I return the favour of a lot of info I have recieved from many of you. This is what I researched - hope it helps
THX ULTRA Speaker Systems:
Feature: Front Speakers feature focused vertical directivity.
Benefit: Listeners enjoy a sound of unparalleled clarity, with minimal intrusion from the effects of the listening room.
Feature: All THX Ultra Front Speakers in a system must have a virtually identical sonic signature.
Benefit: Listeners hear the exact position of front images and pans.
Feature: Fronts, Surrounds, and Subwoofers are required to reproduce substantial continuous sound levels.
Benefit: THX Ultra Home Theatre owners enjoy a large dynamic performance margin, and can play at or above reference levels with any program material (producing 105 dB and beyond) with no distortion

THX SELECT Speaker Systems
Feature: THX Select Front Speakers have a simplified and refined directivity pattern.
Benefit: THX Select Speakers may be smaller and easier to place, yet have superb tonal balance and clarity, and encompass a much wider range of speaker design philosophies and sound types.
Feature: All THX Select Front Speakers in a system must have a virtually identical sonic signature.
Benefit: Listeners hear the exact position of front images and pans.
Feature: THX Select Front Speakers can have bass extension beyond that of THX Ultra Speakers
Feature: The dynamic capability of the product is better suited to small listening rooms and multichannel digital audio.
Benefit: The THX Select specification permits greater flexibility in design and choice of speaker components, so the Fronts, Surrounds, and Subwoofer can be smaller and less expensive, yet have the same peak sound level as existing THX products (105 dB).

ULTRA2:THX Ultra2 uses seven channels of amplification to play back any multi-channel-encoded program through a single fixed seven-speaker/one subwoofer layout. In the new THX Ultra 2 Cinema mode or THX MusicMode, all program material with 5.1 channels or more is auto-detected and proprietary processing is applied that blends the directional and ambient surround information prior to replay through four surround speakers — two at the side and two at the back. Ultra2 receivers and controllers also feature switchable Boundary Gain Compensation (BGC) to alleviate "boomy" bass performance that can occur with near-wall listening positions.
THX Ultra2 LCR and rear surround speakers have been revised to minimize any changes in perceived timbral balance over the widest possible listening area, and Ultra2 subwoofers now have bass extension down to 20Hz, to better reproduce the very low frequency information increasingly found in modern digital multi-channel recordings.
Ultra2 SUBS: To pass the Ultra2 specification it had to extend to 20 Hz at its -6dB point. The response also had to tightly follow a target of a Linkwitz Reilly sixth-order shape to within 1dB.
Dougofthenorth








This message was edited by Dougofthenorth on 12/20/01 08:36.55.