Hi,

I have a 15" Velodyne, nice sub... Onkyo 805 receiver, 15 x 25' rectangular room, 8' flat ceiling, corners between vertical walls and ceiling are rounded (inside coving).

Bass is good, but when I move closer to a corner (especially the one the sub is closest to) I can hear A LOT more bass concentrated there. I tried moving the sub with no results.

Is this fairly normal? If not, would some of those bass traps solve this problem?

Any insight would be greatly appreciated.:)

Bass hangs out in the corners. Bass traps will absorb some but it might not have the effect you're looking for. Have you analysed your room with REW? Is your sub capable of putting out more power?

Bass hangs out in the corners. Bass traps will absorb some but it might not have the effect you're looking for. Have you analysed your room with REW? Is your sub capable of putting out more power?

What is REW and where can you get it? I've asked this in another thread, but got no replies. Thanks.

Information about REW can be found here:
http://www.hometheatershack.com/roomeq/
and some discussion about it here:
http://www.hometheatershack.com/forums/rew-forum/

I have only used it once, so I'm still learning its proper setup and use. It is much, much better than plotting test tones manually one frequency at a time!

Matt

Thanks fordmaker. That's exactly what I was looking for.

Is this fairly normal? If not, would some of those bass traps solve this problem?

You already got the answer - bass "hangs out" in corners. Actually, it collects there much the same way as cupping a hand behind your ear focuses and amplifies the sound. Bass traps do indeed give you more bass at the listening position. They do this by absorbing the bass that is reflected back at you from the corner which is out of phase with the bass coming directly from the loudspeakers. In truth, some to the reflected bass is in phase, creating peaks. Bass traps help that too.

--Ethan

Ethan, can you talk more about this. Particularly about the 'out of phase' aspect. I haven't heard much about this and now i think that is why i really haven't dialed in, my sub. {i think i am going to have to send you a picture of my room, so you could give a recommend.
I trust your thinking.
"They do this by absorbing the bass that is reflected back at you from the corner which is out of phase with the bass coming directly from the loudspeakers. In truth, some to the reflected bass is in phase, creating peaks. Bass traps help that too."

You already got the answer - bass "hangs out" in corners. Actually, it collects there much the same way as cupping a hand behind your ear focuses and amplifies the sound. Bass traps do indeed give you more bass at the listening position. They do this by absorbing the bass that is reflected back at you from the corner which is out of phase with the bass coming directly from the loudspeakers. In truth, some to the reflected bass is in phase, creating peaks. Bass traps help that too.

--Ethan


Ethan,

Thank you and everyone elso who responded... Do you recommend any particular traps? Should I tread all 4 corners or just the culprit one?

Thanks again,
Danny

Ethan,

Thank you and everyone elso who responded... Do you recommend any particular traps? Should I tread all 4 corners or just the culprit one?

Thanks again,
Danny

Well Danny,

In light of the fact that Ethan is the principal in a company which manufactures room acoustic treatment products, Realtraps, Ethan's recommendation will come as no surprise! :) Another albeit more expensive option comes in the form of ASC's original TubeTraps. One can also DIY effective bass traps very simply and quite inexpensively if you are so inclined. If possible treating all four corners of a rectangular room is ideal.

Happy Trails!
Vince@Freewheelcycle.com

^^ Thanks Vince!

Ethan, can you talk more about this. Particularly about the 'out of phase' aspect.

It's very simple, and this image shows what I'll describe below:

http://www.realtraps.com/standing.gif

A loudspeaker is 10 feet away from a wall and pointing at the wall. You stand somewhere in the middle, let's say three feet from the wall. Now play a sine wave through the speaker. At some frequencies and distances the time delay between what you hear directly from the speaker and what is reflected will shift the phase 180 degrees. That gives a null. If the shift is 360 degrees you get a peak at that location. The peaks and nulls repeats at ever-higher frequencies too, and the net effect is called comb filtering because the shape of the response graphs looks sort of like a hair comb:

http://www.realtraps.com/art_spaces2.gif

More here:

http://www.realtraps.com/art_spaces.htm

--Ethan

You already got the answer - bass "hangs out" in corners. Actually, it collects there much the same way as cupping a hand behind your ear focuses and amplifies the sound. Bass traps do indeed give you more bass at the listening position. They do this by absorbing the bass that is reflected back at you from the corner which is out of phase with the bass coming directly from the loudspeakers. In truth, some to the reflected bass is in phase, creating peaks. Bass traps help that too.

--Ethan

Cupping hands around ears. Yes I hear what you're saying Ethan, I understand it, never thought of that before even thou I’m aware of what it does when you need to listen to someone in loud street.

So the corner needs to be flat with (bass trap) to make the corner flat rather then pointed or (L shaped) it needs to be simply flat to redirect the bass no?

So what is best to allow it to create peaks and then iron it out with EQ to be bit more flatter after the bass traps have been installed?

Thanks.

I don't really understand your question, but bass traps are usually mounted straddling corners like the ones behind the pianist here:

http://www.realtraps.com/mini8.jpg

I tried using a pillow in a corner just for fun:D suprisingly it helped, i noticed i had more bass at my listening position.

Interesting conversation. There are some aspects of bass traps that flew by me since I've always attacked things differently. Since I'm redoing my room, I'm definitely going to incorporate them in my now. Thanks for posting the pic Ethan. When I look at it, I see the light sort of speak:)