Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Shawn A Fieseler]

Small band, running our own sound. I've done several outdoor shows, but never really paid attention to proper subwoofer placement until the last gig i was at...

Outdoor gig, contained in a large fenced in area. Pretty good sized stage, in front of a giant sand pit (owner puts on volleyball tourneys). The guy running sound just placed the subwoofers right in the sand. So it got me thinking, is there a best-to-worst list of ways to do this? Like, dropped in the sand VS just putting them on stage. Or sitting on concrete parking lot VS setting them on a pallet.

Basically, i'm wondering if the type of surface the subs site on, have any affect at all on quality of sound for outdoor gigs.

[Paul G. OBrien]

The guy running sound just placed the subwoofers right in the sand. So it got me thinking, is there a best-to-worst list of ways to do this? Like, dropped in the sand VS just putting them on stage. Or sitting on concrete parking lot VS setting them on a pallet.

The main objectives with sub placement is that which produces optimal boundary loading and a favorable output pattern. Outdoors there aren't many boundaries so on the ground will produce the most output and all subs clustered will produce the most uniform coverage. Even coverage isn't always desired though, sometimes it's beneficial to steer most of the energy on an axis to avoid annoying neighbors, other times logistics or ignorance gets in the way and people just setup a stack on either side of the stage.  On the ground on a pallet is functionally the same as right on the ground but will offer some dirt/water protection to the subs, on stage can also do the same but if the stage is high some boundary loading is lost and some comb filtering can be introduced which would put holes in the response at very important frequencies like at the kick drum fundamental. 

[Doug Fowler]

Small band, running our own sound. I've done several outdoor shows, but never really paid attention to proper subwoofer placement until the last gig i was at...

Outdoor gig, contained in a large fenced in area. Pretty good sized stage, in front of a giant sand pit (owner puts on volleyball tourneys). The guy running sound just placed the subwoofers right in the sand. So it got me thinking, is there a best-to-worst list of ways to do this? Like, dropped in the sand VS just putting them on stage. Or sitting on concrete parking lot VS setting them on a pallet.

Basically, i'm wondering if the type of surface the subs site on, have any affect at all on quality of sound for outdoor gigs.

Put them in the sand, you won't notice any difference.  Might want to source some cheap plywood just to keep them cleaner.

[Yoel Klein]

Put them in the sand, you won't notice any difference.  Might want to source some cheap plywood just to keep them cleaner.

Wouldn’t sand act as a absorption? It’s for sure not the same coupling like hard pavement provides.

[Russell Ault]

[...] on stage can also do the same but if the stage is high some boundary loading is lost and some comb filtering can be introduced which would put holes in the response at very important frequencies like at the kick drum fundamental.

It's not just comb filtering, it's also dispersion pattern alteration. Raising a cluster of subwoofers off the ground will alter the dispersion pattern of the array from roughly omnidirectional to... well, it depends on the height, but as the subwoofer cluster and the phantom cluster on the other side of the boundary move further apart, the dispersion pattern will start to get narrower in the horizontal (since the array is getting longer), eventually going somewhat toroidal, producing a power alley at the boundary with different frequencies lobing at different angles above the horizontal (but typically with less energy being sent straight up into space).

Of course, this is all relative to the wavelengths involved (e.g. ~8 feet at 125 Hz), which is why subs on a pallet isn't going to make any real difference to the sound. It's also assuming that the ground is a perfect reflector (which it's not), with the effect of the phantom cluster being diminished as its "output" is attenuated by boundary absorption.

-Russ

[Keith Broughton]

Wouldn’t sand act as a absorption? It’s for sure not the same coupling like hard pavement provides.

I think that at the wave length of bass frequencies, the sand would act, more or less,  as a "solid" surface.

[Rob Spence]

I would watch out for surfaces that might resonate at sub frequencies. A cheep palette might or thin plywood.

[Dave Pluke]

I would watch out for surfaces that might resonate at sub frequencies. A cheep palette might or thin plywood.

I try to carry a few 2x6 boards for use under the subs in outdoor applications.  Can be just enough to keep them above the beer spillage line.

Dave

[Mark Norgren]

I try to carry a few 2x6 boards for use under the subs in outdoor applications.  Can be just enough to keep them above the beer spillage line.

Dave

I like that idea Dave!  I have a few carpet samples that I keep i the trailer to use for the subs.  I may add a few 2x4's as well!  Thanks!

[Ivan Beaver]

Put them in the sand, you won't notice any difference.  Might want to source some cheap plywood just to keep them cleaner.

Pallets will give a little bit more clearance from the sand getting kicked onto the subs

[ProSoundWeb Community]