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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: Mark Norgren on November 20, 2019, 08:01:28 am

Title: Subwoofer Placement, Low End Issues
Post by: Mark Norgren on November 20, 2019, 08:01:28 am
I am wondering about placement of subs in a ballroom we currently play occasionally.  The room is much wider than long, maybe 160 ft wide and 80 ft deep?

We seem to get a lot cancelling in the low end about 30-40 ft out in the center.

I own 4 KW181's and I run  2 of the KW153's for tops, Midas M32R for a board.  I have been stacking a 153's on two 181's on each side.  The subs are pointed directly out and the tops, slightly inwards.  I am contemplating putting all four subs together in front of the raised stage, either four in a row center front or 4 as a stack of two each next to each other (2x2).

Not sure if this will help the cancelling or create more problems.  I will have to figure a way to get the tops in the air, I may be able to have them on stage with us and still have them high enough to get out over the dancers?

I appreciate any suggestions or help!
Title: Re: Subwoofer Placement, Low End Issues
Post by: Ivan Beaver on November 20, 2019, 11:48:49 am
I am wondering about placement of subs in a ballroom we currently play occasionally.  The room is much wider than long, maybe 160 ft wide and 80 ft deep?

We seem to get a lot cancelling in the low end about 30-40 ft out in the center.

I own 4 KW181's and I run  2 of the KW153's for tops, Midas M32R for a board.  I have been stacking a 153's on two 181's on each side.  The subs are pointed directly out and the tops, slightly inwards.  I am contemplating putting all four subs together in front of the raised stage, either four in a row center front or 4 as a stack of two each next to each other (2x2).

Not sure if this will help the cancelling or create more problems.  I will have to figure a way to get the tops in the air, I may be able to have them on stage with us and still have them high enough to get out over the dancers?

I appreciate any suggestions or help!
It could be room modes (cancellation based on the physical dimensions of the room).

Not much you can do about that-except with a bulldozer------------
Title: Re: Subwoofer Placement, Low End Issues
Post by: Luke Geis on November 20, 2019, 03:56:54 pm
Subs are best either as close together as they can be, or as far apart as they can be. Both of those options may not be practical for you. Another rule of thumb is to place the speakers in the 1/3rds locations of the room. So with a 160' wide room, you would want the subs to set around  40' off of each sidewall and would have the subs setting about 40' apart and then with an 80' deep room you would want to have the subs setting about 20' off the back wall. This has the subs setting in real estate that usually isn't practical or available for that purpose.

Placing all the subs next to each other may work better provided there aren't any room modes that are hindering things. Getting the subs 20' off the back wall may not be a problem, but a long line of subs may narrow the coverage pattern too much off the sides ( perhaps not a bad thing? ). Going with a cardioid array may help rid cancellations caused by reflection off the back wall? Prediction software may help with that. There are a lot of variables and not anyone is the magic fix. It will likely take some experiementing and if you have access and time, a bit of energy spent with a predictions software may really help.
Title: Re: Subwoofer Placement, Low End Issues
Post by: Mark Norgren on November 20, 2019, 08:23:28 pm
Thanks guys!  I will try the upfront approach next gig there.  Will report back!
Title: Re: Subwoofer Placement, Low End Issues
Post by: David Morison on November 21, 2019, 08:04:33 am
Another rule of thumb is to place the speakers in the 1/3rds locations of the room. So with a 160' wide room, you would want the subs to set around  40' off of each sidewall and would have the subs setting about 40' apart

Posting before coffee this morning?

40 is 1/4 of 160, not 1/3.

Title: Re: Subwoofer Placement, Low End Issues
Post by: Luke Geis on November 21, 2019, 01:37:19 pm
^^^^^^^^^ My brain went rogue..... Yes you are correct. The distance off the wall should be about 53.33' with a distance of about 53.33' between the speakers. In either case, it isn't practical to have a 50'+ gap between the speakers unless the stage is that wide.
Title: Re: Subwoofer Placement, Low End Issues
Post by: Douglas R. Allen on November 24, 2019, 03:58:16 pm
I am wondering about placement of subs in a ballroom we currently play occasionally.  The room is much wider than long, maybe 160 ft wide and 80 ft deep?

We seem to get a lot cancelling in the low end about 30-40 ft out in the center.

I own 4 KW181's and I run  2 of the KW153's for tops, Midas M32R for a board.  I have been stacking a 153's on two 181's on each side.  The subs are pointed directly out and the tops, slightly inwards.  I am contemplating putting all four subs together in front of the raised stage, either four in a row center front or 4 as a stack of two each next to each other (2x2).

Not sure if this will help the cancelling or create more problems.  I will have to figure a way to get the tops in the air, I may be able to have them on stage with us and still have them high enough to get out over the dancers?

I appreciate any suggestions or help!


https://www.prosoundweb.com/wp-content/uploads/2019/10/PSW_OpposingSubs_WP.pdf

Douglas R. Allen
Title: Re: Subwoofer Placement, Low End Issues
Post by: Mark Norgren on November 25, 2019, 05:09:38 am
Thanks for the great read!  That helped a lot!
Title: Re: Subwoofer Placement, Low End Issues
Post by: Steve-White on January 21, 2020, 01:01:28 am
^^^ I've used the single location with subs with consistent results overall.  Definitely give it a try.  Having all the bottom end from one point works good for me in difficult rooms.  Corner or wall locations are preferred by moi.