# Seeking advice for best audio compromise for multipurpose room



## NegativeEntropy (Apr 22, 2009)

Hello,

Barring a job loss prior to implementation (estimating this January for purchases), I'll be finally setting up a front projector in the basement family room this year. I've been researching off and on for ~6 years, so while I'm anxious to pull the trigger, I'm also patient. The basement itself has been 98% finished for about 2 years, only low voltage work remains. I ran conduit to likely needed locations when I built it as well as power to the ceiling where I intend to hang the projector.

My goal with this thread is to try to reach the best compromise in the space with respect to audio quality. Given the odd room geometry and limitations due to it's multi-use nature I recognize the final result will necessarily be sub-optimal. What's the best balance of speaker budget, placement, 1 sub vs 2, room treatments, etc? My goal is to try to answer those questions.

I have attached 2 files. One shows the entire basement layout for broad context. The other is an MS paint "drawing" of the "family room" detail (rotated 90 degrees CCW from the floor plan drawing). As you can see, the room is, broadly speaking, 16' x 19' x 8' high.

Users will be me, wife, 6yo kid and eventually the currently 20 month old kid. It will be a mix of music, video games and movies, TV, both day watching and night time (including when everyone but me is asleep). I'm open to headphone use to keep the volume down when necessary.

Total budget is 5-6k USD. $1500-2500 of this will be projector (model TBD - if I were to buy today it'd be the Panny AE4000 as I love the auto aspect ratio change for 2.35:1 vs. 16:9 vs. 4:3). This includes projector, receiver, blu-ray player, DIY screen, HDMI cables, speakers and any room treatments. I already have the equipment rack (but no shelves) and a roll of 12 gage speaker wire and all the coax cable/ends I need. All possible equipment will be in adjacent utility room.

Here are the boundary conditions/limitations/other info:
1) This is a multi-purpose family room. It's current primary uses are as a general play area (e.g. Lego building for 6 year old) and free exercise space (i.e. no fixed equipment). These uses will not go away.
2) Wall positions are set and very non-optimal, but they are what they are.
3) It's carpet over concrete floors. Walls are standard 1/2" drywall over 16" OC studs. Can lighting. See drawings for other geometry as it is far from rectangular in the corners. No exposed glass as the patio door is covered by heavy blackout curtains (which also provide excellent light control).
4) The furniture has little room for adjustment. I could likely move it up to 1' further away from the rear wall, but, for example, rotating everything 90 degrees is most likely out.
5) I'm sure speaker placement will be subject to nudge, moving out of the way for various activities, etc. Return placement to within an inch and a degree of original location cannot be guaranteed.
6) I'm a major geek and generally mechanically/electrically inclined so I'm open to DIY, REW, etc.
7) I have a good ear and my wife is an orchestra teacher, so we appreciate good sound. My current reference source is a set of Senn HD580 cans. I like their flat response.
8) While I'd like tower mains, budget may dictate bookshelves + stands. I prefer direct radiating surrounds. I'm leaning toward Ascend Acoustics speakers/Rythmik sub(s), 5.1 setup.
9) Since the right surround is likely to be in the main walkway, I'm leaning toward a high placement on a bracket, say 7' high, for the surrounds. 

So, what say you? Just get a receiver with Multi EQ XT and let her buck? 1 or 2 strategically placed room treatments will pay serious dividends? Don't bother with good speakers it'll sound sub-par no matter what you do, etc.

Thanks in advance. I hope to check back in on this thread each evening (I do not have the luxury of checking and posting from work).

Edit: I should ad that the seating position marked as "primary" is about 15' from the projector screen (but centered) and the nearest seat is 12' from the screen (the MS Paint drawing is not quite to scale .


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## robbo266317 (Sep 22, 2008)

The only problem with the room is that the width and heights are multiples. This means you _could _have peaks at around 70 Hz. Although with the openings at the far end it may not be an issue. REW will be your best tool here. Once you have made some measurements someone with more knowledge of room treatment can advise if this room can be improved with traps.

Several subs distributed around the room will give a smoother bass response.

As for moving the speakers you could mark the floor, after you optimise the speaker placement, to make it easier to realign them?

Cheers,
Bill.


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## NegativeEntropy (Apr 22, 2009)

Thanks for the reply. Yeah, I do have a few inches in my favor (actual room width is 15'10") but I'm crossing my fingers the odd shape will help, as you indicated.

I could try marking the carpet with painter's tape under the speaker corners + taking measurements. Good idea.

I'll likely have to decide 1 sub vs. 2 before taking any measurements - I can see it being a decision of, for example, 2 subs @ $500 each vs. 1 better sub @ $900 (I've got my eye on a F12 or F15 Rythmik). Sub location options will likely be limited to the indicated corner (not optimal, I know) or the front wall somewhere.


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## Guest (Oct 12, 2011)

I'm not an expert in room responses, but from what I've noticed in the past playing with placement and what not, I don't think that is a very good place for the sub. You will probably not get very much low end gain being so close and it will probably need to be phased 180 degrees.

I'd do front and center myself. It should fit below the center channel just fine, and give a good room gain to the seating area.


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## BarrRobot (May 24, 2011)

I would certainly suggest trying to balance the effect of the blackout curtain with some broadly similar acoustic treatment opposite to maintain left-right symmetry. After that, as robbo266317 says, you will need to make some measurements when everything is in place and take it from there.


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## NegativeEntropy (Apr 22, 2009)

Thanks for the responses.

It looks like learning REW is in my future  The curtain balancing I can experiment with via mocking up with blankets and such.


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## BarrRobot (May 24, 2011)

Picking up on some of your points:

"7) I have a good ear and my wife is an orchestra teacher, so we appreciate good sound."
and 
"Don't bother with good speakers it'll sound sub-par no matter what you do..."

I think you will find that above a certain price point, it is worth spending a reasonable proportion of the extra money on acoustic treatment in parallel with better loudspeakers etc. Don't ask me what that price point is, though, it depends on your circumstances - how willing you are to install acoustic treatment vs considerations of décor and domestic bliss. Of course any treatment you put in must be tolerant of the general use of the room. There's not enough information to even attempt to do the sums to determine how your room might sound, but a first glance gives me the impression that it won't be too bad. As you say, a compromise seems inevitable because the drier acoustic you want as a theatre may well feel too oppressive as a playroom. If you do decide that you want to deaden the room (lower the reverberation time) for theatre use, I'd suggest that you might want to consider covering over some treatments, or use (say) hinged panels, when the room is in use for other purposes. 
If you want to try doing the sums, it's quite easy given a spreadsheet, the hard part is getting the data for the materials you use. And a further complication is, the maths uses assumptions that aren't valid on small rooms and the answers will be wrong anyway, hence the suggestion to try it and see what your ears and REW tells you. And then tweak as necessary.

The good news is making your own treatments isn't that hard given reasonable DIY skills, so as "a major geek and generally mechanically/electrically inclined so I'm open to DIY, REW, etc." you shouldn't have too many problems. There is loads of information on the web about constructing various absorbers. I suggest reading some of the articles regarding studio treatment in "SoundOnSound" (available online: look under "Technique" - "Studio SOS" in the back issues).

You should find that as the acoustics of the room improve, the loudspeaker and seating positions become less critical.


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## KalaniP (Dec 17, 2008)

One quick tip re speaker placement (and re-placement): If you expect you will have to move the speakers around a bit, take a tip from the live theatre crews, and mark the speakers positions on the floor with some gaffers tape (or even a little bit of spray paint once you're REALLY sure and if you're worried the kids will move the tape!). Put it UNDER the speakers (Mark 1 or 2 corners, or front/back, the full square... whatever works for you), so you don't see it when they're in place, just when they've been moved. Then it's a breeze to put the speakers back in in the exact same place every time... just "hit your mark" like the actors have to.


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## NegativeEntropy (Apr 22, 2009)

Excellent advice - thanks! 

I have been re-reading some of the articles I downloaded on speaker placement and acoustics. I also checked out the site you recommended BarrRobot. I think the use of acoustical treatment will be severely curtailed by WAF but we'll see. She's open to the idea of trying dark fabric near the projector screen to mock up a darker paint on the ceiling. If I convince her of that, she may be open to a few room treatments!

Making any treatment kid durable will be a challenge. I can see accommodating diffusion (say, building a bookshelf) being easier than absorption.

Perhaps wrapping an absorptive acoustic treatment in canvas covered with an art print would be doable from an appearance perspective.


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## SAC (Dec 3, 2009)

Another very viable and effective option for 'durable' absorbers is the use of perforated metal.

They are actually very similar in terms of the degree of difficulty as the porous framed variety and they VERY effective and extremely resilient.

You have the choice of employing a metal brake to create the bends at the sides (one could easily take a few panels to a metal shop an pay them a few bucks to do this extremely simple task), or attach the panel(s) to a wood frame. Also, they can be powder coated as well (at additional expense at a car paint facility).

Not necessarily too much different in price, these are the go to designs for use in commercial and industrial areas - and especially in gymnasiums, etc., where the possibility of being impacted by basketballs, tennis balls and other varieties of impact are common.

I suspect kids would fit into that category as well.


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## NegativeEntropy (Apr 22, 2009)

SAC, that makes a lot of sense. Get a mesh with a large % of open area, bend it for attachment to a frame, and paint it an appealing color prior to attachment. I like the powder coating idea too - there's actually a place on my way to work that does that - as it's so durable.

Thanks for the suggestion!


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## SAC (Dec 3, 2009)

You can get an expanded metal cover for a traditional porous absorber, but that was not exactly the design to which I was referring.

Perforated metal sheets have long been used for nose control in industrial and metropolitan areas in applications such as as highway and train nose control barriers. (And it seems that_ only _the audio community is unaware of the much wider realm of industrial noise control! But then, many in that community have this fantasy that audio is beyond the capabilities of science to comprehend, as well!:rofl2

The design is actually rather straightforward, and the metals are readily available as they are widely used in industrial applications.

The perforation characteristics determine the tuning of the absorber. Additionally, porous material may be placed inside of the cavity to moderate the effective frequency and bandpass as well, as the spacing of he material with respect tot he from and back of the enclosure will change the response characteristics.

If you need more details regarding this, PM me.


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## BarrRobot (May 24, 2011)

Slat absorbers would be durable too, and may give a more 'domestic authority'-friendly finish (and would not work as a climbing frame if the slats are vertical!).


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## SAC (Dec 3, 2009)

Unfortunately slat 'absorbers' are far too reflective to be used as broadband absorbers. In fact, they are used as quasi-diffusors - low degree scatters. The percentage transparency (transparency index)_ far_ exceeds anything even remotely close to acoustical transparency.

(And the aforementioned perforated panel absorbers are tuned with precise calculations- although not prohibitive - not simple random 'grab some perforated material and go' devices!)


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## BarrRobot (May 24, 2011)

It all depends on what will be required. I was working on the presumption - quite probably erroneous, but without complete details we just don't know - that carpet and normal furniture and fittings would result in a moderately satisfactory absorption characteristic, albeit probably on the 'lively' side, and the addition of the thick blackout curtain would then require only moderate additional treatment to make the room suitable for serious listening. As I wrote earlier, NegativeEntropy (the OP) should measure what he has, and then he will be in a much better position to move forward. At this early stage, it's better to know what all the alternatives are, then he can do his detailed research and make an informed decision.


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## NegativeEntropy (Apr 22, 2009)

Thanks for the continued discussion. As BarrRobot indicated, the "educate the OP" goal of the thread has been met (though I am always open to more ideas/suggestions/education!).

SAC, a google search for the products you described turned up hits that educated me further. Thanks!

At this point, I'll continue to do homework on the subject and start planning for my REW related purchases (in addition to all of the audio gear, but that's another thread in a different sub-forum when the time gets closer).


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## SAC (Dec 3, 2009)

Carpet and curtains unfortunately normally only slightly effect the high frequencies. they are NOT broadband absorbers. Thus their effect is to "EQ" the reflected sound, absorbing the short wavelength low energy content high frequencies and allowing the higher energy longer wavelength mid frequencies to continue totally unabated.

The result is the coloration of the direct sound, as well as destructive interference due to superposition - a double whammy.

That is why all absorption and diffusion must be truly broadband across the lower mid range of he specular energies - from about 300 Hz up to about 5 kHz. I know many are not excited to hear that, but that means thicker spaced panel absorbers and slightly more complex lower extending diffusors.

Many of the oft cited web myths die hard.

Another reason to download REW and learn to use it - in particular the ETC response for analyzing behavior and optimizing and verifying the effectiveness of treatment....The positive side, it will likely result in a reduction of the necessary treatment (as well as cost) as you will ONLY be surgically applying that which is absolutely necessary - and not over damping the room.


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