Accidental Room Treatments

DarqueKnight

I have been installing steel tweeter brackets in my SDA's. Bracket installations in three pairs of CRS+'s were completed last Tuesday and brackets were installed in my SDA SRS 1.2TL's last night.

I really wasn't expecting much, if any, sonic improvement. I just wanted a better mechanical connection. After the brackets were installed in the first pair of CRS+'s, I was immediately surprised at the improvement in bass detail and image weight. However, I will save those details for a later thread after the brackets are installed in the SDA SRS's in my home theater system.

After I completed installing brackets in the right 1.2TL, I sat down to listen and immediately wondered what the hell happened. There was more vibration coming through the right armrest of my seat. The bass was a little more defined. I wasn't astonished at those things. Based on my listening sessions after the tweeter bracket installations in the CRS+'s, I had some expectation that I might hear similar things with the 1.2TL's.

I was astonished at the dramatic increase in clarity, detail, depth and image weight at the sides of the sound stage. Some synthesizer and guitar sounds on both sides moved two feet forward. I knew it couldn't be due to the newly installed tweeter brackets on the right because I was also hearing increased image weight and depth on the left. After staring at the sound stage for a few minutes, it dawned on me what might be going on.


Figure 1. I accidentally found out that SRS grilles make great acoustic panels.

Usually, when I take my SRS's apart, I put the grilles far out of the way, usually in the next room. This time, I placed them against the wall next to the speakers. When I did put the grilles in the next room, the image weight and depth at the sides went back to previous levels.

I have always appreciated the sonic improvements brought by room treatments. I just don't like the way most of that stuff looks. If I had a dedicated listening room, I wouldn't care about the aesthetics of room treatment. Since I don't have a dedicated listening room, I do care about aesthetics and I really don't want that mess in my living room. In 2007, I began researching room treatments to see if I could find something that performed well and that didn't crack the proverbial mirror. Auralex panels were the most aesthetically pleasing solution and they had a good performance reputation. In January of 2008 I sent my room dimensions and sketches of my stereo equipment and speaker setup to Auralex and requested a free room treatment analysis. I dug up that analysis and found that the arrangement of the grilles shown in figure 1 is where Auralex recommended I place two Elite Pro Panel C24 acoustic panels. They also recommended a third acoustic panel between the speakers in addition to the placement of Venus Bass Traps on the wall above each speaker (where the wall and ceiling meet) and on the wall behind the listening seat.

I thought the appearance of the C24 panels was tolerable, but the bulky, "anechoic chamber" look of the bass traps was totally unacceptable for a living room environment. I would only use those in a sound studio or a dedicated listening room.


Figure 2. A third makeshift "acoustic panel" filled out the sound in the center of the sound stage.

I got a third grille from one of the SRS's in my home theater system and hung it on the wall between the speakers as shown in figure 2. The resulting increase in center clarity, detail, weight and depth was commensurate with that experienced on each side. The improvements in clarity, weight and detail are apparent even when listening from an adjoining room, but of course, not to the extent as when sitting in the stereo sweet spot.

I listened for two hours and then went and shopped around for a good price on three Auralex C24 panels (2 feet x 4 feet x 2 inches) in the "sandstone" color. The SRS grilles are staying in place until the Auralex panels arrive.:)

The "room tax" on an audio system can be quite substantial. My living room does not have horrible acoustics, therefore I was never interested in hearing what my living room's "room tax" assessment was on my audio system. I knew that I definitely wasn't going to turn my living room into an anechoic chamber. Now, after being "tricked" into hearing what a substantial reduction in room tax sounds like, I can't go back. If speaker grilles placed on the wall sound this good, I can't wait to hear what an engineered product will sound like.

The thought did cross my mind to DIY three panels. If the Auralex panels are not a substantial improvement over the grilles, I might make my own.

More later...

Face

http://www.gikacoustics.com/gik_artpanel.html

DarqueKnight

Mike,

I had read some of your posts on the GIK panels. The 242's seemed interesting until I saw that they were nearly 4 inches thick. Still, I am considering ordering three of them to compare to the Auralex C24 panels.

Conradicles

I installed Auralex panels a few weeks ago and was very pleased. FYI...I always put the grills for my SAD-1C's like that when I listen to them naked.

Face

DarqueKnight wrote: »

Mike,

I had read some of your posts on the GIK panels. The 242's seemed interesting until I saw that they were nearly 4 inches thick. Still, I am considering ordering three of them to compare to the Auralex C24 panels.

Yes, but the increased depth makes them more effective at lower frequencies.

pearsall001

I have 4 of the 244 (nearly 6" thick) panels & 2 of the Monster bass traps (over 7" thick). I can attest to the build quality & the performance of the GIK products. There was an immediate audible difference in the room. All for the better of course. Give them a whirl, I'm sure you'll be very pleased with the results.

Now I'm actually eyeing their new Diffusion panels. Room treatments have such a profound impact on a room that it's almost hard to believe until you experience it first hand.

mdaudioguy

A chance discovery of a positive nature is always nice!
Good thing those tweeter brackets were a change for the better, huh? You'd have probably spent hours finding a better material or design. Nice looking room there. I only wish I was far enough along that room treatments were a concern.

DarqueKnight

Face wrote: »

Yes, but the increased depth makes them more effective at lower frequencies.

OK. I'll go ahead and order a set and see (and hear) for myself.

DarqueKnight

mdaudioguy wrote: »

I only wish I was far enough along that room tr:peatments were a concern.

Be careful what you wish for...particularly with regard to THIS hobby.;)

Toolfan66

Mike,

So is the panel it self only 2" thick with a 2" space behind them?

Face

Close: http://www.gikacoustics.com/gik_242.html

I have 6 of these: http://www.gikacoustics.com/gik_244.html

2 of these: http://www.gikacoustics.com/gik_monster.html

And a pair of PI Audio Group diffusers behind the listening position, but they're no longer made.

I may pick up another pair of the super thick traps and stack them to the ceiling, but I'm happy with the sound as is.

Vette C6.r

Love those floors DK.

organ

Awesome set up man! Glad to hear your room treatment is working. I'm sure it should improve even more once you get the Auralex there.

Please don't laugh. I don't know about SDA speaks. Are those amps on the front of your speakers? Powered woofers?

agfrost

organ wrote: »

Please don't laugh. I don't know about SDA speaks. Are those amps on the front of your speakers? Powered woofers?

Plates to which the crossovers are mounted.

organ

AAaah Thanks! They make the speakers look so cool.

SCompRacer

IIRC, GIK offers Guilford of Maine fabric in 48 colors as an extra cost option to match your decor.

I have four GIK corner Tri-Traps and three GIK 244 traps behind my dipole speakers. My wife picked the color, Silver Papier.

organ

Amazing set up, guys! So much space:cool:.

mmadden28

DK, what is it about the panels do you think made a difference?

I guess it would have to be the fiberboard frame since they have an acoustically transparent fabric covering right?

I wonder, since the frame is not solid, if might hear a difference by moving the L & R frames up a little higher.

How close are your SDA's to the wall?

Man, if something as simple as a grill cover (at least wrt how these are built) can make an audible improvement--Polk should pack some extras in the box for just such a use. :cool:

It is pretty cool when you accidentally stumble upon something like that--I had a similar experience where I was listening to my rig in the basement, and my son opened a nearby door (~20') to the HT room and the overall sound changed dramatically. I knew then that something as simple as a door being open or closed could make a big difference in how my rig sounded.

headrott

That's quite a coincidence Raife! I was doing the same thing with my 3.1TL grills. I used to put them far away from the speakers, until I thought about it and started moving them to the side walls facing the side of the speakers. I then moved them to approximately the same place you had yours in the picture. This is where they made the biggest difference. Although they made a nice difference on the side walls as well, but not as substantial. I will have to try one in the middle of the 2 speakers too.

I should really do it right and order some "real" acoustic panels for my room though. Thanks for sharing your find, it substantiates what I hear as well. Another great post DK.

Greg

Toolfan66

Room Treatments are the shizznits.. I like mine but I want to go with the bass traps and 4" panels..

joeparaski

Ok ok....I gotta ask........just how much "increase in clarity, detail, depth and image weight at the sides of the sound stage" can you get with those speakers?? It seems every time you do something to them they improve. Have they not yet peaked in what they can do? I know this is a room treatment thing this time, but how many more levels of improvement can be had from the SRS? The more you improve your SRS, the more I get the feeling that mine are crap.

Joe

DarqueKnight

mmadden28 wrote: »

DK, what is it about the panels do you think made a difference?

I guess it would have to be the fiberboard frame since they have an acoustically transparent fabric covering right?

I only have the most basic understanding of acoustics. This is on purpose because I know how my mind works. In-depth acoustical study would lead to experimentation. Experimentation would lead to my living room looking like an anechoic chamber.

I do know that acoustical transparency of a sonically porous barrier depends on the sound frequencies and on the proximity of the barrier to the sound source. The acoustical transparency of speaker grilles is somewhat analogous to a black mesh window screen. If you put your nose against the window screen, it becomes invisible. If you stand back a foot or more, the screen becomes visible and darkens and obscures the view behind it.

A speaker grille covered in a thin, lightweight fabric is transparent (or nearly transparent) when it is right next to a speaker's radiating surface. When the grille is placed far enough away from the speaker's radiating surface, the fabric becomes absorptive.

The grille panels are reducing wall reflections behind the speakers, so I am not hearing as much of the rear wall's reflective influence on the direct sound from the speakers.

Based on the improvement I am getting from my accidental acoustic panels on one wall, I expect that the results for a whole room acoustic treatment would be spectacular...but that will have to wait until the next house with its dedicated listening room.:)

mmadden28 wrote: »

I wonder, since the frame is not solid, if might hear a difference by moving the L & R frames up a little higher.

I wondered the same thing myself.:) Actually, the room treatment plan I received from Auralex specified that the C24 panels adjacent to the speakers be placed 16 inches above the top of the speaker.

After the shock of this recent sonic revelation wore off a bit, I went back and carefully re-read Auralex's treatment plan. After putting the grilles up 16 inches on the wall (figure 4), I heard further increases in image weight, clarity and ambient details at the sides, and surprisingly, in the center also.


Figure 3. This was a great improvement.


Figure 4. This was an even better improvement. The panels shown here are in the locations recommended by Auralex.

To illustrate the improvement the change in panel placement provided, consider the following: The soundscape for the song "When we come together" from saxophonist Jackiem Joyner's "Lil' Man Soul" CD consists of percussion instruments in front of the left speaker, an organ next to the inside edge of the left speaker, an electric bass to the right of the organ, a drum kit in the center, flutes and percussion instruments in the center behind the drum kit, and alto saxophone in the center and three feet in front of the drum kit, an electric guitar to the left of the right speaker, percussion instruments in front of the right speaker, and an acoustic piano five feet in front of and two feet to the right of the right speaker. Added to all this is an envelope, or "cloud" or synthesizer sounds in the speaker plane that stretches from two feet to the outer side of the left speaker to two feet to the outer side of the right speaker.

With no acoustic panels (speaker grilles) on the rear wall, my ears are drawn primarily to the saxophone in the center and secondarily to the electric guitar at the right and the drum kit in the center. Everything else is clearly heard, but it all blends into the background. The piano sounds like a clump, or ball, of piano notes far to the right that is about three feet wide.

With the two speaker grilles resting against the wall with their bottoms on the floor and with one grille in the center, all instruments sound heavier, louder and clearer. The piano at the right stretches out to five feet wide and sounds heavier and clearer. I also hear faint echoes of the piano notes in the right center next to the electric guitar. The organ and electric bass at the left of center have more edge and growl. The percussion instruments in the center rear and left became louder and more defined. The synth cloud became more three dimensional and moved forward from the speaker plane to envelope the saxophone.

Moving the side panels up 16 inches resulted in the side images becoming heavier and clearer and in further definition refinements to the growl of the electric bass and organ notes. The acoustic piano note echoes in the center right transformed from faint to clear and distinct. The synth cloud became a little heavier.

Auralex also recommended the placement of five Venus Bass Traps (figures 5 and 6) in the room. These traps are 4 feet wide x 2 feet high x 1 foot thick. One would be placed above each speaker and on the other walls. My mind won't even allow me to contemplate how these would look in my living room.


Figure 5. Auralex Venus Bass Trap.


Figure 6. Auralex Venus Bass Trap colors.

Big 4 foot x 2 foot wide blocks of red/green/purple/blue/orange/brown/black/plum foam in my living room? Guess what? No.

mmadden28 wrote: »

How close are your SDA's to the wall?

11 inches.

mmadden28 wrote: »

It is pretty cool when you accidentally stumble upon something like that--

It was like winning a small lottery prize.:D

headrott wrote: »

I then moved them to approximately the same place you had yours in the picture. This is where they made the biggest difference.

Since SDA's are designed to be placed close to the rear wall, I speculate that they are more sensitive to rear wall reflections than conventional speakers.

DarqueKnight

joeparaski wrote: »

Ok ok....I gotta ask........just how much "increase in clarity, detail, depth and image weight at the sides of the sound stage" can you get with those speakers??

It seems that there is no end to this Joe. There is always room for improvement. Sorry. I think that I am on a good path to hearing the full potential of my SRS's, but I don't know if I'll ever get there in this lifetime.

I have participated demonstrations of room treatments in dealer showrooms and friend's homes, but I never ventured to experiment at my home because I was afraid that my ears might fall in love with something hideously ugly.

This exercise has given me some keen insight into what could be achieved if I were to do a full room treatment program. Consider my example above with the piano to the far right. The piano sounded good being blended into the background. It sounded better when it was stretched out to life size. It sounded better still, and more lifelike, when I could hear the ambient echoes of the piano notes reflected from the right center of the sound stage.

joeparaski wrote: »

It seems every time you do something to them they improve.

Yes. It is wonderful to keep discovering new sound in old speakers. It is no different from taking an automobile that has a good, solid engine and chassis design and continually hot rodding it with better brakes, tires, and engine enhancements.

Another thing to consider is that my sound stage dimensions average 20 feet wide by 8 feet deep by five feet high. It is easier to pick up on sonic changes, even subtle ones, with an expansive three dimensional soundscape. The concept is analogous to it being easier to pick out differences in camera lens shapeness when photos are blown up to poster size or bigger.

joeparaski wrote: »

Have they not yet peaked in what they can do?

Nooooooooooooooooo. No. No. We (SDA SRS hot rodders) are probably not even close to halfway to reaching their peak potential. When I documented my last two channel system upgrade, I expressed my surprise that I really could not find anything I liked better than my SDA SRS 1.2TL's:

DarqueKnight wrote: »

The inscrutable monoliths have seen a lot of gear come and go over the years. They, on the other hand, just stand firm and get better with age.

joeparaski wrote: »

I know this is a room treatment thing this time, but how many more levels of improvement can be had from the SRS?

I don't know. Probably as many levels as there are in associated equipment and room acoustics. This question has been asked by me, other members of this forum, and by other SRS owners elsewhere. We are still searching for the answer.

joeparaski wrote: »

The more you improve your SRS, the more I get the feeling that mine are crap.

You should feel, and believe, exactly the opposite. My stock SDA's and SRS's were not, and did not sound like, crap. Crap can't be continually refined and optimized. Crap does not provide continually improving performance in conjunction with improved associated equipment. Crap remains crap no matter what you do to, or with, it. It is a testament to the brilliance of the SRS's basic designs that they can be continuously improved and that they are so positively responsive not only to modifications, but also to continual improvements in amplification, source component quality, cabling, and room acoustics.

I fully expected that I would be replacing my SRS's during my last two channel system upgrade, which was quite significant. The SRS 1.2TL's had the last laugh as they watched everything else, from cables to source components to amplification to the equipment rack, get REPLACED and sold off. The 1.2TL's retained their place and were upgraded.

You may find the following two threads interesting:

Link: How Much Money Can You Throw Into SDA's?

Link: People Who Love Big SDA's Upgrade To What?

hearingimpared

Ray, I have four inch foam pads, they are ugly green and my wife was going to use them to make a window seat.. One is six feet long the other four feet long. Whenever I listen to my rig I set them up in the corners that the speakers are on and always place the 1.2TL grills over them, mainly to keep them in place. I'm now going to have to see what they sound like with the grills over the foam and without. . . BTW I never listen to my 1.2TLs with the grills on!

This could turn out to be quite interesting.

DarqueKnight

Joe,

I look forward to reading your comparison results.

The only thing I would ask is that you do a scientific blind test in order to rule out your imagination playing tricks on you.:)

hearingimpared

LMAO! I don't keep the grills on while I'm playing music . . . why? . . . because in my head ANYTHING covering over the tweeters, drivers and PRs will affect the sound! I've never heard them with the grills on so I don't know if they would make a difference.

Now I could do a blind test with the grills over the foam pads in the corners but I think I would need to put wax in my ears so that I can't hear the person moving the grills off and on the pads.:rolleyes:;)

Conradicles

DarqueKnight wrote: »

You should feel, and believe, exactly the opposite. My stock SDA's and SRS's were not, and did not sound like, crap. Crap can't be continually refined and optimized. Crap does not provide continually improving performance in conjunction with improved associated equipment. Crap remains crap no matter what you do to, or with, it. It is a testament to the brilliance of the SRS's basic designs that they can be continuously improved and that they are so positively responsive not only to modifications, but also to continual improvements in amplification, source component quality, cabling, and room acoustics.

That is sig material.:cool:

DarqueKnight

My GIK Acoustics 242 panels arrived yesterday (8/18/10). I placed the order on 8/13/10 and they were shipped on 8/16/10. The sound performance was great, but they left something to be desired in the area of looks. From the GIK website, I knew the GIK panels weren't as nice looking as the Auralex C24 panels, but I was surprised at all the surface irregularities (ripples, crumples, ridges). In figures 1 and 2, note the ripples near the right edge of the center panel and the crumpled lower right corner of the right panel.


Figure 1. GIK 242 panels, SRS 1.2TL grilles off.


Figure 2. GIK 242 panels, SRS 1.2TL grilles on.

The heavy stock grille cloth on all my SDA's was replaced a long time ago with a lighter, thinner cloth. I cannot hear a difference whether the grilles are on or off. This is true whether I am at the regular seated listening position or standing two feet in front of of either speaker. I could easily tell the difference between grilles on or off with the old cloth. With the old cloth, grilles were taken off for critical listening sessions.

Figures 3 and 4 show the difference in light transparency at a distance of 1 foot and 1.25 inches from the camera lens front. The SDA SRS 1.2TL grille frame is 3/4" thick.


Figure 3. Picture of computer workstation monitor taken through SDA SRS 1.2TL upgraded grille cloth 1 foot from camera lens
front.


Figure 4. Picture of computer workstation monitor taken through SDA SRS 1.2TL grille cloth 1.25 inches from camera lens front.

All of my stock SDA grille cloths are in a box in my attic marked "Old SDA Grille Cloths". One day in the future, when I am more dedicated to audio than I am now, I am going to retrieve the stock SRS 1.2TL grille cloth and show the visual difference between it and the upgrade cloth.

Further Comments on Aesthetics

The panels I received looked more like DIY-type homemade items than finished manufactured goods.

Figures 5-7 show closeups of the fabric irregularities. I sent an email to GIK asking if putting a layer of 1/4" thick batting over the current fabric and then a smooth, tightly drawn layer of fabric over that would have any detrimental effects on the panel's performance. I received a reply the next day that my idea would work, provided the fabric did not have any type of backing.


Figure 5. GIK 242 panel crumpled corner.


Figure 6. GIK 242 panel ripples.


Figure 7. GIK 242 panel crease due to wood frame underneath.

From looking at the pictures on the GIK website, I thought I would have some negative reaction to the 4 inch thickness of the GIK panels, but that didn't bother me at all.


Figure 8. The Auralex C24 panels have sleek, contemporary beveled-edge styling with a textured fabric finish.

The Auralex panels will be here next week and will be compared to the GIK panels. I am 98% certain who the aesthetics winner will be. I expect that the GIK will provide superior bass smoothing performance due to the greater thickness. However, even if the GIK panels perform better than the Auralex panels, they are going back if the fabric irregularities can't be fixed to my satisfaction. I promised my house that I would never install any visually unappealing room treatments.:)

Room Response Measurements

An ADC Sound Shaper SS-412X Equalizer/Spectrum Analyzer with calibrated microphone was used to take room response measurements at the listening position in the center of the stereo sweet spot. I used the white noise track of the Precision Test Signals CD by Contemporary Communications, Inc.

The room is 21 feet long by 17 feet wide with a 10 foot ceiling, hardwood floor, and heavy leather furniture. The SDA's are placed along the long wall. There are three large openings into the foyer, dining room and breakfast room.

Polk has never published a response chart for the SDA SRS 1.2TL. When I asked for one, I was told that it was proprietary information. A response chart for the SL3000 tweeter was published in a September 1989 Polk Audio technical paper. That paper showed a fairly flat response for the SL3000 from 1,700 Hz to over 20,000 Hz. I expect that the RD0198 tweeter has similar or better response.


Figure 9. Room response at listening position with bare rear wall.


Figure 10. Room response at listening position with three speaker grilles on wall.


Figure 11. Room response at listening position with a GIK 242 panel in the center.


Figure 12. Room response at listening position with a GIK 242 panel in the center and a GIK 242 panel at the right.


Figure 13. Room response at listening position with three GIK 242 panels: left, center and right.

Discussion of Results

I measured a substantially flatter and stronger bass response from 250 Hz downward when the GIK panels were installed on the wall behind the speakers. This improvement began with a single GIK panel placed in the center and continued as GIK panels were placed at the right and left (figures 11-13). Compare the bare wall and three GIK panel response (figures 10 and 13).

What I heard was:

1. More weight and clarity overall, especially in the center and particularly vocals.
2. The pace of music sounded a little faster and the rhythm of instruments was tighter and more coherent.
3. Electric bass lines moved about a foot back and became louder, faster, clearer and more articulate with more micro growls. There was also more of a sense of the electric bass being in a "layered" space of its own.
4. There was an increased sense of free flowing liquidity and smoothness to electric bass notes and electric guitar notes.
5. There was more tactile sensation (subtle rumblings and vibrations) against my chest and coming through the floor and seat.

I revisited "When we come together" from saxophonist Jackiem Joyner's "Lil' Man Soul" CD, which I first mentioned in post #22 of this thread. In addition to the changes mentioned in 1-3 above, the electric guitar at the right was heavier and more flowing and "liquid" sounding. There were some subtle, "warbling" guitar notes that I had not noticed before. The staccato passages of the alto saxophone had more speed, articulation and reedy "bite". The electric bass moved further back and the synthesizer "cloud" moved further back with it. There was more of a sense of each instrument being in its own space and doing its own thing, yet being part of the collective rhythm soundscape. Jazz aficionados know what I am talking about.;)

This was a simple, inexpensive tweak (a little over $200) that really paid off handsomely. It is fascinating how I keep finding new music in old speakers.

Toolfan66

Ray,

where did you buy your grill cloth?? I bought some from parts express and it just wasn't rich in the black as I like, almost a deep purple if that makes sense so I went looking for another company for grill cloth and found speaker works. There I was able to buy a small sample for $1 and it was black as night. So now I have 6 yards of grill cloth from parts express cut to fit a set of big boys in box that I know I will never use.

I know this is kinda of topic just curious. I will be buying some more room treatments in the next month or so..

Face

It's possible QC isn't the same as when I purchased my panels. One or two of mine have slight imperfections, but none as bad as yours.

I'm glad you're enjoying their improvements though. I'm up to 6 244's, 2 Monster Bass Traps, and 2 PI Audio Group diffusers, but I may switch over to GIK's diffusers for appearance reasons only.

DarqueKnight

TOOLFORLIFEFAN wrote: »

where did you buy your grill cloth?

The upgrade grille cloth came from Hancock Fabrics.

"Ponte" Knit Fabric
Can be purchased locally or ordered online
SKU #708545
$6.99 per yard
www.hancockfabrics.com

Face wrote: »

It's possible QC isn't the same as when I purchased my panels.

Maybe so. None of the various forum threads mentioned the types of appearance QC issues I experienced.

I was also surprised that they didn't tape the plastic wrapping bags closed. Two of the very thin wrapping bags had slipped halfway down the panel inside the box. The third panel's bag had slipped down 1/4th of the way. There was also no type of padding around or between the panels.