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Author Topic: end fire under a stage?  (Read 991 times)

Dave Garoutte

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end fire under a stage?
« on: September 25, 2017, 03:28:33 pm »

I'm in the process of purchasing a pair of TH118s (from Mr Pyle).
I often use my portable truss stage which is 24" under the platform (1 1/8" TinG plywood with carpet).
The subs will physically fit under the stage with 1 1/2" clearance.
I'm wondering if it's feasible to run an end fire configuration in that space.
Will it function as intended?
Will it transfer too much bass to the platform?
One in front and one under?  Both under?
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Ivan Beaver

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Re: end fire under a stage?
« Reply #1 on: September 25, 2017, 03:53:57 pm »

I'm in the process of purchasing a pair of TH118s (from Mr Pyle).
I often use my portable truss stage which is 24" under the platform (1 1/8" TinG plywood with carpet).
The subs will physically fit under the stage with 1 1/2" clearance.
I'm wondering if it's feasible to run an end fire configuration in that space.
Will it function as intended?
Will it transfer too much bass to the platform?
One in front and one under?  Both under?
Any electronic steered system, which is based on interference (like endfire and cardioid) rely on the sound being able to fully propagate around the cabinets.

When it is restricted (by a stage deck or wall etc) the overall character changes.

How much?  It depends on a number of factors that none of the models (that I am aware of) are able to deal with.

So the best advice is, try it and see what happens.  But BE SURE to see what is happening in a number of different areas-behind, on stage deck, in front etc.

One place may be fine, but others may suffer-or not.

I have never actually done it, so my experience is based more on "theory" than reality in this case
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Ivan Beaver
Danley Sound Labs

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Ivan Beaver

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Re: end fire under a stage?
« Reply #2 on: September 25, 2017, 03:56:32 pm »

Also remember that any electronically steered/intgerference system will have LESS forward output/SPL, than the same number of boxes when they are simply side by side or stacked facing forward.

I have heard it said that a directional system is louder than simply stacking.

The WRONG idea is that the energy that "would" be going behind the cabinets is actually redirected to the front, so that it combines with the normal front energy.

WRONG WRONG WRONG.
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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!

Spenser Hamilton

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Re: end fire under a stage?
« Reply #3 on: September 25, 2017, 04:01:12 pm »

I'm in the process of purchasing a pair of TH118s (from Mr Pyle).
I often use my portable truss stage which is 24" under the platform (1 1/8" TinG plywood with carpet).
The subs will physically fit under the stage with 1 1/2" clearance.
I'm wondering if it's feasible to run an end fire configuration in that space.
Will it function as intended?
Will it transfer too much bass to the platform?
One in front and one under?  Both under?

I recently did a gig where we couldn't block the banner on the front of an SL100, so we placed 8 Outline DVS18-2 under the deck. After a full day standing on the monitor wing, I actually felt fatigued from the bass rattling the stage. I would say that I am pretty accustomed to being subjected to the rear wash from large PA systems, but this felt like someone was hammering my feet for 8 hours.

Something to keep in mind.
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Tim McCulloch

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Re: end fire under a stage?
« Reply #4 on: September 25, 2017, 04:23:41 pm »

I'm in the process of purchasing a pair of TH118s (from Mr Pyle).
I often use my portable truss stage which is 24" under the platform (1 1/8" TinG plywood with carpet).
The subs will physically fit under the stage with 1 1/2" clearance.
I'm wondering if it's feasible to run an end fire configuration in that space.
No

Quote
Will it function as intended?
No

Quote
Will it transfer too much bass to the platform?
Yes

Quote
One in front and one under?  Both under?

Either scenario is wrong.  Ivan's reply regarding all the subs needing physical clearance is spot on.  How much clearance?  At least 1/4 wavelength of the lowest freq for end fire and 1/4 wavelength for the center frequency of rear cancellation for cardioid.  Exact half wavelengths are VERY UNDESIRABLE.
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Dave Garoutte

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Re: end fire under a stage?
« Reply #5 on: September 25, 2017, 05:06:37 pm »

Oh well.
I'll probably play with it in the parking lot, but I figured the chances of it working well were low.
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Events.  Stage, PA, Lighting and Backline rentals.
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