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[Geert Friedhof]

A sub array doesn't magically make more noise. It 'directs' the sound by cancelllng out the sound at the places you don't want noise.

[Keith Broughton]

So if the building and street measure out and mathematically are causing a Null Would using and endfire cardioid sub array be a help if pointed forward into the crowd.  By narrowing the sides and elongating out to the front as the float move forward.

These types of arrays sacrifice output to create the directivity so you use up valuable power.
If you need more bass, use more speakers, more amps and a bigger genny!
How much bass do you "need" and how much do you want to spend?
If you just want to get the most out of what you have, keep the subs together, up against a "wall" on the trailer and be done.

[Stu McDoniel]

First off let me thank you for taking the time to read this and many thanks for your helpfull advice ! That said, i have read many articles and forums and watched videos on sub placement , corner coupling , ect. And they cover a wide range of conditions. Homes, halls, outside, auto. But what im looking for is the best place to put my subs on a trailer with sides. I have a trailer (inside dimensions) around 30 ft long 8 ft wide with 4 ft high walls. We use this in mardi gras parades and for the last few years i have just put two 18's on the floor in the center of the float facing one side as its the most convenient for the riders. But this just doesnt produce the sound i know i can get. So after reading so many different things such as corner coupling and dont put subs within 8' of a wall unless next to the wall. I am wondering if i would be better off with the subs against one side or one end or both or any other suggestions for placement. The rest of the speakers are on an overhead platform and sound great but i could really use some gelp with these subs. I will attempt to attach a picture of the trailer for refrence.

Two 18"s and just what are they? Make/model?
You might need to get better subs and that is a simple fix because the center cluster
thing should actually work fine for you.
Can you share with the folks here just exactly what your subs are and how you power them and cross them over?
Details?

[Ivan Beaver]

A sub array doesn't magically make more noise. It 'directs' the sound by cancelllng out the sound at the places you don't want noise.

There are several "un talked about" aspects of directional subs that the "fan boys" like to ignore.

I do use directional subs, BUT ONLY when the cancellation is more important than anything else.

Among the "penalties" that come with cardioid deployment include: Not as much output as the same number of subs all facing forward, less "punch" and impact due to the cancellation of the upper end of the bass range, and less deep lows-which means the extension of the cabinets does not go as low as when facing forward.

I know some people who like to do it simply because they think it is "cool" and different, without realizing they are compromising the sound for the audience.

As with everything, it depends, and all the factors must be considered before jumping on the directional bandwagon.

[Brandon Broadus]

First question.  Are the side walls made of plywood or is it a 2X4 frame covered with fabric. 

I am accustomed to 40ft tractor trailer bed with a 2x4 frame. If you want to max it out, parade floats are more for the spectators not the folks on the truck. 

You could consider two stacks per side and one in the back.  1 as close to the cab firing outwards and one to the back leaving about 4 feet in the back to do a rear stack.  That being said make sure that you are aware of max height regulations and that you are able to secure the cabinets that they don't tip over and KILL PEOPLE  More cabinets in most cases means taller stack on a moving truck that can rock back and forth.  You have to be able to secure them in such a way that if the driver has to jam on the brakes, it won't rock back and crush the people on the float or rock back the other way and kill or maim someone on the street. 

A more conservative approach is to lay a sub on its side and put your tops on top of the sub.
Still 5 stacks but lower to the ground.  Still requires securing everything but lessens the risk.  also requires more than the two subs you are currently using.  Probably at least 6 if not 8 subs.

Also make sure that the generator you have can support the added equipment.

One last thing, If it's a plywood wall, the plywood walls are your issue, cut a hole in the plywood the size of the front the cabinet and place the sub there. if the subs are firing into a wall, you will absolutely get cancellation. 

Think about it this way, if you put your subs under a stage and then covered the front of the stage with a sheet of plywood, you stop the energy from going out.  You would essentially be (not fully) containing the energy under the stage.  Only the folks on the truck are getting bass based on your current setup.

yes it is a 2x4 frame plywood wall covered in fabric. Yes it is all secured and my gen can handle it. I have been doing it for years. And dont get me wrong it sounds good i was just looking for better. Wanted to try a different  placement this year if it will help . Its all peavey cabs. Black widows in the 18's scorpions in the 15's all crown amps. I do get lots of complements on the sound of my float. And asked every year if i will do other krewe floats. But i am just looking to get the best placement i can and i think against one side may be better than center. But i dont have time to experiment with it (work every day from now to parade) so i figured i would ask some pro opinions before i waste what little time i will have to find a spot just to find it was better in the middle

[Brandon Broadus]

These types of arrays sacrifice output to create the directivity so you use up valuable power.
If you need more bass, use more speakers, more amps and a bigger genny!
How much bass do you "need" and how much do you want to spend?
If you just want to get the most out of what you have, keep the subs together, up against a "wall" on the trailer and be done.

.yes thank you. I am not looking to go buy a bunch of new gear just for this. I do have more i could add but space is very limited . And it does sound good. I just wanted to know if it would be better in the center or against one side. And get the best with just the 2 peavey 18's

[Joe Pieternella]

Among the "penalties" that come with cardioid deployment include: Not as much output as the same number of subs all facing forward, less "punch" and impact due to the cancellation of the upper end of the bass range, and less deep lows-which means the extension of the cabinets does not go as low as when facing forward.

I thought cardioid subs only worked over a narrow pass band and that the lower you went from the center freq. The less it would cancel front and back.

Wouldn't the longer wavelengths of the lower frequencies make the relative phase difference between the forward and rearward facing drivers smaller up to the point where they might sum again.
I always imagined the normal vs cardioid response of the same system (at least right in front of it) to look like someone added a dip on a eq centered on the cardioid frequency. And the width/q/bandwidth of the dip to be dependent on the front to rear facing ratio.

The frequency where this would happen could be below practical non EDM freqs. though. But would still not mean less low bass unless the frequency chosen would be stupid low or the ratio stupid high. Am I correct!?

EDIT: it seemed like I was contradicting myself. And all of this assumes the spacing and delay used are correct.
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[Ivan Beaver]

I thought cardioid subs only worked over a narrow pass band and that the lower you went from the center freq. The less it would cancel front and back.

End fire arrays are sonically better than cardioid.  But they are more like you say, a narrow passband of cancellation.  Cardioid has a wider range of cancellation

Endfire does not have the cancellation in the audience of the lowest freq or the upper end of the bass range like cardioid does.

So yet again, it depends.

What really is important is to understand how they work, what the advantages and disadvantages of each setup are.  That allows you to make the best decision for a specific case.

[Jerome Malsack]

my point for bring the end fire up was the two buildings on each side of the road.  Depending on the spacing can they create a null?  yes it would be possible.  By using the end fire sub can we narrow the sound field at the edges on the buildings some and reduce the null,  Maybe.  It all depends on the many unknown factors. 

And as Ivan has requested what is the make and model of the subs being used. 

[Chris Hindle]

yes it is a 2x4 frame plywood wall covered in fabric. Yes it is all secured and my gen can handle it. I have been doing it for years. And dont get me wrong it sounds good i was just looking for better. Wanted to try a different  placement this year if it will help . Its all peavey cabs. Black widows in the 18's scorpions in the 15's all crown amps. I do get lots of complements on the sound of my float. And asked every year if i will do other krewe floats. But i am just looking to get the best placement i can and i think against one side may be better than center. But i dont have time to experiment with it (work every day from now to parade) so i figured i would ask some pro opinions before i waste what little time i will have to find a spot just to find it was better in the middle

Brandon, that "wall" is NOT a boundary, as far as speakers go. In essence, the subs are running free-field. NO gain from a boundary. Trailer floor ? A bit, but not significant considering the thickness, and size. Place the subs, clustered, wherever they don't get in peoples way. Have fun. Rock on.
Chris.

[ProSoundWeb Community]