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rear and surround placement-Opinions wanted


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14 replies to this topic

#1 of 15 OFFLINE   Ed O'Neill

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Posted March 24 2003 - 12:46 AM

Hi all

I'm in the last stage of my home theater.... the speaker wiring, and as we all know the fronts and center are fairly easy seeing as we can move them around. Well my problem is where to put the rear speakers as well as the side spekers.

The opinions have varied and I am looking to you guys seeing as this is a forum for this.

My reciever has a 6th channel for surround ex, but if you go to www.dolby.com and read my spec/set up sheet it says it is better too have 2 rears instead of one but according to my receivers owner's guide if you are going to use 2 then you need an external amp to power the two rears.

My room size: (converted 1st floor bedroom)
12'6" wide x 12'9" long x 9'6"

My room layout:
Along the 12'6" walls are the tv and couch. The couch is actually a sectional minus the corner unit giving me almost all the back wall space used. Now when viewing the tv on my right side wall there a two windows side by side the window casing starts around 40" from the back wall.

My equipment:
SIDES - Cambridge sound works multipole for the sides speakers
REARS - haven't bought yet but I have a small pair similar in specs as the fronts (ensemble)
RECIEVER - Onkyo 787 (brand new in the box) - got cancer/major accident/cacer again - 3 yrs straight!)

My questions:

1. Where do I put the sides?
...I'm thinking 36" from back wall.

2. What would I gain from putting 2 rear speakers as opposed to one ? Is it seperation?

3. Could I just run the two rear speakers from the 6th channel output (it's 100 watts)?

4. Where on the back wall should I put the rear speaker(s)?

5. This is the most important question and the most varied... At what height should I mount the surround, and rears?*

*NOTE CEIDA (I think thats right)and ONKYO say 3 feet above the listners ear,the local custom install shop says 8' feet from the floor, and the speaker company said 7'from the floor. Well according to my calculations... Three feet above the listners ear is 7 FEET !

Please Your input is important.

Help me finish a 3 year project.. seeing as I am going to be housebound for another year...LOL (no choice but to laugh)

Thanks in advance
Ed O'Neill
Methuen MA

#2 of 15 OFFLINE   TimForman

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Posted March 24 2003 - 01:03 AM

7 feet up for surrounds has worked out well for me. I have them mounted on ceiling brackets that can be adjusted to tilt down so they're firing directly at the listener. Adding additional rear speakers will help in the spacial quality of the rear effects. Ideally all the speakers should be equal distance from the acoustical center of the soundstage. If your rears are closer than your fronts you need to delay them accordingly. 1 ms per 1.17 feet.

#3 of 15 OFFLINE   Ed O'Neill

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Posted March 24 2003 - 01:45 AM

Thanks Tim, I also forgot to ask.. What is the diffrence from using in wall speaker wire and using 12 gauge regular monster cable speaker wire. I always though the bigger the better. Keep the opinions coming Signed Ed

#4 of 15 OFFLINE   Tom J C

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Posted March 24 2003 - 01:59 AM

Ed, little confused as to your setup. seems like your confusing your two rears with your sides. normally the rear surrounds are standard on a 5.1 setup and a rear center for a 6.1 setup. two sides would be for a 7.1. are you thinking of putting your rears on the sides and only putting one rear center behind the listening position? Or am i interpreting your post wrong.

#5 of 15 OFFLINE   Ed O'Neill

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Posted March 24 2003 - 07:20 AM

LOL Tom,

Did I Confuse you also...sorry.

Tom wrote:
seems like your confusing your two rears with your sides.

Not really I want both. My system is for 6.1 but www.dolby.com recommend two REAR as well as two sides. Where I get confused is how do I make it 7.1 ?

Tom wrote
normally the rear surrounds are standard on a 5.1 setup and a rear center for a 6.1 setup.

That is what I have 6.1 receiver, but I think its 7.1 ready.

Tom wrote
two sides would be for a 7.1.

Actually I think here is where YOU are confused sides (some people refrer to them as surround or rears) can be used on sidewalls especially if you have bipole/dipole speakers. Sides can be used in 5.1, 6.1 and 7.1. Depends on what your setup is, The best speaker set up surround ex always have sides(surrounds) and a rear(back). Now 6.1 actually adds 1 rear center speaker and 7.1 adds two rear speakers.

Tom wrote
are you thinking of putting your rears on the sides and only putting one rear center behind the listening position?

well like I said I want 2 REARS and 2 SIDES (7.1 ready?)

Or am i interpreting your post wrong.
Either that or I confused you ..LOL

Hey TOM were both on the same team.... TEAM MASSACHUSSETTES, and just like you said we live on oppisite sides of the state. You south and me north(I'm actually the last city in MA on 93. AH shopping for audio/video gear in TAX FREE New Hampshire...You gotta love it.

I'm actually going to Cambridge sound works tonight and tweeter to look at tvs. I'll get it figured out (I Hope)

Thanks again TOM

Signed Ed O'Neill

#6 of 15 OFFLINE   TimForman

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Posted March 24 2003 - 09:11 AM

I know this is HOME Theater Forum but I'm curious about how the side speakers are handled in the multiplex type theaters. They have half a dozen pair of side speakers or more. It would be even better to be able to tour the Cinerama here in Seattle with their incredible sound system. I'm amazed every time I go there.

#7 of 15 OFFLINE   gregstaten

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Posted March 24 2003 - 10:56 AM

In answer to your questions:

[quote] 3. Could I just run the two rear speakers from the 6th channel output (it's 100 watts)? [quote]

The short answer is "absolutely not." If you attempt to power two speakers from a single amp channel you change the speaker's impedance. (If memory serves you halve it so an 8 ohm load becomes a 4 ohm load.) This increases the power demands on the amp and may cause it to operate outside of its spec, possibly causing it to overload.

-greg

#8 of 15 OFFLINE   Ed O'Neill

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Posted March 25 2003 - 12:33 AM

Thanks Greg,(cool another New Englander) You wrote: The short answer is "absolutely not." If you attempt to power two speakers from a single amp channel you change the speaker's impedance. (If memory serves you halve it so an 8 ohm load becomes a 4 ohm load.) This increases the power demands on the amp and may cause it to operate outside of its spec, possibly causing it to overload What you described is a parallel connection? Isn't it? Couldn't I use a series connection. Then the amp would see this actually as a 8 ohm. Well off to the internet I go to figure this out. Also I have been on Dolby site many times where exactly did you see the info on the rears.On dolbys listening page it says 4 feet apart. Wanna help with the wiring? Anyone Else have any imput Signed Ed O'Neill

#9 of 15 OFFLINE   TimForman

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Posted March 25 2003 - 01:12 AM

Two 4 ohm speakers in series will yield 8 ohms. I'm thinking you could use 4 surround speakers two off to the side as Greg suggested and two in the rear. I guessing the farthest distance from the listening postion you could place these will be 4 feet since you're in a 12x12 room. Just think of your listening area as a circle rather than a square as diagramed in this AES Document

#10 of 15 OFFLINE   gregstaten

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Posted March 25 2003 - 10:13 AM

Ed and Tim: I'm certainly no engineer and can't remember exactly how ohms are calculated as you add speakers to a single circuit. But, I do remember being told by an audio engineer that it was generally a bad idea, especially with consumer amps. If I have a chance this evening, I'll pull up the manual for my THX Ultra 2 processor. It documents the correct rear wall spacing per THX spec for direct radiating and dipole speakers. I could have sworn it said 2-4 feet, but I'll try to dig it up. -greg

#11 of 15 OFFLINE   TimForman

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Posted March 26 2003 - 05:39 AM

I would probably stay away from wiring speakers in series too. In this case it's not necessary anyway. In a room this size three surround speakers (especially dipole) are more than sufficient. I don't think you gain much in a 7.1 system over 6.1 since I have yet to see a DVD recorded in 7.1. Also, the two rear centers are mono anyway.

#12 of 15 OFFLINE   Ed O'Neill

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Posted March 26 2003 - 10:15 AM

Tim,

Yes, you gain more defined rear sound .
It is stereo sound, but it's matrixed.

You will never see a movie produced/recorded in 7.1.
7.1 is mereley just 2 rear speakers for surround ex.
This is the recommended set up. Just look on www.dolby.com.

What I am actually trying to do is set up my speaker system for the future. The new receiver that I want is 7.1 so why not wire it in that way and just pull out the un- need wire later. Insted of re-wiring and rip down walls laster.

Just to update everyone I emailed dolby today to see what they had to say and I am probably going to email Onkyo as well.

Thanks and keep the reponses coming.

Signed
Ed O'Neill

#13 of 15 OFFLINE   Chris Kane

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Posted March 26 2003 - 10:15 AM

If I can move the discussion back to surround height it might help my dilemma. I'm currently setting up my speakers in our living room and I'm using two tripoles (M&K) for the surrounds. However, besides movies, I will also be listening to SACD and DVD-Audio and the two don't seem to compliment each other as far as rear speaker placement goes. So, I'm thinking that I'll put the surrounds in the rear corners - a kind of compromise between surround backs and sides. Now, what about height? Will surround sound (movies) be disappointing if I place the rears at ear level for SACD/DVD-A? Thanks, Chris

#14 of 15 OFFLINE   Ed O'Neill

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Posted March 26 2003 - 02:25 PM

Chris, Here is what ! have learned in the past few weeks Height should be anywhere from 5-8 feet or 2-3 feet above listners ears. I'm going with 7 because it has been the most common answer I have received. Surround(aka side speakers)- as in typical 5.1 should be on side walls. They should be in line with the viewers head, however slightly forward or backward would be ok. Rear center speaker(s) - As in 6.1/7.1 should be on back wall no closer than 4 feet and centered to the wall.They should also be the same height as the surrounds(side speakers) Example My back wall is 12'6" so I went to the center of the wall and went 2 feet to either side and 7 feet high. Hope this helps You Signed Ed O'Neill

#15 of 15 OFFLINE   Chris Kane

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Posted March 27 2003 - 04:12 AM

Ed, Thanks, I understand that aspect. What I want to know is - What sonic experience do higher surrounds provide that surrounds at ear level cannot? What will I be missing? Thanks again, Chris




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