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eltabor 09-30-2007 06:30 AM

Will 7.1 sound good?
I have been in the process of setting up my system for a year and have encountered a problem. The room I use is a converted carport 12' x 20' with the couch and TV backed up to the wall with 12' between them. I believe it is an acoustically dead room which is what I gather we want. Concrete floor covered with vinyl and 10' x 6' rug, 12' wall has 6' of windows and in front of it a 8' x 2' x 2' aquarium. 20' wall with 6' of sliding glass, 2' bookcase to the ceiling and AC hole filled with glass and one 3' doorway in each of the remaining walls. 2 front speakers are JBL Studio L 890 and I will get the JBL LC1 or 2 for my center. My rear are JBL Decade L26. Now here is my problem I have a pair of JBL Studio S36AW II 3-Way for my surrounds. What I read says they should be placed behind me and there is no behind me. The fronts are towers on the floor, the rears are on the wall even with the front of the couch and at standing ear level. Do I mount these surrounds over my head or do I forget about it and use 5.1? No sub yet. Any advise would be appreciated and I can give more details if needed.

tigeraudio2007 10-01-2007 03:25 PM

Re: Will 7.1 sound good?
Definitely do not go for the 7.1 setup. You will regret it in the space that you have describe. Not to mention, there is barely a handful of true 7.1 mixes out there. So all you are getting is an extrapolated extra couple channels, blurring the spatial distinction between your rear L and rear R.

A couple other notes about the setup you have described. A dead room is not always the based. This is a matter of debate among acousticians, but I am a believer that a truly dead room takes the life and warmth out of the sound. EQ can do wonders but you are still starting with a dead room.

You say that you have a pretty dead room but I don't see how that is possible with the amount of glass that your have in that space. Glass has a fairly low absorption coefficient, as does most concrete. So basically your reflective rate with the materials in your room should be really high. You need carpet on that concrete, drapes on the walls, and fiberglass has nice high absorption coefficient.

And finally, you said you have the surround speakers to the sides, aligned at the front of couch at ear level. If you are listening to true 5.1 mixes, this may present a problem as you have no surround speakers behind you. I, personally, would not put the couch all the way against the wall and place the rear speakers behind you. And make sure you get yourself a good subwoofer to fill in your space.

In the end though, with the materials in your room, and the speakers that you have, I would say that a good EQ Room Calibration is in order.

eltabor 10-02-2007 08:06 AM

Re: Will 7.1 sound good?

Originally Posted by tigeraudio2007 (Post 3826)
I, personally, would not put the couch all the way against the wall and place the rear speakers behind you. And make sure you get yourself a good subwoofer to fill in your space.

In the end though, with the materials in your room, and the speakers that you have, I would say that a good EQ Room Calibration is in order.

Thanks that saves some money. In this limited space The couch must stay, and besides where would the spiders live? About the subwoofer, should I use JBL since everything else is JBL, or another, I was considering Velodyne? My Onkyo TX-S605 has Audessey EQ, is that enough or do I need some of the other calibration things I saw in Home Theater magazine. I believe one said it worked on six locations one on eight and the standard EQ from two. Onkyo set up worked from three. I don't know how accurate it is since I am missing the center channel and subwoofer.

tigeraudio2007 10-02-2007 10:21 AM

Re: Will 7.1 sound good?
Without seeing your complete room layout it is hard for me to visualize other possiblities. Might I suggest that you align the rear speakers with the rear of the couch? Is there glass behind you? If not you may want to experiement by angling the rear speakers a little toward the back wall and use reflective sound. But that gets mighty tricky when it comes to EQ and time delay.

Based on the materials that you stated you had in your room and the rough dimensions presented, I calculate that you have a reverberation time of about .8 seconds at 1kHz, which isn't that bad. Higher frequencies will reverberate a little longer but not much. Lower frequencies should have less reverberation time for the most part. So at 1kHz the decay time for sound is about 75db/sec. Do I definitely think that you can work with that in the EQ.

First, get yourself a center channel and a subwoofer. Matching all your speakers with the same brand is not necessary. Unless you are buying super high-end speakers they are not going to matched pairs anyway. Velodyne has some good subs. It all depends on your budget.

After the center and sub are connected, the Onkyo receiver you have does have audyssey EQ. The Auto Calibration measures sound from 3 positions: listening position, at least 3 feet to the left of listening position and at least 3 feet to the right of the listening position. Try this first and see what you get. Some people say that the auto EQ of the receiver is not good at all. Personally, I have the TX-SR674 and the auto calibration had a great impact on my apartment. But it is different for every space. You can also manually set the EQ within the receiver. To do this, you will need a computer with some Frequency analyzing software. Bob Hodas recommended some earlier (ie: Smaart, EFT, etc.) You will also need a calibrated mic. You may be able to get away with the included calubration mic that comes with the Onkyo receivers. Otherwise, find yourself a good omnidirectional mic. Feed the test signals into your system. It should give you an idea of which frequencies are problematic. You can then use the receiver's EQ to make adjustments to those frequencies. In the end, nothing beats professional calibration. However, with experimentation and careful attention to detail you can yourself pretty close. Close enough if you are not picky.

Bob Hodas 10-11-2007 04:15 PM

Re: Will 7.1 sound good?
Before you do any auto EQ, you should spend some time optimizing the speaker and listening locations. Look in the article archives and read my How To articles on room setup. If the speaker positions are bad, no amount of EQ will sound good.

Watermonkey 10-11-2007 09:30 PM

Re: Will 7.1 sound good?
Hello! I'm new here, though I've been receiving the newsletter for quite some time now.

I'm just wanting to throw this out there: Have you considered a Sunfire sub? They're self-amped so you won't have to buy or use a separate amp and they displace (move) more air than most other subs twice their size (including my 15" Mackie). I'd certainly consider it if I were you. And put some carpet on that floor man!

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