Has anyone used 'inward tension' using line/rope/long bolts to stiffen a cabinet? - Page 2 - diyAudio
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Old 23rd September 2009, 10:54 PM   #11
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Default using bolts to tension speaker

You might want to consider using all-thread (threaded rod) and putting nuts and washers on the all thread, to sandwich the panels between nuts. Maybe a gasket material also to decouple the washers from the wood.

To me this sounds like an adjustable version of a wooden dowel, with potential advantages.

Good luck.
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Old 24th September 2009, 12:40 AM   #12
sardonx is offline sardonx  Canada
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Quote:
You might want to consider using all-thread (threaded rod) and putting nuts and washers on the all thread, to sandwich the panels between nuts. Maybe a gasket material also to decouple the washers from the wood.

To me this sounds like an adjustable version of a wooden dowel, with potential advantages.

Good luck.
Yeah that's basically what i'm doing except the bolt is not all threaded. Just at the end. But it will work the same way. Funny thing is a couple of days after i opened this thread I went to a friends house who used to be in the speaker business and he had bought back a pair of his old speakers which had exactly what we're describing here! What are the chances.
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Old 26th September 2009, 09:31 PM   #13
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I used allthread in tension years ago to brace an MDF cabinet. Over time, the wood 'relaxed' and bent inwards, relieving the tension and making the braces useless. Wood does that.
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Old 2nd October 2009, 05:34 PM   #14
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Somebody mentioned putting nuts on both sides of the walls. That should work quite well and would be a boon for people who don't have the equipment to install bracing easily (dado, etc.)

If you wanted to install them on enclosures that are already glued up, you could cut the threaded rod into two sections each and use clamp-on threaded shaft collars once the rod goes inside.
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Old 2nd October 2009, 05:54 PM   #15
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Originally Posted by sardonx View Post
Yeah that's basically what i'm doing except the bolt is not all threaded. Just at the end. But it will work the same way. Funny thing is a couple of days after i opened this thread I went to a friends house who used to be in the speaker business and he had bought back a pair of his old speakers which had exactly what we're describing here! What are the chances.
Nobody here remembers this guy?

http://www.michaelgreenaudio.com/
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Old 3rd October 2009, 02:45 AM   #16
sardonx is offline sardonx  Canada
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Nobody here remembers this guy?
That's who my friend made them for. Actually he had a guy in town build them (who i worked with at a different time) for him and then sold them to Michael Green. The pair with the bolts at his place have a Cambridge Audio woofer, which was news to me(sounds great though), and what looks to be a Vifa tweeter. Nice little elegant floor standers.
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Old 3rd October 2009, 05:57 PM   #17
ChrisA is offline ChrisA  United States
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What if you were to use a series of strings (say bass guitar strings) and actually tighten and tune them to certain notes, or all 7 whole notes. The issue would be that not all music is played on instruments tuned to A440 but I'm wondering if the right combination of stiffness and damping were used, along with the tuned strings, would this blur the music or would the specific resonances enhance the experience..?
I can tell you first hand. I've got a bass guitar. If you want decent sound most bass players will tell you you have to mute the strings you are not playing. Bass playing is as much about muting strings as striking them. So you idea could work but you's need to mute the strings. Maybe just pack the cabinet with that white "fluff".

It turns out that strings don't just resonate with their own note. The E string will pick up harmonics from a C and many other combinations all going on at once. Sounds like mud. you really do have to keep a finger on the un-played strings. You want the cabinet to be acoustically dead

You do NOT ever want to but anything in a hifi speaker cabinet that even comes close to resonating. Guitar cabs are different. I just built one using 3/4 inch pine. It adds to the tone and sounds good. (Just to see what would happen I tried playing some solo piano music through this guitar cab. It was quite poor, really bad)
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Old 3rd October 2009, 06:54 PM   #18
Ron E is offline Ron E  United States
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Point contact isn't going to do much to brace the panel. You want line contacts to divide the panel into smaller ones (the aim of bracing). The smaller panels resonate at higher frequencies and these are easier to damp.

I Once saw a test where they used single dowels (glued, IIRC) and the first resonance of the panel was nearly unchanged. IIRC, a brace at right angles to the sides/top did better than a diagonal one, perhaps a counter-intuitive result.

I believe the best arrangement is a brace along the longest dimension of the panel, just off center. IMO, shelf braces and ribs are the most practical/effective thing to do. I try not to have more than 4-6" of unbraced panel.
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Old 7th October 2009, 07:11 AM   #19
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You might want to consider using all-thread (threaded rod) and putting nuts and washers on the all thread, to sandwich the panels between nuts.
I did this very thing 16 some odd years ago, with my 3x10" driver, 4x4" ported sub box back in my mobile audio days. Everything came through the front panel and was far too busy to effectively use traditional bracing...., (with any ease that is).

Worked like a charm to stiffen up the front baffle, and wouldn't think twice if the occassion called for it.
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Old 7th October 2009, 07:19 AM   #20
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I did it too , but 14 years ago , as for plastic in the bottom and on top , reinforced with wood , it was the only way.
http://www.diyaudio.com/forums/attac...2&d=1246432242
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