Where Should Our PA Speakers Be Placed?December 22, 2010 6:00 am Live Sound
When I run sound for Rusty Strings, we use a PA setup featuring two identical “main” speakers (on stands, with the drivers about six feet up), which we position somewhat arbitrarily to the left and right of the playing area, facing the audience. Wherever we first put them, that’s where they stay.
This procedure usually works OK, which is a good thing too, since we rarely get a sound check (unless you count the first two or three songs as a “sound check”) and we are pretty much stuck with the sound we have as the show begins.
Recently, we had an opportunity to play in a small performance space attached to a record store, where we were able to set up and check the sound during the afternoon, then come back for the evening show with everything ready to go. What a luxury! I knew that some tweaks would be necessary once the throngs of Rusty fans (and their bodies) filled the sonic space, but that would be nothing compared to “flying blind” in our usual manner.
Sure enough, thanks to the afternoon sound check it was one of our best-sounding shows ever! As it turned out, determining the best position and orientation for the main speaker (only one was needed for the small venue) was, I believe, what made the difference in the sound that night. Based on what we observed, I would offer the following four rules for speaker placement, for use in those cases where you do have the luxury of a sound check.
Rules To Position By
1. Keep the main speaker(s) in front of the “mic line”.
One objective of speaker placement is to obtain the maximum gain before feedback, referring to how far you can turn up the overall volume level before you start getting feedback from the mains back into the mics.
To do this, make sure that each main speaker is in front of the mic line, defined as an imaginary straight line between (and beyond) the two mics that are positioned the furthest forward (toward the audience). As long as this is true there will at least be no direct acoustic path from the speakers to any of the mics.
2. Check the feedback point at various positions.
This was a real lifesaver in our case, since we ended up needing all the gain we could get before feedback to get the vocals up over the instrument amps. The idea is to set all the mic faders to somewhere near their final positions (0 dB?) and then bring up the mixer’s Master Gain fader until you just start to get feedback. Note the Master Gain setting, then repeat the test after changing the placement of the main speaker(s). Try it here, try it there. Does the edge-of-feedback point get higher? Lower? Use a series of these tests to determine the minimum-feedback placement for each speaker.
Note: Especially in acoustically active spaces (like the hard-walled, hard-floored space we set up in), a position change of even a few inches can make a surprisingly big difference in the feedback situation.
3. Consider moving the speaker(s) away from the band.
As I mentioned, we sort of reflexively position the main speakers right near the band, and this does seem like the “normal” way to go. But in the challenging case I am discussing, we had the best result with the main speaker positioned a full eight feet to the left of the band as seen by the audience. The room was very reverberant, which masked the exact placement of the speaker (as well as the instrument amps) in the room, and the gain before feedback was significantly increased.
4. Rotate the speakers for the best audience sound.
Once you’ve determined the best place for your speaker(s) feedback-wise, give a little thought to their left-to-right orientation. This is best accomplished while the band is actually playing. (Hey, it’s a sound check, might as well use it!) Choose a spot in the middle of the listening area (or where the record-label executive is going to sit) and see what rotational position gives the clearest sound there.
This adjustment will mostly affect the treble frequencies and can have a big effect on the “presence” of the vocals and the intelligibility of the lyrics (if that’s important to you).Tags: live mixing, microphones -->