My GIK Pillar Trap Review

**thewire** · **02-22-09, 01:13 AM**

It could also sound less bright since I took all the concrete out the back of the room.

**thewire** · **02-23-09, 05:27 PM**

There is no cutting of OC 705 required.

It would help if I could remove the old screen frame which I might end up doing. That would allow it be inserted with a friction fit.

Here is one of the rear traps being built. I had an espicially difficult time with the left side because my stapler began to jam no matter if I put in newer staples or not. It was also difficult on the left side because the jigsaw is missing the peice to hold it straight and the angle of the blade was not ideal for cutting angles on that side of the room when I needed to keep the blade angled away from studs. At least the drill is fixed, but we did get a new cordless also. The trim does not match perfectly but it was as close to deep cherry as they had. I am wondering if I could not spray a transparent red over it to make it look cherry. I have never stained before but I know that it is difficult to match a stain. Maybe I should not worry about that. At any rate I got them cut pretty close to being flush but I'm sure I will do better without having to worry about the straight cuts and fabric on the next one. I might need more trim to finish, and I am debating whether to cut my losses and return what I have then stain some instead. I had not realized that the cut edges of the fake wood would look like unpainted cardboard.

**thewire** · **02-24-09, 03:33 AM**

I had to do more corrections. Everytime I change something I have to go back and change 10 times as much.

Took the kraft paper off insulation in the stage & uncompressed it some
Moved more 2" panels over the stage
Covered the front wall with OC 705 2"
Moved the Pillar Traps away from the corners some & removed insulation under them
Moved speakers away from the listening position inches
Didn't equalize bellow 50Hz

Hope this looks alright. This is the left speaker.

My right speaker shown in this graph I had to go back and take extra absorption out from behind the speaker that I added inside the cabinet.

This shows just how sensitive these graphs are to my speakers from around 7' away pretty well.

I fixed that so hope it looks better and more like the left speaker next time I measure.

Here is a new RT60 graph (interpret at your own discretion). The area above 1Khz went down in level after removing the kraft paper and moving the speaker and not just after adding the 6 panels of OC 705, which I had done earlier.

**hjones4841** · **02-24-09, 06:27 AM**

I admire your determination (and energy level!) in getting your room treatments right. You have me thinking about treating my ceiling after all.

In a previous post you mentioned track lighting. What brand/style did you use and do they rattle? I have recessed cans in the ceiling that supplied enough light until I blacked out the ceiling. Some track lights around the room perimiter would help.

**bpape** · **02-24-09, 08:02 AM**

I would strongly recommend against track lighting - exactly for the reasons that are being described here. Just their basic design and flexibility (advantages) make them inherently non-rigid. I had track lighting in one house many years ago and whenever I'd get the sub up and moving, not only would I get buzzes and rattles, I'd pop bulbs unless I used the rough service ones.

Bryan

**thewire** · **02-24-09, 09:57 PM**

Quote:

hjones4841 wrote:

I admire your determination (and energy level!) in getting your room treatments right. You have me thinking about treating my ceiling after all.

In a previous post you mentioned track lighting. What brand/style did you use and do they rattle? I have recessed cans in the ceiling that supplied enough light until I blacked out the ceiling. Some track lights around the room perimiter would help.

Bryan is right they are not good for HT. When I shopped for track lighting I had a sales representative allow me to climb the latter and physically shake each of the lighting to test them for rattles. The ones that gave me least rattles were the style I choose. The ceiling joist are all decoupled from the walls and they are secured further by furring strips that are wedged from the joist into ridges that are on the steel ceiling. That helps prevent the entire joist from physically bowing around with sine waves and aids in the perfomance of my ceiling tiles but does that help the plastic track lighting? Nope. I have placed a small amount of cardboard under them, but the fact that there is loose tile between the wood and the parts attached to the track lighting gives them no support in those areas. What I found shaking was the parts that contain the bulbs, but this is something I notice sitting in the rear of the room, not the front of the room. I need to be sitting under them because otherwise I have not heard it up until now. My sconces are caulked to the walls except in the front where there is carpet behind them. I tried all forms of lighting before I got the track lighting. Lamps, flourecent lighting, night lights. Some battery powered LED lighting would be best but it isn't going to fully light my room, and it isn't cheap. That's way low down at near 20Hz that shook the track lighting. It isn't sound I'm able to hear well. It is mostly felt.

I got mine at Lowes. Here is a photo of it.

I have an example here with what happens when I remove treatments from the room. Removing the extra absorption behind the speaker in the cabinet made the right speaker worse, so I am going to try and see what I can do to improve the results more. As I removed all the treatments, then began to add them, the room began to sound larger and bass became more easy to hear. It also sounded like I was adding larger speakers.

Room treatments where they are.

Removed 2" panels from the front of the stage.

Removed a pair of 2" ATS panels and 6 GIK 244's from first reflection points.

Removed the pair of GIK Pillar Traps. Ouch!

Removed the pair of GIK Moster Traps.

Removed the 6 panels of OC 705 from the front wall.

**thewire** · **02-25-09, 12:31 AM**

It looks like adding some Rockwool 60 to the speaker cabinets moved the resonance down near 100Hz. I noticed that the response looks more flat with the wires reversed from however they are (not sure at this time). I thought the idea is to get the crossover area the highest in SPL but this looks better to me. There were low frequencies that were effected with my mains ran in full range mode with the subwoofers getting double bass but perhaps that was normal. These might be the correct results.

Left + subwoofers

Right + subwoofers

edit: the center channel was added back in the room for these also. Mic was pointed at an angle for these also. Can't wait to start watching movies!

**hjones4841** · **02-25-09, 06:25 AM**

Quote:

thewire wrote:

I switched to Disney "Lamp Black" because the Home Depot in our area said they did not carry it anymore.

Is Lamp Black a Behr color? I may pick up some cheap ceiling tiles and try painting them. I don't have a spray gun, so I will either have to roll it on or use flat black spray cans. The old tiles were USG Radar style. They had holes for "acoustics" and never would paint well. If I can find some smoother surface tiles, then painting may work OK.

**thewire** · **02-25-09, 12:37 PM**

Quote:

hjones4841 wrote:

Is Lamp Black a Behr color? I may pick up some cheap ceiling tiles and try painting them. I don't have a spray gun, so I will either have to roll it on or use flat black spray cans. The old tiles were USG Radar style. They had holes for "acoustics" and never would paint well. If I can find some smoother surface tiles, then painting may work OK.

Those tiles are for things like classrooms. I would recommend some Sonex ceiling tiles.

http://www.sonex-online.com/SONEX%20Ceilings.htm

The Lamp Black was BEHR Premium.

**hjones4841** · **02-25-09, 05:37 PM**

Quote:

thewire wrote:

Those tiles are for things like classrooms. I would recommend some Sonex ceiling tiles.

Shhhhhhh... Recommending foam acoustic products will get you banned from this forum for LIFE

That stuff is way too expensive for me. Painted regular ceiling tiles with R30 over it wil be fine.

**thewire** · **02-25-09, 06:01 PM**

Quote:

hjones4841 wrote:

Shhhhhhh... Recommending foam acoustic products will get you banned from this forum for LIFE

That stuff is way too expensive for me. Painted regular ceiling tiles with R30 over it wil be fine.

Regular tiles will be better than drywall, but I thought you already tried that and had problems with them rattling. Are you going to glue them?

**hjones4841** · **02-25-09, 06:51 PM**

Well, something is still rattling up there when I do LF sweeps - either the grid or the sheetrock "tiles."

The sheetrock tiles just don't look very good - the beveled edges where the tape and mud go in normal use are up against the grid and are quite visible. Did not bother me at first, but now it does. Plus, I need something acoustically "porus" for the R30 to go on top.

Can't glue some of them due to needing access to pipes, otherwise the whole ceiling would be solid sheetrock. I am toying with building wood frames instead and covering them with grill cloth - Ethan's site has photos of a studio done that way.

**thewire** · **02-25-09, 07:24 PM**

Quote:

hjones4841 wrote:

Well, something is still rattling up there when I do LF sweeps - either the grid or the sheetrock "tiles."

The sheetrock tiles just don't look very good - the beveled edges where the tape and mud go in normal use are up against the grid and are quite visible. Did not bother me at first, but now it does. Plus, I need something acoustically "porus" for the R30 to go on top.

Can't glue some of them due to needing access to pipes, otherwise the whole ceiling would be solid sheetrock. I am toying with building wood frames instead and covering them with grill cloth - Ethan's site has photos of a studio done that way.

That's the problem with the ones I see at the local hardware stores. They are not porus. I was doing my best to find you some Mineral Wool Ceiling tiles but I am having trouble finding any. You could also cut your own out of Mineral Wool and cover it with fabric. If I remember right it was around $300.00 if I wanted to cover my entire ceiling with Rockwool 60 2". This is a cost effective way to have tiles and I have seen members on this site with mineral wool ceiling tiles but they were able to get them easy from the location they lived at.

The bass passes through my tiles like they are nothing. They are after all close to paper thin PVC.

**hjones4841** · **02-25-09, 07:56 PM**

I am really beginnng to like the idea of making ceiling tiles from mineral wool, 703 or 705, cover them with black cloth and line the perimeter of the room. Then I could use the same black cloth and cover the remaining sheetrock panels to match.

A question about cutting various materials: I will need to cut 1/4" off each dimension to fit into the grids. Which material will be the best for that? I heard that mineral wool panels are kinda brittle. Would 703 or 705 work better in the long run? Might be worth the extra $s to put up something that 1) works and 2) wont' sag over time.

**thewire** · **02-25-09, 08:14 PM**

Quote:

hjones4841 wrote:

I am really beginnng to like the idea of making ceiling tiles from mineral wool, 703 or 705, cover them with black cloth and line the perimeter of the room. Then I could use the same black cloth and cover the remaining sheetrock panels to match.

A question about cutting various materials: I will need to cut 1/4" off each dimension to fit into the grids. Which material will be the best for that? I heard that mineral wool panels are kinda brittle. Would 703 or 705 work better in the long run? Might be worth the extra $s to put up something that 1) works and 2) wont' sag over time.

I'm not sure why OC would not work just as well. I think that it was just recommended to use mineral wool because it is just as effective as using the OC for the ceiling. I forget exactly how to apply the fabric but I think that spray adhiesive might work. The mineral wool I am thinking of comes with a paper facing on it. I did a search in google and had a hit to the Roxul site but it did not show a picture of it. When I did a search for faced Roxul I also got hits for some but they are sites in the UK and china.

One idea however that may work.

I acutally wrapped Roxul in newspaper then I tapped it so that I could wedge it between my projector and the ceiling without worrying about it crumbling. I'm sure you could spray some adheisive on some 2" Roxul Rockboard (this stuff I have to cut with a hacksaw) and put some newspaper on it, then put some fabric on it and glue that somehow if you are worried about it crumbling.

I should have paid better attention to that part in THX training.

**bpape** · **02-25-09, 08:24 PM**

The idea with the drywall is to maintain mass, minimize high frequency absorption, and still allow the cavity above (insulated) to provide some bass control.

Sonex is way too expensive and also is very high frequency absorbant. Standard firmer ceiling tiles faced with something like FSK and then covered in cloth will be quiet, high frequency reflective, and allow good bass control with just pink stuff up above.

Bryan

**hjones4841** · **02-26-09, 05:58 AM**

OK, part 1 is done: Joann's on-line has a 40 yard bolt of Bengal burlap 10oz, 35" wide on sale for $72 plus tax and shipping (about $90 total). I just ordered one bolt in black, which will almost do the whole ceiling (won't quite do the rear-most row, but I can buy more by the yard). I plan to wrap the 35" width around the 24" dimension of the sheetrock pieces in the center of the room and then pick up some lay-in tiles for the perimeter and use the burlap around them as well.

That price is more than re-painting the existing sheetrock pieces, but I think that the burlap will cover the beveled edges and look better. Plus, it should not have any sheen, which is a problem with the existing paint. Having the fabric around the edges of the sheetrock may help prevent rattles as well.

Bryan: I suppose there is no need to put R30 above the sheetrock (5/8") panels since they won't pass bass very well, right? Also, I should not need to put R30 above the tiles in the center of the room anyway since bass peaks will be around the room perimeter, correct?

**bpape** · **02-26-09, 06:58 AM**

Well, that's a tough call. While it won't pass it as well as a ceiling tile, it can still be a resonating cavity.

If it were me, I'd likely try it at least across the front of the room since you have most of your treatments now in the rear.

Bryan

**hjones4841** · **02-27-09, 07:42 AM**

Bryan: Posterboard should be an acceptable substitute for FSK for the ceiling tiles, right? I thought it would provide a better, no wrinkle surface to glue the burlap to. Also, I could use black posterboard to make sure that the white tile does not show thru the burlap.

**bpape** · **02-27-09, 08:59 AM**

That should work OK.

**thewire** · **02-27-09, 11:21 PM**

Since my subwoofers don't have a limiter or anything, would one of these help protect my subwoofers, or prevent low frequencies from possibly harming my projector, or burning out bulbs in my room, shaking track lighting, etc?

http://store.hlabs.com/pk4/store.pl?view_product=12

**robbo266317** · **02-27-09, 11:39 PM**

Good call.
I hadn't considered the fact that the bass would shake the filament, potentially downgrading it's lifespan, or even worse, causing catastrophic failure!

**thewire** · **02-27-09, 11:56 PM**

Quote:

robbo266317 wrote:

Good call.
I hadn't considered the fact that the bass would shake the filament, potentially downgrading it's lifespan, or even worse, causing catastrophic failure!

I'm almost 100% certain it is what has caused my projector to stop working. The second bookshelf I had in the back of my room was starting to fall apart so I took it out before it was destroyed like the other one. I'm very nervous about putting this new projector right above my subwoofer in the back of the room.

I am going to try and build the shelf like a tank but I don't exactly have a plan how to do that yet. I don't think it would be covered under warranty if my new pj was destroyed. I have never burned out any track lighting bulbs but the ones in my sconces go out around twice a month. The dishes in the kitchen shake on the other side of the concrete wall if I leave the HT door open and the candy counter in the lobby is lucky to be intact. I burned out a light on the deck outside once when I turned that on during some movie previews.

edit: I have a couple of subdudes left that I might use for the pj.

**thewire** · **02-28-09, 01:10 AM**

This is the back row LFE response with the master volume at 0.

This is the back wall where the projector will be. It looks like the mic could hear the track lighting hum possibly. I can't say that I ever noticed that unless I dimmed them alot and listened very close. It might be because the mic was hanging next to Romex that powered them.

**thewire** · **02-28-09, 02:22 AM**

I went and ordered one of those subsonic filters to see what I can do. My subwoofers are suppossed to be rolling off at 35Hz to be flat to 20Hz so it will be interesting to see what a high pass filter will help accomplish. My amps are flat from 20Hz.

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