got one cabinet 60% done and the other is not far behind. tomorrow i get #2 up to 60% and finish the bracing and maybe start a form for the horn flanges while the boss is still out of town.
Last edited by Phil-G; April 18th, 2013 at 10:27 PM.
Sonic Barbarian
Looks real nice. Please take lots of pictures of your horn flare layout, construction techniques, and progress. It sould be really interesting.
OT; Just why are only four screws sufficient to secure a woofer on to the baffles? Wouldn’t eight be better?
"James, a little knowledge is a dangerous thing!" World's scariest Volvo: [url]http://www.youtube.com/watch?v=AKn-LTNa4rc[/url]
Lookin good Phil!
If the baskets had 8 spokes, yes, it would be better to have 8 bolts.OT; Just why are only four screws sufficient to secure a woofer on to the baffles? Wouldn’t eight be better?
Where the spokes are is where the bolts need to go, that's where the majority of stress is. Altec frames are over built enough that they provide ample clamping force to seal the gaskets without warping/distorting the basket if you just bolt them at the spokes.
That said, there's certainly nothing wrong with using 8 bolts, a little overkill maybe. But i'm all for whatever makes folks sleep better at night.
Last edited by bowtie427ss; April 19th, 2013 at 09:52 AM.
Not all vegetables make good leaders.
Originally Posted by VolvoHeretic
if they were someone else and i was charging by the hour i would definately go with the other eight bolts and tee nuts.
Sonic Barbarian
FWIW, the proper torque value to mount drivers, even very heavy ones, is very low compared to what it takes to warp, break just about any frame I've run across except for some popular driver's plastic ones. I imagine the sticking gaskets is due to over-tightening unless they've been installed for decades. That said, for prosound where speakers are often physically abused, mounting at the legs is a good plan.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
thanks GM.
in regards to the round tune port. should it be off center? or in line with the driver?
Sonic Barbarian
today i got the horn front/back mounting cleats cut and i started the 31" radius form for the horn sides. i made a radius template to mark and cut the the form supports. the form is 3/16s luan that i heated in the oven to make it more pliable and weighted it down on the supports till it cooled. you could almost use this same procedure in forming the traditional horn sides. it would make it easier.
tonight i'll let this set . tomorrow i'll prep it and get ready to start laying up the glass monday.
Sonic Barbarian
The WL's it's pumping out are low, large, so it doesn't matter. What matters in a high aspect ratio cab is vertical spacing, so in most cases the vent normally works best overall down around 4/5 or ~40.5*0.8 = ~32.4" on center.
If the vent required turns out to be more than a few inches long, then better overall to locate it right at the bottom, so that the local boundary will effectively lengthen it acoustically. In some cases, it needs to be in a corner or even one in each corner or worst case, a slot all the way across to further reduce its physical length enough.
Regardless, acoustically, the A7 cab is more a crude, high tuned BLH or big vent reflex [BVR] as I like to call them when the vent plates are left off, so vent location isn?t critical beyond needing to be in the lower half, though you?ll get more ?bang/buck? by placing it down right at the bottom to maximize boundary loading; and if pushed hard up against a wall, then using one or more down at the cab?s rear corners or even bottom firing with the cab spaced up to is what I?d do.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
here's my horn layup so far.
i worked the form down to a 32nd" with filler. then sealed it with resin and sanded it down to 400. after coating the mold with mold release i can start.
the first or outer layer is 1 1/2 oz mat. this gives you something to sand if you need to further smooth it out. (but somehow i have a feeling that adding a textured coating will be suggested in this thread somewhere down the line.)
the next two layers are 1708 cloth. this is a 90 degree strand weave.
after this is "wetted out" i go over the layers to work out the tiny airbubbles with a roller.
tomorrow (after i finish work) i will cut my coring. i'm using plywood instead the normal high density closedcell foam, because rot and weight will not be an issue. the final layer will be 1208 a biaxual cloth.
i should be able to stand on the finish part without it flexing at all.
Sonic Barbarian
Why would anyone with a 'lick o' sense' want a textured finish on a horn baffle's surface? Do they apply textured finishes to supersonic jets, land speed record contenders, etc.? with sound waves vibrating at ~770 mi/hr we want it so smooth, non-porous that if a fly lands on it, it will slip and bust its a$$...........
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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