For 7.1, the side speakers should be placed at plus and minus 90 degrees; i.e., directly to the sides of the primary listening area, not behind the listening area. The rear speakers ahould be placed at about 150 degrees; i.e., spread out on the back wall away from the centerline.
From my own experience, 7.1 provides a much more enveloping surround environment than 5.1.
Regarding 6.1 sources, there are one discrete and two matrix formats. Notwithstanding this, the material should be played back on a 7.1 speaker array rather than a 6.1 speaker set up. One reason is to avoid the potential for back to front reversal if a single rear spealker is placed on the centerline. Another is it spreads out the rear channel information as the rear is not intended to be a point source like the front center channel.
Since ther are no 7.1 sources available, at least at this time (high def DVDs may include 7.1 audio tracks?), you need to apply some type of processing to either 5.1 or 6.1 sources to best enjoy a 7.1 setup.
Some Prepros simply replicate the suround information in both the side and rear channels, but I don't consider this very desireable.
Lexicon has long provided 7.1 processing with Logic7, and now DPLIIx is a viable alternative. In either case, these processes wil take the original surround information and redistribute that surround information across discrete side and rear speakers, generating stereo rears. For more details on exactly what happens, I suggest going to www.avsforum.com and looking for posts by sanjay.
Hope this helps,
Bruce |
I saw in one post the mention of THX and it calling for mono-pole speakers, from what I understand only a dipole spaker is truely a THX surround compliant speaker, now you dont need these in the back, it would help but not needed, but for the sides dipole is THX standard, atleast im fairly sure of it...good thread though...p.s. I dont have the 8 ft behind my couch, I run 7.1 and found that with my Rotel processor the effects sound better when I set up the digital delay for 10 feet for the center backs...just personal preference. |
At this stage of my system i agree with slappy. At one time I had a 10 channel system with 3 sets of Polk SRT s two extra SRT sub enclosures and 4 top of the line Polk bipoles ; two in the very back spaced 4 feet apart and two above my head for height illusion . Each speaker had an Adcom 555 11 in mono for 600 watts . The Lexicon MC 12 ran it all. For theatre it was a visceral experience i will not forget. I now focus on a natural , effortless musical mulltichannel environment and have found 5.1 works best , for me at least . The meridian 861 was a real eye opener and i discovered a simpler more rewarding path. |
Yeah, i hear ya
When 5.1 came out, it was a good thing. now everying is trying to expand it and have the latest and greatest, when in all reality they just make it more confusing.
one of the many reasons i stick with 5.1 |
OK, I have started some good dialog here! I specifically have (currently) Left, Center, Right, Sub, Left Surround and Right Surround as defined by my Pre/Pro manual (Parasound C2). However, my Surround speakers are placed an the rear wall of my room as many articles and people suggest for a 5.1 system. BTW, Ultimate AV has a very good article on placement of equipment in this months issue. So, it looks like the "other" 2 channels I can add in a 7.1 system are "Rear channels". So, if I am deciphering all this correctly when I get my new dipole speakers I will hang them on the left wall and right wall of the seating position and assign them to the SURROUND channels and take the monopole speakers hanging in the rear of my room and assign them to the REAR channel. According to the C2 manual, back channel info is always derived from the SURROUND channel so it is a matrix and not a discrete channel. Apparently, some people take 1 speaker and assign it to the REAR channel and the L and R REAR channel signals are mixed to the 1 center rear speaker. Hmm, maybe I'll look at getting a 3rd dipole and doing that and take my current speakers on the rear wall (1NTs) and move them to my upstairs 2 channel system...
This is rather confusing. |
From what I understand there are only five discreet channels plus the LFE. All the extra channels in other surround schemes are matrixed.
This idea of 2+2+2 from Europe does sound very interesting. This actually seems more like a movie theater set up to me. Not that movie theaters sound that great, but...
In the mean time I'll stay with my meager 5.1 system which has been serving me well since 1998. |
I still think that the best 6-channel setup for audio is the 2+2+2 scheme from Europe. High and Low Fronts, and two in the rear. No LFE channel is needed. If you want a subwoofer (or two, or three) get an electronic crossover and drive the SW from the Front signals. Actually I think that the two Highs could be the same signal, or one signal matrixed with the appropriate Low, and that would leave one channel free for Center, which I find very important. Unfortuately, no one has made recordings this way.
I suppose it will all shake down to a universal standard in about 25 years. I won't need to buy all new equipment, as I expect to be playing the harp by then. |
Maybe its a case of semantics here but here is my understanding. In the post Dolby surround era the 5.1 means mains , center , and surrounds { commonly refered to as rears }. The .1 signal sends the lfe to a dedicated sub. Im not getting into THX specs .The most respected theory was postulated by the team at Widescreen headed by Gary Reber and challenged the THX camp and has in reality been adopted by about everyone now. All monopole { preferably all speakers identical or at least the same in timbral character } , equidistant from the sweetspot using equal amplification and speaker cable legnths. The info was discrete. The coming of 7.1 refered to side "surround " speakers placed directly to the sides of the listener . Again equidistant if possible , if not , the delay feature could compensate somewhat. This configuration was at the heart of the lexicon processors and they led the way with some exciting white papers backing their position that a side image was a necessity.They still make some of the top theatre processors on the market . This signal sent to the " sides " was not discrete but matrixed. Enter DD EX and DTS ES . Theory was that the back of the soundstage needed filling and processors as well as software were trickling in a discrete single back channel that was to be placed at the same tweeter level as the others , equidistant once again with equal amplification and ideally be again , of the exact same model as the others. Ideal world indeed . I can not comment on what specifically commercial movie theatres do . |
naaa,,. by 6th channel i mean surround-rear channel, for 6.1 surround.
the .1 is the LFE. and the 6th is a track for rear effects.
Ill agree, this stuff is all poorly explained. Im pretty sure DTS can do 6.1 surround with descrete signals to all 6 speakers plus sub. When using the 7.1 it splits the 6th channel (rear channel) between the two rear speakers and will matrix these with the surrounds on each side to give the feel of 7 channels.
Its all a real pain in the ass if you ask me.
I have 5.1, thats it. My Denon 3805 will do 7.1, but due to the fact that i only ran 2 speaker cables beneath my floor when i was installing the hardwood im sticking with 5.1 instead of 6.1 or 7.1
Ive used 7.1 in the past in the house i was renting before i bought my own, and i thought it worked pretty well, but not well enough for me to string a cable to the other side of the room for the rear channel. You really need to have some room for 6.1 or 7.1. The biggest issue is you need space behind you for the rear speaker, at least 8 feet. if you dont have the space then using 6.1 or 7.1 will feel kinda gimicky and the whole effect kind of collapses. With my house the couch is pretty much against the rear wall. No room for anything more than 5.1 and i really dont feel like im missing a thing.
5.1 works great, and im sticking with that. :) |
Slappy...If the 6th channel, LFE, is being used for rear ambience, how do they do the exploding cars? All this stuff is very poorly explained. |
Eldartford,
the rear surround can be discrete in DTS i believe.
The Rear-right/rear-left setup uses the discrete 6th channel and feeds it to each rear, at the same time depending on track it will matrix the surround left with the surround rear and the surround right with the surround read to give a more diffuse sound field and better ambience affects.
i think.... |
I think that there really are just 5 discrete channels, 6 counting the LFE. The rears are matrix-derived from the surrounds. Is this correct? |
In a 5.1 the sound will go to the designated "Surround" speakers while the rears will remain silent.
Not sure what you are refferring to as "Side" Speakers, even in 7.1 systems you have the left, center, right, surround right, surround left, rear right, and rear left. If you mean the "Sides" as the Surround then yeah they wil still play. It is the rear speakers that will not.
As far as i know you should set up a 7.1 system the same as you would a 5.1, the only difference is the inclusion of the 2 rear speakers. The "Surrounds" location would be the same in a 5.1 or 7.1 system.
the hard part of comparing it to a commercial theater is the size of a theater, andvery diverse seating possibilities. Normally the speakers on the side are the surround channels, while the side-rear would be the rear channels. Home Theater and Commerical Theater have as much in common as they they do differences. |
