Should I drill holes in my pine frames?

[joshj]

Hi guys, as I now have all my supplies for my bass trap building project, I am now ready to break out the tools and begin. One little itty bitty question though... should I drill large (1" or 1.5") holes in the bass trap frames to increase exposed surface area on the rockwool. I've heard "yea" and "nay" with one person telling me it negatively changes the absorption properties. My personal thought was that this would only help... what are your thoughts? Thanks!

[TMFK]

Im sorry,Im a newbie.. just curious, besides the corner in my room that traps all the bass and amplifies it to an extraordinary level that sounds way off, whats a bass trap?

[joshj]

Hi, a bass trap is basically a piece of rigid or semi regid fiberglass that is hung across corners or on walls for exactly the reason you said. Bass and mids can sound really muddy (especially in small rooms) and bass traps help tame that. Go to www.realtrap.com or http://www.saecollege.de/reference_material/index.html
for more information.

[TMFK]

ohh ok thanks! yeah my room is kinda small, and it has a stepped layout acting like a waveguide system guideing all the bass into a hutch erea built for my desk.. bass lovers dream, musicions nightmere

[crankz1]

If you are implementing the absorption unit as just a mass of absorption material held together by a simple frame .... I'd say, sure put holes in the sides to increase the surface area. However, if you are building a sealed panel trap ... then you wouldn't want to drill any holes.
Sounds to me as though you are just using the framing to hold the rockwool together around the sides, with maybe a fabric covering the face. In that case holes won't hurt. The will, in fact, add to the surface area of the absorptive material.

[joshj]

yes, sorry I didn't clarify, this is NOT a membrane trap. It is indeed a bass trap to hang in corners just like a "RealTrap" design. It is not sealed. Thanks!

[knightfly]

Josh, that type trap is more often referred to as a broadband trap, because it covers a really wide range of frequencies - the wider you make it (more of the corner taken up) the lower it will have effect.

crankz1 nailed it on the holes... Steve

[joshj]

I humbly kneel at the knowledge of knightfly and crankz. Young grasshopper WILL drill holes in frame. Much gratitude and may the hummingbird of prosperity nest in your beard.
Thanks guys!!!

[chris-from-ky]

Originally Posted by knightfly

- the wider you make it (more of the corner taken up) the lower it will have effect.

Confused. Does this mean that the wider trap won't be as effective in trapping or does it refer to the range of frequencies it traps, ie lows/ mids/ highs?

[knightfly]

Sorry, some clarification -

Using a wider absorbent across a corner will absorb more sound in all ranges, partly because by being wider it will have more surface area; because the absorbent material is wider, it also means that the absorbent, at its center, will be further away from the wall in the center of the absorber, where the actual corner of the two walls will be located.

As you increase the effective depth of an absorbent material by spacing it further from a wall, you cause it to absorb lower frequencies better; this is because an absorbent works most efficiently when its total depth from a boundary (wall, ceiling, etc) is equal to (or greater than) 1/4 wavelength of the sound.

Keep in mind that audio wavelengths can get pretty long; for example, the wavelength of a 32 hZ tone is 35.3125 feet, which puts 1/4 wavelength at 8.828 feet - so it isn't usually practical to use this type absorber for really low frequencies; this is where panel type traps come in.

So, what I meant was that with more space between the absorbent and the wall, the lower the frequencies that will be absorbed by the trap... Steve