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Cardioid pattern.
Al Rettich:
In my background I was trained that to properly do cardioid you needed more forward pressure that rear pressure. Today I saw a set up that puzzled me. Six stacks of L’Acoustic KS28’s. Two high. Bottom cabinet turned around. Total of twelve subs. On top of that he had them in a 70 degree sub arc. I was watching soundcheck and my friend was pushing the low end. Much harder than normal he said. Can you do cardioid with just two cabinet stacks?
Chris Grimshaw:
Yep!
Just turn the front-facing cabinets up a bit, or the rear ones down.
Chris
David Morison:
--- Quote from: Al Rettich on August 24, 2023, 09:18:57 PM ---In my background I was trained that to properly do cardioid you needed more forward pressure that rear pressure. Today I saw a set up that puzzled me. Six stacks of L’Acoustic KS28’s. Two high. Bottom cabinet turned around. Total of twelve subs. On top of that he had them in a 70 degree sub arc. I was watching soundcheck and my friend was pushing the low end. Much harder than normal he said. Can you do cardioid with just two cabinet stacks?
--- End quote ---
Yes, you can do cardioid with only 2 boxes per stack.
The more common ratios (2:1 or 3:1, forward to rear) are done because in many situations, getting several dB of rear attenuation is enough to be useful, and having more forward boxes gives a bit more forward level.
If you had a really important reason to try and get more rear attenuation, then 1:1 forward to rear would actually help achieve that, at the expense of a bit of forward output as your friend found.
Whether or not combining that with an arc is at all useful would be beyond my current knowledge though - modelling would almost certainly be required.
Ivan Beaver:
--- Quote from: Al Rettich on August 24, 2023, 09:18:57 PM ---In my background I was trained that to properly do cardioid you needed more forward pressure that rear pressure. Today I saw a set up that puzzled me. Six stacks of L’Acoustic KS28’s. Two high. Bottom cabinet turned around. Total of twelve subs. On top of that he had them in a 70 degree sub arc. I was watching soundcheck and my friend was pushing the low end. Much harder than normal he said. Can you do cardioid with just two cabinet stacks?
--- End quote ---
You will get the most rear rejection when you use the same number of cabinets for both the front and rear cabinets.
Many cases you see do not take full advantage of the possible rear rejection, if some are turned backwards.
For the most forward output and rear cancellation, both cabinets MUST be facing forward, with the proper spacing, and proper DSP applied.
For cardioid that in the rear cabinet is reversed polarity and delay added. But you pay a price for that extra cancellation, which is a rolloff of the low end and the top end (less punch).
An endfire situation (physically the same setup), has better overall fidelity and greater output, but does not have as much rear rejection.
It all depends on what you are trying to achieve and what is most important for that particular situation. One size/application does not fit all usages
Al Rettich:
Ivan,
This venue the promoter doesn't like giving up space for subs. When I tried to get him to pay for flying them, he didn't want to pay, and told me to stack them as far away from center as possible. However, all the acts have complained of all the low end on stage. We have twelve subs, in carts stacked two hight. Everything I've been taught has that two facing forward, and one flipped. I was always able to "play" and get a bit more rejection by moving the delay time around. (and flipping out of phase) I keep wanting to learn about end fire, but if you search youtube there are quite a few folks who go against each other. My goal has been to get even coverage, and try to have a bit less low end onstage.
--- Quote from: Ivan Beaver on August 28, 2023, 12:15:30 PM ---You will get the most rear rejection when you use the same number of cabinets for both the front and rear cabinets.
Many cases you see do not take full advantage of the possible rear rejection, if some are turned backwards.
For the most forward output and rear cancellation, both cabinets MUST be facing forward, with the proper spacing, and proper DSP applied.
For cardioid that in the rear cabinet is reversed polarity and delay added. But you pay a price for that extra cancellation, which is a rolloff of the low end and the top end (less punch).
An endfire situation (physically the same setup), has better overall fidelity and greater output, but does not have as much rear rejection.
It all depends on what you are trying to achieve and what is most important for that particular situation. One size/application does not fit all usages
--- End quote ---
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