Originally Posted by audioguy
Trial and error as well. I used either The 5.1 Audio Toolkit that Mark provides or Avia. One of the options on those disks will play a signal out of a front and same-side rear speaker simultaneously. While sitting in the LP adjust the rear distance until the image from that signal appears to come from the center of that wall. You will need to switch between the setup screen on your prepro to adjust the distance and the playing of the DVD. Adjust by the .2 foot increments until the image is where you want it and repeat for the other side of the room. Works like a champ and will really improve the whole envelopment phenomenon. It is certainly possible that the distance Audyssey comes up with will be correct but it has not been for my room and my speakers. IIRC I changed the distance by .4 feet for both speakers. fWIW I used to try to accomplish the wall centering trick by increasing the volume of the rear speakers but this is a lot better way.
I'd like to say I came up with that idea but I stole it from Mark Seaton. (who else).
I finally busted out my 5.1 Audio Toolkit
and tried this. Quite a revealing process.
First, I checked the L/R distances. Audyssey/Integra had set the left speaker slightly further, (0.2 ft.), than the right. When I played the pink noise from the L/R speakers, the phantom image produced was slightly pulled to the left. I reduced the left speaker distance by 0.2 ft, and made it identical to the right speaker distance. The phantom image immediately popped right into place in the middle of the front soundstage. I knew right then that I was on to something.
I then checked the L/C phantom image... perfect, right between the L and C speakers. The R/C was the same... dead on, so I knew the CC distance was correct. I then checked the R/RS. This phantom image was much closer to the R speaker, and no where near in the middle of the two. At this point, I decided to check the levels of the speakers before I proceeded any further.
The 5.1 Audio Toolkit
has precisely recorded 75 dB test tones. I played them and found that the front 3 speakers were all set 2 to 3 dB lower than the surrounds. So, before I went any further, I reset the front speaker levels to equal the surrounds at 75 dB all the way around. (I then went back and verified that this didn't change anything from the previous distance setting checks on the front speakers... it hadn't.)
Going back to the R/RS, I again checked the phantom image with the pink noise. It was even worse now with the higher R speaker level setting. I increased the distance of the RS by 0.6 ft. This moved the phantom image to the exact middle between the R and RS speakers.
I then did the same for the L/LS and RS/RRS and LS/LRS. The only one I didn't need to adjust was the RRS. All the others needed 0.2 to 0.4 ft. adjustments to center their phantom images.
Not being sure I could trust my ears on these phantom images, I decided to listen to something to verify that these changes were beneficial. I put in King Kong, starting with the "Finding the Footprint" chapter. At the beginning of this scene, the rescue party is walking through the forest and there are all kind of bugs flying around in the surrounds. These new settings added a new dimension to the depth and immersion, (and creepiness), of the surround field. A few moments later, rocks start falling into the canyon from overhead. The rocks clearly sounded like they were falling from overhead. Then the brontosaurs star stampeding through the canyon. As they hit the canyon walls and run into each other, the sound moves throughout the speakers. Yet it stays as one massive, immersive soundfield. Previously, there was always a bit of a disconnect between the front soundstage and the surrounds... almost like there was a hole between them. With the new settings the integration of the surround field with the front stage was seamless, increasing the size of the whole presentation. This was the best presentation of this scene I've ever heard on my system.
I should mention that I always use Neural THX Cinema mode for watching movies. This extracts rear surround channels for the R and L Rear Surround speakers. I really like Neural THX Cinema mode for movies. I also often use Neural THX Music mode for music.
Anyone who has a Submersive should also have the 5.1 Audio Toolkit
and can do the same thing I just did. I'm impressed enough with the results that I can highly recommend checking this out.
I simply suggest you write down your original settings so you can go back to them if you don't find this to be an improvement.
Mark, do you have any other little tricks or tweaks up your sleeve? audioguy, thanks for pointing out this technique.