Diy & bass traps - Page 3  

Thanks for the links, Bob. I had something a little different in mind. More like what's pictured here at Kinetics. That URL is a flash page, so click on "Acoustical Kit" and look at the wedges in the corners.

I don't want treatments are are super intrusive in the room. No offense to Ethan, but his traps just wouldn't go over well in my room. Tubes could probably be blended in a little better, but my better half still didn't like that idea. These wedges are probably the least intrusive, so they'd be my best bet as far as WAF goes.

I'll read up on the link to DE's posts....

Toeside:
I missed what you had in mind.
Perhaps you could do something like GPowers Fabric Frames, except shaped like Kinetic's quarter pyramid upper corner wedges.

You can make wedges in any shape, e.g. Paul Woodlock's Music Recording Studio (which are a little intrusive, but you can scale back):
http://forum.studiotips.com/viewtopi...asc&start=1211
http://forum.studiotips.com/viewtopi...asc&start=1183
http://forum.studiotips.com/viewtopi...asc&start=1196
http://forum.studiotips.com/viewtopi...asc&start=1141
http://forum.studiotips.com/viewtopi...asc&start=1155
http://forum.studiotips.com/viewtopi...asc&start=1120
http://forum.studiotips.com/viewtopi...asc&start=1102
http://forum.studiotips.com/viewtopi...asc&start=1088
http://forum.studiotips.com/viewtopi...asc&start=1061
http://forum.studiotips.com/viewtopi...asc&start=1040
http://forum.studiotips.com/viewtopi...asc&start=1044

Thanks, Bob, for the links. That has to be the most mineral fiber and MDF I've ever seen in one location!

Scale back a LITTLE!? Tha's great for a studio - not so good for a HT.

I showed my wife pictures of the Kinetics treatments. She's approved the corner wedges (DIY, not actual Kinetics) should we need them. She's still not thrilled with other wall treatment ideas, but I told her I really want to address first reflection points at a mininum.

Hopefully I'll be read to take these measurements in a few weeks.

There are several things you can do to increase the visual appeal of the treatments. You can cut them into 2x2 squares and hang them as diamonds - using different colors if you want for interest. You can use a patterned material. If she's a good seamstress, she can sew a pattern from different appropriate materials for the covering, etc.

Just don't get hung up that they have to be these monolithic 2'x4' monotone rectangles hung on the wall.

Thanks BP for the reminder.

She is a pretty good seemstress, so that'll be something she can work on. We still need to agree on a color scheme. So far, the only thing that's been agreed on is the black GOM on the screen wall.

Esthetically, the best thing you can do with room treatments is to hide them behind acoustically transparent fabric. Commercial movie houses use pleated fabric on the walls. Home theaters typically use tightly-stretched Guilford fabric.

I'm sure there are other creative solutions for those who can think outside the home-theater-in-a-box. ;)

- Terry

I know most home theatres here have GOM walls with Linacoustic or an equivalent from the floor to ear level, then poly batting above that. I had a hard time getting my wife's buyin for a fabric front false wall, and it's already been determined that fabric walls all the way around is a no-go. I'll be one of those people thinking ouside the "home-theater-in-a-box". :)

Hi Toe,

Yeah, you've got your work cut out for you. Usually the only thing most wives agree on in a home theater is that all the walls SHOULD have fabric on them. ;)

Larry

Ok, I had some time this weekend, so I decided to create some bass traps. I did a very simple square using corner piece edging from HD ($1.89/ft). I already had the insulation (same as OC 705). I still need to wrap the top half with 2mil plastic (my mains are bi-polar, and I don't want to absorb the rear-firing mids/highs), and then wrap them in some black GOM I have. You also may notice I have them about 3" off the ground....that's because I have speaker terminals on the front walls close to the corners and wanted to be able to run wires under the bass traps.

This first pic is the simple skeleton of the trap without insulation.

-Jason

Here is a picture of the completed trap. It's roughly 12"x12"x36"

BTW....there's 4 (2'x4') sheets of insulation per trap. I guess I should also note....that low and behold....they actaully DO make a difference....and in my case....a pretty big difference in cleaning up my low end. I guess in laymans terms....my bass sounds/feels much tighter.

Not that I didn't respect him before....but I just gained more respect for Ethan

jasplat88:

I like it !

I like it jas. Toe, cover that in some nice cloth, stain and seal the top plate to match the furniture, put a nice plant on top of it and poof - instant WAF.

Very good idea. Nice design, jasplat88.

I have a couple ideas based on this, let me know what you think:

1) build two of them and use them as stands for my front speakers; JBL E30 bookselves
2) using full 2x4 sheets (or slighly smaller) make an ottoman

I don't know if placing my L&R speakers on one of these traps is a good idea. Nor do I know if placing an ottoman-shaped version in front of the front row would be a good idea.

As far as just building what jasplat88 has, I could easily put them in the front coners (they'll be behind my false wall), and in the rear right corner, but the rear left corner will have my A/V rack. There's only about 5" between the rear wall and the edge of my rack.

I wouldn't use them for stands for a couple reasons.

1. They're not sturdy enough to make good speaker stands which should be very rigid.

2. If you're limited on location (you are) and need to maximize more broadband bass absorbtion (you do) the corners are the best place for them - not where your main speakers are.

If you can get 3 of these in the room, that would help out significantly as your space is pretty good sized. Or, since 2 will be behind the false wall and you don't care what they look like, just get some 3-4" and straddle the corner from floor to ceiling. Then build just one like this and put it in the back.

Jason,

> Here is a picture of the completed trap <

Very cool!

--Ethan

Here's a silly question: could you clad a colum trap like that with a relatively thin (say 3/8" or thinner) wood panel, or would that be too reflective for the acoustical benefits that we're trying to achieve?

I'm wanting to incorporate a similar type of trap material into my rear corner columns and I'm just trying to decide what the best covering material would be. I could easily go with the same GOM fabric as the rest of my walls, but I think stained wood would look much better.

Hi,

A point to remember is that we're all not trying to achieve same thing because we don't have the same acoustic situation to deal with.

For example, you say that the rest of your walls will have Guilford of Maine fabric on them. This implies to me that you intend to acoustically treat your entire room. If so, the reverberation time for your high and medium frequencies could be sufficiently low with the wall treatments. Jason's bass trap without a reflective covering appears to be a simple broadband absorber. Therefore, without a reflective cover it will absorb a whole spectrum of frequencies. In a room whose walls are already treated this may make the room too dead in the higher to mid frequencies.

I would be interested in hearing what the experts have to say in response to your question, but before they can answer it intelligently they have to know what type of absorption the user needs. In other words, putting a reflective covering on it may be a good thing for a user who is only interested in low bass trapping.

Larry

Thanks for the reply, Larry.

You bring up a good point, as I was curious as to how a wood cladding around a bass trap like this would affect the bass absorption in a room with what seems to be the more common Acoustimat (bottom) / poly batting (top) covered with GOM. In my case, my room will be fairly small (roughly 15 X 12), so I don't know whether the wall treatment alone would be a little too absorbent of mids and highs (in which case I could benefit from the wood cladding) or I would need a bit more broadband absorbtion.

Hi,

As I understand it Acoustimat is a Mass Loaded Vinyl material used for sound isolation, not acoustic treatments. It would not be installed just on the bottom of a wall, but rather loosely attached to the entire wall.

You may have confused it with on of the various rigid fiberglass products which are usually 1" thick attached below ear level on the side walls with polyester batting above ear level. If so, that's what I have in my home theater.

In measuring the reverberation time of my theater I find that it is already adequately low with just the wall treatments. However, to improve bass response will require some bass trapping in the lower frequencies only.

Larry

IMO the wood cladding is going to throw the effectiveness and range of absorbtion of this unit totally up in the air. If you're going to cover it up with something other than a transparent cloth, it should only be done on one side. The other 3 sides then must be made rigid and airtight. What you've effectively done is turn this broadband absorber into a resonant panel trap (and not a very good one if the insulation is touching the one side that is SUPPOSED to vibrate).

The frequency range absorbed will now be dictated by a combination of the depth of the devide and the density of the resonant panel. The Q of the device will be pretty wide with that much insulation inside too - but not wide enough to cover the whole bass range (the design of this kind of absorber is specific to NOT cover the whole range.)

Now, could you cover it with something like very thin paper (like FRK) or some sort of plastic membrane and still have it be broader? Yes. BUT, that kind of defeats the whole purpose of covering it in something attractive - doesn't it?

Yeah. I just threw the name out as I assumed that it was basically the same as Lincoustic (sp?) and other 1" material that is commonly mentioned here.

I was anticipating the need for additional bass trapping. I don't know if I'll actually need it or not, as I likely won't be able to start construction until next fall, but this is part of my "contingency plan" that I'm putting together. I figured that if I'm going to have columns, then I might as well use them for conceiling bass traps if needed, since my columns will be in the corners.

Thanks again for the reply!

Well...it was worth a shot, eh? It's actually no biggie at all, as my design right now incorporates GOM into the covering. GOM matched with some stained corner trim should still make for a very attractive column that is still set off from the rest of the wall.

Thanks for the input, bpape.

3/8" is way too thick. It would reflect not only high frequencies, but a good chunk of the low frequency spectrum as well. If you used oak panels, for example, I would expect a peak absorption at roughly 60 Hz, with it falling off to half of this at around 100 Hz.

Go with the GOM covering!

- Terry

LarryChanin:

Theoretically it could be used as the membrane in a panel absorber. I don't think I've ever seen anyone do that though -- thin wood seems the popular choice.

Mass-loaded vinyl is a common choice for the membrane of a high-end membrane bass trap. We've built a lot of them. It has the "ideal" property of being a limp acoustic mass. There is no stiffness to worry about. This eliminates coincidence resonance at high frequencies.

- Terry

Thanks Bob and Terry for the information, but aren't you guys taking the reference to Acoustimat out of context?

I mentioned that it was mainly used for sound isolation applications and the poster then admitted that he erroneously thought that a product by that name was a brand of fiberglass to be used as an aborber for the bottom half of a wall.

Are you suggesting that it would be a good candidate for covering Jason's column bass trap?

Larry

Nope. Mass-loaded vinyl makes great tuned bass traps (which you would use with differently configured fiberglass) for targeting a specific frequency. But it doesn't have the broad frequency coverage of the "thick chunk of fiberglass" absorber.

- Terry

Terry,

> Nope. Mass-loaded vinyl makes great tuned bass traps <

Right, and that's what RPG uses for the front "panel" of their Modex corner tuned bass traps.

If the goal is to not absorb too much at mid and high frequencies, I think the best material is more along the lines of thick paper or thin carboard.

--Ethan