The making of: The Two Towers (a 25 driver Full Range line array)

A week ago I dropped off the aluminum for the baffles at my friends house. He won't be able to start right away so I got to learn to be even more patient than I have been so far :D.

After working out the last details on the enclosures:
Last-steps.jpg

(painted the bottom black as it was seen in the polished aluminum feet)

I decided to park the enclosures in the living room for the time being...
room.jpg

(it is more or less where they will end up but I will play with aiming to the far seat for imaging,
hopefully creating a large sweet spot on my couch)


So all this is giving me some time to work out the best damping materials. I have started on a test enclosure to measure the different materials and combination of them.
I have:
Real wool felt ~7 mm thickness 15 m2
Fibreglass insulation material
Twaron angel hair

Hoping a test with a behringer microphone and REW and/or True RTA will help me decide the best way to incorporate the materials.

Any suggestions or tips are welcome!
 
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Probably not much if any, although different opinions do exist. Original plan was to use the wool felt in those locations. That's why I got it.

I had plans to finish my test enclosure today but had to work on my car. My car is 31 years old so every once in a while something breaks. My after market alarm (13 years old) decided to quit on me leaving me with a car that wouldn't start due to circuit breakers. :(
It might be related to the car being outside all summer/early fall while I was building the enclosures in the dry garage...

Got the car running again so hopefully I will continue with the test enclosure tomorrow.
 
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Today I'm going to show a few pictures that really hurt me. Not the type of pictures I wanted to show obviously. But to possibly prevent others to encounter the same problems I just have to.
crack-1.jpg

crack-2.jpg


One of the towers is broken in half. There is a 2 mm gap right about in the middle. Yesterday evening they were still fine, although I usually knock on them before going to bed to hear what the enclosure sounds like. The sound was high pitched. So I figured the enclosure was under some stress.
They were both in one piece though.

This morning I found one of the towers broken almost exactly in the middle.
Trying to figure out what to do next...

:(

I always knew it could happen. I had some doubts about the threaded rods but figured I had enough rubber at both ends to counter the expansion/crimp. It obviously wasn't enough.
 
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Oh sh!t...After the amount of work that's gone into these this must be heartbreaking.

There are metal rods running vertically. When the wood wanted to shrink even a tiny amount per layer the metal wouldn't let the tower get shorter.

If it were me I would fill the crack with colored epoxy and keep going.
Evan

I just saw your edit...I've said nothing you didn't know.
 
It was a sudden change in weather over here, from a damp rainy day to clear conditions (frost outside). I observed my wooden floor and noticed the change over the past couple of days, you can see the seems in the floor opening up (oak floor, glued but it still moves) after more than a week of being very even and closed up.
I had been eyeing my enclosures to observe but didn't expect (or hope) this to happen.
It was the ultimate test I guess.
Now I regret not packing them in fiberglass matt and epoxy as I originally planned. Don't know if that would have helped though. The diffenece in expansion from the wood and the threaded rods might still have been an issue.

I'll attempt to rescue the broken enclosure. No way of knowing it will work.
A sad day after half a year of work ;).
 
Sorry to see this. Seconded re filling the crack, assuming it's not totally snapped the enclosure.

I'm afraid translam construction is notorious for this sort of thing happening; either delamination on glue-lines, or cracks through supporting inserts etc. :(

The crack is all around, but not at a seam I glued... it's the multiplex part that cracked over 2 different seams.
A re-run of the pictures for the new page:
crack-1.jpg

crack-2.jpg


I found out sitting behind my desk, turning around towards the towers and suddenly realizing a streak of light coming trough. I wasn't even shocked. As this had been on my mind. You don't want to know how long I was in doubt to use wooden dowels or threaded rods. Not to say it couldn't have happened if I had used dowels.
 
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Oh sh!t...After the amount of work that's gone into these this must be heartbreaking.

There is a very similar crack in my heart right now ;).

One more picture inside the chamber, you can see it wasn't a glue line between my layers:
crack-3.jpg


If I can't fix the crack another way I'll probably wrap the entire speaker with cloth and epoxy. I do hope not to have to do that though.
 
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Mon dieu! Merde! Ce n'est pas bien!

...I'll probably wrap the entire speaker with cloth and epoxy. I do hope not to have to do that though.

Before you rush in, do ensure that you understand what caused the crack.

I am suprised as the rods are compressing the stack, not stretching it.

I'm confused how this happened - as it has delaminated the plywood there must have been substantial forces at work.
 
So sorry to see this...

Really feel for you here....

Just one thought before I offer some ideas.
You already have a fabulous pair of speakers that will still sound and look amazing....I bet 99.9% of the speaker guys on here would love to own your speakers as they are right now.
You still have so much good stuff here!

Damage limitation:
(1) Can you loosen the bolts or even remove the rods? This might avoid further damage.
(2) Is it possible to have each speaker as a two piece...A la Triangle Magellan I think?
(3) Would it be easier to clad your plywood stack in thin curved ply wood? ( See photo's)
This worked really great...We shipped from Norway to the Arizona and never had any climate related issues.
(4) Each Encore bass cabinet weighed over 135Kg and the two pack glue was stronger than the ply itself so we never needed rods even at such extreme weights.

Hope some of this helps and all the best
Derek.
 

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