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Multi-Way Conventional loudspeakers with crossovers

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Old 14th November 2012, 07:30 PM   #551
sippy is offline sippy  United Kingdom
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Try 2 part Pu foam, living where you do, it should be available from a boat building/composite supplies type place...... the squirty stuff in cans is ok but can leave voids, but is not a patch on the stuff that can be mixed and poured though.
Tis essentially same stuff as surf board blanks are blown from, but minus the 'bleaching agents'.
I've used this stuff for repairing 'Dory' hulls and the odd 'Whaler' windsurf board:
Foams & Core Materials, 2 Part Polyurethane Foam Liquid, - CFS Fibreglass Supplies
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Old 14th November 2012, 07:32 PM   #552
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Wall paper!! I wonder if we could use a nice finish to pass the WAF test
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Old 14th November 2012, 07:34 PM   #553
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Flowers and butterflies, I'm thinkin'
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Old 14th November 2012, 07:44 PM   #554
tinitus is offline tinitus  Europe
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I have not used birch plywood very much
cant afford the best, so the type I got was a bit rough and 'scruffy', and hard to get nice finish
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Old 15th November 2012, 10:26 PM   #555
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okay I'm pretty set on the 8 cell.....to start with

What are the ideals for placement & what issues are there regarding support etc? How are they connected to cabs with the Altecs etc?
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Old 15th November 2012, 10:42 PM   #556
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??? Ideally you need to time align them.

Historically, they had fixed brackets at the two lower mouth corners and a vertically adjustable one attached to a mounting lug cast to the throat adapter, then the whole assembly was mounted to a plywood 'sled' for shipment, mounting to the cab with wood screws once aligned.

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Old 15th November 2012, 10:46 PM   #557
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Ok that makes sense. I was trying to figure out how the heavy front end wouldn't slip over the front.

With the minidsp I can dial in 7.5ms delay (from what I can quickly find) of time alignment. Is that an equal substitute to physically aligning the voice coils? What does 7.5ms equal in physical movement anywho?
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Last edited by JRKO; 15th November 2012 at 10:49 PM.
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Old 15th November 2012, 11:01 PM   #558
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Don't see why not, the pros and DIYers sometimes have to dial in hundreds [thousands?] of degrees of offset with some tapped horns, stadium, Cinemax, apps, etc..

Depending on who you ask and/or where the location is, the SoS varies a bit, but ~344 m/s is pretty common, so 1 ms = ~34.4 cm x 7.5 = ~258 cm.

Pretty sure your speakers won't be this deep unless the bass bin is a Klipsch corner horn or similar.

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Old 15th November 2012, 11:09 PM   #559
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no way mrs jrko would let me have speakers 2.58m deep!!

I guess that means I can have the front of the horn not too tar in front of the bass cabinet thou which will look better.

are there any issues with the bottom row of cells sitting close to the bass cabinet or driver?
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Old 15th November 2012, 11:38 PM   #560
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Multi-cells are very truncated horns, so they rapidly flare out, dictating a bit of distance from any reflective boundary if not designed as part of the flare or at least a fast expanding flat baffle.

Short of making foam mouth extensions to allow setting them directly on top of the cabs, some space is needed, though have never seen any hard n' fast rules/math, so I've used the same as would be used for a vent or other truncated duct, i.e. take the horn mouth radius [if round] or the height/2 [if rectangular] x 0.613 to get a 'good enough' distance.

For a 13" high 805, I'd use 13/2 = 6.5*0.613 = ~3.98" min..

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