Venturing into the realm of room acoustics and treatments...

I wanted to revisit this again...

After re-reviewing my email from GIK as well as reading in a few forum posts from Maggie owners (with similar sized rooms), we have all been recommended to use the 4" Alpha 2D panels on the front wall directly behind the speakers as they absorb and diffuse sound as well as function as bass traps. GIK also recommend the same for the back wall, however I chose to go with the 2" Impressions panels on the back wall. I have four panels coming for the back wall, but not sure that I will use all four of them back there. They would have to be butted right up against each other as one continuous 8' wide panel so to speak. I may just put two back there and one on either side of my listening position on the side walls.

Again, it's not like they are permanently affixed to the walls, so if things don't sound right, I can always move them around. Also, with the 2" Impressions, if I want, I can mount them with 1" to 2" stand-offs for an air gap between them and the wall to lower their frequency of absorption some.

I'm also interested in those tri-corner triangle panels that mount up at the ceiling/wall corners. I've found some by ATS Acoustics and PrimeAcoustics, and they refer to them as tri-corner bass traps. I don't know how effective they are vs large bass traps that get stacked in the corners of the room, floor to ceiling. Probably nowhere near as effective, but I also don't want to take up a bunch of floor space nor do I want the room to look odd or like a studio. The PrimeAcoustics Cumulus tri-corner traps are said to be effective down to 100 Hz, and I effectively have 5 corners in this room where I could mount them.

also, I just got in that thermal/blackout curtain to go on the front wall behind the TV, so I'll be installing that shortly. We don't ever use that window, and if the curtain ends up absorbing too much and killing the sound, I can always open it up some and mount a couple of diffuser panels in the center of the window. The only main reason for that curtain is to cover the ends of the window to make it look centered on the wall instead of off to the right like it is. Plus, we are both tired of looking at those garish homemade hillbilly looking window treatments from the previous owners of this house.

I might look into getting a matching curtain for the large window in the right wall, but lighter/thinner as to not be too absorbent. Though I have to say, with the way the Maggies project sound, there's very little to no difference with having the blinds in that window opened or closed. IOW, not much in the way of 1st reflections on the side walls, which is a good thing.

At any rate, that's where I'm at at the moment with this "project".

I don’t agree since the Alpha 2D’s work optimally at 500hz (not sure how that’s “bass” in their definition). But at least, as you said, you can move them if they don’t work out well. I think you’ll find a midrange suck out and find you have to play them louder since the back waves are being absorbed. But trial and error is the only real test. Will be interesting to see what you hear.


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I don’t agree since the Alpha 2D’s work optimally at 500hz (not sure how that’s “bass” in their definition). But at least, as you said, you can move them if they don’t work out well. I think you’ll find a midrange suck out and find you have to play them louder since the back waves are being absorbed. But trial and error is the only real test. Will be interesting to see what you hear.


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That's the nice thing about this... Nothing is set in stone, so everything can be adjusted, added or removed to get to the desired result.

I agree with you. I don't know why GIK refers to the 4" 2D Alpha's as bass traps since like you said, they're tuned for around 400 - 500 Hz. Maybe when placed in corners and you have like a 12" air gap behind them... Maybe. Maybe mounting them on the side walls behind the speakers will do something. I guess we'll find out soon enough.

One major improvement on the other hand (cosmetic/visual more than anything else), I installed the curtains, and removed both of those ugly homemade things the previous owners threw up over the windows. Man I'm glad those are gone. I honestly don't know why I waited nearly a year to remove them. Geeze, the 1st of next month it'll be a full year!

Anyway, the curtains... I really don't notice any difference in sound that I can tell yet, which I suppose is a good thing. They just make the room look a lot better, and the ceiling a bit taller.

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The 2" Impression panels came in Friday, the 4" Alpha panels showed up first thing yesterday morning around 9am! That alone was shocking! They were supposed to ship out on the 24th and arrive by the 29th! Good on GIK Acoustics for that. As for fit and finish, I've read that a lot of these panels arrive looking like they were rushed, bad corners, wrinkled cloth, etc, etc. I have none of that with these panels. They look great front to back, top to bottom.

All day yesterday, and I do mean all day, I played around with location. I tried the Alpha and Impressions panels everywhere in the room, swapped one out for the other in each location, tried all combinations, tried all types of locations, and the simplest actually ended up providing the best results.

Music was from Phil Collins, Norah Jones, James Taylor, Depeche Mode, Neil Young, Diana Krall, The Cure, Peter Murphy, Gregory Porter, Holly Cole, Fleetwood Mack, Pink Floyd... Basically, artists and music I know extremely well and a lot that I have been listening to recently with the current system.

I first tried the Alpha panels in the 1st reflection points on the side walls. They gave me a solid center image, but they killed the width of the sound stage. Any stage width I got it was restricted to only between the inner edges of the speakers. Even the ambient width in the recording was sucked out almost completely. While keeping the Alphas there, I tried putting the four Impressions in various locations to see if they would resolve these new issues, but they didn't. Even completely out of the room, these new issues stayed.

So I swapped out the Alphas for the two Impressions you currently see in those 1st reflection locations. With no other panels in the room, these "removed" the walls, widened the sound stage considerably beyond the walls, and still give me that solid center image. This is something these speakers and room needed, and the Impressions in these locations deliver.

I then tried the Alphas on the back wall and the other two Impressions on the front wall. They seemed to work really well, but something was off. After more listening of various tracks, I realized that stage depth had flattened and vocal height had dropped to about just below center of the TV screen. Also, some of that ambience in the recordings had gone away again, though not as bad as before, but it was noticeable. Lastly, imaging focus had become a little bit fuzzy. Again, just because I could, I removed the Impressions on the sidewalls while keeping the other panels in place and that just made things worse, so those Impressions went back to the sidewalls.

And because Mike had me a bit worried about the Alphas behind on the front wall and sucking out the midrange, this is the very last place I tried them. I can honestly say now that I am relieved. What the Alphas did on the front wall is what the room/system needed. They opened up that front wall giving more space, air and much needed stage depth to the sound, as well as lifting the vocal/instrument height to realistic heights as if those vocals/instruments were in front of me. The ambience of the venues in the "live' recordings are back in strides and very clearly apparent, giving even more space and air within the room. The second pair of Impressions are on the back wall where they help reinforce what the Alphas are doing up front as well as the fact that there's zero slap echo in this room now.

As an added bonus to these panels, and something I wasn't expecting them to do much of if any, is that they have in fact improved the bass in this room. I don't know if they helped clean up some of the upper bass or bass harmonics or what, but the overall sound of the bass is just a bit more clean, solid and planted. Almost to the same effect as putting the subs up on those IsoAcoustics sub stands I have them on. Definition and sharpness of attack just seem to be better. And no, the Maggies, the subs or the sub settings were never touched through any of this.

Lastly, in order the mount one of the panels in front of the window, I mounted a couple of "legs" to the side of the panel, put a couple of eyehooks on the back of them, and a couple of L hooks in the wall, so installation and removal is simple and literally only takes seconds to do. Also, instead of using the sawtooth hangers that GIK provided with the panels, I decided to use heavy duty D-ring picture hangers for the wall mounted panels.

All in all, I am extremely happy with the results and am quite amazed at how much was achieved with only six panels. They far exceeded my expectations. This doesn't mean I'm done however. I still want to get some diffusors for behind/above the TV, and maybe a few other things here and there after some more research and advise seeking.

Anyway, here's some pics...

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I’m not surprised that the GIK impression series panels created “something off” when you tried them. I am surprised the Alpha panels didn’t do the same since their frequency specs are the same and it’s only their dispersion patterns which are different.

Anyway, IMO, any kind of absorption behind a dipole should be avoided, but if you’ve found something works, that’s great.

I would listen for a week with the panels, and then remove them from behind the speakers entirely and listen for another week. Pay special attention to the midrange. I suspect you may find it more muted and recessed with the panels after the comparison. But maybe not…who knows?


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The Alphas absorb more, obviously since they are two inches thicker. But yes, their curves are basically the same.

I have tried removing the Alphas several times today on certain tracks I listened to, and I haven't noticed any muted/recessed midrange with them added. I plan on doing the same next weekend. Something else I'll be doing next weekend is taking measurements with REW. I was going to do that this weekend but never got around to it as I had other stuff to do as well.

Maybe I can coax you over for a listen some day. :ninja:
 
The Alphas absorb more, obviously since they are two inches thicker. But yes, their curves are basically the same.

I have tried removing the Alphas several times today on certain tracks I listened to, and I haven't noticed any muted/recessed midrange with them added. I plan on doing the same next weekend. Something else I'll be doing next weekend is taking measurements with REW. I was going to do that this weekend but never got around to it as I had other stuff to do as well.

Maybe I can coax you over for a listen some day. :ninja:

Yes indeed! Love me some Maggie listening.


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A little update...

Since my last post in this thread, things came to a standstill as shortly after my significant other had full hip surgery scheduled. So the week of, I took off from work to take care of her and help her around the house and such, then back to work the next week. Also, other things family related have occupied my spare time as well. Needless to say, I never got around to getting REW up and running and doing all of that jazz.

However, last weekend, I did manage to get a few quick hours to myself. For about an hour, I played a track here and there of very familiar recordings for about an hour, quickly removed the Alpha panels from the front wall, then played those same tracks again, in the same order. The results were the same as before, no suck-outs of any kind and increased air, space, height and depth.

With that being said, I do have to retract one statement where I said there was "zero slap echo now". There's still some, but nowhere near as bad as it was. It doesn't ring out as long as it used to, but it's also difficult to tell where it's coming from (side walls, ceiling, maybe front/back walls still?). If I loudly say "AH!" in really short bursts, or clap my hands, I still hear this short echo that has more of a "zing" quality to it that rises in pitch by the time it ends. I would say maybe two tenths to a third of a second at most? So far I haven't noticed it in any music that I've played like I used to before the treatments.


In other news, for the most part, I have preferred the sound of the Maggies with the tweeters on the outside edge for a bit wider sounds stage and a larger center image with very little to no toe-in. Just for giggles, I swapped them a couple nights ago and now have the tweeters on the inside edge with a fair amount of toe-in (tweeters intersect about a foot in front of my head). I was expecting a smaller center image and a narrower, somewhat closed in sounds stage. To my surprise, the opposite happened!

First thing I noticed is that the sound stage now extends out past the side walls by at least a foot or two, well beyond the speakers themselves. There's also a 3D or surround-sound like effect depending on the recording. You're placed IN the recording venue, hearing the natural acoustics and reverb of the live recording venue. Of course, highly engineered studio music does the same, sometimes to extremes. One recording I was listening to (can't remember what it was now) had an acoustic guitar being played close-mic'ed, and I swear it was a foot behind my head to the left. You could actually hear the pick come in contact with the string, and that string sounded like it had a rough texture to it like a round-wound string. However, that late at night I was starting to get really tired (was up 26 hours, 14+ hours of that at work) and failed to make note of the album/track or even put it in my favorites for that matter. It was just something I randomly picked on Qobuz.

The second thing I noticed is that the size of the center image has remained the same (as with the tweeters out) but now that center image is sharper and has more roundness and dimensionality to it. Also, that center image is its own entity between the speakers. In no way does it sound like it's coming from either speaker.

I had these Maggies set up this way a while back when I was experimenting with placement, and I was getting none of this, hence why I had them with tweeters out and very little or no toe-in. All I was hearing before was like a large mono speaker in front of me with some stereo ques here and there set up as they are now, only without any of the room treatments. It's a totally different story now with these GIK panels installed!
 
All I was hearing before was like a large mono speaker in front of me with some stereo ques here and there set up as they are now,

For my taste, for a bigger, more believable stage and stereo illusion, the farther the speakers are from each other, the better.
 
For my taste, for a bigger, more believable stage and stereo illusion, the farther the speakers are from each other, the better.

If stereo imaging is what's wanted, then an angle between listener and speakers of more than about 60 degrees will spoil the stereo effect and create a hole in the middle. Perhaps this is what chops is experiencing from his description.

My horn speakers offer exceptionally accurate imaging - close your eyes and you can confidently point towards any individual instrument or singer. This requires careful setting up, in paticular distance from listener, distance between speakers (as mentioned a 60 degree triangle is a good start), position relative to rear and side walls, toe-in (probably the most critical small adjustment) and maybe tilt. Get these right and you are sitting in the best seat in the auditorium. Peter
 
spoil the stereo effect and create a hole in the middle. Perhaps this is what chops is experiencing from his description.

How did you manage to get that out of what I said? I've always had a solid center image, never a "hole in the middle".
 
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