Polk RTA12 Hat Repair Question--3D Printing?
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motorcityguy
Posts: 53
Hi folks. I have a really nice pair of Polk RTA 12's (first version) complete with the "top hats" (tweeter covers). Although the hats are in very good shape, the corners of them are "curving" because the original fabric is pulling tightly on the thin plastic corner pieces. The pictures will probably explain it better. First one shows the curved side of the outside of the hat. Second photo is a view INSIDE the hat showing the plastic corner pieces that are supposed to control the shape of the fabric.
The sides of the hat should be straight and vertical, not shaped like an arc. In my case, the plastic corner pieces have relaxed (flexed) with time. Unfortunately the plastic is also very brittle from age and in some places is starting to crumble/crack. So flexing the plastic back into the correct geometry is not an option. I'm thinking the corner pieces need to be replaced, but with what?
What I'm wondering is how others have addressed this. Is there a hack to re-create the corner reinforcements? Has anyone 3D printed them?
The sides of the hat should be straight and vertical, not shaped like an arc. In my case, the plastic corner pieces have relaxed (flexed) with time. Unfortunately the plastic is also very brittle from age and in some places is starting to crumble/crack. So flexing the plastic back into the correct geometry is not an option. I'm thinking the corner pieces need to be replaced, but with what?
What I'm wondering is how others have addressed this. Is there a hack to re-create the corner reinforcements? Has anyone 3D printed them?
Comments
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I don't know of anyone that has 3D printed the parts, but seem to recall folks making new frames out of wood or metal.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Bull nose drywall corner bead?- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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My top hats have very thick,truss-like supports. They do not flex at all. I believe yours are homemade.
I'll try to get a picture or 3 for you soon of these original ones. I thought of making some out of wood but have yet to do it.
I guess mine are like yours...but mine seem sturdy as heck. I'll still go pull one out and look again tomorrow.
https://forum.polkaudio.com/discussion/200401/rta-12-12a-first-version-top-hat-cover-supportMost people just listen to music and watch movies. I EXPERIENCE them.
“Anger is an acid that can do more harm to the vessel in which it is stored than to anything on which it is poured.”
--Mark Twain.
“If at first you don't succeed, then skydiving definitely isn't for you.” - Steven Wright -
The bull nose corner bead is usually plastic and could be easily trimmed- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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I just checked again.
Yes, mine are just like these;
Most people just listen to music and watch movies. I EXPERIENCE them.
“Anger is an acid that can do more harm to the vessel in which it is stored than to anything on which it is poured.”
--Mark Twain.
“If at first you don't succeed, then skydiving definitely isn't for you.” - Steven Wright -
Bull nose drywall corner bead?
Thought about that, but it's too flexible. The snug fit of the Hat fabric pulls against the corner pieces, so they need be be quite rigid to maintain the desired shape of the corner. -
My top hats have very thick,truss-like supports. They do not flex at all. I believe yours are homemade.
I'll try to get a picture or 3 for you soon of these original ones. I thought of making some out of wood but have yet to do it.
I guess mine are like yours...but mine seem sturdy as heck. I'll still go pull one out and look again tomorrow.
https://forum.polkaudio.com/discussion/200401/rta-12-12a-first-version-top-hat-cover-support
This is very interesting and helpful! Thanks for posting the picture. This is indeed very different from mine. However, I am confident mine are "original" corner pieces (not replacements), as the speakers were purchased from first owner and are extremely minty. Perhaps they are earlier (or later) manufacture than yours? My hat fabric still has original staples holding it to the hat base, so it's clear they have never been disassembled. (And I can't see how the corner pieces could get inserted and glued without disassembly of the hat.) My serial numbers are 12-05490 & 12-05487, and all four MW6500's are dated 3-80. How does this compare to yours? Your version of the corner pieces looks more complex, but sturdier, so I'm guessing it is a later version. -
I'm wondering if you could glue a rod, wooden or fiberglass, into the corners to beef them up?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I'm wondering if you could glue a rod, wooden or fiberglass, into the corners to beef them up?
I had that same thought. -
Thinking about this a little more. Perhaps glue isn't the best idea as it would likely ooze through the fabric. So, I'm thinking double sided tape.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thinking about this a little more. Perhaps glue isn't the best idea as it would likely ooze through the fabric. So, I'm thinking double sided tape.
Part of the problem is the brittleness of the corner pieces. They apparently took a "set" over the years, and if I try to straighten them up, in order to reinforce them from behind, I'm certain they will crack and break.
Another thing is that my original corners have holes in them, and the other version (as shown by TonyM) has slots. I'm assuming the perforations are to minimize block of the tweeter dispersion. So I've been thinking any fix or replacement would also need to be perforated or slotted. -
Given all the known constraints, I believe the best solution is a frame (as shown), to be placed at the deepest point of the side concavity, halfway between the top and bottom of the "hat".
It could be made of plexiglass, thin wood, or even small diameter steel rod, and secured with a tiny amount of adhesive at each "corner".
I think this would be the most effective, yet minimally intrusive (acoustically) solution.
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Regarding being set in the bent condition...
I wonder if you might apply gentle heat with a heat gun on low, or leave inside a car on a hot day; see if it restores any flex, then decide if you could brace them to straighten.
It's quite possible that this will not work well enough, if at all, but worth a shot if you want to keep them original.
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