My GIK Pillar Trap Review

**thewire** · **01-28-09, 04:43 AM**

I had pretty much dismised the idea that I could sit anywhere near the front of my room. My room is under a garage and has concrete on every side with some added reinforcement of 2" thick steel on the ceiling. I had installed Helmholtz Resonators in the back of my room, some GIK 244's centered on the back wall, a drop ceiling by Ceilume with a direct mount system using back panels filled with insulation, then Quiet Batt or insulation above that. I also had each tri-corner stacked with 12" Roxul 60, a stage filled with tons of insulation, riser with lots of insulation, and four 2" panels at each of my first reflection points, with another 2X2 2" panel under my center channel. I used my equalizer to cut the peaks in my room.

I won a GIK Pillar Trap in the Shack giveaway and gave that a try in my front right corner, where I had found needed the most improvement. The bass would all the sudden get real loud from the corner and overpower the rest of the sound without the trap there. When I first placed it there I noticed that there was more life to sounds from that direction. I would measure that it was eliminating all kinds of peaks in the corner when I used REW.

I tried the trap in my left corner where I less problems feeling bass from, but instead where I heard more midbass punchiness. I decided I wanted another one there also. I won yet again another Shack giveaway and used the money to get a second GIK Pillar Trap and another pair of GIK 244's. I also received another pair of GIK 244's as a gift from my family. I used one pair of my new GIK 244's spaced away from the walls at my first reflection points, and placed the new trap in the left corner. I decided to raise it up some using some methods and am in the proccess of treating some more area under my screen. I placed my four subwoofers at each walls (pretty close to being

) midpoints per Bryan's recommendations and adjusted my seating, and the ringing is gone from when I had tried this before.

REW will now recommend a filter at 25Hz but I am not hearing this problem yet and I am currently watching movies without the use of equalization. I am still trying things with the second pair of GIK 244's which I have placed over the large openings in the back of my room that are some openings into the Helmholtz Resonators in the middle of the room bellow my other GIK 244's. I have tried many things with the Helmholtz Resonators and may try filling those with insulation again.
I am still in the experemental stage, treatment stage, but the room sounds fabulous right now.

Edit: I will post some photos of the rooms progress and a couple measurements later this AM.

**thewire** · **01-28-09, 08:20 AM**

Here are photos of the rooms progress and a measurement of the front rows center seat with the left channel with subs, and right channel with subs. The measurement is taken as is.. I think I will trying some more concrete tiles under the sub on the stage. As it is one layer is helping for the back row, but I have some others not in use I may as well try placing under there as well. I have the needed materials to finish making the frame for the stage traps and the fabric has been ordered.

There are small holes in the corners of the room behind the carpet with the Helmholtz Resonators, and there are holes in the stage behind that opening in the center that were big enough to place my hand inside, then stuff more insulation. I can't fit anymore insulation in that stage.

Spectral decay of the left and right channel. Notice in the frequency response how close left and right match. That was my primary objective so to speak as I always had problems with this in my last HT. My other goal was tight bass to at least 25Hz and no audible distortion. My other goals are surround sound music, and video games. I have not yet gotten to the games, but the surround sound music was accomplished awhile back, and will need to check on that again.

**bpape** · **01-28-09, 09:17 AM**

Looking good. Glad things are working for you.

Getting the subs right makes a ton of difference.

Bryan

**thewire** · **01-28-09, 10:54 PM**

Yes it does, and I now have more room to bring other seats in when we need to do so. I think I knocked loose one of the bi-wiring in my right surround inside the ceiling when I was moving materials up there. I'm having to connect that right surround to the rear right surround. The subs wiring I can run to the older wiring between the Helmholtz Resonators and move the wire from the left surround I'm using for that currently. You can see some of it there in the photo hanging out of the wall. I'm not sure it will be worth to fix the surrounds wiring since I will be moving that later anyway. I may just run one of my black wires until then, but if I am in the ceiling already, I may as well.

The 12' fabric 56" wide will be enough to cover the front area, then using some left cover the stands for the Pillar Traps that I used to elevate them. Then if I can clean things up some it will be in good shape I beleave. Firing the two subs at the left and right walls midpoints resulted in a 5dB dip at 70Hz hence they are about half a foot apart. I will let you know how it turns out, and be sure to get some better photos.

**thewire** · **01-30-09, 07:21 PM**

I am think that cutting out the front of the stage and the platforms, then placing some fabric over those as well might be benificial to the 30Hz - 40Hz, and 70Hz area. I don't see how it would hurt anything, and if the dip from 30Hz and 40Hz decay (which is a smooth dip in the response) is improved by doing so, as was adding more insulation inside the stage, I could move my front back 1', and my back row forward 1'. When I had all the subs at the walls midpoints, the ringing at 25Hz was substantially lower in my measurements, so if getting rid of some resonances means being able to do, I think it may help. I did not notice any changes when placing the GIK 244's across my front stage, which makes me curious whether the zero point energy is being directly reflected off the front of the stage in these frequencies, or it is a resonance. My modes are spaced fairly far appart there.

Here is a mode calculator example of what I am thinking may help at the front wall/floor.

**thewire** · **01-31-09, 01:14 AM**

I'm now in the testing phase with framing the front stage bass traps. I decided to remove the upper portion of the stage, and took a couple 2X4's flanking out the front of my wall with it. I'm will be testing with the entire thing of R19 there this time. That's cardboard at the top there that is stapled to the framing in the front.

**thewire** · **01-31-09, 02:23 AM**

Sorry I had to do these with my hush box fan running. I was able to reduce the ringing down low as I was hoping. The ringing low was removed prior to moving the subwoofer so they were firing at the same points along the walls. The mains are not calibrated as of yet, and it seems they went down in level. It might have been the small amount of insulation I removed from the corners, or I need to adjust the traps again. I doubt it was anything to do with the cable management I have been working on. I adjusted the gain a couple decibals higher. Here is a comparrison of before and after what I just did looking at the lower range. I almost gained 1Hz lower extention, and the 30Hz - 40Hz area is improved. I noticed that the other gain went up overall after moving the subwoofer, and positioning the seating effects the 50Hz - 200 Hz area gain. I saw very little change to 30Hz - 40Hz this time, but moving the seating was effecting my left right speakers response more, which I did not move.

Before

After

**bpape** · **01-31-09, 09:19 AM**

Nicely done. This is a perfect example of a very methodical exploration of, and finding solutions to low end issues.

Bryan

**fredk** · **01-31-09, 10:28 AM**

And a fine example of exaclty how much bass trapping is required to tame a nasty room. Sigh... That doesn't bode well for me as I do not have the kind of room thewire does.

Nice job on the HT my friend. It has been an interesting read.

**thewire** · **02-01-09, 10:39 PM**

Quote:

fredk wrote:

And a fine example of exaclty how much bass trapping is required to tame a nasty room. Sigh... That doesn't bode well for me as I do not have the kind of room thewire does.

Nice job on the HT my friend. It has been an interesting read.

Thank you. I have also measured results using one subwoofer in a much larger space in my living room. I placed a sub in at the right wall and the GIK Pillar Trap in my kitchen, and observed the best improved decay with it there having the mic near the dinning table. I concluded that would be a difficult area for me treat then. This area is meant to be a game room in the future and the kitchen is suppossed to become the snack area. I am still trying to learn in preperation for the media room project which is in the planning stages. I also hope that my room treatments will give me as good as results should I take them to another room in the future.

The 50Hz and 80Hz area is espicially difficult to treat as that would require lots of absorption on my back wall.

The only changes I have made since to the room was placing the sub under the new bass trap at the front of the room with the 2" panel behind it, and removing the stack of concrete behind it to see what difference this makes. I also removed some insulation above my projector since the tubes have been shutting on/off, and I thought it might be something to do with heat, regardless that my hush box fan is attempting to remove the hot air inside.

**thewire** · **02-02-09, 06:25 AM**

To be fair to others, and since I have been contimplating the idea to move my seats back a foot, here is with the GIK Pillars now stacked on the back center wall onto the 4 other GIK 244's. I moved the left and right speakers away from the walls as well, and moved my surrounds behind the back row.

You can see how the 250Hz area in the decay now results in a better match, and the lower ringing has changed. The ringing is so low that I must zoom into 200ms with the waterfall to observe the decay more closely. This is again with the hush box fan running. The lower ringing now moves to the 20Hz area, bellow my first room mode.

**thewire** · **02-02-09, 07:22 AM**

Some photos also for better understanding of the layout measured.

**thewire** · **02-02-09, 11:32 PM**

This sounds very good also, espicially in the LFE. Simply moving my speakers out however does not seem to be addressing the issues I heard in the front corners in my first post. I'm thinking then it must be related to the subwoofers output, somewhere in the range of 90Hz, - 120Hz, but it also treated much higher for the mains response, and much lower for the subwoofers response. If the problem in the right corner that I am feeling can't be heard, then these traps must be treating very low.

**thewire** · **02-05-09, 11:35 AM**

I isolated my subwoofers on the platforms and the stage using my subdude and put holes in the stage. It seems I now have no need to adjust the trim for the left or right speakers to match. Drilling all these holes without moving the speakers was difficult.

I had to arrange the panels so that reflections from the ports at the bottom of the speakers would be absorbed, and I moved the subwoofers slightly. These measurements were after equalizing the subs.

**thewire** · **02-06-09, 11:43 AM**

Next I might like doing something like this with more trapping. The rear traps I could optionaly place insulation behind. A false wall was out of the question back there because of the sconces. There seems to be a slight bit more bass from the sub on the right wall when in the right seat, and sitting in eather the left or right seat up front which are closer to the walls, the spaciousness seems about lost as more bass seems to come from the speakers closest. Having traps above the subwoofers at the walls midpoints seems to help that but not 100% sure. It just seems to make the balance from the mains to the subs more smoothed out for those seats. That seems to happen at around 92dB or more. It could be something to do with second reflection points but I suspect it's just some sound off the walls moving. More traps would deffinitly help the back wall.

**thewire** · **02-08-09, 12:22 AM**

I'm ordering some Roxul and then I will be adjusting the other room treatments to see what results I can get.

Anyone know where I can get 6 Roxul Rockboard 60 2 inch, Case of 6 for less than $461.44 shipped to area code 65072?

**bpape** · **02-08-09, 07:45 AM**

Roxul - probably not. If you can use IIG, I know I can get some for you for better than that.

I have a commercial FedEx account for my business. I'm getting about $19.50 per box for shipping so that'd be about $117 for the 6 boxes. I'm guessing I could get you the mineral wool for around $300

I used to carry it but have been having QC issues and problems with the warehouse so I discontinued it. I'd be willing to grab you some though and ship to you. We're not that far away - It would be just as easy to meet somewhere in the middle if you have a truck and we can figure out a time.

Bryan

**thewire** · **02-08-09, 08:47 AM**

Quote:

bpape wrote:

Roxul - probably not. If you can use IIG, I know I can get some for you for better than that.

I have a commercial FedEx account for my business. I'm getting about $19.50 per box for shipping so that'd be about $117 for the 6 boxes. I'm guessing I could get you the mineral wool for around $300

I used to carry it but have been having QC issues and problems with the warehouse so I discontinued it. I'd be willing to grab you some though and ship to you. We're not that far away - It would be just as easy to meet somewhere in the middle if you have a truck and we can figure out a time.

Bryan

I'm without any kind of transportation for awhile until we replace my van that just went into retirement. I'm not familiar with IIG. Is that acoustical cotton? For some reason the more coverage I get in the back of the room the better results I measure. It needs to be very thick according to measurements. My projector also just went into retirement and until we can get a 1080P DLP after the tax season and paying off some dentist bills for our family I will be using my 32" flat screen with progressive input and anamorphic sqeeze for the HT. The good news is that I can treat the front wall or the back wall, and move my speakers away from the walls. As they had to be they were 20" from my side walls for the best response, but it landed them right into a null from my axial width modes.

I really need as much as I could get my hands on. Having this room size is espicially challenging and I need to have a live-end dead-end approach to get it sounding anywhere good for movies I think. My front wall and back walls modes are so bad that I have them all the way up into the 120Hz area.

You can see the modes that I am currently after in this image. If I have any left-over but which I doubt I would have there is plenty of room in the ceiling to deal with the third order and first order modes.

When I tried 4' thick pink R19 in the rear of the room I had very impressive results but not down to 57Hz as much as I would have liked. It did very well for the 80Hz area in my mesurements. I tried some Quiet Batt back there also but it didn't sound right for some reason. I tried filling those Helmholtz Resonators with pink also but it did not improve the decay much and it somehow seemed to do more harm than good as they seem to effect the 67Hz first order ceiling mode in a negative way, espicially if I change the volume inside. I had not tried any Roxul in that before, but I see the treatments helping over a more larger area, espicially on the sides of where the GIK 244's are currently back there. The biggest problem I have with those is that they are flanking the back wall some. It actually travels right up the wall through the garage and into my room in the back right corner away from the door. My projector hush-box also has some issues with flanking but that's not as difficult to deal with.

I thought Roxul 60 might work well for a cost effective approach in covering such a large area. If your willing to pick some up for me and ship it also that would be great. I'm still open to other ideas however. I will probobly need to wait until monday before I could order anything over $400, and I need to check what I have in there after some recent expenses.

**bpape** · **02-08-09, 09:08 AM**

IIG is just a different brand of mineral wool instead of Roxul brand.

Rear wall is fine for thicker. Doing too much on the front will skew too much of the boundary effects IMO. Usually we just do 2" on the front in most rooms.

Bryan

**thewire** · **02-08-09, 09:30 AM**

Quote:

bpape wrote:

IIG is just a different brand of mineral wool instead of Roxul brand.

Rear wall is fine for thicker. Doing too much on the front will skew too much of the boundary effects IMO. Usually we just do 2" on the front in most rooms.

Bryan

I see. The MinWool-1200® Industrial Board looks like I would need then. If that is easiest for you to get I will go with that then. I don't really have a preferance for which brand.

**bpape** · **02-08-09, 10:00 AM**

Lemme check with my supplier and see what they have in stock

Bryan

**thewire** · **02-09-09, 10:16 AM**

Checked my account this AM. Are you able to get the $300.00 of the mineral wool? I wanted to set some aside in case I needed an extra pair of 244's.

**bpape** · **02-09-09, 10:26 AM**

Check your PM

**thewire** · **02-09-09, 11:48 AM**

If shipping is more that is alright by me. The Pink insulation in the back didn't seem to help more than 2' thick but I'm not sure the difference with mineral wool. If it is enough to go 2' thick, 4' high, and however wide stacking them would be so that I cover the back wall around 10' wide I would be happy. That would be plenty to try out in other areas also. If shipping is more that is alright, or if I don't have enough I could wait until next week or later if that will help. I will have the other pair of 244's on the back wall to see if adding more may help, but it will take longer for me to determine if more will help or not. I will first try without covering the center area where the 244's are currently which I did last time. I thought it might be better to think ahead just in case, but the back wall is the main agenda.

**thewire** · **02-10-09, 02:05 AM**

I could also instead make it look nicer and place a second pair of 244's spaced on the back wall, then fill in the area behind them with as much Mineral wool as I could get, disregarding the side walls for now. I'm sure that would look nicer and I don't think I have the needed materials for the another frame, and I certainly don't have enough fabric although I have some black curtains that may work.

This is the left and right speakers with some 244's moving absorption to left or right side walls as shown in the previous image. The mains have a X-over of 80Hz.

These RT60 measurements never seem to change much, or if they do, I can't remeasure the same thing twice. They look similar having my my subs on also. The panels depending on where they are placed on the side walls makes the area around 250Hz go lower.

This is how the subwoofer measured with absorption on both side walls and with them also spaced more than 1' off the back wall on each side of the other 244's. The x-over on the sub is 80Hz but 120Hz is also sent tracking a 120Hz X-over.

green is with them on the back wall
blue is with them on the side walls

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