, left-rear, rear center fill and sub. A lot of new Blu-ray discs and some newer, standard DVDs feature the 7.1 format. 7.1 offers C, R, L, RS, LS, RR, LR and subwoofer channel information.
In summary you will want a DVD player and receiver capable of decoding both Dolby and DTS digital audio formats. If you have the extra money and want to brag about it – go for the THX certification but that is not really absolutely necessary in my humble opinion.