Power Alley

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   Was recently lucky enough to go to the Canary Islands on a holiday, and to my surprise they were setting up a large scale carnival music event. I have put some photos below.

The subs were in two stacks at each side of the stage as shown in the photos.

The best bit for me was that during setup / soundcheck there was little security, so I was able so have a good long listen and walkaround the whole audience area before the crowds started to arrive.

I note that the system was L'Acoustics K1, but I think my comments are relevent to other systems set up in a similar way.

During my long walkaround I was really quite shocked at how narrow the "power alley" was.

I based this just on feeling the "kick in the chest" rather than anything more sophisticated.

In the "power alley" it sounded great. Proper kick in the chest. But out of it (ie. For rather more than 50% of the crowd area) there was simply "nothing there".

So more than million pounds of pa system was being used, and the majority of the crowd would be feeling very little bass! Thats a bit sad I think.

The question I am asking is this:

When I have done smaller outdoor events with two stacks, the power alley has been quite wide relative to the stacks. I think that this is because the stacks have been quite close togther (say less than 10m) so there is an element of "point sourceness" even though there are two stacks.

But in a large event like this (typical festival stage size?), because the stacks are say 20m apart, this is not the case.

I understand that for a large event it is not as simple as stacking all the subs together in front of the middle of the stage, because of the height affecting sightlines of the stage, also going too wide would cause "beaming".

But if I was the client, and the pa company charged me a lot of money for a system that offered such poor crowd bass coverage I would not be particularly happy.

What do other people think?

Is this an unsolvable problem for large festival stages like in this case?

Or are there better options for the system setup for this type of event?

nearest coles from my location

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APC321 Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 24 August 2013 Location: West Midlands Status: Offline Points: 797	Post Options Post Reply Quote APC321 Report Post Thanks(0) Quote Reply Topic: Power Alley Posted: 12 March 2025 at 4:28pm
	Was recently lucky enough to go to the Canary Islands on a holiday, and to my surprise they were setting up a large scale carnival music event. I have put some photos below. The subs were in two stacks at each side of the stage as shown in the photos. The best bit for me was that during setup / soundcheck there was little security, so I was able so have a good long listen and walkaround the whole audience area before the crowds started to arrive. I note that the system was L'Acoustics K1, but I think my comments are relevent to other systems set up in a similar way. During my long walkaround I was really quite shocked at how narrow the "power alley" was. I based this just on feeling the "kick in the chest" rather than anything more sophisticated. In the "power alley" it sounded great. Proper kick in the chest. But out of it (ie. For rather more than 50% of the crowd area) there was simply "nothing there". So more than million pounds of pa system was being used, and the majority of the crowd would be feeling very little bass! Thats a bit sad I think. The question I am asking is this: When I have done smaller outdoor events with two stacks, the power alley has been quite wide relative to the stacks. I think that this is because the stacks have been quite close togther (say less than 10m) so there is an element of "point sourceness" even though there are two stacks. But in a large event like this (typical festival stage size?), because the stacks are say 20m apart, this is not the case. I understand that for a large event it is not as simple as stacking all the subs together in front of the middle of the stage, because of the height affecting sightlines of the stage, also going too wide would cause "beaming". But if I was the client, and the pa company charged me a lot of money for a system that offered such poor crowd bass coverage I would not be particularly happy. What do other people think? Is this an unsolvable problem for large festival stages like in this case? Or are there better options for the system setup for this type of event? nearest coles from my location

snowflake Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3443	Post Options Post Reply Quote snowflake Report Post Thanks(0) Quote Reply Posted: 12 March 2025 at 5:32pm
	A_Practical_Guide_To_Bass_Arrays.pdf https://www.sounddesignlive.com/wp-content/uploads/2020/09/A_Practical_Guide_To_Bass_Arrays.pdf

KDW32 Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 April 2010 Location: Green Hell Status: Offline Points: 770	Post Options Post Reply Quote KDW32 Report Post Thanks(0) Quote Reply Posted: 12 March 2025 at 11:20pm
	No centre or in fill speakers which is what looks like is missing

Phil B Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 21 November 2004 Location: Melbourne Status: Offline Points: 2353	Post Options Post Reply Quote Phil B Report Post Thanks(0) Quote Reply Posted: 13 March 2025 at 6:37am
	Having done a few "big" gigs it looks like the stage height has meant it's only a L-R stack of subs. But they could have gone 2 high across the front with frontfill ontop?? Having them setup in cardioid mode with bottom ones reversed won't help with the power alley but might reduce stage sub a bit? .p.
	Mostly harmless.... except if catering is shut. Solar Sound System Shennanigans..http://diyhifi.biz/

DMorison Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 14 March 2007 Location: Aberdeen Status: Offline Points: 1740	Post Options Post Reply Quote DMorison Report Post Thanks(0) Quote Reply Posted: 13 March 2025 at 4:31pm
	Aye, in general, the wider the spacing between 2 stacks of subs, the narrower the main power alley will be. Spacing out several smaller stacks can work; one trick to make the coverage wider is to create a virtual curve using delay. You'd start with zero delay for the stacks nearest the centre, adding a little more to each successive outboard location. It's important to use modelling software to check the amount of delay as it will depend on the spacing of the stacks, how many there are and how wide you need the overall coverage to be. There is also a downside to this method: by however much you widen the forward pattern of the array, you're also going to narrow down any spill behind it. In some cases you get away with it, but as it has the effect of concentrating lots of sub on the stage, it can frustrate the performers a lot.