bass traps?

panhaed · Post by **panhaed** » Thu Jan 13, 2005 5:33 am

i am trying to lay out my mix room, and am somewhat confused about bass trap's.
i will be flush mounting my speaker's in the corner's.
i see a lot of plan's for bass traps call for a sealed trap filled with fiberglass.
my plan was to seal the corner's, by facing with a 1/2'' thick plywood ( minus the cavity for the speaker ) filling the cavity with fiberglass to make a bass trap, but i notice on some plans, their is porting at the bottoms, as show here http://www.saecollege.de/reference_material/index.html
is this more efficient or just different
i will be posting a photo of my layout later i will have to photograph it first.
thanks

knightfly · Post by **knightfly** » Thu Jan 13, 2005 10:12 am

Sealing the cavity with a plywood face makes it into a panel trap, which has a specific resonance peak and so needs to be tuned to specific problem frequencies; in most rooms, you're better off doing broadband absorption first, then if any specific frequencies are not handled by that do some sort of tuned traps, like panel, helmholtz (slat resonator) -

The reason for the ports near the bottom, is that corners are where bass builds up most - by putting the port into the trap at that location, you get most bang for your buck.

Looking forward to your pix... Steve

panhaed · Post by **panhaed** » Thu Jan 13, 2005 3:36 pm

thank you very much for the reply,
so once the room modes have been calculated i should plan the slot, and slat sizes for the volume of the cavity i have set aside for slat resonators, targeting the mode frequencies? mostly those that are close, i believe from what i have read, but i am not sure how close is close.
i will have some more question's i will get to later
thank
you very much for the reply
panhaed

knightfly · Post by **knightfly** » Thu Jan 13, 2005 9:19 pm

Modes tend to not cause much grief above maybe 300 hZ, close depends on the frequency (it's a portion of an octave thing, so lower frequencies close can be 4-5 hZ, while upper ones 10 or even 20 hZ is OK.

IF your room is all parallel walled, it's pretty easy to figure modal distribution - and the larger the room, the less it matters. Unless the modes are spaced either too close or not close enough, you won't need to trap for them at all.

Gettin' past bedtime so I'll have to cut this short for now - do search on harmon for more reading... Steve

panhaed · Post by **panhaed** » Fri Jan 14, 2005 2:47 am

thanks i will let you know what i come up with
here is a drawing showing the direction i hand in mind, i was going to get something done a bit more legible, but this will give you a idea. the room is 10' x 12'. my plan was to make the corners in front bass traps and in-between them a slot resonator, then layout the side walls, filling with fiberglass, and covering with cloth. i was going to also angle the ceiling making two divisions, one half for slot resonator, and then fill the rest with fiberglass and cover with cloth.
i am finding lots of information on calculating mode's, golden room size, resonators, bass trap construction, and how much wall's should be angled.
however i am not finding a lot of info on what to do with the mode calculations once i have done the math.
well here is the attachment maybe I'm not to far off track.
if so well just need to do some more learnin.
thanks panhaed

panhaed · Post by **panhaed** » Fri Jan 14, 2005 8:35 am

my cousin is going to layout my drawing on the computer so it will be more legible i will post that as soon as i get it thanks

panhaed · Post by **panhaed** » Fri Jan 21, 2005 6:17 am

ok i think this will be in the wrong place now so i will post the new pictures in the studio design forum
thanks
Steve hope to hear from you over their
pan