[mfsoa]

Greetings all,
I just got four GIK 244 panels and I've been playing with placement. Two are straddling corners on 16" speaker stands (for now) for bass trapping.
I was planning on putting one more horizontally between the speakers (which are 7' apart on long wall of 17x13' room, rear of speakers 27" from front wall, big bookcases at first reflection pts on side walls, three 242 panels vertically behind listener, low rack centered between speakers) and mounting the last straddling the wall/ceiling, also between the speakers.
Well, since I don't have the mounting hardware yet, I was playing around with these last two panels, laying horizontal on the floor straddling front floor/wall either skooched up next to the corner traps, or closer to my rack.

BUT then I stood them up vertically on the floor behind my speakers with a slight tilt back so they'd stand there and HOLY (insert AC-approved explitive here) what an amazing difference. The clarity and purity of the signal is simply amazing, as are all aspects of soundstaging. Sure I do lose a bit of "ambience" and I know that many would bemoan what they think is my overly dead room. But that ambience was simply a nasty, out of phase, altered frequency response, comb filtered no good varmint that I'm glad to do without. I've been sliding the panels L and R and I like them not centered behind the speaker, but slightly to the inboard side to better block first reflection off the front wall. Imaging in center is far improved as is the width because there is still ambience to the outside of the spkrs.

An analogy: Imagine two people talking exactly synchronized with the same timbre, inflections etc (I said imagine!). You may not notice it's two people, but when one stops it becomes obvious that the single speaker is clearer, cleaner, less confusing to your senses - This what I hear when much of the back-reflection is blocked as described.

A story: (optional reading for extra credit) - There's a planet where the preference is that the ideal listening space has openings behind each speaker that lead to the outside. Since their rooms are kinda small, they have no problem with getting plenty of bass, but they just love the unclored purity that the lack of back-wall reflection provides. But then the Axis of Evil takes over the planet and demands that these holes in the wall must be filled in! Oh no! Well, I can tell you these poor people hate the sound of their systems now - A tremendous amount of the sound in their rooms now comes from unwanted reflections (Arrgh) that were never intended to be there. The sound is too bright, too phasey, too insistinct. EigthRealAcoustics to the rescue!

You get the point - I think that what we accept as a pleasant ambience is composed of sonic garbage that was never intended to be there. Again, I think many of you would be aghast at the thought of a too-dead room, and there are trade-offs for sure. But for now I can't get over the purity, simplicity, honesty, ease of listening, imaging etc. etc. that I get from blocking much of the first reflection point behind my speakers.

Anyone else? Don't try it if you aren't prepared to live with it!!

My guess is that similar if not better results could be had with diffusion. Now if I could just swing a RealTraps diffusor for the exact center of the front wall, that would truly be a treat! Next up - gotta do those front ceiling corners! And yes, my wife has ceded practically all control of the living room, bless her soul!

Thanks for sharing this with me. Sorry if I sound like an excited fool    but I am.

-Mike

[bpape]

What you did when you stood them up behind the speakers is to help deal with the SBIR.  You're now hearing the bottom end coming from the speakers and not the mix of that and what's coming off the front wall and causing peaks/dips.  You're also cleaning up some of the really late bounce off the back wall then back to the front and back at you which is another whole set of issues.

Bryan

[mfsoa]

Bryan,
I just googled SBIR and found a great little artice written by, well, you!

I am familiar with the physics behind it but didn't know this term.

In my room, the drivers are ~ 47" into a 13' space, they aren't coming out any more than that but still the benefit was huge!

Thanks, GIK!

[koiman]

Mfsoa,
How about some pictures of the set up.
Lee

[Ethan Winer]

Mike,

> HOLY (insert AC-approved explitive here) what an amazing difference. <

Another convert.

> Sure I do lose a bit of "ambience" and I know that many would bemoan what they think is my overly dead room. But that ambience was simply a nasty, out of phase, altered frequency response, comb filtered no good varmint that I'm glad to do without. <

Exactly. Personally, I think the "value" of a live room is often overstated, and not really in the best interest of achieving excellent sound. And as you observed, diffusion (in a room large enough to support it) can retain a nice ambience but without all the phasey comb-filtered nastiness.

--Ethan

[Daygloworange]

Personally, I think the "value" of a live room is often overstated, and not really in the best interest of achieving excellent sound.

I agree with you on this Ethan. The LEDE thing can be nice in a recording environment, but although for a long time recommended in a monitoring situation, I don't feel it's a good idea. I think the time to let go of that idea has come.

I have been playing a lot with diffusion and bass trapping. Although far from finished with ideal mixes of diffusion and trapping, the results are tremendous.

Cheers

[mfsoa]

OK Koiman, it's pictures you want...

It's a small room so it was hard to fit things in the pics. Hope the quality is OK, but it'll give you an idea.
From right rear:


From left rear:


From right front, so you can see how room opens at left rear (and Oscar):


From left front to see how room opens at right rear:

[koiman]

Thanks that is what I wanted to see..
Lee

[Glenn K]

OK Koiman, it's pictures you want...

It's a small room so it was hard to fit things in the pics. Hope the quality is OK, but it'll give you an idea.
From right rear:


From left rear:


From right front, so you can see how room opens at left rear (and Oscar):


From left front to see how room opens at right rear:

Looks like to me we have some new pictures to put on our website..  aa

Glenn

[mfsoa]

Looks like to me we have some new pictures to put on our website..

Thats fine by me. But the room is still really unfinished and these pics were quick snapshots.

My wife is really good at interior design stuff but always seems to be putting splotches of the "next" color over the stuff that was just done, as you can see in some shots.

I promise I'll send some more pics when it's more presentable!!

Thanks again for quality product with good price and service!

-Mike

[nathanm]

That looks really good.  I like the three rear panels, it doesn't call too much attention to itself like, "Hey I've got sound-absorbing panels in here!"  It looks more like a design\decorative element.    If they were painted it'd look like a mounted canvas I'd suspect.

[Daygloworange]

BUT then I stood them up vertically on the floor behind my speakers with a slight tilt back so they'd stand there and HOLY (insert AC-approved explitive here) what an amazing difference.

I was having some room loading issues with my new rear ported speakers that I wasn't having with my previous transmission line speakers, so while at the local Depot, I bought a couple of bats of R-12 insulation and just plopped them down behind the speakers in the corners.

Totally changed the low end response. It wasn't subtle either. Performance was much tighter, and cleaner. We usually talk about improvements in detail in the upper frequencies, but I noticed quite a bit of improvement in detail in the low end.

I'll be looking much more seriously at bass trapping as time allows, and probably be doing something along the lines of what arthurs has done with his, as well as getting into the measuring aspect as well.

Keep up the reports. 

Cheers

[mfsoa]

Nathanm,
Thanks. It was my wife's suggestion to leave an inch or two between the panels to give it some "architectural interest" and it did work as she thought (as always).

We've been discussing if/how/what to cover them with . It's really a tough choice - It would be really easy to over-do it with a single motif, yet if your gonna cover them, might as well do something interesting. Tough to find the balance. Another choice is to get/make a larger fabric print to cover all three at once, which'd be pretty cool.

Wifey is a good abstract artist, so we're also thinking of doing custom who-knows-what on removable fabric to toy around with.

I don't know if it helps significantly (won't hurt), but I found that using ~ 2" sections of thick foam pipe-wrap, slit length-wise, make great "C-clips" that clip to the back of the frames to stand the panels off the wall an inch or so.

I do have the latest RPlusD software ready to roll, but need the time to take the measurements (or to "Make that PSSSSHHHHT" sound", as my friends daughter called it!)

[bprice2]

I purchased two 4' x 2' x 2" panels a while back and have been playing around with positioning them in different locals in my living/listening room.  Because I'm listening to bipole speakers (fires from front and back) I thought the best place to put them was like Mike did...behind his speakers.  My reason for this was my concern that having back-firing speakers blasting directly into the wall would create massive first reflections.  The result of this placement was nothing, nada, zippo.  I still do not know why this is.  I thought for sure there would be some positive effect.  As time went on I clued in to placing the panels in two of the corners.  This made a difference...smoothed things out a bit and created a wider/bigger soundstage.  Imaging, while better, was slightly skewed to the left though, so I moved both speakers to the right 6 inches.  Imagining seems to be dead on now.

The reason I'm telling you all this is because I want to ask you:

• Why did the panels directly behind the speakers seem to do nothing?
• Is it b/c I am trying to treat two different things and simply do not have enough panels to go around?
• If I did have all the corners treated, do you think placing panels behind the speakers like Mike has will make a difference?

Sorry if this is unintelligible.  Its hard to ask the questions when you don't really understand what you are asking.

[Russell Dawkins]

Mike,
I'll admit at the outset that I am a LEDE advocate, this configuration almost always having worked for me.

My first thought in looking at your set up is I'd like to see more absorption on the front wall, behind and between the speakers and at the same height as the top sections of the speakers. For what I have in mind - mid and high frequency absorption - the 242 panels would probably be OK to test. I am thinking about absorbing the center wall bounce of the diffracted HF output off the inside edges of your speakers. My guess is that it will sharpen imaging, and if it works, you might be able to get away with two (horizontally) instead of three behind the couch.

You could probably experiment without committing yourself by resting the panel on top of the two 244 panels if you moved them slightly closer together

[bpape]

I'll agree that something between the speakers up higher would be my preference too.  However, I wouldn't want to lose the absorbtion on the rear wall with the couch that close.  They are helping to minimize the boundary buildup of the bass at that proximity.

Bryan

[mfsoa]

Bprice,
I'll take a shot at it-
Perhaps when you placed them behind the speakers they weren't "inboard" enough to be blocking the first refection point off of the front wall? What I mean is that if your speakers are a few feet off of the front wall and the panels were directly behind them, and your speakers are placed wide enough apart relative to your listening position, the first reflection point may not have been blocked by the panels. Try moving them (the panels) in closer to each other, centering the panel at the reflection point or even further in - Worry more about that reflection point than trying to maximize the % absorbed.

Or, does you front wall have some sort of diffusion already - Mine was bare sheetrock so maybe it was more noticable.

Just a guess, of course! Good luck

[bprice2]

Mike,

There may be something to that.  Assuming I understand correctly, you are saying that I may have had my panels spread too wide?  I did place them a little wider than the speakers, b/c with toe-in the back side of the speaker is firing further out (away from the listening position).  If I am understanding you correctly, then maybe my thinking has been backwards.  I've been thinking first reflection is the beeline from the wizzer to the wall.  Is first reflection instead any reflection that comes back to the listening position?

Once again, I'm not sure if I'm making sense to myself, much less you guys.  I don't know why its so hard to wrap my head around this issue.

Brett

[mfsoa]

Brett,
Yup, you've got it.
Pretend you're making a pool shot from your listening position and need to bank the cue ball off the front wall and hit your drivers.
Try the panels there if you can.
-Mike

[mfsoa]

Russell,
Thank you for your input.

My first thought in looking at your set up is I'd like to see more absorption on the front wall, behind and between the speakers and at the same height as the top sections of the speakers

This is exactly where I thought I wanted one of the panels, horizontally, centered at the mid/tweeter section. But then I started playing with the two panels and arrived at where they are for now. Agree that something else will go there, whether it be another panel, a diffusor or most likely a decorative wool rug. I'm certainly not done with the room - Can't do it all at once. Some temporary pillows would be worth a shot just to try.

My guess is that it will sharpen imaging, and if it works, you might be able to get away with two (horizontally) instead of three behind the couch.

Yeah, two would probably do but I wanted three for the good vertical coverage and so that each listener (like I ever really do have 3 people listening.. I can dream...) had good coverage from that back wall.

Thanks, everyone!