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Discussion Starter #1
Sonnie, I was looking at pictures of your home theater, specifically at the accoustical panels.
  1. Did you make them?
  2. If so, what did you make them out of?
  3. And how did you determine where to put them?

JCD
 

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I was almost scared to open this up in fear of reading some redneck hillbilly joke... whew!

1. No.
2. Refer to answer #1.
3. I guessed?

Okay... seriously... I got those from Acoustics First and they are their Respond panels. At the time it was the cheapest place I could find them. Still not so cheap and I'm sure if you have the abilities you could build them for less.

I really had no ideas where to place them but from reading around I decided on the first and second reflection points on the side walls and then the rear wall directly behind the speakers.

But as I've stated elsewhere... I really couldn't tell any difference in the sound. I wasn't having any echo or too liveliness problems or at least I don't think I was. I merely wanted to see if it would help my sound. Yet, my ears are not that critical so they could be helping and I just don't realize it that much.
 

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Discussion Starter #3
Sonnie, I wouldn't make any cracks about you being a redneck hillbilly. :dontknow:

OK, I'm lying, I would and probably will eventually.. I have been known to be a little, umm, sarcastic/acidic/etc with my humor. :devil:

But, back the issue at hand. I'm going to be building some panels for my listening room and wanted to get some feedback from your experience.

To that end, I have a few follow up questions:
  1. Are they 1" or 2"?
  2. Did you play around with the placement at all?
  3. Is there a space between the wall and the panel?
  4. Did you play around with this at all?
I've heard of two tricks for the placement of the panels.

The first is to use a mirror pressed against the wall and have someone else slide it on the wall until you see the tweeter from your sitting position. As soon as you see the tweeter centered in the mirror, that will be the dead center of the panel.

The second trick is to put a little bit of space between the panel and the wall. I think I've seen that 2" is the most effective, but I can't imagine I'd ever do that -- low WAF, claustrophobia (the walls are caving in!!:laugh: ). But maybe 1"?

JCD
 

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You better not... :nono:

1. 1"
2. Nope
3. Nope
4. Refer to #3

I did the mirror trick from my front row center and second row center (not really sure you would actuall call that second reflections as I stated above).

I have read the same thing on spacing behind... it increases the absorbtion abilities. I think this is supposed to better trap the sound, but I'm not 100% sure on this, but it makes sense.
 

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Hey guys, The air gap is to lower the bottom range of absorbtion, but this isn't to be confused with increasing the absorbtion. I.E. Nothing will change at 1khz, but but you'll get better bass trapping at 80Hz. Same goes for using thicker material.

FWIW, I just stuck my first reflection panels flat on the walls and ceiling too. But I've got lots of bass traps in the corners and ceiling wall junctions.
 

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Discussion Starter #6
Derek said:
FWIW, I just stuck my first reflection panels flat on the walls and ceiling too. But I've got lots of bass traps in the corners and ceiling wall junctions.

How was the sound changed?
Or did you notice a difference?

Sonnie said he didn't notice a difference when he put up his panels, hence the questions to see if maybe a different placement may make a difference.

JCD
 

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When I put the side panels up I noticed a slight inprovment in imaging. Vocals were more defined. Nice but not eye opening.

The ceiling was a waste of time, but they sure do look cool in the room. Sonnie and I have the same speakers which have very limited vertical disspersion. Sitting or standing makes a big difference. I actually have mine on stands (these are 40"+ towers)

Side wall and ceiling panels set me back about $150, and it was fun. It did make the room "deader" and it was pretty live to begin with. A lot of slap echo.

Bass traps: I feel about these like others feel about PEQ's. I wouldn't have a room without them. HUGE improvemnet!!!! Even the wife wants bass traps in the family room (2 channel system) when we remodel it. I'll never have another system w/o them.

All in all I'm very happy with the sound in my room. Like Sonnie, I'm not really a critical listener though. Been there in years gone by, but now I just enjoy the music or movie not the equipment.
 

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Those RM30's also have very limited horizontal dispersion unless you got the waveguides installed.

Funny you mention putting them on stands Derek... I can simply lean my head over or slump down in my chair and the highs seem to come more alive.

Another thing to keep in mind JCD is that I had no slap echo at all before installing my panels. I also have my RM30's toed in and pointing directly at the center listening position so I would have less reflection off the side walls as a result of toe-in. Now when I get my new RM30's with the waveguides, it could be a whole different story. I may be thankful I have the side panels then. Only thing is I really won't know because although my panels are supposedly removeable... I have been unable to get them unstuck. lol
 

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Discussion Starter #9
I did remember about the relative 'deadness' of your room, but when I looked at the pics of your HT, it looked like the panels were a little low/out of place -- it's hard to tell from the picture. Anyway, if they could be moved, it's a free and easy tweak to play with -- I like both of those, free (I am a CPA after all :D ) and tweak (I enjoy 'playing' with my system:wave: ). Also, I have very limited first hand knowledge with accoustic panels, so I wanted to know how much of what I've "read" matches up with the real world. Especially since I hope to build some in the near future.

JCD
 

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Gentlemen:

I dropped off a dozen 2" x 2' x4' c703 rigid fiberglass panels and some "transparent" fabric at my favorite craftsman's upholstery shop today. He's going to make frames to avoid crushing the fiberglass and to facilitate affixing and stretching the fabric. I'm planning on 6-8 panels for the sidewalls and ceiling for "first reflection" points. The others will probably "front" my corner traps with acoustical cotton behind.

We have good readings on our dual sub FR without treatment and know our room is prone to slap echo. If we can tame the echo and clean up the waterfall plots on the bottom octave with the wall/ceiling treatments and corner traps, I think room eq wizard and my bfq2496 will help me take care of the rest. My hard goal is +/- 3db from 15-100hz, then killing any midbass nodes and reducing the reflective hash that reduces coherent spatial cues.

I've got a decent idea where I'm headed with this, but would appreciate any hints from others.

BTW: JCD, Roll on you Bears. Cal '79, living a bit south of the Bay Area but still a hoops season tix holder...
 

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Discussion Starter #11
jmprader said:
Gentlemen:

I dropped off a dozen 2" x 2' x4' c703 rigid fiberglass panels and some "transparent" fabric at my favorite craftsman's upholstery shop today. He's going to make frames to avoid crushing the fiberglass and to facilitate affixing and stretching the fabric. I'm planning on 6-8 panels for the sidewalls and ceiling for "first reflection" points. The others will probably "front" my corner traps with acoustical cotton behind.

We have good readings on our dual sub FR without treatment and know our room is prone to slap echo. If we can tame the echo and clean up the waterfall plots on the bottom octave with the wall/ceiling treatments and corner traps, I think room eq wizard and my bfq2496 will help me take care of the rest. My hard goal is +/- 3db from 15-100hz, then killing any midbass nodes and reducing the reflective hash that reduces coherent spatial cues.

I've got a decent idea where I'm headed with this, but would appreciate any hints from others.

BTW: JCD, Roll on you Bears. Cal '79, living a bit south of the Bay Area but still a hoops season tix holder...
Seems to me that you've got a pretty good handle on what to do.

Here are a couple of pictures of the first reflections you might want to look for:





Other than that, I have these:
1) Use the mirror trick above to place your panels
2) If possible, have a 1"-2" gap between your panel and the wall
3) The rule of thumb I've heard regarding treatments is that you don't want to treat more than about 35% of the surfaces
4) Try and diffuse sound at the back of the room

JCD

Oh, Class of '89.. Go Bears!
 

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Those panels of mine were really just right when I had my PSB speakers. Now that I have my VMPS RM30's they are too low.
 

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JCD, Cool.

jmprader, What size is your room? That seems like a lot of fiberglass. I have the equivalent of (8) 2x4 panels and it really deadened up my room. ~4,500 cubic foot. I just made 2x2 panels and mounted them in a square pattern, so I have some leway for speaker positioning. I don't think I'd want to add any more. I wish I'd framed mine, but this was quick and easy.

Here are some photo's. I'm sure there's a better way to show it, but I'm not good with computers.:blush:

http://home.earthlink.net/imagelib/sitebuilder/misc/show_image.html?linkedwidth=560&linkpath=http://home.earthlink.net/~afordfan/sitebuildercontent/sitebuilderpictures/acousticpanels2.jpg&target=tlx_new

http://home.earthlink.net/imagelib/sitebuilder/misc/show_image.html?linkedwidth=560&linkpath=http://home.earthlink.net/~afordfan/sitebuildercontent/sitebuilderpictures/guitarmounts.jpg&target=tlx_new
 

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Derek said:
JCD, Cool.

jmprader, What size is your room? That seems like a lot of fiberglass. I have the equivalent of (8) 2x4 panels and it really deadened up my room. ~4,500 cubic foot. I just made 2x2 panels and mounted them in a square pattern, so I have some leway for speaker positioning. I don't think I'd want to add any more. I wish I'd framed mine, but this was quick and easy.

Here are some photo's...
Good pics. Is that a duo of IB subs? Any vignettes on those?

Our room is just over 16x22 with a sloped ceiling (only about 10' at the peak vs yours which looks like 14-16'), so about 3500 ^3 . Very live, hardwood floors , a wood wainscoat and several windows. A thick rug and heavy velvet drapes help but...

We are going to start with just 4 panels for the "money seats", then the back wall and second row sidewalls and see where the point of diminishing returns is. The panels will be easily removable so that "she who must be obeyed", the chair of the interior decorating committee, can have it her way at times...

Some of the pros that post at other spots often advocate lots of treatment...I'm looking for improvements while maintaining harmony in the household until I can get the custom HT room addition passed by the appropriations committee (she chairs that one too :D )

I do appreciate hearing experience and opinion, it is a great help. Sometimes there are no right answers, sometimes there are several...there are always compromises and that's where the advice/experience of others makes a big difference.
 

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Discussion Starter #15
I wouldn't get too crazy with the treatments -- I've been in an over-treated room and I'd rather have it completely UNTREATED.

If you're going to start "slow", then I would go with treatments in the following order:
  1. Side Walls
  2. Front Wall (behind speaker)
  3. Ceiling
  4. Back Wall -- I've heard diffusors (as opposed to absorbers) are better on the back wall
Another fuzzy memory moment, but I think if a sound wave has to travel more than 12ft, the need for absorbers is not as important, hence the reason the back wall is last on the list.

I may have 2 & 3 reversed, so I'd experiment with the two locations. Of course if SWMBO has a preference...;)

JCD
 
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Hi Derek, on the bass traps.

You really like them but I see that they are quite some distance from your listening position and that they don't cover all the corners.

This is good news for me as I have been considering bass traps but was worried that I would need to have them in *all* corners.... and just wanted to add them as you have done. So I was wondering if you could explain the difference in sound that you experienced particularly in the context of IB bass being pretty 'clean' anyway.

Cheers
 

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jmprader, Thanks. Yes, I have a pair of IB's directly above my mains. Seperate 250w PE amps for them too. Same signal though. Sorry but I don't know what a vignette is. Wouldn't know one if I dropped it on my foot.

Rodn, I have a total of 8 RealTraps in the room. One in each vertical corner and two on each side of the room at the wall, ceiling transition. They didn't make the room live or dead, but they tightened up the bass and gave distinction to musical instruments. It took a lot of muddiness out. They do not impact the first octive, but there's not much music down there. Basiclly everything from above 40 hz up is pretty clean. Bass traps are about coverage, so I've considered adding some to the room, but I'm not sure were I'd put them that wouldn't look weird. If you only put a couple in your room, it won't make a difference
On a similar note, a friend had a vmps larger sub and hated it. Couldn't get it integrate well, it was boomy and easy to locate. We tried all kinds of settings, but it just never sounded right. I kept telling him it was his room (Horribly live) but he didn't believe me and wanted to condenm equipment. Finally I talked him into buying a Velodyne SMS-1 PEQ instead of a new sub. This is a very cool EQ with a graphic interface that shows your frequency response real time. He still believed bass traps were a waste of money. The EQ did a great job taming peaks and integrating the sub with the mains. He was able to see why his sytem sounded so boomy. It worked so good, I bought one hoping I could get the kind of improvment he did. It did not cure the problem of slap echo in his room from a bay window, hardwood floors, etc. Six months later I talked him into buying six GIK bass traps. These are simple fiberglass in frames, so they attenuated upper frequencies as well and they're cheap too. Echo was gone, upper bass was cleaned up and he ended up removing the SMS-1 from his system ( I think he should keep it and tweek it). He prefers the sound of his room now.
I ended returning mine a few days after I bought it. It did improve the sound, but not $600 worth. Don't get me wrong, I do believe in EQ's but for me they are the last compnent in the system to fine tune it. I have a Sherwood Newcastle Pre-Amp with built in auto EQ, and if they ever get the software de-bugged, it's gonna be icing on the cake. I have one big peak at 25hz and one big dip at 35hz. After ~40 Hz it smoothes right out.
Oh yeah, IB's can sound boomy depending on the room acoustics. What they do is play "effortlessly" and "fast". Yes, 50 Hz is still 50Hz, but the cone can start and stop with less resistance when there is no box. There's less distortion when the cone hardly moves because there is so much surface area moving.
 
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Ok seriously Where do you get 703? i need some bad. or Roxul, here in florida NOBODY that ive talked to has it. And they all want me to order like, a metric ton of it and wait 7 weeks... so where do you guys get it?

Thanks alot
Chris
 

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Discussion Starter #20
It is really hard to find locally.. the primary purpose of the OC 703 is to insulate HVAC ducting, so I'd call the local HVAC suppliers in your area.

I ended up buying mine at http://expressinsulation.com/. It wasn't Owens Corning, but an equivalent from another maker.

Be prepared, the stuff is a little pricey. As I recall, one 2x4x2 sheet was about $13.50.

Good luck.

JCD
 
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