New Speaker Stands

[glass50]

Last July I took some well deserved flack about stacking speakers on four foot folding tables. August was pretty slow, so I went to work on a better way.

Wanted subs at ground level, tops elevated with horns above ear level, and easy to pack. Researched all sorts of small scaffold with nothing being just right. Settled on building with 16 Onstage 1.375" steel speaker pole inserts, 3/4" furniture grade birch plywood and heavy wall 1.375" x 3' Aluminum tube.

The 1st pic show results. Red ratchet strap hold three tops together, orange straps secure assembly vertically. 2nd pic shows how it all packs up. BTW tops are Community CSX drivers and cabinets modified with Carvin horns and crossovers.

[RBIngraham]

I know you'll hate me for saying so, but honestly I would just make at least that top shelf big enough so that no speakers are hanging off over an edge. Then I would probably have straps that go up and over the entire thing and back down the other side. That way the shelf is large enough to hold the speakers and any support straps are only there to make sure they don't slide off the shelf or the wind doesn't blow the thing over, etc....

[Frank DeWitt]

Looks good. May I suggest something like this
http://www.reidsupply.com/sku/SC-37011/
To hold the tops together, and maybe some industrial strength Velcro between the speakers and the "Table."

You could still use the straps but it would add another layer of safety.

[Donnie Frank]

David,

With all due respect - structurally speaking - I have to side with Richard on this one. I'm sure the rig is fairly sturdy but there is no redundancy built in. And dollars to doughnuts the safety factor is way under par. If any one component gives, speakers are going to fall. Speakers hanging 6"+ over the edges of that homemade deck does not instill confidence. If I were a client with a large insurance premium, I would be concerned. The straps should be an added measure of safety - redundancy. They should NOT be the main means of support.

Acoustically speaking, I like - and I think most would agree - a 2:1 ratio of Subs:Mains. Looks like you have a 2:3 ratio of subs:mains. I would stack another sub on top of the existing sub, make sure they interlock, then cut the poles down to size and expand that deck - or just get rid of one of the tops.

I highly recommend reading "Arena Rigging" by the late Harry Donovan. This book will give you a much greater perspective of safety margins, rigging, geometry and how it all ties in together. The stuff you build is well-engineered with a common-sense approach and would satisfy 99% of the stuff you could throw at it. The problem is that safety and rigging are counter-intuitive. Where one might think that something needs to be rated at twice the rate of the item it is supporting, in reality, in the rigging world, it needs to be 5-7 times sturdier and needs to survive 100% of what one might throw at it. It's the 1% that kills or injures people. The book makes you look at stacking and hanging and rigging from an entirely new perspective.

Arena Rigging is an expensive book. If you are willing to pay shipping, you are more than welcome to borrow mine. That will save you over $100.00.

You have a *lot* of weight stacked up there. I could think of several situations that could bring that stuff tumbling down. This is why when a company like JBL builds a "speakers on poles" rig, it's not stock aluminum that slip fits into a receiver. It's heavy steel poles that *screw* into the receiver. They know how to mitigate risk.

Here's a blurb from a rigging website:

Loudspeaker rigging mainly utilizes shackle sizes of 1/2-inch, 5/8-inch, and 3/4-inch It***8217;s rare to encounter any that are larger, though smaller ones are sometimes seen for light loads. Typically, a 1/2-inch shackle will be rated at two-and-a-half tons or 5,000 pounds. A 5/8-inch shackle is usually rated at three-and-one-quarter tons (6,500 pounds). The rating is usually displayed on the shackle like this: ***8220;3¼T***8221;.

But what does this mean precisely? Can you load them up to their stated rating? Absolutely not!

Most ratings, especially of older products, are based on a 4:1 safety margin. This was the safety standard that was used in the crane and rigging industry for many decades. Some newer parts may be rated at 5:1, or an even higher ratio, but you can***8217;t count on it unless it***8217;s clearly notated on the part itself, or the spool it***8217;s wound on (for wire rope).

Five to one! Who'dathunkit! I build almost everything with a 5:1 safety factor. When I see DJ lights hanging in a club over dozens of people on "toy trussing" purchased at the music store, I cringe! Once you read the book, you'll cringe, too.

[airickess]

Are you top speakers made to array like that? In my experience, tight packing of top point-source cabinets like that produces some fairly unpleasant comb-filtering. Have you ever considered just using two top speakers per side rather than three? Put a fairly decent splay in between the two cabinets.
You should try that configuration and listen to it. If you like what you hear with only two cabinets then that would certainly help solve the overhang issue that has been mentioned in previous posts.

[soundchicken]

With all due regards to safety;
David is not rigging these speakers over peoples heads but ground stacking them. And there are plenty of systems - yes, manufacturer designed - that use schedule 40 pipe to hold up speakers, one or more, to a single pole. With all things safety more will always be better but it comes down to (bad pun ahead) risk vs reward with a little "how does it fit in the truck" thrown in.
Do you really need 2.5 ton span sets to link three 50lbs cabinets that are ground stacked on floor level? Probably not, but would it make it safer? Not noticeably more that a 350lb tiedown. (There are good and bad ratchet straps and I never skimp)

Would two subs stacked give a firmer base? Heck yeah, but it would also take up more space in the pack and if David and his customers budget are happy with one cab per side, then the increased safety is not worth it.

I do have to agree about the deck size. But can offer a potential offset. As Frank started pointing out, if you have some method of locking the cabinets together to create one solid unit the fact that the platform is smaller than the unit becomes less of a concern than two speakers hanging over the sides. I'm not sure if Community has a frame for a horizontal array but this (http://www.fullcompass.com/product_image.php?imageid=148158) is what I'm talking about. Since you are not flying them a system could be designed that would easily attach to your cabinets forming them into one solid block.

I love the addition of the front/back legs. Too many times I see systems that are all ratchet strapped together but stand 10 ft tall and are only 2-3ft deep. The addition of those legs, even made of standard 2x4s, will decrease your chance of a tip over. (...would 2 in steel be better? Heck yeah)

Overall I think you have done an excellent job of increasing the safety of your system.

[ssrsound]

Yep -- nice job. I built some like that using speed-rail, and tying to a bottom platform rather than directly to the subs. Mine's more flexible in that I can use them without the subs on gigs that don't need thump, but I like how portable and easy yours is.

I'd echo what everyone else says about going with a larger top platform. You might also want to consider black motorcycle straps instead of the bright orange ones... it'll improve your aesthetics.

[Donnie Frank]

Are you top speakers made to array like that? In my experience, tight packing of top point-source cabinets like that produces some fairly unpleasant comb-filtering. Have you ever considered just using two top speakers per side rather than three? Put a fairly decent splay in between the two cabinets.
You should try that configuration and listen to it. If you like what you hear with only two cabinets then that would certainly help solve the overhang issue that has been mentioned in previous posts.

+1 on this. I was going to bring this up but felt I picked on David enough with the other issues....<;^)