New theater(dedicated) in the works. I have structured wiring in the home and my CEDIA installer wired the HT for 10:1 just in case!
Currently planning on 5:1 surround with M&K 150's and tripole surrounds. Got (2) LFM-1's also. QUESTION: since CLEAR dialogue is the most imp. aspect of my HT, should I consider the sixth channel speaker(ie. rear center surround)? Would I gain that much ?
Thanks in advance.

That center rear channel is an effects channel and won't really have anything to do with dialogue, unless the effect is to have someone behind you. Still, it wouldn't be there for very long.

It does add to the surround experience plus more and more movies are being offered in that format. If you can afford it, I'd do it. If you can't, you'll get along fine without it.

the 6th channel will add very little over two good 4th and 5th channel speakers. why wouldnt you go for 7.1 instead of 6.1 in the first place though? not that 7.1 is much better than 6.1, but what are you going to do with/get 1 speaker? if you upgrade in the future you dont want one oddball. 7.1 is for larger rooms, because it gives a broader sound stage, 6.1 does this to an extent but is more for the very rear sounds. tripole/dipoles achieve that sound very well anyway, so the point is moot. if you were going with standard bookshelfs for the rears, then you would see more of a difference, but with tripoles, its a waste of money.

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This post has been brought to you by curegeorg, thanks for reading.

A rather small HT @ 13'x17'.
All matching speakers within (M&K). thanks for the response(s).I'm thinking 7.1 will be overkill for a smallish room.(?)
Been building this friggin house for nigh on 13 months now- with my 950/770 and (2) LFM-1(s) STILL in the boxes!

i doubt 6.1 will offer much improvement, but "the more the merrier" i guess, and at least you wont have to second guess yourself. i say that because you seem to be for 6.1, just looking for some reason not to do it.

its only money, who cares?

good luck.

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This post has been brought to you by curegeorg, thanks for reading.

A single rear speaker behind your head is a bad idea because it can cause back-to-front reversals. It's a well researched and documented psychoacoustic phenomenon where sounds along the centre line can sometimes appear to reverse direction momentarily. Sounds along the centre line are heard equally in both ears, and it can sometimes take our ear/brain mechanism a moment to figure out whether the sound is in front of us or behind. This is not a problem with a single centre speaker directly in front of us, where our hearing is at its absolute best and we have visual cues. However, it can be a problem with a single speaker directly behind, where our hearing is not so hot.

The solution is as simple as it gets: simply use two rear speakers, placed well away (at least 30 degrees) from the centre line. This is one of the primary reasons why Dolby and DTS and THX all recommend using two rear speakers, even for the mono surround-back channel of EX/ES soundtracks. Note that this is the only channel where it is recommended that two speakers be used for playback.

If you check the Dolby, DTS and THX websites you'll notice that none of those companies refer to the third surround channel as the centre surround or centre rear or 'centre' anything; instead calling it the surround-back channel. More than just semantics, the contents of this channel are supposed to image from behind you in general, not specifically from the centre of the back wall. Another good reason to use two rear speaker (7.1 instead of 6.1).

Like you, I too feel that dialog intelligibility is most important when watching a movie. The last thing you want is for surround-back information to image directly in front of you, right where the dialog is. Going beyond a 5.1-speaker set-up has three immediately noticeable benefits. Better envelopment; four surround speakers wrap around you better that two can. More distinct localization; you'll clearly hear surround effects to your right, to your left and behind you. And greater stability in the surround field; no matter where you're sitting on the couch, sounds intended to come from behind you always appear to come from there - not some side-ish, rear-ish direction. No magic involved, simply a pair of speakers physically located behind you (makes it hard for those sounds to come from any other direction).

All of the above is difficult, if not impossible, to do with only two surround speakers, where you're relying much more on phantom imaging (inherently unstable, moving when you move). The best surround speakers can't be in two places at once. Size doesn't matter. Wait, let me rephrase that: room size is not as important as where the listening area is. For example: you may have a very large room but, if the couch is against the back wall, you won't be able to properly set up a 7.1 system because there will be no room behind you for the rear speakers. If your seating area is away from the back wall, then you have the makings for a good 7.1 layout.

Sounds along the side walls should come from your sides, sounds from the back wall you should image behind you. This directionality should remain consistent, whether you're watching a movie in a large auditorium or a cozy living room. Your 17 foot long home theatre is plenty big to accomodate a 7.1-speaker set-up and enjoy its benefits.

Good Luck,
Sanjay

Excellent summary, Sanjay. I originally set up a 6.1 speaker system in an 11'x19' space with matching dipoles on all three surrounds, but I've currently got a 7.1 speaker system with dipoles on the surround backs and bookshelf speakers on the side surrounds - which I definitely prefer. In both cases, the listening position was well off the back wall, as Sanjay points out is important to making it really work. The rear surrounds do make a difference. If your layout is conducive to rear surrounds, it would be worthwhile - and with the amp channels and speaker wiring already in place (which I'm assuming is the case since you mentioned that the installer wired it up for 10.1), the bulk of the work is already done.

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gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

sanjay did a good job of explicitly saying why 6.1 sucks and 7.1 is preferred, and i agree with what he said. hopefully the different approaches shed some more light, err i mean sound on the subject.

like i stated, 7.1 is typically better with the 6th and 7th channels being direct radiating bookshelfs (or towers if you are up to it) and the sides (5th and 4th channels) being multipolar.

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[This message has been edited by curegeorg (edited September 22, 2004).]

You do?!? But a few posts ago you said "not that 7.1 is much better than 6.1". In fact, the main reason I posted in this thread is to counter your comment above as well as your claim that "7.1 is for larger rooms". I wanted to make sure MurphyMan knew that 7.1 IS much better than 6.1 (and why) and that even small rooms can benefit from 7.1 set-ups.

Anyway, I'm glad you agree with my comments. Just a little surprised I guess.

Best,
Sanjay

You better read Gonk's post again. He said just the opposite. He prefers dipoles on the rear and direct radiators on the sides. Then again, maybe Gonk just mis-stated his setup.


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Tekdredger

[This message has been edited by tekdredger (edited September 21, 2004).]

[This message has been edited by tekdredger (edited September 21, 2004).]

Sanjay, great explanation of the reversal effect. It's something I hadn't really considered but once you described it I know exactly what you are talking about.

Anyway, I'm one of those poor souls who has to have the listening seats up against the back wall so I have eschewed rear surrounds for now. What I'm wondering is have any of you outlaws tried putting the rear surround speakers on/in the ceiling and maybe aiming them at the back wall (or not)? It might be difficult to set up something to experiment with but my intuition tells me it might be somewhat effective. Granted it would be less than ideal, but I'm just wondering if anyone has some first hand experience with anything like that.

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Tekdredger

I'm currently running dipoles on the rear and direct radiators on the sides because I can't mount my dipoles on the sides - room limitations. I do prefer dipoles on the sides. As for the rears, I really like the effect I get from dipoles back there. Direct radiators would probably work equally well, but I wouldn't rule out dipoles in the rear.

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gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

my bad, i edited that post above...

7.1 IS primarily for larger listening areas (typically meaning larger rooms), and is not significantly different than 6.1. to clarify what i agreed with and what i did not... however, if one is thinking more than 5.1, 7.1 is the way to go.

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This post has been brought to you by curegeorg, thanks for reading.

rears in the ceiling is a bad idea.

ear level is always best, and until they come out with a channel that is supposed to be in the ceiling or floor, the effects do not sound right coming from above (below either) or reflecting off of another wall.

many reasons why, so little time to explain them all! :-)

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This post has been brought to you by curegeorg, thanks for reading.

What does room size have to do with 7.1 set-ups? Roughly how big does a room have to be before you can start considering 7.1? The difference is significant, as I explained above. I guess you don't think there's a significant difference between "sucks" and "preferred", which is how you yourself described 6.1 and 7.1 respectively.

BTW, companies that historically have been on the cutting edge of surround sound (Meridian, Lexicon, Fosgate) have built their surround processing technologies around a 7.1 set-up, not 6.1. They all wouldn't have done that if the difference wasn't significant.

Anyway, I guess it doesn't leave much in my original post for you to agree with.

Best,
Sanjay

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Tekdredger

Originally posted by sdurani:
What does room size have to do with 7.1 set-ups? Roughly how big does a room have to be before you can start considering 7.1?

That is a silly set of questions. To benefit at all from surround sound, there needs to be separation between each channel. If you were sitting on a stool with each speaker right beside you, you would not hear surround sound, you would just hear a lot of sound. Surround sound is meant to provide localized sounds. I suppose you are nit-picking, but that is what room size has to do with surround sound in general and specifically 7.1 vs 5.1 vs 2.1, etc.

Likewise if you were at a movie theater, and it only had 5.1, or 7.1 for that matter, there would be huge areas with less than optimal surround sound effects. Why, because depending on where you sat, you could behind the last set of speakers or if the speakers were placed in the corners, then the distance would be too great to reveal the surround effect.

Obviously, most people dont have an enormous area, such as a movie theater, but it is an example of size and why it is relevant.

Room acoustics play a large part in sound reproduction, besides merely size...

As for a specific size, I doubt there is one. Speakers/other gear dictate the specifics.

There is a bunch of technical info, on correct speaker placement, etc. which is all relative to room size and listening area. Each situation requiring a different setup.

I am not going to specify a room size because, a total sf is not all that is relevant. Length and width in relation to listening position are key.

Give me a break.

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This post has been brought to you by curegeorg, thanks for reading.

Like Tekdredger, I had been considering mounting the rear surrounds on the ceiling with them firing at the back wall, since my seating is also against the back wall. It seemed like it might work, but I was unsure if my ears would pick up the sound from the speakers before the reflected sound, really screwing up the directional aspects of the surround sound. Another option was using in-walls for the rear surrounds. Again, not perfect but maybe effective. Has anyone tried this or have any comments?

The first room I had available for surround sound was small and the couch was against the rear wall. The only place for rear speakers was in the upper horizontal corner between rear wall and ceiling. I used small steel cable and small eyelets (eyelets into wood, not drywall) to support the speakers at almost 45° in the 90° corner. The surround effects blended quite well, even in this position relative to the listeners.

Separation between channels doesn't have to be done with distance alone. It can also be done with angles.

I've listened to a system made of 7 nearfield monitors, all of which were little more than arm's length away. There was no problem with localization; especially in the surround field, where I heard solid rear vs side separation.

Despite the close proximity of the speakers, most listeners could localize sounds at their sides vs sounds behind them. The difference in direction is easy to spot. Even moreso when they are listening to speakers physically at those locations rather than relying on phantom imaging. I still respectfully disagree with you, and it's not for nitpicking sake. I've seen too many people discouraged from doing fine 7.1 set-ups because they were led to believe that their room falls below some size threshold.

As I said earlier, if you're in a large room but your couch is against the back wall, your situation is not conducive to a 7.1 set-up. But you could be in a small room and be sitting near the middle and have an excellent 7.1 system. Size is not the deciding factor, seating location and how much room you have behind you is what matters most.

Lateral sounds should come from your sides, surround-back content should come from behind you. There's no reason why this should hold true for large rooms but not small ones. Please understand, I'm not saying this to be nitpicky or give you a hard time. I've just never seen a size threshold applied to 5.1 vs 7.1. OK, you can take 15 minutes. But then it's back to posting.

Best,
Sanjay

i also talk about the listening position as important as well. i guess you missed that.

i do not think that people can get good surround sound from the speakers being too close together.

7.1 is "generally" for larger rooms, but that does not in any way mean that it is NOT for normal sized rooms. ill concede that much, as i have before.

also I have not touched upon the lack of 7.1 material available, last time i checked it was only BEGINNING to be produced with 6.1. thus, most titles are 5.1 and the 6th and 7th channels are duplicates of the 4th and 5th, which lends itself to stadium type of seating (or multiple rows) in which there is a larger listening area. if there is no difference between the 1st and 2nd surround sound "row", there will be no "side" sounds and no "rear" sounds, instead it will be all rear. hearing the same sound coming from two different places in a room as an effect will not enhance the experience (in fact, if not properly setup, has a greater chance to lessen it), and definitely would not be a big improvement over 5.1 speakers. and if the material is encoded for 6.1, then the "rear center" channel is split between the 2 rears which is not ideal, seeing as the sound was intended to come from the middle rear.

its so easy to get off topic, but the jist of what i have been saying is that 7.1 is fine and dandy, BUT the cost vs reward right now is low. if i was wiring, i would wire for anything possible. if i was buying, i would not buy 7.1 unless i had a large enough room (or listening area) to appreciate it, and i planned on scouring dvds for discs encoded with the likes of es or ex.

i am talking from personal experience as well as audio knowledge, and i have found that what i said holds true.

i guess if sound could travel the speed of light placement wouldnt matter, but alas the laws of the universe make it travel a slower and that enables us to detect its movement.

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This post has been brought to you by curegeorg, thanks for reading.

to answer your question murphy, no i wouldnt bother with 6.1, and no you wouldnt gain much. if you are considering more than 5.1, 7.1 is the better choice for the future (for now you wont see much of a difference though).

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This post has been brought to you by curegeorg, thanks for reading.

What does source material have to do with it? I've been running a 7.1 set-up for the last 8 years. In fact, the 7.1 processes I mentioned earlier (from Lexicon, Meridian, Fosgate) all existed before consumers had access to discrete 5.1 DD and DTS material. Discrete 7.1 source material has never been a prerequisite for 7.1-speaker playback. No offense, but this makes no sense at all. What in the world gave you the idea that the two pairs of surround speakers are playing "duplicates" of the two surround channels? 5.1 to 7.1 surround processing, such as Pro Logic IIx, results in unique content in each of the four surround speakers. Heck, even simple EX/ES decoding puts sounds behind you that are not otherwise heard at your left or right, and vice versa. This definitely enhances playback, at least on my system. Some surround content (ambient sounds: rain, traffic, room reverb) sound better coming from my sides while other surround effects (back-to-front flyovers) appear more natural when they disappear behind me. How does this "lessen" the experience? "Ideal" playback of the surround-back channel is through two speakers, not one speaker. The surround-back channel is not a "rear center" and was definitely not "intended to come from the middle rear". I just finished detailing the reasons why in my first post in this thread. The rewards seem low to you because you're approaching it from multiple false premises. For people who actually understand how 7.1 systems work, the experience is highly rewarding. I've described real world advantages that 7.1 has over 5.1, advantages that are easily audible. If you feel that any of the information I posted is not factual, please point it out.

Best,
Sanjay

otay- so 6.1 is NO improvement. What if my back(preferred) seating area is basically against the wall? can I still benefit from 7.1?
BTW - my surrounds (M&K 150's) are tripoles.
Next- does that mean that I should swith them to dipoles if adding two(2) more back surrounds.
Stumped.

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Personally, I wouldn't bother with a 7.1 speaker set-up if my couch was against the back wall. you really do need some space behind the listening area for proper speaker placement, since the surround-back channel(s) should image from behind you.

However, if you're determined to go 7.1, here's a suggestion. Place the side speakers on the side walls, directly to the sides of the listening area. In yor situation, this will mean the side speakers end up in the rear corners of the room. Elevate them above ear level so that all listeners have a clear line of sight to the speakers.

Move the couch forward a few inches and place the rear speakers on the floor behind the couch, pointing up. This should bathe the back wall in a wash of sound. Will it sound like it's coming from behind you? Kinda, sorta. But, at the very least, they won't sound like they're coming from your sides. Not optimal, but at least you'll have some side vs rear (quasi-rear) imaging in the surround field.

I've only heard a set-up like this once, in the living room of a friend who insisted on a 7.1 set-up despite having his L-shaped sectional in one of the rear corners of the room. He had originally tried ceiling mounting the rear speakers and that didn't sound as good as spreading them out behind the couch.

Like I said, with the couch against the back wall, I'd personally stick to 5.1. With the speakers so close to the back wall, the tripole setting will probably work better than dipole. However, you should try them both ways, and choose what sounds better to you. After all, you're the one that's going to have to live with the set-up, not us. The resulting sound should be one that pleases you most. Experimenting with both settings is the best way to find out which one sounds better in your set-up.

Good Luck,
Sanjay

[This message has been edited by sdurani (edited September 25, 2004).]

I can't agree with that. I had a 6.1 system and disabling the center rear was instantly noticeable and worse. With the center rear on surround information was clearly localized behind the listening position. But the listening position was almost equi-distant between front center and rear center speakers. I suspect a very near rear wall would degrade your experience significantly.

As for the research showing front-rear reversal, OK, whatever. For me, in my setup, with the visual and audible cues in the movies I was watching, it was never an issue. All the speakers were perfectly matched, so maybe that helped.

I'm reasonably sure 7.1 is better, but 6.1, IMO and experience, is worth it over 5.1. For sure.

My couch is about 6 feet from the rear wall so I opted for a 6.1 setup. I just didn't have room for two speakers since the room is a little narrow. I think that it sounds better than 5.1 and don't have any problems with the back-to-front reversal mentioned. I knew about it when I set up the system and was worried, but no problems.

tm