Need advice for acoustical treatments in my HT

Hi -
Time to tap into the great amount of knowledge at AVS. 5 years ago we finished off our basement and put in a dedicated HT room.
My primary goal at the time was sound isolation so that I could watch my favorite action/adventure movies at an engaging volume and not disturb the rest of the family who might be reading, watching TV or sleeping . So far that has worked out. Now I want to tackle a little DYI project to work on improving the acoustics.

Details of the room:
The room has lots of hard, reflective surfaces. To keep the sound in, the walls were made of 1/2" sheet rock + Green Glue + 5/8" sheetrock on staggered 2x6's filled with fiberglass batts. 2 of the walls have poured concrete behind them, and beneath the carpet and pad is a concrete floor. The room's basic dimensions are 14.5' wide x 18' long x 8' high. I have a 2' wide soffit around the perimeter to run wiring, HVAC and rope lighting, so the ceiling is lowered to 7.5' around the edges. The ceiling is also drywalled. Wall surfaces are painted dark colors for a black-out effect and total immersion in whatever is playing on the big screen.
The room doesn't have a lot of depth, so we sit fairly close to the rear wall ( 5' - 6'). The screen wall (I have a FP setup) is dominated by a non AT screen, 115" diag 2.35:1 aspect screen, so there's only about 2' below and 18" above the screen that can be used for absorption. The screen wall is a false wall, so there's 2' of depth behind it that can be used for multiple purposes, one of being a good place to do bass trapping (stacked bundles of fiberglass R19 insulation).

That's the basics of it. I use the room for both movies and music - I'd say I'm 50-50 on that one. I still like 2 channel audio and have been getting back to my analog roots with a growing collection of used vinyl LPs. For speakers I now have a 7.1 set up, with a well-loved venerable old pair of Vandersteen 2 Ce for the main channels. I set the receiver to THX Ultra Cinema mode to convert all 5.1 sources to 7.1 and like the enhancement so far.

I sketched up the room in Visio, so I hope I have no trouble in attaching the file. I tried to be as exact as I could on the dimensions and proportions, as this was the first time I've ever done something like that. I usually like to draw things out the old school way on paper with my t-square and architects ruler.

So my goal is to try to address some problems this room has. I know it is not a perfect room. Dimensions/proportions could be lots better, but there were a lot of obstacles like numerous support posts and massive microlam beams to support an open floor plan on the first floor plus a second story bedroom level. Don't get me started about the support posts ! Some of the subcontracts said they hadn't seen so many posts in a house our size !
Perhaps treating the 1st reflection points will do wonders and treatments for the rear wall. I'd like to hear what recommendations are made for the rear wall - there seems to be differences in opinion on whether or not diffusion would be effective when the seating location is less than 6' away.

BTW - I'm interested in making my own treatments. This is a hobby for me, so I get more out of when I put in my own sweat equity !

Thanks for looking - Bill

Benz's Man-Cave Drawing.pdf 98k .pdf file

Hopeful -
When listening to music, I try all three modes I have at my disposal( pure direct, dolby prologic II - music, and DTS Neo-music) and go with the one that sounds most pleasing. My music input is analog regardless of the source, so sometimes engaging a surround mode causes a loss in detail that isn't always worth the trade-off for a larger, deeper soundfield. Maybe some of that has to do with my processor/receiver, an old Denon 5803.

I think it would be wise to invest in some measurement gear - you make a good point. No sense in trying to heal a patient when you don't know what's ailing them ! I've heard of REW and I believe there are others for software. I have no microphone that's decent. I have YPAO setup mic that came with a mid-level receiver back around 2005 that I could use, but not sure of the quality, and if I can find a calibration/compensation file for it. As far as computers go, I have a ASUS laptop I bought a year ago that has a Core i5 processor and 4 GB of memory. Don't know if the onboard audio chip that it came with matters much for this kind of work. Advice on this part would be helpful too. Another option I've thought of that is a bit pricier would be to buy an Anthem MXR300 receiver. Considering that it comes with what seems to be a decent microphone and stand, plus their ARC software, I could see running ARC, looking at the graphs, then working out what treatments are needed, install them, and then measure again, and then finish off with with deploying the ARC solution in the receiver.

What I'd like to improve ? Not sure. I know the bass response in room is uneven. I believe there's a nodal peak around 60 Hz and above 100 Hz the response drops off again, making the bass sound anemic for music, but on movies the LFE channel always seems potent enough for explosions and effects. I've managed to reduce the bass buildup in corners by piling up bales of fiberglass insulation in the corners behind the screen wall. Before I put that back there, there was a very noticable difference in loudness when I walked from the center along the rear wall to either corner. The same applies to the seating area. I'd like to see if that also improved the octave to octave response from 30 to 120 Hz.

Dennis -
Thanks for the input.
1) Yup, know that. Ideally, the L/R mains should be farther away; 3 to 5 feet or more from rear and side walls. My room's dimensions don't allow for that - if I moved them farther away from side wall, they'd block the screen; farther away from the wall behind and they'd be getting perhaps too close to the seating location. As located now, they form an equilateral triangle with the seat closest to the middle seats.
2) Yes, they're not timbre matched, if you define that as having the exact same driver complement for L,C and R. The center is from the same manufacturer, Vandersteen, and according to the designer, this center was designed to mate with the 2Ce i have. I think the design goal of the center, which uses a concentric woofer/tweeter was to have even lateral freq response, but my ears can tell me that the two don't match.
3) The surounds are monopoles and are above seated ear height (about 6.5' off the floor), slightly behind the row of seating and angled towards the row of seating. (also, the drawing doesn't show it but the recliners are designed to fit together in a gentle arc). I used to have a pair of dipoles (NHT HDP1s, I believe) but they were designed with limited HF response (made before we had discrete full range surround channels for home) that I didn't care for. Rear surrounds - same speaker, same height about the floor. I'm not convinced the rear surrounds are doing more harm than good. Save for the ocassional guy's movie night and with the kids moved out, it's just the two of us (or myself) watching movies in the center two seats. Things that I can ascribe to having the rears engaged is that I hear better panning from front to rear and from the sides and around behind the listener. This includes discriminating or highlighting directional tracking along the side walls,between the fronts and the sides, and to the rear or right down the middle of the room overhead when called for. I also hear more layers of sounds between the center and the L/Rs, and also between the L/Rs and my seating location, as if I had an extra set of speakers on the walls (and ceiling) between the surrounds and the mains. That's what I hear; If that's mucked up, then I can't say that I notice something is horribly or drastically wrong with it. A sonic mess isn't the last thing I would call it as the soundfield is very discrete and yet seemingly integrated, when called for. Granted, this doesn't happen with all movies, as some have better, more active surround mixes than others, especially with the newer HD codecs from Dolby and DTS. In summary, I'm pleased so far with the addition of the rear surrounds.
4) Yes, I can tell by ear or with my RS SPL meter that the bass response varies around the room. Have read here online that it is tricky and takes more work to balance more than one sub in a room, I've stayed away using multiple subs. I will admit that adding the bundles of fiberglass insulation to the tricorners behind the screen has resulted in decreasing the variation from location to location. Once I have some tools, we'll have a better understanding of what actually is going on.

And yes, your final comment is understood - information from the tools doesn't fix anything if you don't understand what they mean or how to fix them. I deal with that sort of thing all the time in my day job (IT technical support). To use a medical analogy - I can look at my blood work results, but without my doctor's knowledge and understanding to interpret it for me, I cannot by myself figure out if I'm healthy or have some sort of disease or deficiency.

Thanks for the preliminary response. I'm anxious to learn more.
Bill

Thanks for all the suggestions.

Rosso -
How much isolation do you need/want ? There's always a cost/benefit ratio to consider.
Walls/Ceiling: The drywall sandwich is hung on resilient spring channels with isolation clips for both the walls and ceiling and all cavities are stuffed with fiberglass insulation. I can't personally vouche for how well that was installed, as I had a builder's crew and subcontractors do the work and was not there to inspect the work before or as the drywall was hung. More could have been to insure the wall framing and drywall was decoupled from the first floor's floor joists ( = ceiling joists for the basement HT) so there is physical transmission going on between floors.
Ductwork: we have one line in to the room for heat and I had duct liner installed for about 10' from the vents back towards the furnace. Same goes for the cold air return.
Windows: the room has one exterior wall, half of which is above ground. It has two 25"x36" double-pane argon filled casement windows (we live up here in the frozen tundra where winters are long and cold). Window treatments are duet pleated blackout shades.
Door: I did not go to the trouble or expense to put in a sound proof door to the room. I went with a solid core door and weather striping. .

So, how did it turn out ? I'm playing Pixar's "The Incredibles" on Bluray at the moment with the volume on my Denon 5803 at -10. If you aren't familiar with this movie, there is a lot of deep, powerful bass whenever Mr. Incredible does battle with the Omnidroid robot. My SVS Pb Ultra 13 in 20 Hz tune is capable of wall-shaking, pants -flapping pressurization of the room . As I write this I'm sitting in the room directly above with the TV on. Only the really deep bass is coming through with some vibration of the floor. Other than that, I can't hear anything else - no dialogue, no music. No sound is coming through the HVAC ductwork. On the flip side, in the room, I can hear some footfalls (when first built, I don't remember hearing footfalls from the 1st floor) but not much else. Outside noise suppression is fairly good - when we have summer thunderstorms, thunder claps are pretty muted and are barely heard over the sound of whatever I'm watching.

Dennis -
Some speaker details:
L/R Vandersteen 2Ce
Center - Vandersteen VCC1
Surrounds: (4) Klipsch Reference Satellites model RSX 5
Surround Side speaker elevations and angles: 6'1" above the floor, tweeters are 6'8" above floor (distance to soffit above is 12") Angles: Horizontal ~ 15 deg toward listening pos, Vertical ~ 20 deg downward
Surround rear elevations and angles: Same height as sides, same vertical angle; horizontal angle - pointing straight ahead (0 deg)

Single sub preference ? - at the time I didn't want to deal with the complexities of positioning and calibrating two subs, so I went with one. If I added a second sub, does it need to be identical ? Are the current room correction software programs such as Audessey XT32 or ARC capable of addressing/fixing my room bass response issues if I stayed with a single sub ?

I realize some problems are caused by this mixture of speakers I have. I realize it would be ideal to have all timbre matched speakers in a 5.1 or 7.1 system and to run dual subs, but for the time being I'm going to have to make do with what I have. I'd love to get new speakers as most are now 20 years old but we're trying to watch what we spend. We're in our mid 50's with retirement not too far off, so we're putting as much money as we can towards extra payments on our mortgage and keeping our credit card debt at zero. So I'm going to aim for being smart and do what I can to improve the sound with a small investment relative to swapping out most of my gear.

Bill

LBNL -
Thanks ! added to my bookmarks. Easy first question - will I be able to put together REW and a suitable USB microphone with just an ordinary laptop, or do I need to get a desktop computer with a dedicated soundcard ? For home computers, we only have an iMac and an ASUS laptop (it does have a microphone miniplug input)

Bill

Thanks for the replies. I started doing some reading - lots more to go. I plan on ordering that mic soon too.

Bill

This week really flew by and I still need to order the USB mic and download REW. I looked at the dayton UMM-6 mic that gets a lot of recommendations for a good low cost quality mic for this task. It comes with a small table-top tripod stand. Would it be a good idea to pick up a floor standing mic stand ? Being that I should be placing the mic at seated ear height and taking multiple measurements every couple of inches, trying to balance that little tripod stand on top of the recliner's head cushions seems like a headache.

Bill

Thanks Tim. I saw a nice tripod mic stand with adjustable boom on PE's website for about $20. Am I correct in assuming that the umm-6's mic holder can be removed from the mini tripod mic stand and threaded onto any boom mic stand ? Most of the mic stands I saw for sale at PE did not appear to come with a mic holder but seemed to end with a threaded coupler. I'm totally new to this type of product, so bear with me. Last thing I want to do is order stuff, wait a week for shipment to arrive, unbox and assemble only to realize I need to order one or two other items to hook it up !

Also, I've been reading up on what I need to connect my laptop to my receiver/pre-pro. My old Denon 5803 is pre-HDMI, so I believe my only option is to use a mini-plug to RCA L-R cable to connect from the headphone jack on my laptop to a AUX input on the receiver - correct ? I have one in my box of misc cables, but it's only about 3' long. Maybe I'll order a longer one ~ 20 ft to give myself some flexibility in setting up the equipment. My HT equipment rack is outside of my room, so I have to factor in all the cable lengths (max USB cable run from boom mic to laptop: 15'; max RCA cable length from laptop to receiver: 20 to 25')
Am I covering my bases pretty well so far ?

Bill