What we are really looking at here are two separate things:

1) The THX logo on the sleeve of a DVD
2) THX certified equipment

The confusing thing is they are actually two are completely different issues!

In effect when you see the THX logo on a DVD, it’s only indicating that the disc has been through a set of THX quality control steps. This should guarantee (supposedly) that the quality of the picture/audio reaches a certain set standard. If you really want to know each element that is measured check out [Link: thx.com]

Actual equipment that is certified as THX is a more complicated issue. If we look at just amplifiers for instance... They must also reach a certain standard in their specifications, but in addition they also offer THX post processing which, yes, is really only another 'mode'. However this is REALLY over simplifies what the processing does.

I really don't want to get technical and besides, all the info can be found on THX website [Link: thx.com]

Here's a quick summary of the main elements the processing encompasses...

Re-equalization
Timbre Matching
Adaptive Decorrelation
Bass Management

The main one most people notice is the re-equalization, which progressively rolls off the treble upto about 5db at it's extreme. If you do any A - B comparisons, this of course seems to remove detail (especially if you swap between modes mid film), but really only places the treble further down in the 'mix'. I've always found you can actually play a soundtrack much louder with THX engaged because of this!

As a test, just try listening to a whole track with THX and then without. I usually find on a lot of movies, when THX is engaged the overall sound, especially panning effects seems to 'gel' much more believably/smoothly. Any thoughts on this?

Overall, it really comes down to a matter of personal choice (as ever!). If you like it, great, if you don’t just switch if off ;-)

This message was edited by Phil Clelland on 10/07/01 08:54.54.