Originally Posted by jontyrees
I'm still in the dark on what the Home THX options are doing. I need to dig out the manual, but they seem to layer on top of the selection of audio format.
this is what THX surround processing is all about
it includes their technologies - ASA for back speakers, Boundary Gain Compensation for THX Ultra 2 certified subwoofers, Re-EQ, Timbre Matching, Adaptive Correlation.
you can read descriptions on their website.
some like the effect of adding THX, some don't. I'm in the "don't" category
nearly all receiver mfgs have dropped THX processing & certification, except Pioneer & Onkyo. many find it irrelevant nowadays with hi-rez audio formats. I'm also in this camp
THX had a lot of relevance enhancing std Dolby Digital on DVDs but not so much for Blu-rays, although there are still some who prefer to add it on top of DTS-MA and Dolby TrueHD.
but some do like it's effect. it's biggest impacts are a gentle rolling off of high frequencies for the home cinema market to "better" match a large cinema venue, and the effect on the surrounds, which is to blend the sides and rears in a way to make them more diffuse, and supposedly seamless. however, the blending can actually reduce the discrete localization of surrounds. keep in mind that THX certified speakers and many surround speakers from speaker mfgs are dipolar and designed to spray the surrounds so it is intentionally diffuse. some don't like that effect and prefer a more discrete surround effect & just use Dolby ProLogic IIx or DTS Neo.
THX Surround EX was developed in conjunction with Dolby for their Dolby EX...same thing but with THX post processing. EX is only monophonic surround even if you have 2 rear speakers, compared to PLIIx, which derives stereo rear surround channels from the 2 side channels. you are have true 7.1 discs, then you will have 2 stereo rears by the track itself. but if you are playing 5.1 tracks, adding Surround EX (THX or Dolby) sums the rears into the same sound, while IIx preserves some side to side separation between the 2 rears. EX mode was mostly for playing Dolby EX encoded tracks on DVD's, pre-Blu-ray era, while DTS-ES Matrix was DTS's version for DVD's, pre-Blu-ray.
Hope this helps.
After you read about THX processing, try them out, see if you prefer THX or just PLIIx or Neo X.