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Author Topic: sandbags on speaker stands  (Read 1577 times)

Brian Jojade

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Re: sandbags on speaker stands
« Reply #10 on: April 27, 2021, 04:40:44 pm »

Brian, I hope you never hit underground power or sprinkler hosess or wires!
Sandbags can damp sway if a wind gust gets speakers moving.
I have to do what the university safety offer says  -  we we are on good terms and
I want to keep things that way    : -)

    Does anybody know of printed industry standards along these lines?

No, I never have hit anything.  Proper precautions are taken when doing outdoor shows to make sure everything underground is marked.  It's the same as the tent company driving stakes into the ground, or temporary fences, etc.

This is documented ahead of time as to where things will be placed and are to be free for driving things into the ground.

My concern with sandbags is that if there's enough wind to sway the tripod, placing sandbags in support positions that are not marked for sandbag placement trades one risk for another.

Putting a 50 pound weight on a cross arm that is not designed to hold that weight adds a new potential failure point that didn't previously exist.
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Brian Jojade

Tim McCulloch

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Re: sandbags on speaker stands
« Reply #11 on: April 27, 2021, 09:16:08 pm »

"I will use whatever brand and model of stand you find that documents such use of sand bags in the user/owner manual, and I will use them only in full conformity with the manufacturer's instructions."  See where this is going?  /nudge, wink

If the client wants to prescribe a "solution" then the client needs to prescribe a "fully designed solution."

Edit ps:  the topic of stabilizing tripod-style loudspeaker stands comes up maybe once a year?  I recall a few years ago the discussion got into the geometry and wind loading calculations (maybe involving Langston Holland? Can't recall for sure) and was very informative.  If anyone remembers and can find that thread...

My thoughts - 60lbs at 10 ft to the bottom of the loudspeaker is a force multiplier on a big vertical mast, the resistance at the bottom a factor of base area and friction.  I didn't take statics.. but there's a bending force (moment?) caused by the wind load.  I'd wager that most aluminum, folding tripod loudspeaker/lighting stands are not designed for this dynamic, lateral loading.  Adding weight to the leg braces seems like a way to cause the legs to pull in and reduce the base area; the concrete block/eye bolt with a tether that puts the load on the apex of the tripod (where the legs meet), or a T-bar fence post driven into the soil, with the post secured to the stand's upright mast seem preferable.  The former would not cause the base area to change but does nothing for the dynamic load on the mast; the latter solves that issue up to the top of the fence post.

How windy is "we don't have much wind here"?  In Kansas we call a day with 20 MPH winds "calm." ;)
« Last Edit: April 27, 2021, 09:36:14 pm by Tim McCulloch »
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Weogo Reed

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Re: sandbags on speaker stands
« Reply #12 on: April 28, 2021, 10:19:55 am »

Hi Kevin,

    That's the first I've seen a bag like that.
I like the four feet on the stands.

    Mal, gotta love those sponsor banners.

    Dave you are correct about the chuckling.
Am adding steel anchors and ropes.

    Brian, I already cleared driving steel in the ground  - 
no sprinklers, power or control wires there.
The stands are steel, and fairly stout:
 http://www.worklifters.com/products/lw-130

    Tim, It would be great to see stand manufacturers specify
what can and can't be done with their stands as far as anchor
weights, points, etc.
 
Thanks, good health and be safe,  Weogo
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Jim McKeveny

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Re: sandbags on speaker stands
« Reply #13 on: April 28, 2021, 10:59:16 am »

These will be away from foot traffic.

Unpaved?
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Mal Brown

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Re: sandbags on speaker stands
« Reply #14 on: April 28, 2021, 11:45:16 am »

Driving stakes is prohibited in the waterfront parks and event spaces where I normally work.  Too many irrigation breaks.  The folks who payed out the system for the city are long gone and left no map behind...  We are the self proclaimed wind surfing capital of the world...  Hood River, OR Winds here are no joke April to mid or late September.

Out walking the dog, I've already seen one guy attempt a full loop while foil boarding this year.  Usually it's at least June before the knuckleheads try that ;-)  Been crazy warm so the water people are early this year.  Fire season is going to suck...
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Brian Jojade

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Re: sandbags on speaker stands
« Reply #15 on: April 28, 2021, 04:19:20 pm »

Driving stakes is prohibited in the waterfront parks and event spaces where I normally work.  Too many irrigation breaks.  The folks who payed out the system for the city are long gone and left no map behind...  We are the self proclaimed wind surfing capital of the world...  Hood River, OR Winds here are no joke April to mid or late September.

Out walking the dog, I've already seen one guy attempt a full loop while foil boarding this year.  Usually it's at least June before the knuckleheads try that ;-)  Been crazy warm so the water people are early this year.  Fire season is going to suck...

In cases like that, a tripod speaker stand may not be the appropriate tool for the job then.

If the equipment isn't engineered for a specific task, and you decide to do your own napkin engineering and get it wrong, you're asking for trouble.
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Brian Jojade

Art Welter

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Re: sandbags on speaker stands
« Reply #16 on: April 29, 2021, 05:25:08 pm »


Edit ps:  the topic of stabilizing tripod-style loudspeaker stands comes up maybe once a year?  I recall a few years ago the discussion got into the geometry and wind loading calculations (maybe involving Langston Holland? Can't recall for sure) and was very informative.  If anyone remembers and can find that thread...

How windy is "we don't have much wind here"?  In Kansas we call a day with 20 MPH winds "calm." ;)

More than a few years ago, but statics are the same now as in 2009:

https://forums.prosoundweb.com/index.php/topic,118012.20.html

Speakers have changed..

Art
« Last Edit: April 29, 2021, 05:27:57 pm by Art Welter »
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Weogo Reed

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Re: sandbags on speaker stands
« Reply #17 on: May 11, 2021, 05:33:41 pm »




Hi Folks,

    Follow-up notes:
We had 25mph winds Friday for setup, and rain showers twice.
Saturday commencement had winds up to 15mph.
Am glad I didn't count on the usual calm air around here!

    The 60# speakers were anchored with two 35# sandbags and
tied to pins in firm soil.(It took significant effort to get the pins out.)
The site electrician showed me where power was run so
no chance of hitting electrics with the pins.
The speakers didn't need to be raised all the way up, they were at about 9' height.
Smaller, lighter fill speakers got two 15# or 25# bags.
Everything stayed absolutely in place.

    Thanks for all the comments and advice!

Good health,  Weogo
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ProSoundWeb Community

Re: sandbags on speaker stands
« Reply #17 on: May 11, 2021, 05:33:41 pm »


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