yeah i'm going for a polished flat and parallel surface . this is the input i appreciate the most.Originally Posted by GM
It's quite popular to coat cabinets with bedliner these days, for sound reinforcement use. It's probably more for durability than anything else, Though, not sound quality.
Audio_by_Goodwill
Michigan, USA
yeah i'm going for a polished flat and parallel surface . this is the input i appreciate the most.
Last edited by Phil-G; April 24th, 2013 at 11:19 PM.
Sonic Barbarian
Yes, I know, but you can get a very smooth finish that seals/protects the horn and do its exterior textured. The few pics of ~current PA FLHs I've seen are this way, so hopefully there's no reputable manufacturers just 'cutting loose' with truck bed liner on every exposed surface.
GM
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On a relatively large short horn such as the A7's, there's enough difference to at least subjectively notice a difference if one's hearing isn't shot and as the horn shrinks in size it can be relatively dramatic. If we had bat hearing it would probably be a 'night n' day' difference, what with all the ultra high pitch 'singing' going on due to the friction caused by a pitted surface. Dr. Geddes's higher order modes [HOMs] would take on a whole new meaning.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Takes me right to the 2-cycle engine building bench where we leave a very coarse rough texture on the intake side and polish the exhaust to a mirror finish.Why would anyone with a 'lick o' sense' want a textured finish on a horn baffle's surface?
Texture in intake runners and ports = molecular deflection, a really good thing for keeping fuel molecules suspended in air and preventing surface condensation, not good for much else.
On the exhaust side, priorities like smooth surface finish, smooth and uninterrupted joints/junctions, and flare/expansion rate become very similar to a well engineered acoustic horn. Apparently, physics remains universally constant across different applications.
Not all vegetables make good leaders.
Yep, Mother Nature isn't prone to fix what ain't broke! I learned TL, horn, acoustic filter theory primarily to design high performance intake, exhaust systems, which BTW was mostly from a late '50s NACA muffler experimental design study that had a young Don Davis on the team. The test rig was driven with a 15" woofer. I thought these guys were bleeding edge brilliant and had made major breakthroughs in acoustical engineering until a few years later when I found out that they had basically just built upon already well proven designs, or at least theories, the pioneers of audio had published decades before!
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
So well said ! Man heard first and drove much later
But air at high speeds does not flow smoothly over smooth surfaces. Air tends to want to stick to a smooth surface due to friction and turbulents develop causing drag. By introducing turbulators, the friction is distrupted allowing air to flow more efficiently. For example, golfballs with dimples fly farther than smooth golfballs.
These turbulents are a real problem for jets. NASA - High-Speed Research (HSR) - Smoothing the Flow Over Supersonic Wings
I'm not sure how this relates to sound waves, but there is a distinct gain in efficiency NOT having a smooth surface in when it comes to high speed air flow.
Last edited by alancohen; April 25th, 2013 at 04:01 PM.
i went ahead and used the closed cell foam. 1 because i had it. 2 it would be more compatable with the bonding putty. this putty uses the same catalyst as the resin.
the foam gets bedded in the putty. it can get messy. after the putty has hardened. the foam it trimed and smoothed. and finally covered with the last two layers of cloth. 1208 biaxial and a cover of 1 1/2 oz mat.
and there it is one part down, 3 to go.
once this is cured, i'll trim it to fit and make adjustments to the process if necesary.
i went ahead and tried stress testing it and yes i can stand on it with 1 foot (tomorrow i could probobly jump up and down on it) without any flex
i have more pictures, but i seem to have used my 1 mb limit. ? and i'm not sure if i can delete some of the pics in the attachment box
Last edited by Phil-G; April 26th, 2013 at 08:45 PM.
Sonic Barbarian
Lookin' good Phil!
Not all vegetables make good leaders.
whoa thanks tom.
i'll have cleats all the way around each panel. one at all 4 sides. once i have all 4 flange panels fitted, im either finishing them with gelcoat or imron. the back of each panel will get undercoated. and then bedded with 3M 5200 fastcure. i'll also probobly fill in behind them with isulation. i'm also thinking of putting handles in this space just under the VOTT sticker.
the box seems to be sealing well, the test will be covering the speaker hole and seeing if the box will hold a vacuum.
Sonic Barbarian
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