Aiming your PA tops

[Steve Browning]

We all know that speakers distribute sound in a certain way.  Habit tends to be firing straight forward. 

 

That is unlikely to be the optimal solution, so how should we aim our PA top cabs for best results?

[Bill Fitzmaurice]

You should aim them as the room demands, which is to cover the most listeners possible. That's listeners, not people. We've all played those rooms where far too many are more interested in their conversations than the music. When I played those rooms I aimed the PA where it would be most appreciated, at the dance floor. 

[Downunderwonder]

Aka cross fired, the pub formation.

[Chienmortbb]

 Look at the dispersion angle of the speakers and the distance apart. Generally straight ahead with a slight toe-in. Too much cross-fireing will increase reflections and cause dead spots at the side of the front. 

 

[Phil Starr]

Hi Steve, I think it's well worth looking at this if you haven't aleady seen it. It shows the 'heatmap' for typical point source speakers on stands and straight ahead is pretty much what you want in most gigs. I think it's the heat map which is useful, it helps to be able to picture your cabs shining out sound into the room and you can take that mental picture with you to rooms that are sub optimal.

 

 

[Bill Fitzmaurice]

He fails to mention wall loading subs, which gives higher output. Not all venues can take advantage of that, but most can, and as sub output is omni-directional they can be placed to either side of the stage. 

[Chienmortbb]

I think he usually works in large auditoria where sub placement is generally in the middle.

 

All the YouTube live sound influencers talk about splitting the room in two then placing each speaker in the centre of each side. That obviates the need to use too much toe in. You do need to be careful with the dispersion angles. I have some passive speakers with 60 x 60 and in many cases that would not be enough to cover the room.

[Phil Starr]

I think the clue is in the title, Speaker Placement Basics. He doesn't go into a lot of things but has stuck to the sort of set up most beginners will be working with if anything I doubt many bands have this much equipment to play with. Wall placement isn't a panacea and wall reinforcement is unnecessary if your subs are adequate. Placing them to one side means you can't match the level of the sub to both of the tops. Subs may be omnidirectional but the sound level still falls with distance so the bass will potentially be too loud on the side nearest the tops and not loud enough on the side further away.  In any case most people viewing this for the first time probably won't have access to subs or centre fills. Steve's question is about directional speakers and where to point them and the heat maps are a really useful way of looking at this.

[Bill Fitzmaurice]

Wall placement gives not only up to 6dB more output, the equivalent of doubling the sub count compared to well away from the wall, but also eliminates reflection cancellations. Uneven room response is seldom an problem in typical pubs and small to medium sized clubs. Every room is different, so experimentation is key to find the best spot to place them. Where you'll usually get the worst result is below mains, so that should be avoided whenever possible.    

[Downunderwonder]

To get the best placement of a sub in a pub you need to get in before opening.

 

Put your sub in the middle of the dance floor designated area. I say designated because it could well be a dining area during daytime.

 

Play some music with a little booty in the bottom. It doesn't have to be loud, only discernible.

 

Check out the possible actual locations for the sub for best bass thump. When the sub is swapped in there and cranked up, hey presto, thump on the dance floor.

[Bill Fitzmaurice]

That works, it's called the Sub Crawl. https://www.audioholics.com/home-theater-connection/crawling-for-bass-subwoofer-placement

[JPJ]

Every now and then you get a gig that completely defies logic. This was the “stage” area we were presented with last night. We were basically in a corner with a 1 metre (3ft 3”) partition in front of us with the main ‘audience’ watching through the window, and a small bunch of music lovers off to our right. Solution, one top pole mounted on a bin facing right and running at about half power, and one top facing through the window running flat out. The problems were compounded by ceiling beams and a low ceiling. Did we get a great sound - er no, did we get an acceptable sound at an acceptable level for what was a small’ish villiage pub, then yes. Sometimes life gives you lemons and you just have to get creative.

[Bill Fitzmaurice]

Not exactly the Royal Albert. 😉

[JPJ]

11 minutes ago, Bill Fitzmaurice said:

Not exactly the Royal Albert. 😉

Not quite, but typical of what you can face on the UK pub scene. It sort of brings the whole speaker placement discussion into sharp focus.