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Author Topic: Arraying horn loaded subs,options?  (Read 1645 times)

Eugen Jeličić

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Arraying horn loaded subs,options?
« on: August 06, 2017, 06:43:36 am »

So last week i have been mixing a 2 day open air show. 10 bands, some guesting engineers, i did the rest.

Last year i ordered a KV2 vhd2.0 rig for the same show but this year i went for a local hand made soundsystem witch didn't sound as balanced as kv2, but had a lot more power and a much better coverage angle. Overall i was quiet happy but had some weird situations with sub coverage.

So the system consisted of 8 top boxes with some BMS tweeters and 4x10 inch drivers.
Really high sensitivity but a bit thin below 1khz.

The subs are what's known as an Invader Horn. You can find a drawing online. Here is a picture of what it looked like from FOH. We have been limited with how we can array the rig because we didn't have a ramp or anything similar:

https://scontent-frt3-1.xx.fbcdn.net/v/t31.0-8/20545250_10210290380436627_7059157134728030314_o.jpg?oh=0591723f7d01d244415975d9d635ab59&oe=59F08A94

So since it's a standard L/R sub array, there was a summation zone at FOH in the center of the field. And there were holes in the field. Standard...
But there was some weird stuff.
First, in the power alley, exactly on the line in front of the subs, there was not that much power. It seemed that even of you muted one side of the subs to remove cancelation problems between sides, there was more power at FOH then there was right on the line in front of the subs.
And when both sides have been running and you moved away to the side of the PA, there was very very little sub power at all. With clasical reflex boxes it always seemed to me that there is a power alley right on the axis of the subs and you usually find summation in the center where FOH should be. With some power lefover on the sides. This was totaly different. Like subs radiated more power at an angle of the array. Then they did right in front of them.


The other thing that i noticed was that all the power i had didn't sound natural and flat but kind of "pumped up". like you are in a closed room and hear boosts from room resonances.
But we have been in a completly open field. No boundaries at all. A football field in the middle of nowhere.

And i remember that the same thing happens when you array horns like theese with their mouths facing the floor. A usuall monoblock setup. You get a big ball of pumped up resonant power in front of the subs and then it gets lost in the field.

This was kind of like the same thing but distributed differently.
So i was wondering, how horn loading affects the coverage pattern of the subs and what happens when you array them in different ways. We coupled the horn mouths because that way you get more mouth surface and they start going lower. But my FOH engineer friend told me that when you array them the other way around, they give you less power but more natural, better distributed sub coverage.

Subs are loaded with some Fane drivers and pushed with EV q1212 amps bridged. DSP was EV DC1. Crossover was at 70hz because if i ran them higher i would stard getting huge amounts of excess material between 80-120hz giving me a very boxy sounding subs. I didn't like that.

On the other hand i have to compliment theirs transient response. They are very fast and nicely defined.


« Last Edit: August 06, 2017, 02:39:21 pm by Eugen Jeličić »
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Don T. Williams

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Re: Arraying horn loaded subs,options?
« Reply #1 on: August 06, 2017, 04:26:57 pm »

So last week i have been mixing a 2 day open air show. 10 bands, some guesting engineers, i did the rest.

 
But there was some weird stuff.
First, in the power alley, exactly on the line in front of the subs, there was not that much power. It seemed that even of you muted one side of the subs to remove cancelation problems between sides, there was more power at FOH then there was right on the line in front of the subs.
And when both sides have been running and you moved away to the side of the PA, there was very very little sub power at all. With clasical reflex boxes it always seemed to me that there is a power alley right on the axis of the subs and you usually find summation in the center where FOH should be. With some power lefover on the sides. This was totaly different. Like subs radiated more power at an angle of the array. Then they did right in front of them.


The other thing that i noticed was that all the power i had didn't sound natural and flat but kind of "pumped up". like you are in a closed room and hear boosts from room resonances.

I would be suspicious of polarity reversals some place in the system.  It could be input cables wired out of phase, speaker cables inverted, speaker drivers with inverted wiring, basically anything that could cause one side or some speakers to be 180 degrees out of phase with the other.  The main clue to me is that when one side is shut off, it gets louder in the center.  Classic symptom of inverted phase!
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Eugen Jeličić

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Re: Arraying horn loaded subs,options?
« Reply #2 on: August 06, 2017, 05:15:08 pm »

I would be suspicious of polarity reversals some place in the system.  It could be input cables wired out of phase, speaker cables inverted, speaker drivers with inverted wiring, basically anything that could cause one side or some speakers to be 180 degrees out of phase with the other.  The main clue to me is that when one side is shut off, it gets louder in the center.  Classic symptom of inverted phase!

Nope. Checked it in depth. All four subs on each side where in phase with each other, both sides where in phase too.
But i think you misunderstood me. I didn't say there was more power in the center when you turned of one side. No, there was a 3dB loss. The summation in the center was fine.

What i wanted to say is that if you eliminated one side completly. And stood 10 meters away from the 4 running subs on the other side. Right on axis of the subs there was less power then when you went about 30-40 degrees of axis.
So if a monoblock of 4 subs is working, the power alley in front of them looks like a triangle. There was more power at the sides of the triangle then right in the center. I don't know how this is possible.
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Don T. Williams

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Re: Arraying horn loaded subs,options?
« Reply #3 on: August 06, 2017, 07:11:27 pm »

Nope. Checked it in depth. All four subs on each side where in phase with each other, both sides where in phase too.
But i think you misunderstood me. I didn't say there was more power in the center when you turned of one side. No, there was a 3dB loss. The summation in the center was fine.

What i wanted to say is that if you eliminated one side completly. And stood 10 meters away from the 4 running subs on the other side. Right on axis of the subs there was less power then when you went about 30-40 degrees of axis.
So if a monoblock of 4 subs is working, the power alley in front of them looks like a triangle. There was more power at the sides of the triangle then right in the center. I don't know how this is possible.

I stand corrected on the phase inversion.  How it's possible to have more power on the sides than in the center is a complex phase relationship problem.  Is there anyway to set up the subs as a mono center cluster?
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Chris Grimshaw

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Re: Arraying horn loaded subs,options?
« Reply #4 on: August 07, 2017, 03:38:40 am »

Could still be almost anything.
For instance, if one side had a few ms delay, that'd give you all sorts of interesting problems.

Were all the cabinets the same? Did they all have the same drivers? I've often seen operators with lots of bass horns like those with a few different make/models of drivers in use. Some of them are okay for that cabinet, others not so much. There'll be some very interesting relationships between the different cabinets.

Was all the processing zero'd, or sensibly applied?


Couldn't open your Photobucket link, since they've decided to lose all of their users pretty much overnight.

Is there any chance you could sketch a map of where you found the loud/dead spots were?

You've got to bear in mind that large sub arrays will start to exhibit some directionality of their own. In the case of horns like these, it's related to the total mouth area, which can get quite large.

Chris
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Eugen Jeličić

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Re: Arraying horn loaded subs,options?
« Reply #5 on: August 07, 2017, 04:59:17 am »

Could still be almost anything.
For instance, if one side had a few ms delay, that'd give you all sorts of interesting problems.

Were all the cabinets the same? Did they all have the same drivers? I've often seen operators with lots of bass horns like those with a few different make/models of drivers in use. Some of them are okay for that cabinet, others not so much. There'll be some very interesting relationships between the different cabinets.

Was all the processing zero'd, or sensibly applied?


Couldn't open your Photobucket link, since they've decided to lose all of their users pretty much overnight.

Is there any chance you could sketch a map of where you found the loud/dead spots were?

You've got to bear in mind that large sub arrays will start to exhibit some directionality of their own. In the case of horns like these, it's related to the total mouth area, which can get quite large.

Chris

Yes, i don't know wtf is photobucket doing. But i replaced the link in the main text with a direct facebook link.

Here is another picture of me tweaking the DC1 system processor. And the guy from the PA company on the right:

https://scontent-frx5-1.xx.fbcdn.net/v/t31.0-8/20616033_1610317225707178_7252533669470684012_o.jpg?oh=7141f7934e47f30075664a869f5cd83e&oe=59EDC9CB

but the other side of the PA can't be seen in the picture.

Now as you can see, the horn mouth got quiet large when we coupled 4 of them. Plus, considering the horn exit shape, it even made sense to me that they kind of kicked the power off to the sides a bit. 
But i posted this subject because i want to learn more about horn coupling rules because it seems to me that they exibit some rather interesting behaviour when stacked in different ways.
I was interested in what happens when you turn them the other way around,horns away from each other.

All the boxes are the same, they all have the same Fane drivers. All running from bridged EV Q1212 amps.
No delays on any of the boxes.

But the crossover settings were a bit weird. Considering these subs had excess amounts of 80-130hz material and sounded very boxy. The best way to clean that up was a lowpass at 68hz, 24dB/octave. When i did that they flattened up towards 100hz. The top boxes were highpassed at about 130hz. You'd think there was a bit of a hole there but it didn't sound like that.
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George Dougherty

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Re: Arraying horn loaded subs,options?
« Reply #6 on: August 08, 2017, 10:58:53 am »

With my own horn loaded boxes I would tend to orient them so the horns are closest to the ground.  Rotated 90 degrees from how they're shown once I go from 2 to 4 boxes per side.  Could potentially be some issues with cancellations off the ground from the upper subs.

How did you test polarity of the subs within a stack?
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Eugen Jeličić

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Re: Arraying horn loaded subs,options?
« Reply #7 on: August 08, 2017, 12:12:40 pm »

With my own horn loaded boxes I would tend to orient them so the horns are closest to the ground.  Rotated 90 degrees from how they're shown once I go from 2 to 4 boxes per side.  Could potentially be some issues with cancellations off the ground from the upper subs.

How did you test polarity of the subs within a stack?

I stand in front of the subs, another guy unplugs 3 out od 4 subs while running pinknoise trough them. Then, he plugs the next one, then the next one, then the next one. Untill all four are working.
At each plugin, the power rised.
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Don T. Williams

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Re: Arraying horn loaded subs,options?
« Reply #8 on: August 08, 2017, 05:51:25 pm »

w
I stand in front of the subs, another guy unplugs 3 out od 4 subs while running pinknoise trough them. Then, he plugs the next one, then the next one, then the next one. Untill all four are working.
At each plugin, the power rised.

Eugen, that really isn't a comprehensive test method.  From what you described, there is still no way to know if the two sides have the same phase relationship.  That is still my concern with the problem as you described it.  With a XLR M/F "phase reverser" or with your crossover or speaker DSP, can you do the same listening test for the two sides?
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Art Welter

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Re: Arraying horn loaded subs,options?
« Reply #9 on: August 08, 2017, 10:29:24 pm »

1)Now as you can see, the horn mouth got quiet large when we coupled 4 of them. Plus, considering the horn exit shape, it even made sense to me that they kind of kicked the power off to the sides a bit. 
2)But i posted this subject because i want to learn more about horn coupling rules because it seems to me that they exibit some rather interesting behaviour when stacked in different ways.
I was interested in what happens when you turn them the other way around,horns away from each other.
3)Considering these subs had excess amounts of 80-130hz material and sounded very boxy. The best way to clean that up was a lowpass at 68hz, 24dB/octave. When i did that they flattened up towards 100hz. The top boxes were highpassed at about 130hz. You'd think there was a bit of a hole there but it didn't sound like that.
Eugen,

1) Other than the upper range of the pass band the subs operate in, the dispersion will be dictated by the mouth size, "power", as in SPL, will not be kicked left or right.
2) Horn subs can have a huge rising response, like 12 dB per octave, so your 68hz, 24dB/octave may only result in a 12 dB slope with another +6 dB peak here and there in the upper range.
That can still let a boatload of "junk" through in the range between the subs and tops. This "junk" will vary in phase between the two depending on your listening position and the directivity index of the cabinets- the tops will be omni at their bottom, the horn subs may have less than 90 degrees at the top of their bandwidth.
3) No "hole", just multiple phase problems- the subs need to be phase aligned to the tops through the crossover region, and when that region is wide due to the problems described in #2, all sorts of crap response happens, resulting in sound only being good along the axis which is equalized for flat response.

Bottom line- the array is not the problem, it is the interaction between the subs and tops that is messing with your "bass" perception, which may be most critical in the overlap in the octave you crossed at, 68-130 Hz.

Cheers,
Art
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