**Updated, added rear center to the mix 2/02/2009, see post #39
*Minor change 1/10/2009
See Post #36
See post #3422.2 Surround Sound, experimenting in enhancing/expanding 5.1-7.1 formatsCurrent configuration;How it got there
This thread chronicles the progression of the tests to the current configuration.
Some people build model planes and some like to collect coins as a hobby I like to experiment with various aspects of home theatre including seeking surround sound nirvana.
In a previous thread found here
I talked about overhead sound I was getting using a CS3X Jr in my experimental HTPC home theatre system I have in a back bedroom. In that thread CAVX clued me on using two CS3X Jr's to get 4 extra channels, left & right overhead and left & right front side axis channels. I tried it and I like it, here is basically what I did;
I ran the left front & left side surround outs to the left front & right front inputs on one CS3X Jr then used its the SP1 output as left side axis and SP2 output as left overhead. Then did the same with right front & right side surround on the other CS3X for the right side axis and right overhead channels.
This creates a surround sound system very similar to Tom Holman's 10.2 surround sound the only real difference was I was using 2 rear surrounds and a single sub.
Here is a good description of Tom'sIntroducing the 10.2 Surround Format
The addition of the front side axis channels had a big affect on the sound, it was bigger wider sound and the sound transition from fronts to side surrounds was smooth, it was with out a doubt the biggest impact on the sound of any of the additional channels.
I was so impressed with this I decided to take it a couple steps further and added two more CS3X Jr's to the mix. Using the same technique mentioned above instead using the side and rear surrounds to create rear left & right side axis channels and rear right & left overheads.
In my experimental system I have a HTPC and it has a sound test that sends a helicopter sound to each speaker circling around the all the speakers clockwise and the side axis channels grab it perfectly in between the speakers they are placed between. I have also tested it with the THX Optimizer and between it and the helicopter test they appear to work flawlessly.
Now these new rear channels do not have the same impact as the front side axis channels but they do add to the overall effect. You get smoother front to rear and rear to front sound transitions like drive bys, flyovers, bullet whizzes, explosions etc and fuller more enveloping ambient movie sounds like when background music hits all channels.
It also works great for NFL football games particularly ones being broadcast in DD 5.1 it is like having virtual seat in the stadium with the crowd roars all around.
I did say I took a couple steps; the other thing I did after reading the debates on this big subwoofer thread
and coming to the conclusion that to get all the bass possible you really need at least one sub dedicated to LFE and a bass management sub that would get any bass being sent to speakers. So I borrowed one of my M&K 350's from my main theatre and my M&K BMC bass management unit I use for SACD and DVD-A playback in my main theatre.
I set all speakers to large in my experimental system set the 350 as the LFE, and placed it at the front far left of the system. The BMC is only 5.1 so to try get all the bass from all the speakers I ran the sub outs on the four CS3X Jr's to the BMC for the front left & right and surround left & right and used the Center out from the receiver to the Center in on the BMC this way I get most all the bass from all the speakers including the additional channels. I then ran the sub out on the BMC to a small sub and placed it a bout mid way on the right and it works great, I get lows that would not otherwise be produced just using a LFE alone.
CAVX asked for some pictures in that other thread but I never got around to taking or posting any. However this time I did take some mostly to prove I really have this setup.
Now this is a system I use to experiment with, it is a relatively inexpensive system made up of old amps I had lying around, Klipsch THX Promedia speakers ( about as cheap a speaker you can get that still sounds good) and a hodgepodge of speaker stands all in a tight space so it is not pretty. It also does not produce near the quality of sound a high end system in a designated theatre room with adequate spaced out speaker placements, and treatments could but does allow for a good feel of the possibilities.Note on the overheads;
to avoid being beaten about the head by Sanjay or sivadselim it should be stated that it has been established and reiterated time and again there is no designated overhead material in current surround sound formats. What is getting sent up there according to CAVX
is a "difference" signal contained in both channels where one channel is out of phase.
I have found what sounds do get up there works provided you calibrate them so that you can't not sit down watch a movie and discern that they are on but can tell when they turned off. If done correctly only the loudest sounds being sent to the overheads should high enough to be audible to your ears yet blend in with the other speakers producing the same sound, like explosions, rocks falling down, plane crashing, echo effects, ambient music etc This should diminish the possibility of distracting out of place sounds and immersion interruption and create deeper immersion, does for me anyway.
In the future I want to use this setup in my main home theatre, when I do I think the best way would be to use the same speakers I am using for the fronts, for the front side axis the rest matching surrounds. Three subs, two for LFE and one for BM sub, I also think using di or tri poles for the overheads for better sound diffusion from above would be better than direct radiating and reduce the chance of any distracting sounds from above being detected. Also I think I may add yet two more CS3X Jr's for left and right center overheads for six overhead channels using the front and rear side axis channels to derive them.