Multi-Subs for line arrays?

[cacophonix]

Hi,

I've just completed building my line arrays (Selah Audio Symmetrica), and am currently running them alongside rythmik servo sub. My room is kinda small (12x12x9), and not surprisingly, bass is not integrating as well as i wished. In my slightly bigger living room (12x22), the sub is a killer :twisted:, but in this small room, not so much.

Recently I read that using multiple subs can tame a lot of the room issues....and was wondering if there were any plans floating around that i could use to build 3-4 small inexpensive sealed subs. I'll probably get a PE 1000w sub amp to drive all of them.

Thanks!

[Mazeroth]

Have you taken measurements of your subwoofer in its current location? You could be hearing, or not hearing (heh), a null that is making the subwoofer sound lean. Moving the sub and taking measurements will help you identify the best location for it. Or...

You could try the caveman approach and place the subwoofer as close to your listening position as possible (height as well). Then, walk and crawl around the room and find the location that sounds the best. Place the sub in that location and see if it sounds better.

Your best bet is to do the measurements and purchase and equalizer, such as a Behringer Feedback Destroyer, to mitigate peaks in response and give you your best shot at great bass. I have a newborn here needing my attention so I'm going to cut this short. Let us know if you've done measurements or not and we'll go from there. Also, while not ideal, a square room can be made to sound great.

[JonP]

Yep, if you have the measurement gear, download the free and great Room EQ Wizard (REW) to have a look at your room response. It will tell you a lot about what's going on, and that will help you with placement experiments, crossover set points, levels, etc. And if you get the aforementioned BFD box, and the MIDI cable, REW will let you create and download parametric EQ curves to further help things.

I'd recommend doing that first, then armed with the response info, check alternate placements with the current sub. You might find something that works well.

Look around, there are several sites/guides on bass in rooms that are good for the basics, on up to studies on placing several bass sources in varying locations. Bass can be tricky in rooms... I think it's a worthy investment to get some instrumentation on the subject.

[cacophonix]

Thanks for the responses!
I've a computer mic and the SPL meter from radioshack that i can use for REW .. i'll try that out and see if it helps.

[ThomasW]

A computer mic won't work since their frequency response isn't flat.

The problems associated with having a square room should be addressed, and that means building bass traps

[cacophonix]

A computer mic won't work since their frequency response isn't flat.

The problems associated with having a square room should be addressed, and that means building bass traps

I have built 2 2'x4'x3" and 2 2'x4'x4" acoustic panels that i have placed at the corners. Here are my arrays ... since my room is small, i had to take a few pics, and stitch them together.



You can see the panels in the corners. Do you suggest any more to be placed elsewhere?

[ThomasW]

Bass traps need to be very thick/deep

As an experiment take your existing traps and place them diagonally across the corners.

Next google 'super chunk traps'

[JonMarsh]

All damping systems work by impeding/reducing the wavefront propagation; they work best in an area of high velocity and low pressure. That's away from the boundaries. The closer to the boundary, and the thinner the absorptive panel, the higher the frequency range of effectiveness- i.e., they only tend to work in the midrange and highs. This is why, in a speaker enclosure, lining the walls can do a good job of suppressing midrange reflections (which you can to do), but not alter the LF Q all that much (which you don't want to do in a ported box). If you DO want to alter the LF Q, then you have to add damping material that is more in the center of the box where pressure is low and velocity is high.