Open request for photos of your subwoofer configurations

Re: Open request for photos of your subwoofer configurations

Robert Patch said:
I gather this is also true for the spacing front to back on the end fire array?
Click to expand...

You can screw up your spacing and delay relationship by quite a lot, at least 20%, and still attain the same goal... in fact, sometimes the pattern control is improved. However, it makes the array sound like shit since you just went to all this effort to maintain impact and then threw it away by not lining your delays up correctly. If more precise pattern control is required there are better techniques, like logarithmic or fibonacci spacing. Mostly I end up using end fire as a technique to reduce effective array size, though, so I'm benefiting from the pattern control but not worrying too much about it.
 
Re: Open request for photos of your subwoofer configurations

Phil Graham said:
Folks,

For an upcoming FOH article I'd like to solicit photos of "in the field" subwoofer configurations. Preferably configurations that you implemented at live event, and not for a permanent installation.

I'm not looking exclusively for fancy (e.g. endfire) arrays, but also circumstances where you had to make compromises, or did something that felt unusual. I'd prefer it being an event you worked either as a tech, BE, etc., not merely as a spectator. I do need a "fancy" array setup or two.

I'd also like a caption on what the event was, why you implemented the configuration as seen, and how it worked out. All photos and details will be used with attribution.

PM me, and I'll give you an email address to send the photo and caption to.

Thanks in advance!
Click to expand...

This one maybe interesting given you criteria:
· Maximum floor loading - 200kg per square metre.
· The sub could not be stack on the left or right without exceeding the floor load.
· 135 degrees of coverage was required
· 57 acts in 3 weeks covering almost every genera of music
· Preferred to have some level reduction to the rear.
· Minimum space in front of stage
· Stage height 1.1m
The solution - a centre block of 3 over 2 double 18s. The outer 2 blocks were pushed forward and delayed - by the amount they were pushed forward plus some additional delay to widen the pattern. See the plot below - the pattern is not as good as the frequency goes lower... but not much else I could do.

Don’t seem to be able to find a picture, but you can just see them in these videos someone took with their camera I found on YouTube (about 3 minutes into the second one and the level was a little bit much for their mic in places. http://www.youtube.com/watch?v=DaNVKJtq4rU http://www.youtube.com/watch?v=qXpLw5y7kMM
 

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Re: Open request for photos of your subwoofer configurations

kristianjohnsen said:
Would you mind talking me through this one? Why is the perspective of the people behind the array different than the perspective of the people in front?
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The front subs are placed 1/4 WL (wavelength) in front of the rear subs and delayed 1/4 WL. So from the front-the signals from both arrive at the same time.

From the rear perspective the sound behind the subs makes the sound behind the cluster to have 2 arrivals-one from the rear sub and another from the front sub-so 1/4 +1/4=1/2WL. So the signals will be out of polarity and will cancel-at least a good bit. Hence the null.

Of course this only works over a limited freq range. Outside of that range-the effects (both in front and rear) are not as good.

As you can see from the attached model-(with a mic in front and behind the cluster
 

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Re: Open request for photos of your subwoofer configurations

Ivan Beaver said:
The front subs are placed 1/4 WL (wavelength) in front of the rear subs and delayed 1/4 WL. So from the front-the signals from both arrive at the same time.

From the rear perspective the sound behind the subs makes the sound behind the cluster to have 2 arrivals-one from the rear sub and another from the front sub-so 1/4 +1/4=1/2WL. So the signals will be out of polarity and will cancel-at least a good bit. Hence the null.

Of course this only works over a limited freq range. Outside of that range-the effects (both in front and rear) are not as good.

As you can see from the attached model-(with a mic in front and behind the cluster
Click to expand...
Thank you! This makes perfect sense now that you have explained it!:)
 
Re: Open request for photos of your subwoofer configurations

kristianjohnsen said:
Thank you! This makes perfect sense now that you have explained it!:)
Click to expand...
When thinking about so many things in audio-you have to think in terms of wavelength and SIZE OF THE WAVELENGTH and the time that it arrives at a particular place.

Sometimes signals arriving a particular time apart is no big deal-and yet that same time arrival difference at a different freq can be a complete mess-or near perfect cancellation.

That is why you simply cannot look at single freq-either when doing sub alignments-or coverage maps etc. You HAVE to consider the WHOLE freq spectrum and what impacts that-overall.

Just because you make one spot or freq "great" does not mean that you have done a good job-especially if the rest (or majority) of the seats or freq response is compromised.
 
Re: Open request for photos of your subwoofer configurations

Phil Graham said:
Folks,

For an upcoming FOH article I'd like to solicit photos of "in the field" subwoofer configurations. Preferably configurations that you implemented at live event, and not for a permanent installation.

I'm not looking exclusively for fancy (e.g. endfire) arrays, but also circumstances where you had to make compromises, or did something that felt unusual. I'd prefer it being an event you worked either as a tech, BE, etc., not merely as a spectator. I do need a "fancy" array setup or two.

I'd also like a caption on what the event was, why you implemented the configuration as seen, and how it worked out. All photos and details will be used with attribution.

PM me, and I'll give you an email address to send the photo and caption to.

Thanks in advance!
Click to expand...
Hi Phil,

Here is another one we used this weekend …
· Large room with 3 stages
· Needed to keep the bass away from the outer two stages
· When the centre stage was in use there were no subs operating
· No space to construct an end-fire array unless most of the boxes were under the stage.
· Maximum sub/array height 1.1m

Solution
· Hyper-cardioid end-fire array
· First two rows of subs under the stage

Here’s a picture of the array layout, it performance in free field and within a room ... plus a picture under the stage. (sorry my iPhone photos suck)
 

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Re: Open request for photos of your subwoofer configurations

These are all very cool when you're dealing with...6 subs. Throwing it into GPA though (or whatever it is that they call the new Danley version), I'm having trouble making any of these configurations work when you get up to 20 or 24 subs for arena sized venues. Multiples of the arrays Brandon and Peter have brought up don't seem to play well together at all. What then...Bessel arrays?
 
Jason Phair said:
What then...Bessel arrays?
Click to expand...

A Bessel would be far to inefficient for subwoofer use. 5 subs for the output of 2, only with no pattern collapse... Plus the wavelengths are just to big to get far enough away to get smooth coverage. The largest Bessel designs I have seen have 9 boxes and get more and more inefficient as you go from 5 to 7 to 9.
 
Re: Open request for photos of your subwoofer configurations

Jason Phair said:
These are all very cool when you're dealing with...6 subs. Throwing it into GPA though (or whatever it is that they call the new Danley version), I'm having trouble making any of these configurations work when you get up to 20 or 24 subs for arena sized venues. Multiples of the arrays Brandon and Peter have brought up don't seem to play well together at all. What then...Bessel arrays?
Click to expand...

I some what agree, some of these above might not "scale" as good as other. In arenas ("bigger gigs") you how ever, usually have at least two benefits, than on a lot of
"smaller" gigs: More height (and hanging points) and more physical size to put subs in.

In no paticually order, pick your poison.

Vortex/Orgasmatron/Sub fan/L-array: Dave Rat Blog
TM-array: Meyer Sound Laboratories Inc.
Endfire centerflown ala Godsmack: see the Carrie underwood above
Arrays to go the distance : http://www.facebook.com/MadsMikkelsenAudio

Oh and just to throw out a teaser... Physics is your ally , but psycho acoustics really saves days too, conqure both...

mvh
/R
 
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Re: Open request for photos of your subwoofer configurations

Jason Phair said:
These are all very cool when you're dealing with...6 subs. Throwing it into GPA though (or whatever it is that they call the new Danley version), I'm having trouble making any of these configurations work when you get up to 20 or 24 subs for arena sized venues. Multiples of the arrays Brandon and Peter have brought up don't seem to play well together at all. What then...Bessel arrays?
Click to expand...



Hi Jason,

The plots I posted were for specific applications; the last one used 10 subs and was designed to be hyper cardioid to minimise the SPL on the outer two stages.

When more horse power is need I have always wanted to try 2 stacks of Dave Rats Vortex. The trick is to pan the kick and bass (a little) to opposite sides to minimize the power alley and cancelation effects. Stacked 3 high you will get 12 boxes per side.

Here are some links that may be of interest and a plot of a 16 box array

http://www.voidaudio.com/pdf/bass guide.pdf

Dave Rat - Roadies in the Midst

also EV have a paper on subwoofer arrays - can't seem to get the link to work
 

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Re: Open request for photos of your subwoofer configurations

Peter, I'm really liking the looks of that 16 box array you posted. I see you didn't add a shot of the processing page, but it looks like you're taking two endfire arrays and turning them into a slotfire? With the slot-fire arrays I've tried, there always seems to be a lot of energy coming out the back...would you mind sharing what you did to make it so cardioid and wide? I've tried various delay patterns and haven't really got to the predicted field you're showing there.
 
Re: Open request for photos of your subwoofer configurations

It depends on the day and the layout of the room for me... I have to make compromises on a daily basis. My goals are to get the most LF out front possible, and not kill the band members on stage in the process.

My "usual" layout is like this:

attachment.php


While the rear axis rejection is not great, the coverage out front is very consistent, and very powerful. With L/R house subs, I usually end up with 0ms on the middle, .5-1.5 on the next pair, and 1.5-3ms on the outer subs(house).

My favorite layout has been this:

attachment.php


16 deep, and a lot of trickery going on. :) ...Let's just say the coverage out front is a very controlled 90 degrees, and the rear rejection is excellent.


On the cardioid aspect of things:

attachment.php


Big 'ol cardioid stack!

attachment.php


This is a slightly less optimal cardioid stack, but it works well. You start to lose rejection down around 30-40hz, but it does well above that.





Evan
 

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Re: Open request for photos of your subwoofer configurations

Jason Phair said:
Peter, I'm really liking the looks of that 16 box array you posted. I see you didn't add a shot of the processing page, but it looks like you're taking two endfire arrays and turning them into a slotfire? With the slot-fire arrays I've tried, there always seems to be a lot of energy coming out the back...would you mind sharing what you did to make it so cardioid and wide? I've tried various delay patterns and haven't really got to the predicted field you're showing there.
Click to expand...

The centre slot is a standard endfire “slot” configuration with boxes progressively delayed according to the distance they are apart. The outer two slots have the same relative delay between all of the boxes, but the slot as a whole is delayed to widen the pattern.
Think of the output of the 3 slots as being 3 subs. Then delay the out 2 subs to widen the pattern….if that make sense ?
 
Re: Open request for photos of your subwoofer configurations

Well, you can do what the Rolling Stones tour is currently doing - don't use any subwoofers.
 
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