Axiom Home Page Forums General Discussion Technical Questions 7.1 channel speaker plcmnt in a fairly large area?

Hi, I hope you can help me out here. I've got my speakers on order and am very close to finishing my home theater/rec room area of my basement.

My basement area is fairly large for a home theater as it will serve multi-purpose entertainment functions for adults and children.

Overall "approximate" dimensions are;
21' wide
27' deep
8' ceiling (with the exception of a 4' to 5' wide span encompassing the main support beam and HVAC duct work where the ceiling height drops to about 7')

The listening/viewing area is approximately 15' from the 65" widescreen HD rear projection television.

I have a small boxed in support post containing lighting controls (with a 8" by 10" footprint) 14' back from the front wall and 13' in from the right wall.

Ceiling will be 2' by 2' acoustical tiles.

I have a THX-Ultra certified 7.1 channel receiver driving the speaker system which will consist of;

2 - M22ti (Main on a pair of FMS16 stands)
1 - VP150 (Center)
2 - QS8 (Surround - mounted with a pair of Full Metal Brackets)
2 - QS8 (Rear - mounted with supplied brackets)
1 - EP350 (Sub)

I'll be playing with the placement of the subwoofer so it isn't really a consideration.

What concerns me most (since I am finishing my basement with home theater audio in mind) is the recommended placement of the primary speakers (front, surrounds, and rear).

What I am ultimately searching for is the recommended distance between each set of speakers.

Given the room dimensions, can you assist in this? I'm hoping to install the conduit for my speaker wire this week and must mount boxes for the speaker wire/speaker location.

Thank you,
Spence
Madison, WI

Hi Jeff,

Alan Lofft posted this guide on speaker placement which should help you find the right location for your speakers.
http://www.axiomaudio.com/archives/home_theater_layout.html

I have the same speaker set as you except my subwoofer is different. My room size is 20 feet wide by 14 feet deep.

My guess is your front speakers will be no more than 15 feet apart but probably wider than 8 feet. You might want to adjust them depending on your personal likes for sound stage and how closely the sounds match the on-screen action. I found the ideal relationship to the on-screen action occurs when the speakers are spaced just outside the screen. However, I have mine wider than that as a compromise because my screen is much smaller than yours and I wanted a larger soundstage for music.

Your rear surrounds will probably be around 10-15 feet apart based on the information you gave on the Seating position. (based on the recommended range of angles)

Not exactly sure how your side surrounds will deal with that post in your room. I sounds like it might be in the way of your side surround speakers, but perhaps locating them just behind your seating row will get the post out of the way.

Have fun. You're going to love those Axiom speakers.

Jeff, as indicated in the article by Alan, separate the front speakers by about the distance of your seats from them(i.e. 15' or a little less). Put the side surrounds about 6' up and directly to the side. Put the back surrounds about 6' up and separated in a similar fashion as the fronts, i.e. about as wide as the distance they're behind the seats.

Thanks for the replies guys! You have given me exactly the reassurance that I was looking for.

I had researched and read Alan's article here, along with recommendations from DTS, Dolby Labs, and a host of other sites. Alan's article and illustration was the only one that I had read with actual recommended angles for speakers.

Given the 21' width of my room and the 27' depth, I was unsure how far apart to place my rear and surround speakers. As for my fronts, they will be at or a little under 15' apart, and slightly angled toward the listening area. The seperation is needed due to the size of my television set combined with the two oak entertainment towers standing to either side of it (photos of my home theater area at the old house are on my web site www.spencesplace.com).

I was intending to hang the front speakers to keep them above the reach of the hands of my two year old and her playmates but have decided for asthetic and accoustical reasons, hanging them may not be the best solution so I've opted for the stands.

Can't wait to get this project finished and hear first hand how well the Axiom system will sound! I'm replacing my large "boomers" (Cerwin Vega as sceen on my web site) for something a bit more precise.

Thanks again for your input. I'll be placing the boxes for the speaker wires this week and then start working on putting up the walls!

Thanks so much,

Spence

spencesplace

or a direct route to what my old home theater looked like - http://www.spencesplace.com/htphotos.htm

...I'm planning a major update to the site, once my home theater is functional!

Note that the furthest seating position from the 65" screen was about six feet due to the wall directly behind the futon.

I CAN'T WAIT to get the newer, larger home theater on line! I'll finally be able to accomidate more than 4-6 people at one time, and will have far FAR greater accoustics!

Spence

New link

link friend

Gotta love this one:



"The delivery crew departs, I celebrate with a frothy Guinness!"

Yup! I guess that photo pretty much captured the moment (abeit five years ago), but you neglected to point out the pint of Haggen Daz (sp), which was chased, by that pint of Guinness!

How long do I have to wait before I can post links and photos?

I've got a couple far better shots of what my old Home Theater looked like, and a few of the new "Serenity" Home Theater under construction!

As sure as I know anything, I know this. Once the new Home Theater is done, I'll be down there on a weekend bender in celebration!!!

The only other tip I can offer is to make sure that your subwoofer and listening position are not "half a room apart" in any direction... in other words if your listening position is in the center of the room don't have your sub in the corner or you will be sitting in the "null" spot and not get much bass.

My room was set up like that until a couple of weeks ago -- the difference in deep bass response after changing the listening position was hard to believe.

I had heard null-ness (I'm prone to making up words as I go, so bear with me gang) can be made less null by playing around with the polarity switch on one of the two subs.

Have I missunderstood this? Let me know!

Thanks

WOO-HOO! I've been promoted from NEWBIE to REGULAR!

...so can I post links and photos yet or do I have to keep begging?

You can post photos and links anytime you wish. Go wild.

>>I had heard null-ness (I'm prone to making up words as I go, so bear with me gang) can be made less null by playing around with the polarity switch on one of the two subs.

Yes and no. The phase switch helps in two specific cases :

1. You have two subs and the signals from them are cancelling out in a part of the room where you like to sit. Flipping the phase means the signals will add at that point rather than cancel, although remember that this is very frequency specific.

2. You are running your mains in "large" so they are producing bass alongside your subwoofer, with the same cancellation issues as in (1). Here you are flipping phase relative to the mains, but the effect (and frequency dependence) is the same.

With a single sub running your mains in "small" the phase switch can affect how smooth your response is in the crossover region between mains and sub but that's it.

Thanks Obiwan Bridgeman!

It looks like I'll have some experimenting with my sub placement.

Heck, perhaps I'll sell off the Cerwin Vega sub (although I've heard the 350 is "moderate" (not strong) and stick with a pure Axiom system (I know my wife would love for me to give up another object and put the cash toward my toys)!

Here is (I hope) a photo of my old basement. Some of it may be distorted due to the wide angle lens that I had used. You'll get an idea of how close everything was.

http://www.spencesplace.com/images/Temp/P1010060.JPG

and a photo of the new Home Theater, looking from the back wall, to where the entertainment system will be located.
http://www.spencesplace.com/images/Temp/P8070127.JPG

CRAP! How is it that I can make a living, supporting end users and repairing PCs and I can't get a freak'n photo posted!

Here you go.

>>CRAP! How is it that I can make a living, supporting end users and repairing PCs and I can't get a freak'n photo posted!

ROTFLMAO !! Welcome to the club

Regarding speaker placement, Rives has some interesting reading :

http://www.rivesaudio.com/files/spkr_plcmt.pdf

Here is a follow-up to my earlier question. Thank you all for your responses. Given the advice and the links to suggested speaker placement, I have been able to come up with (thanks to my intermediate level of experience with Photoshop) the following, as proposed speaker locations;

Photo at: http://www.spencesplace.com/images/Temp/HT1.jpg

Note:
The view in the linked photo, is taken from where the area where my home theater screen will be located.

Due to limited photographic source material (photos of the QS8's), I was unable to show the orientation of the right and left surround speaker.

Main front speakers (M22ti) will be separated by about 15', about 14' away from the listening/viewing area.

A VP150 center channel speaker will set on top of my 65" Mitsubishi HDTV.

Right and left surround speakers will mount to the underside of the main support beam, about 14' from the home theater screen and will be separated by 16' to 17'. They will aim directly at each other (toward the listening/viewing area), but will be aimed downward slightly, in order to open up the drivers on top of the QS8s.

These will be mounted on the back wall at the same height as the right and left surrounds Rear surround speakers (mounted to the beam), approximately 27' from the home theater screen (about 13' behind the listening area). They will be separated by 6' to 7'.

The EP350 subwoofer will sit (depending on sound quality) in the corner of the room, 8' - 9' to the left of the home theater screen.

A supplemental 15" Cerwin Vega down-firing subwoofer will sit (again depending on sound quality) will be in the opposing corner (left side of photo at the rear of the room).

6" R19 insulation will be installed in all studded walls and between ceiling joists. 1/2" sheetrock will be on all walls, and acoustical suspended tiles (with high noise reduction rating) will make up the ceiling.

Question: The primary seating area will be located to the right of the post, and can be moved to be either slightly forward, backaward or centered on the support post (containing dimmer controls for the house lights). The post will be trimmed out in either sheetrock and painted to match, or oak panel (stained to match the room's trim).

Will the location of the post, in relation to the surround speaker pose any acoustical problem?

If the post poses a problem, I have the ability to move the right and left Surrounds speakers up to 5' to the rear of the post. Should I consider this?

Thanks again,

Spence

The photo assistance squad strikes again!

Spence, I think that I've followed your description and picture and the only thing that I'd suggest would be a bit wider separation for the back surrounds. If they'll be about 13' behind the listening area, they could well be separated by a similar 12-13', to allow for situations in which they'll be carrying different sounds(e.g. through use of DPLIIx on 2 or 5 channel material), and so that there's enough separation for the difference to register at the listening area.

pmbuko, thanks for assistance in posting the photo.

JohnK? Thanks for the advice. I'll be moving each of the mounts for the rear speakers to the next wall cavity, which will give me about a 12' seperation between the two.

I don't want to go too much more than that as it would place one speaker close to the cold air return and I'm trying to avoid conducting sound through the heating system if possible (I don't have the cash to go all out with any type of sound deadedning materials other than R19 in the walls and ceilings).

Thanks again!

Spence