Help with tuning my new basement home theater - AVS Forum
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post #1 of 6 Old 09-06-2006, 07:26 AM - Thread Starter
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Hi all,

I've recently finished my new basement home theater and am having a hard time trying figure out speaker/sub placement, room frequency response, acoustic treatments, etc. (I've attached a hand drawn picture of the room)

I've used Video Essentials and AVIA. I've read numerous posts here on AVS as well as articles on Audioholics. I've purchased the Rives Audio CD and recorded a frequency chart for my room. (Which I've also attached and has me totally baffled). I've even tried running the Room EQ Wizard, but had trouble with that and my sound card.

I originally had my gear setup in our living room with a miss match of speakers. Now moving everything down stairs, I purchased a matching set of Polk speakers (RTi8 mains, Polk Center & surrounds). It just doesn't sound as good to me as it did before. Now from what I've learned here on AVS, I realize I don't have the "perfect" room. But, my original living room setup was far from "perfect" (Although it was smaller and I was sitting at the back wall)

I know I need to do something, but my head hurts from all these different sources of information. My question is, should I treat the room before I attempt messing around with speaker/sub placement or even worry about frequency responses?

Thanks for everyones help!

The IT Dude

 

HT.pdf 18.6015625k . file

 

RivesAudioCD2.pdf 8.310546875k . file
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post #2 of 6 Old 09-06-2006, 11:25 AM
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> having a hard time trying figure out speaker/sub placement, room frequency response, acoustic treatments, etc. <

This is a deep subject, and a complete answer requires far more than will fit into a single reply here. The short version is:

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners.

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

* Some additional amount of mid/high absorption on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective.

> I've purchased the Rives Audio CD and recorded a frequency chart for my room. <

Unfortunately, that's not very useful because it only "spot checks" frequencies that fall on the standard third octave divisions. I'm sure the peaks and nulls are much more severe than shown. This is not to discourage you! Just to point out the failing of a simplistic test tone CD like that.

> I've even tried running the Room EQ Wizard <

It would be worth your effort to get that running because REW will give much more accurate results than third octave tones. REW also shows ringing at each frequency, and that's just as important as the raw response if not even more so.

--Ethan

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post #3 of 6 Old 09-07-2006, 06:17 AM - Thread Starter
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Ethan,

Thanks for your input! I've realized just from reading on these forums that this is an enormously deep subject. Part of the reason I don't know where to start...

I did get REW working with a different sound card. I used it initially just for the subwoofer. As I moved the sub around to different spots, I reran the sweep test. Each time getting slightly different results. I'm not sure I was interpreting the graphs correctly, but I ended up leaving the sub in the spot that produced the data points closest to the line already on the graph. I don't have (nor do I intend to purchase) any kind of EQ for my system, so it seems that for me that this program is really only useful for finding my best speaker location as well as having before/after results for acoustic treatment. I know REW has a dedicated forum on audioholics, so I'll look there for more info on this program.

Thanks again!

IT Dude
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post #4 of 6 Old 09-07-2006, 07:04 AM
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Head over to http://www.hometheatershack.com to get alot more help with Room EQ Wizard and graphs.
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post #5 of 6 Old 09-07-2006, 08:28 AM
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You can do a lot without room treatments. First, place the sub away from any wall or corner, if possible. If you're using a sub for stereo, I like to place the sub between the front r/l speakers, but I have a hard time not localizing the sub. Place the speakers into the room. Vary the placement (including where you sit), moving the speakers from the side walls and toward the side walls, moving the speakers front to back, etc., until you get the best sound. Just spending this much time will help the sound, that is, if you have both the time and the area to spare. My speakers are out from the front wall around 7-8 feet and at least 5 feet from the side wall. I used to sit near field, but now I sit farther back. I spent hours trying different positions.

Bob
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post #6 of 6 Old 09-07-2006, 09:11 AM
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I sympathize! I treated my room extensively prior to moving in based on nothing more than faith based on what I read in this and other forums. (Broadband bass traps on every wall juncture that I could, absorbers at first reflection points, and diffusion at second reflection points and on rear wall.)

I also used TrueRTA and Room EQ Wizzard pretty extensively. Played with locations of subs, phase between units, etc. etc. etc.

Easily spent over 100 hours on this.

Last weekend I had Jeff Meier of AccuCal (a professional audio and video calibration guy out of Houston) come to my home. He got far more done in that half day than I ever would have. He moved the subs around, we moved a small sub I had in another room into the theater, he moved the mains and toed them in differently, and then he dialed in some PEQ. The difference was staggering: far better imaging, tone much better, and far less boomy. (I learned a lot in the process.) It was, easily, worth the cash.

All a long winded way of saying, if you can swing the cash getting some professional assistance offers a lot of bang for the buck.
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