[From Usenet: 1.18.94 0513]

This entry was published at least two years ago (originally posted on January 18, 1994). Since that time the information may have become outdated or my beliefs may have changed (in general, assume a more open and liberal current viewpoint). A fuller disclaimer is available.

[Note: This was originally a post to the rec.arts.movies Usenet newsgroup. I’m including it here for completeness. Originally archived here.]

In article <1994Jan18.042438.17...@midway.uchicago.edu>, s...@ellis.uchicago.edu (Charles P. Samenow) writes:

What are the differences between: DTS, Digital Dolby, Dolby, Dolby SR and THX?

Well, I’m no expert, but here’s what I’ve gathered…

  • Dolby – uses the same techniques as your Dolby cassettes…noise reduction, basically.
  • DolbySR – the noise reduction, plus better placement of where the noises appear to be coming from in the theatre. Stands for Dolby Spectral Recording.
  • Digital Dolby – in addition to the normal sound track, a digital track is printed between the sockets of the film. When a theatre is equipped to read and reproduce this track, it results in near cd quality sound (no background hiss and pops), and also uses six tracks to place the sounds…one center, two front (left and right), two rear (left and right), and one subwoofer channel. End result-some of the best quality sound I’ve ever heard in a movie theater. When it’s used effectively, it can be really mind-blowing.
  • DTS – a similar technique to Digital Dolby, only developed by Sony (if I remember correctly) and Lucasfilm…which can cause some licensing conflicts in theatres already set up with Digital Dolby. Competing systems and all. Major difference…instead of using the space between the sprocket holes, the digital track is printed in a small strip on the edge of the film, which means the actual print can’t be quite as wide. I recently saw Schindler’s list in DTS, though, and didn’t see any noticeable difference in the width of the image.
  • THX – developed by Lucasfilm. Not so much an improvement in the sound itself, THX uses special placing of speakers and translation of the audio tracks to make sure no matter where in the theatre you sit, you get the true stereo effect…something which can suffer greatly towards the edges of a theatre in a non-THX environment.

Where’d I get all the info? Lots of reading, and working in the only theatre in Alaska to have Dolby Digital installed. Anchorage’s Fireweed theatre was (this may have changed by now) at the time the biggest Dolby Digital installation on the West Coast…the auditorium sits over 900. Digital installations has been done before, just not in an auditorium that large. Was a more than $10,000 upgrade to the existing system. Plus, though I don’t work there anymore, the licensing agreements have been settled to the point that it now has DTS also.

Incidentally, except for the DTS (because it’s from a different company), all of the systems are compatable. Using digital negates the need for normal Dolby (noise reduction for digital sound?), however it’s perfectly possible (and has been done) to have a movie recorded in both Dolby Digital and THX, and I suppose in both DTS and THX. Sounds incredible, too…