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Author Topic: Cardioid array in a 800ppl club. Possible options?  (Read 26090 times)

Jay Barracato

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #30 on: February 04, 2016, 07:59:11 pm »

First of all any box used to create cancellation is going to reduce the level compared to using that box as part of the forward signal.

You are making this overly complicated by continuing to try and compare techniques. There really is no difference in how the two techniques work.

Turn it around and for a moment consider this from a standpoint of a listening position. Cancellation occurs when two waves near the same size in magnitude arrive at the listening near 180 degrees from each other.

All sound waves are moving at the same speed so time and distance are the same thing. Forget about spacing, forget about polarity, forget about delay. All those are are different ways of achieving the same thing, two waves approximately 180 degrees apart at a listening position.

All arrays  have a maximum effect at one frequency with differing effects around that frequency.

As I said before I can't give you a meaningful comparison of the types because it depends more on the phase behavior of the boxes than the type of array.

If I had to make a comparison I believe endfire looses less ouput in the forward direction at the expense of needing more processing and space on the ground. Cardiod looses more output in the forward direction but is more compact and needs less processing.

But one again, time (delay) and distance (spacing) are the exact same thing.

I would suggest reading the first section of  Bob McCarthy's sound system design about the combing of signals and the two articles on Bennett Prescott's site and then trying to build a couple of these arrays. That should help you understand what is going on.

With that said, nothing you have said about the venue indicates to me it is a good candidate for needing this or that it would even be effective. You could end up perfectly cancelling the direct wave and still be slammed by the reflections.

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Jay Barracato

Ivan Beaver

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #31 on: February 04, 2016, 09:11:32 pm »



How do i set up a standard cardioid then? I flip one box, flip it's polarity, and then i delay it how much? I tought i need to find the time that sub from the front boxes needs for reaching their back side/the front side of the flipped box.
I didn't think that this time was frequency dependant?


You REALLY REALLY need to read up on how this actually works and read what people are trying to tell you here.

If you don't get the time right-then how is the COMBINATION of time and distance going to give you a 180 out of polarity signal at the rear position?

You figure out what 1/4 wavelength of the freq of interest is.

Then you figure out what delay time is associated with that is.

Now you can vary these independently, but that is best done in models-not by simple math.

You will end up all sorts of "other things" happening at other positions.

That is what the mapping will tell you.

The above procedure works exactly the same way in both cardioid or endfire.

The difference is what cabinet the delay is applied to and whether or not the rear cabinet has reversed polarity.
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Ivan Beaver
Danley Sound Labs

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Eugen Jeličić

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #32 on: February 05, 2016, 04:36:55 am »

Yes, i will need to find some good material to read this more detailed. I think i found MCCathy's book online, i also have a pdf of a Yamaha Sound_Reinforcement_Handbook so i will find something there.

Basicaly i didn't open this subject from a primary reason of finding what will work best in this situation but from a primary reason of learning more.
I do understand what happens with waves then they collide in phase, out of phase, and partialy out of phase but i obviously have holes in knowledge that don't allow me to fully visualise how a cardioid array works.

Ivan, don't get me wrong, i'm really thanksfull for the help but i'm constantly iritated by your posts from a simple reason. I don't need anyone to tell me what is going to be right because it's right. I need explanations to understand why something is right and why something is wrong. I'm 21 years old and i'm working in this club for a primary reason of learning. I do something, it does or does not work, i find all the elements i don't understand and then read to realise what i did wrong and why the solution didn't work the way i imagined. With sound there is a 100000 factors. All these arrays probably won't work even close to the way i imagine because i'm in a complex reflective room. But that's going to make me research a lot more speicific things. I will post a few pictures of the room during the next few days to give you a better idea of what this all looks like.

Now back to the subject.
There is one primary thing i believe i understood wrong because of the misinformations online. If i understand correct what you are trying to tell me now, the principal of sound cancelation in an endfire and a standard cardioid array is exactly the same. Just the endfire array with all boxes pointing forwards will have less energy to use for cancelation.

Because what i read online is different. The way i understood it is: A normal cardioid array has a box flipped backwards. That box is delayed using the time that sound coming from the front pointing boxes takes to get to their back side and that box is flipped in phase. An array like that will have most of the 20-80hz area effectively canceled out.
With an endfire array on the other hand, you have to pick the frequency you want to cancel out and position the back box according to that. The endfire array won't cancel out much other then a targeted frequency.

If what you are telling me is correct then what i just wrote is completly wrong. Both arrays work exactly the same way and both have a central cancelation frequency that i can change by moving the box that does cancelation. The only difference is that a standard cardioid array will have a box turned around and then will use the energy that comes out of the front of that box to cancel sound out. And the endfire array won't have a box turned around but will combine the energy coming from the back side of 2 boxes out of phase to cancel out.

Am i now closer to understanding this right?
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Ivan Beaver

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #33 on: February 05, 2016, 08:52:10 am »

For the most part-it does not matter which way the rear box is facing in a cardioid setup.


This is because at the freq we are talking about (below 100Hz) most boxes (especially front loaded ones) are omni directional.

Yes with the cardioid setup, you will effectively cancel out a wide range of the freq of interest.

HOWEVER-you also need to be conceded with what is happening out front-where the people are.

You can often end up with less energy at some freq out front with a cardioid setup than with a single cabinet.

So the sonic quality the audience hears is affected.

Does that matter? or is rear rejection the biggest concern?

I say that-because in some cases-the rear rejection IS the biggest concern.

Different people have different needs in different situations.

That is where the tuning comes into play.

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Ivan Beaver
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Eugen Jeličić

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #34 on: February 05, 2016, 09:44:08 am »

For the most part-it does not matter which way the rear box is facing in a cardioid setup.


This is because at the freq we are talking about (below 100Hz) most boxes (especially front loaded ones) are omni directional.

Yes with the cardioid setup, you will effectively cancel out a wide range of the freq of interest.

HOWEVER-you also need to be conceded with what is happening out front-where the people are.

You can often end up with less energy at some freq out front with a cardioid setup than with a single cabinet.

So the sonic quality the audience hears is affected.

Does that matter? or is rear rejection the biggest concern?

I say that-because in some cases-the rear rejection IS the biggest concern.

Different people have different needs in different situations.

That is where the tuning comes into play.

I know, the only thing that changes when turning the box around is the amount of energy canceled in the back / amount of energy lost in the front

Is the backside cancelation the biggest concern?
I don't know. I will have to find out. The thing is, there is nothing making a particular problem when talking about the energy on stage.

But i think that what happens is...
Stage becomes one big speaker, all the sub that goes on the stage comes back into the room, late and out of phase, reducing the quallity of what i get in front. So i think i might get better overall sub quallity in the room by canceling out what goes on the stage. I think i will get better sub in front of the boxes by getting rid of what goes on the stage. If what i gain outside is lost by the fact that one or two boxes flipped around themselves are destroying sub quality in the front. Then i won't use that setup. That's what's probably going to happen.

An endfire array with all boxes pointing forwards will on the other hand give me some benefit in the back without loosing what i'm getting in the front. 

There is also another option similar to the endfire array.

It's called, the ICAD array.
Take a look at the bottom of this text under the sector "hybrid arrays":

http://www.fohonline.com/current-issue/74-tech-feature/8711-subwoofer-arrays-in-the-real-world.html
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Jay Barracato

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #35 on: February 05, 2016, 01:10:20 pm »

I spotted your major misconception. A wave cancellation in one location dies not change the wave as it propagates to other locations. Causing a cancellation does not make the wave disappear, it makes a location with no amplitude.

Even if you create cancellation on stage those waves are going to reflect off the back wall and interact with FOH.

If you look back I have already mentioned the problems caused by reflections on small rooms twice

Sent from my XT1254 using Tapatalk

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Jay Barracato

Ivan Beaver

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #36 on: February 05, 2016, 07:35:54 pm »


Stage becomes one big speaker, all the sub that goes on the stage comes back into the room, late and out of phase, reducing the quallity of what i get in front.
No.

What goes out into the room comes back in phase and out of phase-but at a different TIME.

So you will get additions and subtractions-at different freq at different locations.

Try this little test.

Put a 60Hz tone into the system-it does not need to be very loud-a comfortable level.

Now walk around the room and find the spots that are loud and those that are almost completely cancelled.

Now change the freq to something that is not a multiple of anything in the original.

Lets say 73Hz.  Now walk around again.  You will find that the hot spots and nulls have now moved.

This is classic room mode behavior.

Outside it is pretty easy to predict.  But inside, it is next to impossible using all sides and floor and ceiling.

Yes the idea of rejecting the energy to the rear is a good one.  But when you get close to a boundary-everything starts to change. 

The best thing is to play with it and see what you come up with.

Sometimes it is just better to pile them up and "go for it".

Don't get me wrong-I am not against directional bass.

I did a gig back in the fall that was outside and a lot of the acts on stage would have acoustic basses.  Typically those players HATE subs and DO NOT want to hear it on stage.

So I specifically designed a 3 pod cardioid (rejection WAS the main thing here).  There was a center pad of 2 subs and a left/ right pod of the same 2 subs.

I used odd spacing and delay to direct the cancellation to the sides of the pods at an angle.  Behind the left/right pods there was actually a good bit of energy.

Then the center was typical rear cancellation, but not using normal delay or spacing.  I modeled it to work with the left/right pods.

The result was a good solid sub level out front with nice even coverage and on stage it sounded as if the subs were not on.

I also did some level adjustments to smooth out the front coverage.

There were a variety of acts-from progressive fusion rock to traditional bluegrass.  So I needed a lot of energy out front when some acts were on stage.

I was VERY happy with the result.

But without the modeling-there is no way (short of MANY hours of guessing) that I would have been able to figure out where the cancellation lobes would be and how they would interact.

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Ivan Beaver
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Ivan Beaver

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #37 on: February 05, 2016, 10:22:35 pm »

I'm 21 years old
I realize you are young.

Please accept these couple of pieces of advice from somebody who has been doing this a "few" years/decades.

It is REAL easy to get obsessed over a small thing-and totally over the "big picture".  Like not being able to see the forest for the trees.

Also DO NOT assume that every thing you read that is being done on "the big shows" actually works as intended-without consequences.

There are A LOT of people in this industry who do things "different" just to appear as if they are "special".  There have been many things and articles published about things that simply do not work as described.

Just because it is published or on a spec sheet DOES NOT mean that it is correct.

You have QUESTION EVERYTHING and see if the idea/concept actually makes sense.

There is A LOT of BS out there.

One of the things I like about this forum is that if you are wrong-you WILL be corrected. 

Some people don't like that, but the more you know/understand about the TRUTH, the better equipped you will be read through the BS.

I will not mention any names, but some of the most respected people in our industry are simply WRONG on some of the things they do.  I have direct personal experience with this a few months ago.

But because they are respected they somehow get a "free pass".

But that does not make it right or mean it will work.

Some people like to "do something just to do something" to make it their own.  Like a dog peeing on a tire.

Understanding how and why things work can be VERY valuable. NOT just taking other people words for it.

Anybody can be an "expert"-at least until somebody smarter corrects them.

The only problem with understanding things, is that soon you will start to question more and more what people are doing.

Of course that also helps YOU do a better job.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Eugen Jeličić

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #38 on: February 06, 2016, 06:25:25 am »

Jay:
That's a good shot there. I red your reply last night and started thinking about it. It quiet logical actually.
When you throw 2 rocks in a pool, you can find spots where the 2 waves collide constructively, destructively, where you get flat spots etc... but past those areas. Both waves keep moving intact. They keep the same form that they had when the rocks created them and keep going untill they loose their energy by traveling too long or hitting boundaries.

Whitch means i saw this from a completly wrong angle. I tought that once waves collide in opposite phase, theirs energy is completly lost and they are stopped. But this doesn't actually make sense when i look at it now. Because it would mean that every time when waves in the room collide in phase, energy is magically created there...

This makes things a lot different and basically means that in this situation i don't get anything very usefull by canceling out the sub on stage.
The only thing i might get by canceling out certain spots in the club is stopping some wooden elements from vibrating and creating noise. But the biggest one is the roof itself which has been lowered with wood to reduce the amount of reverbation in the room. It resonates loud... but i don't know how would i stop sub from going there.


Ivan:
Yes, i understand, it will come back partialy in phase, partialy out of phase an will be late.
I have already done tests like this and tried flipping the phase of one side to change the  node/antinode pattern in the room and possibly getting something better.... didn't work. You change the pattern but it's still just as bad but in a different way.
Basicaly i'm trying to do anything i can to partialy fix this but it does not seem to be quiet possible withouth using bass traps to stop sub reflection. The situation does of course get slightly better by moving the boxes in a mono block because then at least they don't collide with each other. But that seems to be it. I will of course still try all these options to see what i get.


Don't get me wrong, i'm not trying to be a smartass here. I just want to learn as much as i can. By reading my wrong concepts you both explained me some important things. That's the way it goes. The thing is, when you write "you are wrong and that is not done that way" i will not say thanks because i have come across this attitude with many local sound engineers and it's quiet irritating and pointless. I will keep understanding it my way before someone explains the physics behind his claims. That's the only way a forum can be usefull. If someting is overly complicated for explanation you can allways suggest good literature. But seeing me as someone who refuses to understand just because i i won't accept something you said without being able to visualise it is pointless. We are not doing a live show and having a point of doing a job that is as good as it can be, we are on the forum just trying to learn things. I'm of course very happy to accept advices from people who have been doing this for a few decades :D

 
« Last Edit: February 06, 2016, 06:28:41 am by Eugen Jeličić »
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Eugen Jeličić

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Re: Cardioid array in a 800ppl club. Possible options?
« Reply #39 on: February 06, 2016, 06:37:41 am »

Just a few more questions:

1. If you take a subwoofer and put it in some kind of a concrete horn that won't allow sub to pass trough it's back side, that does not mean this will make the subwoofer more directional. The sub will again exit trough the front of the horn,then go around and back again. As soon as a low frequency wave is free in open air, it starts getting omnidirectional, there is no way to stop this by physicaly enclosing subwoofers right?

2. The mid-high boxes we have, the yamaha c215v, they are not "arrayable" / designed to be used in multiples per side because they have a wide coverage pattern and therefore start comb filtering when many of them are side by side.
We have 3 a side so you can hear this problem quiet a bit.
Is there any way to partialy stop this? Getting the boxes further apart, getting the boxes one on top of each other, putting some of them as a delay stack further in the club, what are my options?

3.
The thing i hate the most about this cw218v yamaha subs is how sloppy they sound. Slow drivers, shitty transient response. You can't feel sharp kick in your chest from them, it's just a mass of molded energy compared to a good sub. What can be done on this quiestion?
Maybe getting amps with better dampening factors and getting them as close as possible to subs to connect them with short neutrik cables?
I usually try boosting the 40-31.5 hz area to extend low end. Then keep them flat at 50 and 63hz because they have quiet decent sensitivity there and can overload the room. Then sometimes i try slightly boosting the 80-100hz area to make kick slightly sharper but the room is very ringy at 100hz so this can become a problem...
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ProSoundWeb Community

Re: Cardioid array in a 800ppl club. Possible options?
« Reply #39 on: February 06, 2016, 06:37:41 am »


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