What is the difference between THX Cinema and THX Ultra2 Cinema? Is the THX Cinema mode taking a 2 channel (stereo) source and making it 7.1 and is the THX Ultra2 Cinema mode taking a 5.1 source and making it 7.1? Or is the Ultra2 just a higher quality version or is there no difference?

I don't know the difference between the two, but I think neither produce a true 7.1. It's really 6.1 since the rear is mono. Having said that, I vaguely remember that there is something like "decorrelation" between the left and right rears, but apparently it's still considered a mono rear.

Ed

"Performance" categories

THX -viewing from 6 to 8 feet
THX Select, Select 2 and Select Plus - viewing from 10 to 12 feet.
THX Ultra, etc. - viewing distance > 12 feet.

Listening mode

THX Select 2/THX Ultra 2 Cinema- processes 5.1 material “To recreate the ambiance of the movie theater". If there are rear speakers THX suggests side by side placement, but newer receivers have a setting if the spacing is greater than four feet.

Personally I use Dolby PLIIx Movie most of the time for DVDs and stereo for CDs, but the THX implementation on my new receiver seems better and at some point I have to take the time to do some serious comparisons. THX Neural Surround anyone?

Thanks for the info. Does anyone else have any other facts or opinions about THX sound modes and what is the best to use?

THX Ultra 2 whenever possible.

Ok thanks. Is Ultra 2 available all the time or is that only if you have a 5.1 source and want to make it 6.1/7.1?

Available virtually all of the time even on high definition audio sources.

The THX Ultra2 Mode is for a Ultra2 setup and the rear speakers are next to eachother. Your THX mode was tested and met THX criteria. A THX Select is for a smaller room or where the loudness requirement of the system is going to be less. It is forwards and backwards compatable. The trouble is that we do not whether a THX RE-EQ will be suitable for a movie because they do not always state on the movie does not already have RE-EQ. If you use it then you have to try and it see how it sounds. It is to reproduce the soundtrack as the director intended. If you had a THX Media Director this would take the info stored on the movie and set all possible settings automatically, but you can overide those.