Axiom Home Page Forums General Discussion Home Theater Large great room. 7.1 speaker placement & dipole v

To be a pain: it should be pointed out that you have an issue to deal with beyond symmetry. Left speaker's first reflection should hit diffusive bookshelf or void of entry way - good delay of reflection. The right speaker hits ultra reflective glass doors - very bad. So while the distance is very important, not sure it will matter as much when you consider a delayed reflection on the left and a hot reflection on the right. Need some heavy drapes on the sliding glass door to try and equal out the reflective properties of the first boundaries. In my room I have a similar situation, and fixing it proved highly beneficial. My fix is not permanent yet, but with temporary absorbers in place, the image is much better than the natural reflective state.

Sorry to further complicate, but you should end up with a pretty sweet sounding system so you might as well deal with all this BS at the front end - ounce of prevention and all the jazz.

I was also looking at that big hunk of glass. As you know from my thread you helped me out on, I’m also looking to cover some glass but just not as bad since the glass in my room is much further back. But your right if we’re going to talk about room/speaker interactions might as well drag that big window into it because it is going to be an issue.

Dean,
Glad you showed me the long hand before pointing out the short cut. Good to understand (a bit of) what makes an icon do it's magic.

It just struck me that the whole discussion of reflections and putting speakers in identical boundary setups is really just hypothetical in this case. The bounce off those books reacts nothing like the bounce off that glass. Not that it has to be exact, but those are almost polar extremes. The void after the books also adds to the dissimilarity as the second and third reflections will end up much delayed (or dead) as compared to the glass side. I have a similar opening void, but it is at the back of the room so not a big deal - actually helps my small room.

Wow! what a novel.

Hey Dave, you sure have thought this out a lot more than I ever did. In fact, if I were to do it over again, I would take a little more time to think things out..

One thing you mention is your worry about blasting out your wife in the kitchen/dining area by having speakers along the rear wall. In my experience, there is not a lot of material (movies) that makes full use of the rear channels. Blu Ray may be different, I haven't taken that step yet.

I use Dolby PLIIx mode when watching movies, which takes the left/right material and extends/matrixs it to the rear channels which is tons better than 5.1, but still it does not "blast" you out as these are just background surround effects.

Maybe your talking about listening to multi channel music, or using one of the other DSP modes on a receiver for movie watching like 7-channel stereo mode?

For full house/room music listening it might be nice to have the speakers back there, but for movies I think it might be to FAR back and hard to hear, especially considering how far the left/right surrounds will be from the primary seat(s).

I'm not sure the surround under the counter will be the best, as it will be a lot lower than the left/right surrounds. I think the goal is to have them as close as possible to the same height for the best seamless experience.

For ceiling mounting, you could use something like Axiom's ceiling bracket, that would allow you to angle them downward. Or, find a way to hang them down/suspend them from the ceiling, they are pretty heavy. In either case, you could mount each Qs8 centered on each half of the ceiling about the same distance back as the left/right surrounds are from you.

How do you plan to run the wiring, do you have access to the ceiling locations/walls? Also, on the left surround, it might be to close to the cupboard and the back tweeter might be comprimised a bit. Can you move it forward more towards the door opening?

Randy

Dean,
1a) Very good info. OK, I mocked up your idea (leave TV room centered, space LF spkr mid way between shelf and TV). The TV is 2' from front wall. fronts and center used to be in line with that. I think I could live with the L & R fronts being forward of screen 1' (WAF unknown but prob. OK). If I were also to lear to be OK with the CENTER being 1' in front of screen, I would be able to use an M22! I'm not AS keen on that (yet). But if this positioning 'should' improve the sound stage noticeably, then I think I would be OK with it (knowing I'm getting 'much' improved SQ).

1b) (sorry for very lousy pic. My camera is wigged out and my wife took her iPhone to work... some nerve, eh. ;o)
With a mock up M80 (tall black image with white paper taped to top trying to aprox. M80 ht), and another mock up on Rt. side:
LF has 20" between shelf and TV. Front of spkr is 1' forward of screen, same distance from front wall as end of shelf. RF is 20" from TV too. Both LF & RF are 77" from the main room walls.
Note: On left main wall, 2 1/2' into room from front of LF, is the 5'W x 7'Tall, passage way down to front door. On Rt. main wall, verticle blinds extend 1 1/2' behind and 8 1/2' forward of the new forwaed front speaker line. If that influences placement of fronts, I do not know.


2a) Dean, so this 1' forward placement of front speaker line leaves:
- Backs of M80's 19" from front wall (20" from shelf & TV)
- Back of a potential M22 2" forward of center of shelf area. There is a tape deck that could either go on the upper or lower shelf if the port on M22 cared. Or if it was better, the tape deck could go away (don't recall last time I used it).
- IF a VP150 were chosen, it would either mount on the top shelf or on a stand forward of AV shelves.
2b) I'd love to hear more opinions on the degree of preference of an M22 vs. a VP150 center for my application.



Doouh, I sit corrected. All is open for brainstorming... I just don't let my wife read over my shoulder for that kind of idea! ESPECIALLY if she likes it... then I have another project.

Big thanks to all for your great help here!

Sorry, this was posted on this thread in error...

Dave

I am a perfectionist too, as it may show with the level of detail and pictures I post. AND I'll have you know, the diagram is darn tootin' to scale! (1/4" = 1' on the original) Who in their right (OCD) mind would do it any other way!!! Big LOL

[quote]Assuming your picture is fairly to scale I would start by trying the single QS8 at the blue dot and the dual QS8s at the red dots. Here symmetry around the listening position is probably most important. And don’t worry about reflection with the QS8s as they are designed to take advantage of them to enhance the surround effects.





The QS8s are actually very easy speakers to place I only suggest that you experiment with their positioning because it sounds like you want to get the most out of your system and that’s the best way to do it.[/quote)

For your 'BLUE' 6.1 dot: I'll try both, but would your guess be mtd at end of counter at ear ht. -OR- mtd at ceiling peak (where it's distance back is moveable) might be better?

For your 'RED' 7.1 dots: where you have them would make them approximately 11' apart, 4 1/4' behind list. pos., SBL aprx 4' from cabinets and SBR aprx. 6 1/4' from uncovered sliding glass door on rt. wall.

Tks,

Zimm, you are absolutely NOT being a pain!!! Most excellent factoring in. You guys have all this wealth of experience with all these variables. I am VERY interested in drilling down to all the details you guys are willing to share your experience with!

So that Rt. side sliding glass door will always have it's vinyl vertical blinds closed when movie watching. I understand a heavy curtain would best absorb (and not reflect) sound waves.
I have never been told how wide an angle sound emanates from the M80 spkr. fronts. 180 degr.? more? less?
You seem to say that sound from the LF, even if it hits say the last 6"-12" of the bookshelf (which actually has lots of framed photos and nick nacks, not books), then continues on into the open entry way (as they correctly would) is in effect non reflective?

Back to the Vinyl vertical blinds. Would they reflect less than the bare glass (I'd guess)? But is it significantly less reflective to be OK, or would planning to change to drapes be significantly better? For testing, I'd guess hanging a regular velux blanket over vert. blinds would help, but still not absorb like good drapes, correct? (WAF pretty high for that blanket idea, I'm sure. )

For light reduction in room, I did think I might add vertical blinds to match on the rear slider. I don't know how moving the front blinds to the back slider and installing a curtain up front would look?? IMO, the vertical blinds have a lighter, less heavy look for the room. But, hey, if we are talking a huge sound improvement... it's on the table.

Thanks

OH, sure. Now I have ISSUES! I'd prefer to leave my issues out of this, and just stick to the audio discussion please! Thank you very much.