SL3 System Upgrade Step 1 - Sound Absorption

[Erictrostatic]

Hello all, haven't logged in for months and just realized the new format. Nice.

I plan to add sound absorption panels to my SL3 based system as the first step to achieve these:

1. Bring out and tighten the bass
2. Make the overall sound fuller, it's a bit thin right now if you know what I'm saying
3. Achieve a true representation of the musical instruments (is it called tonal balance?)

What panels do you use? (Cheap and good)

Where do you put the panels on the side walls? Should they cover all the way from the floor to the height of the speaker or just the length of the electrostatic panel?

What about the front wall? Should they be sound columns instead of panels? Right behind the speakers, or somewhere in between, or in the corners?

Edit: Room size is 11'4"W x 17'10"L x 8'10"H. Speakers on 11'4" side. Floor to ceiling glass (with blinds) behind the speakers. No wall behind listening position.

Eric.

 

[kach22i]

1. Directly behind the speakers diffusion panels or plain old drywall. I built a special wall of thin plywood with a few tiny holes (to absorb excess bass), homosote backer, batt insulation infill and a offset (from the surface) of perforated metal (DIFFUSION PART). I know that sounds complex - just call it a wall.

2. In between the speakers absorbtion panel floor to ceiling (or close to it). The reason is the worst thing you could have between your spekers is someting reflective - The center stage (vocals) are trying to combine here to create an illusion - reflecting them they will cancel out and recess the vocals. I drape a heavy wool blanket over the TV for serious listening.

3. Speakers located on the narrow wall or long wall - not a huge difference. Unlike conventional speakers, the stats have a narrow focus beam of sound, even the curved ones like M/L. Therefore catching that first reflection is not such a big deal, would be nice - just not as important as you might first think.

4. The wall behind your head; get lots of absorbtion there, some diffusion mixed in would be okay so it's not so dead sounding (people claim that records are perfect). I'm stuck with a stupid mirror over the fireplace behind my head - the wife won't let me move it. I covered it once - big improvement but almost broke valuables sitting up there.

5. Corners; wall to ceiling intersections.........the typical stuff will help. That is to say absorbtion, reflection and concial/radial diffusion where you can get it without costing you an arm and a leg or looking like a nut. One stereo store I used to go to placed shirt carboard triangles in the ceiling corners - cheep, and it didn't hurt either. I built my own quarter round - corner absorbtion/diffusion tower.

6. Watch for glare or reflection off the coffee table, floor and ceiling just as you would for the side walls.

7. Under the speakers is important. The upgraded feet/cones help. However all that mechanical/sonic energy is transfered to the ground/floor. Absorbing that energy with a sand-box "Bright Star" or other speaker pad is very effective. It can suck too much energy or life out of the cabinetry - can fine tune with metal plates or concrete cutting disks.

8. Lots of articles on this stuff do a Google search. People will ask you about your room layout and dimensions - post it now and save us all some time in asking.

9. Look up the "flash light" method for "toe-in" in the tweeks/tips area - it works. Nearfield or farfield listening - just keep your head in the middle.

 

[Erictrostatic]

7. Under the speakers is important. The upgraded feet/cones help. However all that mechanical/sonic energy is transfered to the ground/floor. Absorbing that energy with a sand-box "Bright Star" or other speaker pad is very effective. It can suck too much energy or life out of the cabinetry - can fine tune with metal plates or concrete cutting disks.

This is the most interesting point among all your detail and helpful illustrations. Not sure what you mean by "sand-box Bright Star" but I'll google it. I do have thick carpets under the speakers, perhaps the carpets absorb too much low end and thus the bass sounds muffled even with spikes.

It just came to my mind, perhaps I could try putting the speakers with spikes on the pad or just put a pad in between the spikes while the spikes still go through the carpets.

1. Directly behind the speakers diffusion panels or plain old drywall.

2. In between the speakers absorbtion panel floor to ceiling (or close to it). The reason is the worst thing you could have between your spekers is someting reflective - The center stage (vocals) are trying to combine here to create an illusion - reflecting them they will cancel out and recess the vocals. I drape a heavy wool blanket over the TV for serious listening.

What is the major difference between directly behind the speakers and in between the speakers? Is behind to prevent standing waves and in between for imaging? What about drapes covering the WHOLE wall, too much?

 

[kach22i]

What is the major difference between directly behind the speakers and in between the speakers? Is behind to prevent standing waves and in between for imaging? What about drapes covering the WHOLE wall, too much?

Go into any high-end store, you will see them use something centerstage, then listen. Sometimes they just hang a quilt on the wall - also gives you something to stare at. The theory is something I understand but can't explain - so I'll let someone else give it a shot.

Drapes are nice, sound shoots right through them (typicaly) but you can hide stuff behind there that will make a difference. Everything makes a difference one way or the other, finding that magic balance is an art.

I ran out of wood for my sand boxes - which I had Corian tops on them. The aluminum foil is cheap shielding (see holes in base top) - they once had equipment sitting on them, but the speakers needed it more.

 

[kach22i]

Things are tight in my house - I cover the TV with a heavy wool blanket and place a big couch pillow on top of the TV leaning on the oak wall with the perforated metal.

The oak wall is very complex in theory but simple in construction, I'll go into it later. There is acoustic foam behind the wall which covers the stairs behind it.

Have you ever heard M/L's with no wall behind one speaker, and a full wall behind the other? It does not work very well - that's why I have the oak/grided wall.

In the picture you can see my "quarter round" acoustic absorber/reflector - that's a nasty corner without it doing it's thing.

 

[kach22i]

The wall behind the listening position - trust me there is an aweful mirror above the mantle. The turntable sits on the concrete/brick pad in font of the fireplace - tweeked that sucker to the max, sounds better than it looks.

 

[zaphod]

2. In between the speakers absorbtion panel floor to ceiling (or close to it). The reason is the worst thing you could have between your spekers is something reflective - The center stage (vocals) are trying to combine here to create an illusion - reflecting them they will cancel out and recess the vocals.

hi,

well isn't that interesting. one of the things i've been trying to do is solve the problem of my soundstage being mostly behind the CLS. it's deep, but it's set back in all but the best recorded soundstages.

in my recent room overhaul i removed the drapes that covered the back wall. they were dark, ugly and deadened the whole room.

but i suspect that they were also counteracting the effect of the TV that sits bang between the speakers just like yours sits. tonight i'm going to put a duvet over the beast.

wish me luck, my wife really likes watching "House, MD" so this will be an uphill battle

 

[Erictrostatic]

Lots of pointers there. I'll first attack the under speakers and then the front wall. Not likely to do what you have done to your room. Consider the dreaded mirror to be your license to your oak wall!

And oh, that's Golden Tube. I have seen it many times but never registered the name. And hey, I have the same rack.

 

[zaphod]

tonight i'm going to put a duvet over the beast.

wish me luck, my wife really likes watching "House, MD" so this will be an uphill battle

well.

well well well.

i put a duvet over the TV, and then a BIG pillow between the speakers on a shelf behind them. Then i put on the music.

well well WOW.

my soundstage moved from high and back to down and forward. just a wonderful tweek. made me stay up far too late listening.

i added and subtracted "soft stuff" until i came up with a happy medium. functional, but not too ugly. i left it up, we'll see what my wife thinks today, but there haven't been any phone calls, so either she didn't nothice or she didn't watch the morning news before going to work

Eric - thank you very much for this tweek, it has really made a difference.

 

[kach22i]

i put a duvet over the TV, and then a BIG pillow between the speakers on a shelf behind them. Then i put on the music.

well well WOW.

I should of warned you that you can put too large or cushie of a pillow up there and suck all the life out of the music.....experiment.

Also I've accidently left the pillow up there covering the air holes for the TV overnight - a fire hazzard! TV's are always on if plugged in even if turned off.

Try this when the wife leaves the house..........unplug the refrigerator...unplug the computer....unplug the TV.........close all the doors in the house....and turn off the lights......let the music begin.

PS: You will have to plug everything back in before the wife comes home........just too many questions to answer half bent over running around the house.

 

[zaphod]

I should of warned you that you can put too large or cushie of a pillow up there and suck all the life out of the music.....experiment.

yep, at one point i had a big duvet on the TV, and two very large (3'X3') and thick (1') floor pillows stacked on edge on top of each other. this got me soft from floor to ceiling, but no bang, no life.

So i took out some. I ended up with a pair of 3 foot long cylindrical "bolster" pillow (such as you get with a futon) standing on end and a thick standard feather pillow on end, edge toward the listener and propped between the bolsters. I am certain that the shape of this arrangement helped. here is a sketch looking down.

This really placed the soundstage where i want it. On a more permanent basis, i think i'll build something more attractive later, probably a semi-circular thingy.

I think that adding something over/in front of the TV would be good, but i can do that for "serious" listening just like eric does with the wool blanket.

the other thing that i noticed is that not only the placement of sound but the quality of the sound, particularily jazz/latin percussion was greatly improved. the drums were a lot more resonant, much much more. Near the end of Joe Jackson's tribute to New York Night and Day, the drums (all hand work) leap to sit beside you on the left. Last night not only did they return to that position, but they sounded great.

PS: You will have to plug everything back in before the wife comes home........just too many questions to answer half bent over running around the house.

only if i am - what was that term? - al fresco ...

in the plans is to get a couple of balanced power isolation transformers and build myself some boxes to truly get removed from the furnace/fridge/computers/microwave/oven ...

 

[kach22i]

On a more permanent basis, i think i'll build something more attractive later, probably a semi-circular thingy.

There are some handsome units from RPG?

Audio Advisor used to sell them, this is what they carry now:
http://www.audioadvisor.com/store/categorylisting.asp?hdnCat=Acoustic+Treatments&sel=1&CategoryID=2

Yep - RPG is the name alright:
http://www.rpginc.com/residential/index.htm

Got it......one of these centerstage outta do it (see pro-audio section):
http://www.rpginc.com/products/profoam/index.htm

 

[Jeff Zaret]

Zaphod & Kach22i.

I will also add a bit here as far as rear reflection that I got from Jim Power at ML. Also, this is very high on the WAF. He told me for years when they would do shows and and had to improvise as far as setting up a room correctly for reflection they would use something that is fairly cheap and pleasing to the eye. He told me this when I was having trouble some reflection with my Sequel II's. Get some hanging plants (Ferns are good) real or fake and put them behind the panels. This reduces and somewhat displaces the back-wall/rear type of reflection from the panels when they have to be placed closer to the wall than is optimum.

I used some floor standing trees, silk trees. I think they were kind of like birch but that is a guess and it worked very well. It was not perfect but did help a lot and if I had a wife (just a female dog at the moment but looking for female voluteers with two legs) , it is a fairly good compromise.

I did try them on my CLSiiZ's and I actually liked it better without it. When I got the CLSiiZ's I put them in the same location the Sequel II's were in so it was a fairly good comparison. The amount of reflection is minimal with the CLS's now because I angled them more than before and I can live with it........................ for now.

Jeff