# Sound System & Room Acoustics: How do you match them?



## jdh770 (Dec 20, 2009)

I was wondering if there are any sound-system "rules of thumb" when you are starting from scratch with a bare space.

Details - I have a large basement space with a finished ceiling, slate floors, stacked stone fireplace, hardwood walls (floor to ceiling). Mostly hard surfaces and it's fairly open. It has a nice room-reverb for acoustic stringed instruments and vocals, but I would imagine it's not going to be ideal for H.T. Right now, you can consider it a blank-slate in regards to a H.T.

I'm still trying to educate myself on home theater subjects and it's a bit overwhelming. The blind-spot for noobs like myself is that I can't "test-drive" a system in my room. Are there any "rules-of-thumb" that I can consider when choosing a H.T. sound-system? Or is it as simple as "If system-a sounds better than system-b in the showroom, that comparison will not change just because you relocate it to your specific home environment"?

If money were no object, I'd just bring in some pros to perform their sorcery, witchcraft or whatever it is they do to asses the situation... So, hints? Tips? tricks?

Thanks!
JD


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## robbo266317 (Sep 22, 2008)

Hi JD,

It sounds like you have a very "active" room with all those hard surfaces. You will benefit from sound absorbing structures - There are others here more wise in this area than me (eg bpape) who can guide you on this.
You may want to consider your room size and resonances from sites such as http://www.bobgolds.com/Mode/RoomModes.htm as a starting point.

Cheers,
Bill


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## jdh770 (Dec 20, 2009)

Thanks! Wow! Info overload! :scratchhead:

I'll hang on to that link until I can better understand it.


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## eugovector (Sep 4, 2006)

I think bpape will tell you that you should absorb as much of the front wall as possible (2" of 3# rigid fiberglass or similar), bass trap in as many of the corners as you can do (google "superchunk bass trap"), absorb the wall behind the Listening Position with 4"+ for bass trapping (move your sat 2-3' away from back wall minimum), and get something to absorb on the floor between the source and the LP (rug or carpet).

Schools of thought are mixed on absorbing 1st reflection points at the sides. I like the effect, others do not, and there has been science on both sides.


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## robbo266317 (Sep 22, 2008)

jdh770 said:


> Thanks! Wow! Info overload! :scratchhead:
> 
> I'll hang on to that link until I can better understand it.


Sorry, let me know your room dimensions and I will check it for you.

Cheers,
Bill


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## GranteedEV (Aug 8, 2010)

If you're starting from scratch, some constant directivity horn speakers might be the way to go, try reading this, all of it, but especially part 4.3.c which i think is most relevant in a sound system:

http://www.gedlee.com/downloads/Chapter 4.pdf

As I think it is pretty easy to follow and addresses exactly what we're discussing. In my opinion, too much absorption in a room is a band-aid solution to a greater issue inherent in most speakers. To me, a great setup doesn't need to turn acoustic energy into heat.. it utilizes all the acoustic energy with control.

Getting speakers that don't need treatments is a more complex issue, though. I'll name some that IMO are designed for real life rooms:

Infinity Primus P363
Revel Salon 2
JBL LSR 6332
Geddes Abbey
Audiokinesis Rhythm Prism
Linkwitz Orion

To name a few, of course by no means all. The thing in common is an effort to control directivity, in doing so taking advantage of reflections in a manner where sound reproduction is more natural.


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## jdh770 (Dec 20, 2009)

The theater area is a section of a larger, oddly shaped area - like overlapped boxes - that measures 43' x 28' (longest dimensions). With the fireplace (8' x4' stacked stone) in the middle towards one end, I'll presume that would impact the results... As soon as I can figure out how, I'll post some photos.


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## jdh770 (Dec 20, 2009)

Here are the photos:
Album -- http://www.hometheatershack.com/gallery/albums.php?do=view&aid=1929

The two folding chairs are facing the projection screen wall. Behind this wall is a closet where I want to rack all the equipment. I'm thinking a 5.1 sound system.

To make sure I'm tracking with everybody -- I'm thinking that room resonance *will* be an issue in this space, more than average, but there are solutions (either dampening treatments and/or speaker types & perhaps some DSP options as well).

Back to my original quandry... It's nigh impossible to test-drive different components to see how they will sound in my specific space, so is it a more a case of: 

a) "It really does not matter what components you buy as you will have resonance issues either way. So just buy the best gear you can afford and deal with the issues as you go."

b) For really reactive spaces, System-X provides the most (wiggle-room; adjustability; configurable options; etc) to deal with it - though you be prepared to use apply some acoustic treatments as well.

I'm a noob trying to learn -- and it's turning out to be quite an education so far!

Thanks
JD


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## eugovector (Sep 4, 2006)

Pictures aren't working. 

I lean towards option "A" with the caveat of "don't forget to budget for acoustic treatments". If you're the DIY type, $300 will get you a couple bass traps and some wall absorption.


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## jdh770 (Dec 20, 2009)

I can see them, but I also added them... Could be permissions, but the album is "public". I don't see any other controls on the actual photos. I'll try photo bucket or something.


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## jdh770 (Dec 20, 2009)

Same photos are here: http://s1114.photobucket.com/albums/k524/jdh770/


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## eugovector (Sep 4, 2006)

Yes, that's better. Nice basement you have there, I'm jealous.

However, lots of hard/flat surfaces means not so good for Home Theater. Plan on getting a thick rug between the seating position and the screen. Conventional wisdom also has you treating the front screen wall, but with a projection screen, unless you are going acoustically transparent, there won't be much wall left to treat.

Speaking of which, where will you be placing your speakers? Looks like you have a bathroom and entry-way to contend with.

With the bar behind you, you'll have enough irregular surfaces to diffuse sound, so I'd start with just the rug. After you get setup, you may want to treat the sides/ceiling, but see what it sounds like first.

Is that fireplace wood-burning? Used often?


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## jdh770 (Dec 20, 2009)

I'm pretty flexible on where the speakers will go. I'd really want to wall-mount the front L/R and Center on the Projection screen wall. The rear/surrounds will either be hanging from ceiling mounts -or- on wall/ceiling mounts from that hardwood beam that runs across the back of the space just before the bar. However, once I pick speakers, they will probably help me decide where/how to mount them.

We definitely *do* plan on getting a rug, if only because that slate can get chilly in the winter. Also, we hope the furniture (we're still debating what kind) will help dampen the room. I would like a couple of rows of over-stuffed theater seating; wife wants couches and ottomans. There will definitely be a nice thick set of red theater-style drapes in the doorways either side of the screen wall, as well as covering the windows. It's actually acceptably dim in that area, even during the day, but the wife doesn't like the idea of windows she can't cover (peeping-tom paranoia). 

The fireplace is a regular wood-burner, but has a gas-log set in it for now and we only use it for ambiance as the gas doesn't really put out much heat.

It is a nice space - thanks! I wish I could say I built that basement, but I didn't. The original owner had a lumber business, hence all the wood.


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## eugovector (Sep 4, 2006)

Sounds like a great plan and the curtains will help a little bit with front reflections. On seating, a porous fabric, no leather/vinyl, is best. 

Start with your current plan, watch, listen, enjoy, and then evaluate.


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