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.

[Aldo WIngate]

WHERE's MY POST?

[nick4433]

WHERE's MY POST?

Maybe lost in cyberspace? Aldo, this is a forum wher we come together and exchange information on HT and maybe other off topics but everyone generally conducts themselves fairly well.
I have been a member of the forum for at least 5 years now and have known how trolls have been dealt with on this board. Asking "who's your daddy" is not exactly contributing to anything here. You must have a good ability to talk about gear and give opinions and if you can refrain yourself from making yourself someone's daddy then that would be tasteless.
Just come clean and start over again and you should be OK.

[Aldo WIngate]

Maybe lost in cyberspace? Aldo, this is a forum wher we come together and exchange information on HT and maybe other off topics but everyone generally conducts themselves fairly well.
I have been a member of the forum for at least 5 years now and have known how trolls have been dealt with on this board. Asking "who's your daddy" is not exactly contributing to anything here. You must have a good ability to talk about gear and give opinions and if you can refrain yourself from making yourself someone's daddy then that would be tasteless.
Just come clean and start over again and you should be OK.

The topic went off couse because some guy didn't like my 7.1 surround rationale/explanation. While I may have gone astray, it is due to being led astray. I see nothing wrong with pointing out things - even if off course. Are you going to stand there and tell me once a topic and thread begins it NEVER WAVERS FROM TOPIC?
I haven't attacked anyone.


Bottom line is that 7.1 is a complete waste of money when compared to 5.1; a scam by the industry to ultimately steal from you. I guess the proverb should read "blindness is bliss".

[nick4433]

Bottom line is that 7.1 is a complete waste of money when compared to 5.1; a scam by the industry to ultimately steal from you. I guess the proverb should read "blindness is bliss".

Aldo, I agree with your above statement. 6.1/7.1 is very space sensitive and will add nothing spectacular to your listening enjoyment if you cannot place the speakers behind you and not above you. Many here are gullible to switch to 6.1/7.1 and buy more speakers and upgrade receivers.

[Geoffcin]

WHERE's MY POST?

It was way off topic, and as such the moderator has every right to delete it. Fairness is always on my mind when editing posts, but there are some things that cannot be allowed to continue. If you would like to continue a discussion off topic please use the Off Topic Forum. Please be advised that the Forum rules still apply there, so no personal attacks will be allowed.