Bass Trap Placement

[joepandi]

I'm currently building bass traps to help tame the acoustics in my room. Because of the way the room was built, I'm unable to have full 2'by 8' traps on my walls. I'm using 2'by 4' panels instead. I know that the Deep Bass traps, High Bass traps, and Mid/High Absorbers should be placed alternately, but should I stagger the placement of my panels (one dead center on the wall, the next a foot above, and so on) or place them uniformly around the room?

[Bill Foster]

Good discussion [url=http://ntrack.com/cgi-bin/ikonboard/ikonboard.cgi?s=d50b394c37dcd83fe7c916bf0f5b3631;act=ST;f=1;t=387]HERE[/url]

[joepandi]

Thanks, Bill. That's useful. If parallel walls are the enemy, staggering the panel placement seems like it would help. But,... I could be wrong.

[Bill Foster]

[quote]Originally posted by joepandi: [b]Thanks, Bill. That's useful. If parallel walls are the enemy, staggering the panel placement seems like it would help. But,... I could be wrong.[/b][/quote]I'm sure it'll help.. We used to record in an old brick garage, flat roof no less. Couldnt afford bass traps/sonex. Egg crates and old moving blankets. Ha.. Made it work somehow. Good Luck, Bill

[MattC]

Always stagger any absorbent- it will improve the absorbent quality of the material. Just out of curiosity, what are the dimensions of your room?

[Audiobotica]

Staggering is good. Two notes: you'll want deep bass traps in the corners and you'll want mid/high absorption directly in front/behind and to the sides of your mix position to minimize flutter echoes there.

[joepandi]

Audiobotica and Matt C, Thanks for the replies. It's nice to have a little encouragement before I hang all these bass traps/absorbers. >>>>Just out of curiosity, what are the dimensions of your room?<<<<< Matt C, The dimensions of the room are 18'10" by 26' and the height is 8'. It's a basement. The floor is slate. Three of the walls are covered in wood paneling. The other is a brick veneer. Behind each of the walls is concrete. It's not a true a rectangular room. A long bar runs along the brick wall until it meets a pertruding nook, creating two smaller corners.

[MattC]

Any time, bro... Well, I asked for those dimensions because I was going to look up some data on mode spacing and room proportions but, curse it all, I can't find the page I need. I'll look for it later... If you want a good read that'll help you out with respect to sound in general, look for this book: "Master Handbook of Acoustics" Everest, F. Alton,(c)2001, McGra-Hill. It'll give you a thorough background in basic, practical acoustics geared for recording studios. I actually found it at a library- go figure. The best advice I can give you is experiment with the placement of the absorbent. Bass traps do have to be in the corners (that's where low-freq. axial modes pile up), but unless you've got traps for all 4 corners, play with them to find the best placement (you might not need traps in all the corners). As for the rest of the absorbent, hang it near the mix position, but play with the spacing. One technique I've read about is to completely kill the mix position and make the other half of the room "live." This will give a nice little bit'o ambience to the room. You will want to play with it to find the best way to go. If you want to make some quantative analyses, here's what you can do(provided you are using a computer): Find a real-time analyzer plugin for your software package. Get your hands on a flat freq. response mic (Berhinger makes one for this purpose, about $40) and an audio test CD. This CD will have about 80 tracks, comprised of white noise, pink noise, sine waves spaced 1/3 8va apart, and so on. Conduct a basic pink-niose test by playing the pink noise track and placing the mic at different places in the room. What you are looking for is not an even freq. response (even anechoic don't have this) but rather the spacing between peaks and valleys on the RTA. Ideally, you'd have no peaks (not possible) or a lot of peaks evenly and closely spaced. It's a reasonable amount of work, but well worth it. best of luck!

[Ethan Winer]

Joe, > Because of the way the room was built, I'm unable to have full 2'by 8' traps on my walls. I'm using 2'by 4' panels instead. < I assume you're talking about the bass trap plans on my web site? If you haven't cut the wood yet, I urge you to reconsider the short height. If you can't fit the full eight-foot height, how about seven feet? Or even six feet? > should I stagger the placement of my panels (one dead center on the wall, the next a foot above, and so on) or place them uniformly around the room? < Again, you should make the traps as high as you can fit. The goal is to cover as much wall surface as possible. If you make the traps less than the full wall height, only that smaller portion of the wall is absorptive. --Ethan

[joepandi]

Matt C, I'm going to look for "Master Handbook of Acoustics" by Alton Everest. Thanks for the tip. As for the analyzer software... I hate to admit it but it sounds more complicated than I'm capable of dealing with. I won't rule it out though. Ethan, First, thanks for your article "Building a Better Bass Trap" and your input. However, I'm sorry to say, I've already cut the wood. I've been building the frames all weekend. I could have probably gotten away with a 2' by 6' trap, but I chose 2' by 4' in order to save money and not waste any wood. With the damage already done, what would you recommend?

[MattC]

Actually, I made the test sound a little more complicated than it really is. Let me re-do things a little: You can probably find that test cd at radio shack, if fact I'm pretty sure that you can. You can use a decent condenser mic (use one that gives you freq. response data, so you can compare your mic to the results). That RTA is available as a plugin, and it's relatively common and pretty cheap, if not free already. Just play the CD and watch the monitor. If you find the book, it'll give a better dinifition, procedure and explination of this test. It's actually a pretty routine test. Any good sound guy will do this before doing sound in a club, if at all possible. Any major studio will have this kind of test doen quite extensively, especially in the control rooms.

[Tedster]

[quote]Originally posted by Audiobotica: [b]Staggering is good. [/b][/quote]THANKSH...now will y...you kindly exshplain that to this police osiffer here?

[Ethan Winer]

Joe, > I could have probably gotten away with a 2' by 6' trap, but I chose 2' by 4' in order to save money and not waste any wood. With the damage already done, what would you recommend? < All is not lost. :) Have you cut the side rails yet? If not, make the traps an inch deeper than I show to partially compensate for the lower internal volume. And if you already cut the rails too, I suggest you mount some of the traps vertically and others horizontally in a pattern, so as much of the wall surface as possible is covered. --Ethan

[joepandi]

Matt C, I found that book at Amazon.com. It sounds like a very useful book. I'm going to look for the room analyzer software at RadioShack. It doesn't sound too difficult and I'm sure it'll be well worth it. Thanks for your suggestions. Ethan, All the traps have been built, so I'll follow your advice: mount the traps vertically and horizontally in a pattern. Thanks for all your help. Tedster, I'm no Bob Villa. I have trouble operating a hammer. So I intend to "stagger" home from the bar, after I finish this project.