Moving up from 5.1 to 7.1

[nightflier]

(I searched for a related discussion but couldn't find one, so if this has already been discussed, please point me in the right direction.)

I'm about to upgrade to 7.1 speakers and was wondering how the rear channels of a 5.1 soundtrack, such as DD, DTS, etc., are divided up between the four rear channels. Do they have two different soundtracks encoded on the disk?

Also, if DVD's have two different soundtracks, one for 5.1 and 7.1, what about SACD?

[sy_lu]

The DD or DTS EX or ES uses matrix like DD ProLogic to extract the center rear track in either one or two ch. DTS ES discreet has true 6.1 ch. There is no consumer discreet 7.1 movie or sound track available at present that I know of.

[Woochifer]

Okay, here's the scoop ...

The only true discrete 6.1 format is DTS ES. DD EX is actually a matrixed 5.1 format, which means the back surround channel is actually encoded into the L/R surround channels (as sy pointed out, similar to how the center and surround channels are encoded into a 2.0 Dolby Surround soundtrack). There are no discrete 7.1 formats currently available to consumers, which is why I typically refer to 7.1 as "7.1" because it's a true discrete eight channel format. In a "7.1" receiver, the back surround channel, whether a discrete DTS ES or matrixed DD EX playback, is split and sent into two back surround speakers. It's basically a monophonic signal getting split in two, which is actually similar to how a Pro Logic receiver splits the monophonic surround channel into two speaker outputs.

Before you invest in your extra speakers, you need to check and make sure that you got enough space behind your listening position to accommodate those speakers. If your sofa or chair is right up against the backwall, I would say save your money and buy some extra DVDs because adding the back surround speakers would probably make your overall sound worse. Ideally, you would have four identical speakers in the back, and have them arranged so that they're roughly the same distance from the listening position as the front speakers. You can change the delay timing to compensate, but that can only do so much if the speakers are only inches from your head.

Keep in mind that out of over 36,000 DVD titles currently in release, only about 100 of them have ANY kind of EX or ES back surround encoding. The rest of the titles are almost all either 2.0 or 5.1, and both DVD-A and SACD have standardized around 5.1. Given this, I would actually optimize the 5.1 setup first before anything else. You do this by:

-getting a SPL meter and test disc, and making sure that all the levels match properly
-get the speakers placed so that the speakers are all equidistant from the listening position, and roughly arranged 30 degrees off-center for the L/R mains, and about 110 degrees off-center for the L/R surrounds
-follow Dolby's surround placement guidelines by elevating the surrounds so that they're roughly two feet above ear level, and pointed directly at one another.

Once you've done this and evaluated your room, then you can decide whether or not a 7.1 setup is right for you.

[nightflier]

Woo, thanks for the detailed info. One more question: Does SACD drop the extra surround speakers entirely or is the sound split between all the speakers?

[Woochifer]

Woo, thanks for the detailed info. One more question: Does SACD drop the extra surround speakers entirely or is the sound split between all the speakers?

SACD is a 5.1 format, period. If you want to run it in a 7.1 playback mode (and the ability to do that will depend entirely on whether or not your receiver's analog input allows for reprocessing of the signal -- most receivers just pass the signal into the preamp section with no further processing), then that means that the L/R surround channels are going to get processed to extract a back surround channel. That will produce very inconsistent results. It's the same thing with trying any 5.1 source with the EX/ES decoder turned on. Some of them might sound good with the back surrounds turned on, but others will sound terrible because they were not mixed with that type of playback in mind.

[nightflier]

And they said pretty much the same thing: it all depends on the receiver's ability to process that rear channel. I'm using a Harman Kardon DPR1001 receiver, and it is supposed to process the surround channels evenly across the back channels (I have an email out to them to confirm this). Apparently, movies are less problematic because the surround sound is not constant amd surround sounds occur in spurts that are usually higher in volume for short periods of time. SACD music CDs, on the other hand, are much more dependent on the rear speakers on a constant basis, especially if they are recorded well.

Now, with bipolar speakers the situation becomes more complicated. Essentially, SACD is encoded to sound optimally with just two standard rear speakers facing straight out of the corners behind the listening position (at a 45 degree angle towards the listening position). This is often problematic as a slight move out of the ideal listening position produces a noticeable change in sound. Bipolar speakers can help this a bit by difusing the sound, so that for example, several people on a counch can still enjoy the surrouond sound, albeit at the expense of diluting that single ideal listening postion. And I think these are some of the issues I am struggling with. So Axiom recommended moving the bipolar speakers to the sides and placing regular speakers behind the listening position. Although the rear speakers will not have the same impact together with bipolar speakers on the sides, as they would by themselves.

So for now, I will first move the surround bipolar speakers to the sides. If that doesn't improve thinigs, I will put an old pair of front-radiating speakers in the rear to see if that improves things. If it does, then I will add a pair of Axiom front-radiating speakers and put them in the rear. If not, then I guess I will have to live with the bipolars on the sides from now on.

In the end, there is nothing out there (movie, SACD, or DVD-A) that makes full use of the extra two speakers in a 7.1 setup. Correct me if I'm wrong, 'cause I would love to test this (maybe one to the Chesky CD's ?). According to other posters, 7.1 and 9.1 are just marketing hype for most households, unless you need to fill a large room with sound.

Thanks for all the help. I'll add another post if HK tech support has anything else interesting to add.

[nightflier]

...I'll add another post if HK tech support has anything else interesting to add.

Well HK wasn't very elaborate. Apparently the receiver splits the signal evenly between the left and rear speakers. Appart from that they just refered me to p26 of the manual. Not very helpful.

[Rycher]

Basically what Woodchifer said is correct. For movies 6 channels (5.1) are discretly recorded onto the medium, except for the few DTS titles that add one more descret center rear. SACD and DVD-A are only a 6 channel medium. Playing back any of these formats in 7.1 requires matrixing for the extra channels. &.1 sounds really good in movies, but I've never heard a music CD in 7.1.

[nightflier]

...but I've never heard a music CD in 7.1.

This probably should have been my first question: Has anyone with a 7.1 system and SACD heard what happens to the rear chaenels?

I'm going to gess that all receivers conform to the same standard on how they divide up the two analog inputs for the rear channels (?).

[Woochifer]

This probably should have been my first question: Has anyone with a 7.1 system and SACD heard what happens to the rear chaenels?

I'm going to gess that all receivers conform to the same standard on how they divide up the two analog inputs for the rear channels (?).

Whether or not a receiver can do that depends on how they implement the multichannel input. A lot of receivers setup the multichannel analog input as a straight analog bypass, meaning it goes directly into the amp with no digital conversion or processing. Since none of the SACD and DVD-A players I'm aware of do any kind of 7.1 processing of the high res formats internally, then that means that if your receiver uses a straight analog bypass for the multichannel input, your only option is the 5.1 playback that's standard with SACD and DVD-A.

Only a few receivers I know of can do any kind of processing with the multichannel input. With those models, you might be able to get the 7.1 processing done. But, this entails an extra AD/DA conversion, and if the high resolution is one of the benefits with SACD and DVD-A, then this kind of defeats the purpose. The difference between discrete channels versus matrixed channels is very noticeable, because the matrixing does cause audible degradation.

Whether or not you would even want to apply 7.1 processing to a 5.1 SACD or DVD-A track in the first place is much the same as with movie soundtracks -- your results will vary. If the recording mostly has ambient sounds in the surrounds, such as a classical or jazz recording done in a concert hall, the 7.1 processing would likely collapse those ambient cues into the rear center channels and sound pretty bad. If there's a lot of discrete channel separation, then the 7.1 processing might help fill in the rear soundfield and improve the overall sound, provided that you're willing to live with some degree of tonal degradation.

[equate]

Hi,
I just updraged from 5.1 and 7.1. What movies is good to test the system out? Thanks

[KRiTiKaL]

Hidalgo was recorded in THX, sounds awesome!

[equate]

You say movies with THX are great for 7.1? I don't have THX on my receiver. Thanks

[Woochifer]

Hidalgo was recorded in THX, sounds awesome!

Keep in mind that DVDs are not recorded in THX, because that's not a playback format. DVDs with the THX label on them are simply certified to meet minimum picture and sound quality standards. And there are plenty of DVDs out there without the THX certification with stellar sound and picture quality. For example, the DVDs that Warner makes are routinely among the best ones out there for picture quality IMO, yet none of them are THX certified because they don't participate in the program.

[Woochifer]

You say movies with THX are great for 7.1? I don't have THX on my receiver. Thanks

As I pointed out, THX is nothing more than a certification standard. A THX approved DVD has met minimum picture and sound quality standards, but that does not mean that all of them will be better than non-THX DVDs, and it does not mean that the soundtrack will sound right when played back using the 7.1 playback mode. Most soundtracks out there are 5.1 (fewer than 100 6.1 DVD titles exist) and as I mentioned earlier, how it sounds in the 7.1 playback mode varies a lot depending on how the original soundtrack was mixed. It does not matter one bit if the disc is THX approved or not -- if the surround channels were not mixed with a lot of channel separation, the 7.1 playback will collapse the sound into the middle and destroy the surround effect.

You do not need a THX receiver to obtain the best picture and sound quality out of a THX certified DVD, any more than you need a Good Housekeeping approved kitchen appliance to bake cakes from Good Housekeeping approved cake mixes. Focus on optimizing the sound and picture quality on your system, and forget about looking for the THX label.

If you want a good system test for your 7.1 setup, some discs that will work well include The Haunting (the 6.1 DTS ES version), the Lord of the Rings extended editions (again, the 6.1 DTS ES soundtracks), and Gladiator (look for the old 2- disc set because it has the 6.1 DTS ES track on it; the rereleased single-disc version only includes the 5.1 DD EX soundtrack). Master and Commander and U571 are the soundtracks to beat for me, but they're both 5.1 soundtracks and may or may not work well with 7.1 playback.

In general, 7.1 playback is an improvement ONLY if you have the right soundtrack, a room with sufficient space behind the listening position, AND timbre matched speakers that are positioned correctly. Otherwise, if not done right, a 7.1 setup can do more damage to sound quality than good compared to a 5.1 setup.

[kexodusc]

Hmmm, I wasn't going to chime in on this thread but I think I have a meaningful perspective to share.

I added 2 speakers to the 5.1 setup, I must say the improvement is incredibly substantial. I'd say it's every bit as substantial as the jump from "3.1" to 5.1 (if you were to add rear effects).

I'm not exaggerating. Essentially, it allowed me to better place the the rears (to the side) and achieve a real "rear surround field" by adding more speakers to the back to close off the effect. The processing done by PLIIx is very realistic and likewise with the DD/DTS EX/ES selections.

I don't doubt that this was very much dependant on my room rooms size and shape. My listening position was (and is again) approximately centered in the room, leaving about 9 feet from the back wall. The surround backs really close off the sound field well.

I find the "7.1" processing to be a significant (ie: greater than 15% improvement) even in matrixed, or bastardized 2 channel formats that are just being output to 7 speakers. Pro-logic sources sound better in 7.1. 5.1 DD and DTS as well.

I agree with Wooch 100%. If you don't have more than 4 feet behind you, 2 more speakers ain't gonna be much good to ya!
I'm not as sold on the timbre matching though. I have 7 speakers from the same line now, but I didn't always. You can quite often get away with incredibly pleasing results using non-matched speakers as rears in a 5.1/6.1/7.1 setup (too big a difference would suck though). It is, however, very critical that the front 3 speakers be matched as closely as possible.

I tried 6.1 and in my room it was a complete waste of time. The sound was so localized from the one speaker I was using that it seemed a bit, well, fake or something. Using 2 speakers as rears really disperses the sound.

I frequently turn the surround backs off so I'm running in 5.1 mode as a comparison, and I can honestly say, I cannot think of one situation where it the sound wasn't improved at least a tiny bit. There are some movies that don't really make much difference (dialogue intensive movies like JFK without special effects). Anything with good ambient soundtracks or a few special effects really comes off sounding better. And the odd time you do get a 6.1 encoded DVD, the results are even better still.

2 more speakers is a hefty chunk of money though. Make sure your room dimensions and decor (WAF) can accomodate such a setup though. I have no doubt poorly placed speakers would really suck.

And definitely, make sure you've gone as far as you can with 5.1 before adding more speakers.

[Woochifer]

I'm not as sold on the timbre matching though. I have 7 speakers from the same line now, but I didn't always. You can quite often get away with incredibly pleasing results using non-matched speakers as rears in a 5.1/6.1/7.1 setup (too big a difference would suck though). It is, however, very critical that the front 3 speakers be matched as closely as possible.

I agree with you to a point. With most movie soundtracks, the front and back sound elements are kept sufficiently separate such that timbre matching between the front and surround speakers is not as critical. However, with multichannel music and an increasing number of movies, more of the sound elements are mixed into the front and surround channels at nearly equal levels. With those soundtracks, timbre matching is a lot more important because mismatches sound much more distracting when all of the speakers are reproducing the same sounds.

I frequently turn the surround backs off so I'm running in 5.1 mode as a comparison, and I can honestly say, I cannot think of one situation where it the sound wasn't improved at least a tiny bit. There are some movies that don't really make much difference (dialogue intensive movies like JFK without special effects). Anything with good ambient soundtracks or a few special effects really comes off sounding better. And the odd time you do get a 6.1 encoded DVD, the results are even better still.

If you repositioned the L/R surrounds so that they are more to the side than slightly behind the listening position, it will sound fine with the back surrounds active, but leave a fairly large hole in the rear soundfield with the back surrounds switched off. I'm presuming that you use direct firing surround speakers.

Also, it really depends on the soundtrack, not just whether or not effects are in the surrounds. With a 5.1 soundtrack that has a more or less monophonic mix in the surround channels like Raiders of the Lost Ark, Glory, or Lawrence of Arabia, the EX/ES decoder will collapse a lot of sounds into the middle, and in those instances I don't think that 7.1 playback would be beneficial.

2 more speakers is a hefty chunk of money though. Make sure your room dimensions and decor (WAF) can accomodate such a setup though. I have no doubt poorly placed speakers would really suck.

And definitely, make sure you've gone as far as you can with 5.1 before adding more speakers.

Good advice. As you add more speakers, the level of complexity with optimizing the setup increases. The back surrounds represent two more opportunities to mess things up! That's why I question whenever people claim that they don't need a SPL meter to do the level calibration on a multichannel setup. With a two-channel setup, it's easy to tweak with the system by ear, but going to 5.1 or 7.1, you need to account for a lot more variables and compensating adjustments (i.e. delay timing, positioning, etc.).

[kexodusc]

However, with multichannel music and an increasing number of movies, more of the sound elements are mixed into the front and surround channels at nearly equal levels. With those soundtracks, timbre matching is a lot more important because mismatches sound much more distracting when all of the speakers are reproducing the same sounds.

This is true...good point, wasn't thinking about that.

If you repositioned the L/R surrounds so that they are more to the side than slightly behind the listening position, it will sound fine with the back surrounds active, but leave a fairly large hole in the rear soundfield with the back surrounds switched off. I'm presuming that you use direct firing surround speakers.

I guess what I'm trying to describe here is that 5.1 speakers sounded good...so much that I didn't notice any deficiencies...when I added 1 rear center channel I wasn't impressed, even when I slid my 2 rear surrounds forward and to the sides (I had them slightly behind in the ITU 5.1 setup for multichannel audio basicall, that worked best for me). It wasn't that there was a noticeably gaping hole in the rear. With the 6th speaker it really became obvious when the processor channeled a sound to the rear center channel and didn't sound "real" (for lack of better terminology).

With 2 surround backs, I could angle the side surrounds differently, a bit more forward and to the side (much like a movie theater setup). The rear channels no longer became distracting, it was more ambient. Arrows in Gladiators DTS ES were transitioned alot better. The part where that guy swings his mace was awesome...it totally circles the room. There's no "quiet spot".

In normal 5.1 tracks, the processor does a good job of limiting "echo" effects, it just adds some rear ambience as well. It sounds what I felt my old dipole setup SHOULD have sounded like.

Also, it really depends on the soundtrack, not just whether or not effects are in the surrounds. With a 5.1 soundtrack that has a more or less monophonic mix in the surround channels like Raiders of the Lost Ark, Glory, or Lawrence of Arabia, the EX/ES decoder will collapse a lot of sounds into the middle, and in those instances I don't think that 7.1 playback would be beneficial.

That's just it though, wooch...it doesn't seem to do that with 7 speakers. It did do that with 6. Instead it extends the rear further back from left to right, not focusing on a rear center. It's hard to explain...I assume this has to do with the processing, maybe it has to do with the fact my rears are about 6-8 feet apart as well. Believe me though...there's a center image when there should be (a few scenes in U-571), but with the more subtle sounds (ie: being in a jungle) it seems to have the effect of making the room sound a bit bigger and deeper.

This got me thinking though.. I'm not sure I'd recommend placing 2 rear speakers 1 to 2 feet apart as I sometimes see suggested as the minimum acceptable spacing. That would be a highly focused (collapsed) center sound. Might as well stick with 6.1 (which I didn't feel was substantially better)

Good advice. As you add more speakers, the level of complexity with optimizing the setup increases.

I'm going to go out on a limb here, because you're making me think about this. I've been fortunate, both in my old, and new house to have 2 large 400 sq ft + rooms. Since all the speakers are 8 ft or more away from me I wonder if my placement becomes far more forgiving than if I was in a smaller room (like my old apartment)? Perhaps I'm achieving the right amount of dispersion? Certainly a auto calibrating tool like my RX-V1400's YPAO helps (though I'm becoming less and less impressed with the Parametric EQ part for signals above 200 Hz...not noticing much audible differences).

The back surrounds represent two more opportunities to mess things up!

No argument here...that's why we have AR.com. I kinda think the average HT setup is still a 5.1 unit and only the geeks like myself looking for more horsepower or whatever go the extra distance.

That's why I question whenever people claim that they don't need a SPL meter to do the level calibration on a multichannel setup. With a two-channel setup, it's easy to tweak with the system by ear, but going to 5.1 or 7.1, you need to account for a lot more variables and compensating adjustments (i.e. delay timing, positioning, etc.).

In this regard, YPAO is a blessing. I've fiddled with that so much in the past few months. I've come to realize that a 1 ms delay difference will throw of my center image in 2-channel stereo more than 2-3 dB of volume difference. I kid you not. I was quite surprised. I first noticed this when I tried playing with a few different manual settings. I measured my distances to the inch. YPAO can be off by as much as 1.5 feet for ever 10 feet my speakers are away, but it's a relative thing so I don't think the actual number of feet matters, but what it does with that number. When I tried adjusting the number of my left channel to 1 foot closer (as it should have been) it threw Norah Jones way off to the side. At first I wondered if it could have been SPL? So I started bumping up the SPL. I got a slightly better image, but my SPL meter confirmed YPAO was right in it's settings. The delay made a HUGE impact.

Moral of the story...the less human error the better! No doubt 7.1 isn't for everyone.
Can't wait until 8.2 and 9.2 become the standards (don't get me started on my "stereo bass" experiment).

[KRiTiKaL]

Nope, still sounds great! As for the technicalities of THX I just know it sounds good to me. I am glad to know you guys are so smart about these things. I learn something new all the time here. DTS and the other great 5.1 modes sound good too. Hidalgo just stood out to me in clarity. Thx

[kexodusc]

Waldo's contributions to these forums are nothing short of legendary.
Indeed, he has few peers.

[Geoffcin]

With 2 surround backs, I could angle the side surrounds differently, a bit more forward and to the side (much like a movie theater setup). The rear channels no longer became distracting, it was more ambient. Arrows in Gladiators DTS ES were transitioned alot better. The part where that guy swings his mace was awesome...it totally circles the room. There's no "quiet spot".

I'm going to go out on a limb here, because you're making me think about this. I've been fortunate, both in my old, and new house to have 2 large 400 sq ft + rooms. Since all the speakers are 8 ft or more away from me I wonder if my placement becomes far more forgiving than if I was in a smaller room (like my old apartment)? Perhaps I'm achieving the right amount of dispersion? Certainly a auto calibrating tool like my RX-V1400's YPAO helps (though I'm becoming less and less impressed with the Parametric EQ part for signals above 200 Hz...not noticing much audible differences).


Moral of the story...the less human error the better! No doubt 7.1 isn't for everyone.
Can't wait until 8.2 and 9.2 become the standards (don't get me started on my "stereo bass" experiment).

It was only a few weeks ago that I got, (what I feel) is close to optimum out of my 7.1 system. Actually it's 7.1+2 if you take into account that I'm running two sets of mains. It was only when I realized that I should set my CSW T500's to SMALL, and send all of the bass signal to my subs that things really came alive. When set to small there's no signal going to the T500 woofers, so the speakers are acting more like standmounts. The maggies blend well with the Velodyne subs, and OK with the rest of the dynamic speakers, but NOT with the woofers of the T500.

I agree, a big room helps alot. If you think you want to do 7.1 make sure you have about 4-5 ft behind your seats or it won't work correctly. When it does it really adds to effects. We watched X2 the other day and there's a lot of info going to the rear surrounds in that movie. Even little things; like when Striker blows up the wall of ice to get to Wolverine you can hear the ice falling BEHIND you! 5.1 just coudln't give you that effect, or if it could you'ld need to be sitting exactly in one spot. There's something very startling about hearing noises behind you, and 7.1 gives you that effect when it's called for.

[kexodusc]

It was only a few weeks ago that I got, (what I feel) is close to optimum out of my 7.1 system. Actually it's 7.1+2 if you take into account that I'm running two sets of mains. It was only when I realized that I should set my CSW T500's to SMALL, and send all of the bass signal to my subs that things really came alive. When set to small there's no signal going to the T500 woofers, so the speakers are acting more like standmounts. The maggies blend well with the Velodyne subs, and OK with the rest of the dynamic speakers, but NOT with the woofers of the T500.

I agree, a big room helps alot. If you think you want to do 7.1 make sure you have about 4-5 ft behind your seats or it won't work correctly. When it does it really adds to effects. We watched X2 the other day and there's a lot of info going to the rear surrounds in that movie. Even little things; like when Striker blows up the wall of ice to get to Wolverine you can hear the ice falling BEHIND you! 5.1 just coudln't give you that effect, or if it could you'ld need to be sitting exactly in one spot. There's something very startling about hearing noises behind you, and 7.1 gives you that effect when it's called for.

Sweet Jebus Geoffcin, you got 11 speaker boxes in that room??? Superbowl at Geoffcin's everyone!!! I agree totally with setting the mains to "small"...I tried this about 4 or 5 months ago

Even during a the average comedy/chick flick with limited it does seem to fill up the room behind you, really adding to the ambient effect.
I've heard several people swear that dipoles/bipoles are ideal for rears in the 7.1 setup, might have to test that out someday.

[Geoffcin]

Sweet Jebus Geoffcin, you got 11 speaker boxes in that room???

Then I invite them over for a movie, or concert DVD and they change their mind. I'm still trying to justify a front projector but the need for total light control has me a little spooked. (that and $1000+ for a good screen!)

[kexodusc]

You have to tell me how you get the significant other to agree to all this? My second sub lasted 2 days before I lost that battle.
I got 2 systems in 2 different rooms, but 11 boxes in one room...you got room for screen?

You weren't kidding when you said it's pain to get right...my simple little 7.1 seems primitive by comparison.

[Aldo WIngate]

7.1 is just a marketing ploy to get people to spend more money. 5.1 sounds the same.