Moving past 7.1(5.1) into 9.1(11.2) upgrade your HT room via AudysseyDSX / DolbyPL IIz / DTS Neo:X™ - Page 2

You are not alone in your reaction. The DSX heights also output a similar signal as the wides, but it might not be as distracting as it does not spread offscreen so obviously.

Less obvious is that DSX softens the surrounds by applying decorrelation and reducing the levels a few dB. Not a great idea for hearing details.

And you also have the PLIIz option which is a wholly different process that does not derive from the front channels at all, and doesn't diminish the surrounds. Give it a spin and see what you think.

Not sure if your surround speaker wiring is final and buried or not, but be advised that with a 7.1 setup the surrounds (sides) should be at the sides of the front row. While I agree that it is not possible to make every seat the best seat, it is possible to make the MLP better than some of the others. The Audyssey diagram in post 1 is unfortunately incorrect in how it depicts the surrounds for the 7.1 basic setup.

And speaking of toe-in, it works not only for the front speakers, but the surrounds, too.

Absolutely agree on heights and wides. Localization is a very distracting issue.

Being a firm believer in the merits of multiple speakers for surround channels, here's a couple of early simulations I made for my project. Now, the design for my room changed after that, so I ended up going for a 3-1-1-3 configuration and slightly different measurements.

( Disregard the swedish text, really nothing of interest for you in it )


Red for surround channels, dark yellow for surround back. 2-1-1-2 and 3-2-2-3 configurations.

( Do note that I never intended that tight curve for the seats, but that was the available pieces of furniture in Micro$oft Visio )

^^ What do you do about the comb filtering?

I don't have so much hair that I need to filter my combs anymore.

On a more serious level, the configuration of the speakers are a bit non-standard and designed for usage in multiples, so as much as possible has been done there to minimize the issue. Not saying it's completely eliminated, but the advantages definitely overtriumph the drawback imo. They are also 16 ohm speakers, so hooking a few in parallell will not choke the receiver.

Here's the speaker configuration:

What do you do about timing associated with multiple surround speakers and discrete channels?

It's the one that's slightly ahead of your position that has the shortest distance and should take presence in localizing direction. (The Haas effect does the rest, I'd say.)
They are to be placed higher up further back, but it is not a straight arc but rather one that flattens out in the bend at mid-back.

My understanding of the Haas effect has to do with reflection, not discrete point sources playing the same signal at different distances. The later arrival time of the exact same signal eminating at the same time from another speaker can lead to a hollow sound. How are you dealing with the differences in arrival time if the "hollow sound" occurs (which I find happens pretty often)? Are the speakers arranged in such a way as to be exactly the same distance from the listening position? In that case, it would be a single listener. Also, how are you dealing with the SPL of multiple surround speakers? The addition of multiple side or rear surrounds will lead to an increase in SPL, and if they are not exactly equidistant from the sole listener, the speaker closest to the listener may not be adequate for reference playback. How are you getting around that? Just genuinely curious as to how you are getting around all of this. Thanks.

The brain sums the sounds no matter if it's a reflection (aka mirror source) or a real source as long as it's within the Haas window. ( Might not be correct to call it Haas-effect with a true source from a definition point of view, but who cares if it works the same? )

I have never experienced any "hollow sound" with these speakers, so I've never had any reason to look into it. Do keep in mind that the speakers were designed for this purpose rather than having a new job superimposed on them. Do you use dipoles or direct radiators? These are categorized direct radiators despite the dual tweeter setup. Furthermore, they are phase linear - if that has any bearing on it?

No, as I stated earlier, the speaker slightly in front of you will be the closest one.

The SPL will be set with all speakers connected to the same channel playing. They do not use individual amplification, they are connected in parallell to the same channel. Setting SPL is done by the receiver in the normal manner.

If you hook up three of these to a home theater receiver, that one will run out of power before these babies have a problem. They're recommended up to 250W amplification. Three of them yields a sensitivity of 91dB, so they're not very difficult to play loud with. If you have a very large room then you may want another few, perhaps. There was a larger model previously, but it was realized there was no need for it so it was discontinued in 2006.
I know a few people more crazy than I regarding playing loud (way above Ref), but I never heard any of them having issues with surround speaker capabilities.

Well, I am not "getting around it" in any particular way - I'm just leaning on that the speaker designer has done his job well. I've never, ever, heard anyone with these surrounds voice any complaints.

( Well, I have ONE... I need another four for my new theater (currently only have four not in use) and they're not so often on the used market in that particular number. )

Anyway, before we drag this out too long, it's not the right thread for it as it has little relevance to 9/11-channels per se. My mistake for showing my graph.

That's the trouble. The miserable comb has more hair than the head these days.
I assume the tweeters are wired in phase for wider dispersion. These appear to be intended for small cinemas or maybe dubbing stages. In that case the distance helps decorrelate, reducing the combing effect. In a home theater, I'd say it could still be an issue. Particularly since in the 3-2-2-3 config the speakers of each channel are all within a millisecond or 2 of each other. The figures represent time arrival relative to the shortest surround path.



Some electronic decorrelation would be ideal, but expensive and not easy to find. Delays are easier but a little less effective. Play some applause and listen. Lean forward as if to reach for a glass of some of that fine whiskey you keep back there. Do you sense passing through the combs? Compare to using just the 4 surrounds shown with the yellow speakers. Maybe your situation does not seem too bad. Nor will it show up on much content. Bullet dodged.

I had not realized the problem until I was in the rear seats and happened to lean forward during some steady applause and bam, it was wacky, very unnatural. So now I have a different setting for groups that adds 5 ms to the rear speakers which seems to avoid that problem. I'm using direct radiators, so these are probably the least forgiving.

There's not much difference. It applies to both. As an example, Dolby applied delay in the surround channels of their original Dolby Stereo cinema processors, not just because of shorter speaker distances, but to invoke the Haas effect to help mask dialog sibilants that would smear to the surrounds when the optical reader had azimuth errors, or when the logic decoder could not fully steer the dialog during busy mixes. It was very effective as long as the front arrival was at least 10 ms ahead of the leakage. I have not experienced much Haas effect below 5 ms.

Note: I have specified a couple of times not that the closes surround is the one slightly ahead of the listener, so your graph is wrong there.

It will be 3-1-1-3 in the build, but I don't have a drawing of that available. But I can show a pic where you can see the placement of the brackets that will hold them:



Well, it's slightly trickier than that. The tweeters are in phase, though they are reversely phased to the full range element.

Well, I have the same surrounds in my tv-room and I have never noticed any combfilter effects on any material despite walking around in the room. You have to get VERY close to the speakers to actually hear the individual one playing. I bought my first set non-assembled to save money and it was quite difficult to check that all tweeters were playing ok. Not saying that I won't pay extra attention next time there's applause or rain on a track, though.

Don't have much whiskey around, but whisky I have plenty of. (the 'e' denoting it being from the US or Ireland) Shelf is moved, though, to make room for a 1½ foot thick sound dampening back wall. Surround back speakers will be approximately where the lines cross the wall, yes.
Edited by Nightlord - 11/27/12 at 1:32am

Right - lunchtime!

There's nothing to link to regarding the speakers - they are not possible to buy outside Stockholm unless looking for used ones and I doubt there are very many of those outside Sweden. There is an international brand nowadays too, but they don't carry surrounds (yet): Guru audio

Well, I didn't have a build thread when you wrote that, but I have sort of started on now, so I'll figure out how to link to it sooning.

25.4mm for the inch. Just drop the .4 unless it's something really important.

4520... that one would be on my list if I had cash left for one... hopefully it will be cheaper when I'm ready use one...

Fabulous, can I come see a movie What speakers will you use?

Cool I didn't know DTS was not that great

Roger was talking about DSX, not DTS.

There was a bit of discussion about placement of height speakers in the Dolby Atmos thread. Worthwhile re-posting it in this thread.

thanks for the suggestion on PLIIZ. Hadn't thought of that, I will give it a whirl.

BTW, I thought DSX Wides really cut the center channel output too. DSX Heights does not do this. Strange.

err, well, it's your diagram, not mine. You posted two versions, I just picked one I liked. Not important, really.
That's a pretty normal technique so as to get a smooth transition in the crossover region.

Yes, but normally there would be a LP-filter on the woofer/midrange to transition with. In this case, it used full-range in conjunction with the tweeters. (Same kind of element would be in the Guru QM10s where it has some unusual workload too.) Don't have access to do three-dimensional sound radiation plots, but it would have been interesting to see how it behaves.

Anyway, this could very well be the odd one out - I'm sorry you're not anywhere close so I could demo them for you.

Me too! Chances are pretty small, though. I have not been in Sweden since development of the Pro Logic system in the Volvo C70. Really enjoyed that experience.

Some time ago I did a lot of experimentation and listening tests with DSX Heights and I could never get over the impression that my previously carefully designed 'envelopment' was somehow diminished by the use of DSX-H. Sure, DSX-H created a great 'wall of sound' in front of me, but it was just too front-centric. I kept asking myself where my surround sound had gone, where the much loved surround ambiance had gone etc.

 

It was after a conversation here with Roger Dressler that it all became clear. Because DSX-H derives its information from the front L&R channels and because it also decorrelates and reduces the levels in the surrounds, this explained what I was hearing. I switched to PLIIz and have never looked back. PLIIz derives its information from the surround channels and does not mess with the surround channels themselves and, for me at least, it gave me what I wanted: some extra ambient sound high up at the front and preservation of the envelopment bubble I had worked so hard to create in the first place. I occasionally switch back to DSX-H for a few minutes to hear the difference, but I never deviate from PLIIz for movie watching. It's quick, easy and free to try them both of course, so you will form your own conclusion - just thought that my experience might add to Roger's earlier response in some small way.

I am sitting my theater room right now, and I am absolutely shocked at what I'm hearing. I had no idea DSX took so much from the side rear surround. PLIIz sounds so much better. The surrounds are much louder. I think you are right about the heights them being more for presence this way, but I can't believe how much I was actually losing from the sides and rears. I will not be using DSX again.

My room is about 26x30 if I recall. Screen is 120" diagonal. In the picture below, the wides are not present, but I had them hooked up they were on the outside of the cabinets you see on either side of the screen. Of course the couch, seat, and gumball machine were not there either. Sweet spot in my room is the second row.




Edited by fst96se - 11/28/12 at 8:12pm

fst96se,
Good to hear from you. Especially nice to see this great theater again (I saw it years ago - but forget who it belonged to)
So are you telling us you are liking PLIIz thru a 7.1 set-up >> and NOT liking 9.1 or 11.1 (heights and/or widths)?
Just making sure; because I have been very curious (actually a case of "upgrade-itis") about heights and widths, am still procrastinating about finding a way to integrate more speakers into the front of my room.