Compact budget PA set-up to put bass through (without back-line).

[Greg Edwards69]

Thanks Bill, I think I just about understand the science!

 

The test room was a large rehearsal room.  Let's say around 18m x 10m. Band set up at one end in usual gig configuration. Top speakers on either side of the "stage" area , probably around 1 meter from each wall - so about 8m apart. Sub on the floor next to 1 speaker - around 1m to 1.5m from the wall. With some test music playing through the system, and walking from one side of the room to the other at the opposite end of the room you could definitely hear the difference in low-end content.

 

It's also worth noting that the DXR12 tops have a lowest hpf setting of 100hz, so the sub is set to match. Personally, I feel it would be better if they could be set to 80hz.

 

If I understand you correctly, the adjacent wall to the sub increased the boundary effect, and therefore combined with the listening position increase the, shall we call it the "locality" effect - the ability to locate where the sound is coming from.

 

Therefore, in some typical pub venues where the tops and sub are in open space with no directly adjacent walls, there should be less of the "locality" effect?

 

The next two gigs should be ideal for experimenting with this. The first is a large long room with a wide and shallow stage riser. The sub can easily go directly in the middle.  The next is a wide pub with about 5m+ of clear space either side of the stage, but the stage protrudes in the middle into the "dance floor" area, so the sub has to go on one side of the protrusion so people don't fall over it. With both gigs there'll be opportunity to play some test music though the system when we set up.

[Bill Fitzmaurice]

Boundaries will enhance the lows when the sub is close enough..and 1 meter isn't... and will cause low frequency response notches when the sub and/or the listener is in the .75 to 2.15 meter range from the boundary. They have no effect on subs being directionally locatable, as they don't affect the harmonics. One way to both lessen the distance to the wall and attenuate harmonics is to aim the sub at the wall. Try setting the sub low pass to 80Hz. It doesn't necessarily have to be set at the same frequency as the mains high pass.

[Downunderwonder]

One way to find where best to put your sub is a very simple experiment.

 

Put it where you want the biggest bass ie the middle of the dancefloor. Play a bass heavy track and go around the room to find the best booming position of the available wall spots to put the sub for the show.

 

Put the sub there and it will thump back where you want it.