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Venue eq issues.

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Forum Description: Open Discussion / Questions
URL: https://forum.speakerplans.com/forum_posts.asp?TID=92927
Printed Date: 28 March 2024 at 11:16pm
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Topic: Venue eq issues.
Posted By: darkus
Subject: Venue eq issues.
Date Posted: 07 August 2015 at 8:48pm
Hi everyone, some help would be greatly appreciated.

My friend owns a laser tag venue, we do events once a month, all my kit has been up there for ages due to the 8 flight of stairs.

The problem i seem to have is there seems to be very little sub coming out, at first I thought it was my crappy eqing skills which I'll be the first to admit I have a lot to learn and the not so good equipment I have but a friend took half has rig up there and I know his rig sounded very good on the sub at other venues and the same thing happened very little sub, he knows a lot more than me so i'm presuming its the actual venue.

My kit:4 gsubs with 18xbs, 4 black box with 15b's, and 4 black box tops with 12mb, fane st5020 x2, emernace psd3003. 2 x 5000vz, 2 x 3600vz, 2 x 802, 1 x 602. 2 x dbx.

Dbx setting 35-80, 80-150, 150- ????totally forgotten what i set the over settings at but theirs no problem with anything above 80hz so that doesn't really matter.

I can't remember all my friends equipment but he had Ligwa scoops running off qsc amps and dcx.

We both tried many different eq settings but just couldn't seem to get any decent sub, now I'm thinking its the strange shape of the venue and the ceiling. I've hopefully posted links to the pictures of the venue and the ceiling. I also used the dbx rta input but I find the results sound awful.

I marked the floor plan with where we had the stacks, we are limited to where the stacks can go due to power and speaker cable length, the two different stacks were not used at the same time!

I'm sure I should get a half decent sound form the set up even though its getting on a bit, I don't really have the option of getting anymore gear so was hoping to make the best of what i got. 

The venue floor is 300sqm and the ceiling is about 3.5-4 meters high, floor is solid concrete built in the 70's I just thought I'd give everyone as much info as possible. I'm sure I had more sub at other venues but the rig has been up there so long that I can't remember to be truthful. 

My thinking was maybe the funny ceiling shape was causing some wired cancellation of the low freq, maybe a thought could be cover the ceiling with something, bearing in mind its quite a large area. Would a large parachute/drapes help or maybe boarding it up?

https://www.mediafire.com/?qu1f8wxnxlqk53z

https://www.mediafire.com/?5blxtd76ud6oh89


https://www.mediafire.com/?ve7d535xvu79e3l




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Darkus Sound System.



Replies:
Posted By: mini-mad
Date Posted: 07 August 2015 at 9:19pm
Can you not lay all your g-subs along that back wall and power ally the bass down the room?

Anyway, why not test it?

Stick a g-sub in the middle of the room and play a bass heavy track and then wheel it around and see where the bass peaks and really drops off.

Some places are just shat for bass. Cant help it. But by testing you MAY find a sweet spot to chuck your bass section.

Its not just eq'ing its about physical placement too.


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If it sounds like a gorilla is trying to escape, turn it down.


Posted By: darkus
Date Posted: 07 August 2015 at 9:29pm
Whats not clear in that picture is theirs a sort of wooden stage along that back wall, so the stack would have to go in front of it as the stack would hit the ceiling on it. I'll definitely try moving the one around I can join some speaker cables together and wheel it around, I didn't think of using one on its own to test as I had it in my mind of moving the whole thing.

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Darkus Sound System.


Posted By: njw
Date Posted: 07 August 2015 at 9:33pm
Originally posted by mini-mad mini-mad wrote:



Some places are just shat for bass. Cant help it. But by testing you MAY find a sweet spot to chuck your bass section.

Its not just eq'ing its about physical placement too.
   
 
 I can remember when a local venue increased the size of their stage which then meant the bass cabs were 2ft further forwards onto the dancefloor, before this I just couldn't get any decent bass on the dancefloor no matter what I tried (there was plenty in the toilets though!) but that small difference in the placement of the bass cabs made all the difference to the 'oomph' on the dancefloor


Posted By: Robbo
Date Posted: 08 August 2015 at 7:47am
Have you time aligned the G subs with the Black Box 15s as they will cancel bass out due to one cabinet being direct radiating and the other being horn loaded---they are completely out of phase with one another.


Posted By: darkus
Date Posted: 08 August 2015 at 8:03am
Originally posted by Robbo Robbo wrote:

Have you time aligned the G subs with the Black Box 15s as they will cancel bass out due to one cabinet being direct radiating and the other being horn loaded---they are completely out of phase with one another.


No I havent, how would I work out what to set it at or just change it and do it by ear.

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Darkus Sound System.


Posted By: DMorison
Date Posted: 08 August 2015 at 12:37pm
Originally posted by darkus darkus wrote:

Originally posted by Robbo Robbo wrote:

Have you time aligned the G subs with the Black Box 15s as they will cancel bass out due to one cabinet being direct radiating and the other being horn loaded---they are completely out of phase with one another.


No I havent, how would I work out what to set it at or just change it and do it by ear.

The basic method is to flip one box out of polarity, play a sin wave through both boxes at the acoustic crossover frequency (with your normal crossover settings present) and gradually add delay to the reflex box until you get maximum cancellation between the two. Then flip polarity back to normal and you should have maximum summation. Walk the venue after doing this and take a look at the amount of delay added too as a reality check - it should realistically be in the single digits (or possibly low double digits depending  on the boxes) of milliseconds.


Posted By: 70,s hero
Date Posted: 08 August 2015 at 3:11pm
Try increasing the signal to the drive rack , seems the sub out suffers from low input gain, at least on mine if not set right, also the input sensitivity switch on rear of drive rack , may be set for too high a gain.

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Top banana


Posted By: shagnasty
Date Posted: 08 August 2015 at 3:20pm
Try running your black box 60-180 and your mid hi in from 180, the overlap with your sub will give you chance to run a 100Hz test tone and have it appear in both cabs, as Robo right points out the horn will have a massive phase shift against a G-sub.
 
I haven't used B-Box for years and when I did we were on FDS-360s so I never really paid much attention to the crossover point, but 150 sound very low for the 15>12" point and I have used Turbosound 30/100Hz boards to run black box 4 way before so letting the 15 down to 30 is no probs, but 50/60 (I assume your DBX allows overlap) would be a min to get more energy into that area.
 
You really need to do an impulse test to line up, if you don't have anything more hi-tech a 1.5V battery and a 'scope with a mic will do...


Posted By: Jasonstry
Date Posted: 08 August 2015 at 5:15pm
Also, if the term "boundary cancellation" is new to you, do a bit of research. I still remember setting up a system many years ago and wondering where the bass went.....

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Down with signatures!


Posted By: mini-mad
Date Posted: 08 August 2015 at 5:19pm
Does boundary cancellation really appear in such an odd shaped room? I would hazard a guess at the 4m ceilings arent helping as it a half wave of 40hz give or take....

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If it sounds like a gorilla is trying to escape, turn it down.


Posted By: Jasonstry
Date Posted: 08 August 2015 at 5:23pm
Also, if the term "boundary cancellation" is new to you, do a bit of research. I still remember setting up a system many years ago and wondering where the bass went.....

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Down with signatures!


Posted By: mini-mad
Date Posted: 08 August 2015 at 5:24pm
...ok then theres way more i need to learn about it....

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If it sounds like a gorilla is trying to escape, turn it down.


Posted By: Jasonstry
Date Posted: 08 August 2015 at 5:36pm
My worst case was just two walls.....

http://peavey.com/support/technotes/soundsystems/boundarycancellation.cfm




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Down with signatures!


Posted By: Pasi
Date Posted: 08 August 2015 at 6:41pm
Originally posted by Jasonstry Jasonstry wrote:

My worst case was just two walls.....

http://peavey.com/support/technotes/soundsystems/boundarycancellation.cfm




Nice article, as long as you ignore his mathematics at the end.


Posted By: Jasonstry
Date Posted: 08 August 2015 at 9:14pm
It is a long time since I looked at that and, tbh, can't be aresed right now. General idea is right though.



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Down with signatures!


Posted By: Darkstar
Date Posted: 09 August 2015 at 6:55am
I knew about boundary cancellation but never got to struggle so much with it until a few months ago: I had to set up a friend's soundsystem as fixed in a venue which is an austrian fort built around 1800, when that happened the town's ground was significantly below the current level because it was basically built on sand and stones so it kept getting lower but, the ground was constantly raised through the years by putting more stable ground components anywhere it could be possible.
Raising the fort was obviously not an option so it is now 1 floor below the street level, that means the soundsystem was installed inside a room with about 1m thick walls which had as much ground behind them as the whole city has.
For the first party the system was actually put up by my friend and here you can see how he placed the speakers. I must warn you that they were mainly placed there for aesthetics and space management purposes though. 



Room is very small, it's around 7m long and you could not hear the bass from the front at all. On the back of the subs though you were literally getting your internals shaken and killed by bass, it would've been cool enough for the peeps standing back there if it didn't hurt their ears when the party was over.

My thought was that the walls being "infinite" due to being underground were making even deep bass bounce tightly and the waves coming back from the wall to the front would cancel whilst the ones on the back were adding up, this was also a problem from the side walls and the ceiling.
My solution was to push the subs as close to the back wall as possible, so that it would give them the most natural position, and measure the exact room length to add it as a long delay on the LMS (I thought that's basically like subtracting the box lenght).
It worked, and now its response is pretty flat for such a room with difficult acoustics interaction.
The perfect setup IMO would've been to put just one stack in the middle with the tops a bit angled and separated but since it is physically impossible here's what I managed to do at best:



As someone already said, placing subs near walls could help but keep in mind it could worsen the situation instead so best way would be to do the invert phase, find the point at which they cancel the most and invert phase again as it was mentioned before.

PS: corners make it all worse, your best bet would be for you to do a single central stack

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Bass =/= Enough



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