THX "Cimarron" (lost original mix; 1988)
Cimarron is the third promotional/introductory trailer for the Lucasfilm THX Sound System. It debuted in select THX-certified theaters in May 1988 to coincide with the release of the film Willow. "Cimarron" was the first THX trailer to implement computer-generated imagery, courtesy of Industrial Light & Magic, and was made to provide an alternate trailer for cinemas. The trailer has been prepared for 35mm Dolby SR, 70mm Dolby A, and 35mm Dolby Digital. It was included on the THX Ultimate Demo Disc DVD in 2003, but multiple variants exist.
The lost early version sent to theaters was recalled due to complaints of the soundtrack blowing speaker drivers from theater owners. This version begins with an orchestra tuning against a small black-to-grey gradient square centered on a black backdrop. In this box, a conductor's hand holding a baton raises into the frame, silencing the tuning. He flicks his baton, prompting a cyan-to-red wormhole to engulf outside of the box and fill the entire frame, as we go through it. Musically, it is accompanied by a harmony of descending synth tones, sparkling chimes, and an atonal horn section. At the end of the wormhole, there is a reflective THX logo zooming towards us and shifts its angle as it comes closer to pass through us, against a backdrop of red lights at first organized in the frame, and each light moves away one by one until there is few red and more black. During this, we hear a quieter set of descending synths with more mellow musical accompaniment, and an E-flat(?) note is held as the logo is on screen, which crescendos to a higher note as it leaves the screen. The text appears: "The Audience is Listening", "Lucasfilm Ltd. Sound System", with a 1987 copyright and a Dolby logo. Although Lucasfilm sent prints of the revised trailer (as described below) shortly after the first run, some theaters continued to play the recalled version up until the mid-1990s, due to the preference of the projectionist and/or theater manager. The recalled version is known to survive only in the hands of home projectionists. 
The standard version that survives has identical visuals but a different, more neutral, literal score by James Horner. The orchestral tuning still remains, the wormhole has a whimsical Horner-esque ditty, with high-pitched "revving" sound effects, and the logo itself is an orchestral interpretation of the iconic "Deep Note" which symbolizes the brand. A version without the tuning section and "revving" sounds appears on the THX Wow! LaserDisc, the Wow! reel on the THX Ultimate Demo Disc (with the "revving"), and a derivative appears on select THX-certified LaserDiscs with added thunder and wind sounds.
On the Film-Tech Forums, there was a discussion which initially was about the Dolby Digital "Train" trailer, namely its earlier incarnations, including the original sound mix which similarly became lost.  It shortly developed into talking about an original mix of the THX "Cimarron" trailer. Forum member Lionel Fouillen announced he had a microcassette which contained an in-theater live recording of the trailer. He eventually uploaded his recording, and it was archived by forum administrator Brad Miller on Film-Tech.  Forum member Connor Wilson synchronized the audio with the "Cimarron" visuals and uploaded it to his YouTube. A VHS recording of the TV documentary special, Star Wars: The Magic & the Mystery (1997), was found on YouTube by Connor. It became of interest as the documentary included a clip of the early "Cimarron" trailer, up until the logo section which was cut short and overlayed with a Gary Summers interview. This became the source of a partially enhanced revision of Connor's reconstruction. 
After the revision was released, the project stopped until April 2014, when YouTube user Prevue Communications, Inc. released a new revision of Connor's reconstruction.  It wasn't until the following month that Connor noticed and decided to use various sources for revision 2.1, followed by another update in June. 
- THX page on the CLG Wiki, with details on "Cimarron". Retrieved 4 May '15
- Film-Tech Forum: Dolby "Train" Trailer. Retrieved 15 Aug '11
- THX "Cimarron" microcassette recording, Film-Tech.com. Retrieved 21 Aug '11
- YouTube - THX - Cimarron (1988 - 1992?) ORIGINAL MIX (v1.1). Retrieved 17 Sep '11
- YouTube - THX - Cimarron (1988 - 1992 RESTORED/REMASTERED ORIGINAL MIX (v2.0) Retrieved 12 Apr '14
- YouTube - THX - Cimarron (Original Mix, 1988-1992?) Restored v2.1. Retrieved 26 May '14
- YouTube - THX - Cimarron (Original Mix, 1988-1992?) Restored v2.1.5. Retrieved 22 Jun '14