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Duratex & Speakon; La Scala, Heresy & TH subs


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The next project is to retrofit several speakers -- Anarchy Exodus TH subs, La Scalas, Heresys and DIY single-drivers -- with Speakon connectors.  I had already come to the decision to use Speakon connectors in all future builds when the binding posts on one of my TH subs were snapped off.  I'll chronicle the process of replacing the binding posts with Speakon and then applying black Duratex.

 

The first 2 photos show a Karlson slot speaker made for my son.  It sports Duratex and Speakon.  The third photo show TH subs 3 & 4 (note snapped off binding posts on right).  They will soon get Speakon and Duratex.

 

 

 

 

 

 

20170602_094157 (Medium).jpg

K2.JPG

K3.JPG

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When I built these DIY Sound Group flat packs I did not make access panels.  Now I wish I had.  I'm looking for opinions as to how to best cut an access hole that will permit me to replace the broken binding posts with Speakon, enable removal of the driver -- if necessary in the future -- and make for a reasonably elegant resealable panel.  Any advice from @CECAA850, @jason str, @Marvel, @Wardsweb@ClaudeJ1 or others is welcomed.

 

The first issue is cutting an opening without damaging the woofer. From the photo above and the attached diagram you can see that the driver magnet is just behind and above the binding posts.  My as yet unfinalized plan is to mark a rectangular opening large enough to permit the woofer to pass through.  I do not need to reuse the rectangle that will be removed.  I have more BB 1/2" plywood from which to cut panels using a bandsaw.

 

My thought is to place the cabinet between sawhorses with the binding posts facing down, and then, lying on my back, drill many small holes along the rectangular outline.  Using a saber saw, or any saw for that matter, concerns me for two reasons.  First, I don't want to actually strike the driver or the wires, and, second, I don't want sawdust getting into the driver.  By lying on my back and drilling up into the 1/2" plywood, gravity will work against "drilldust" getting into the driver.  Your thoughts are encouraged.

 

The Speakon will be mounted in the removable panel.  The most elegant way to do this would be to use a router to rabbet the panel and the cabinet. I see at least a couple of problems with that plan.  

 

One is that rabbetting 1/2" ply would leave ~1/4" of overlapping material if the re-installed panel, including a gasket, were to be flush with the cabinet.  Screwing into less than 1/4" of ply scares me, as does using T-nuts in that situation.

 

My second concern is that making the "C-Section" opening large enough to allow me to "deliver" the driver would have the rabbet into the sides of the cabinet.  

 

 My plan, such as it is, involves cutting the replacement panel on a bandsaw and then attaching a slightly larger 1/4" BB plywood panel to the plug, using PL adhesive and screws.  The edges of the 1/4" panel would have a round-over like the small Karlson cabinets above.  A gasket under the 1/4" panel and attachment by copious small screws into the 1/2" cabinet should suffice.

 

Any alerts to problems with this plan or alternative suggestions are encouraged.  Once the sawdust starts to fly, options could be reduced.  Naturally, all OSHA stanards will be observed . . . NOT.

 

IMG_0006.JPG

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11 minutes ago, Marvel said:

My larger concern would be all the sawdust that will inevitably cover the driver. Getting those cleaned up might be a challenge.

 

Bruce

 

Bruce,

 

Don't you have better things to do on your birthday? :-)

 

Sawdust concerns me also.  One idea is to insert a vacuum hose into the horn opening while the drilling up into the cabinet is taking place,  that would draw much of the dust away from the woofer.  It would be tedious and time consuming to drill many holes with the bit set to just pierce the 1/2" ply and then gently "connect the dots" by hand with a coping saw blade while the vacuum sucks away the dust.  

 

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Plunge router set just below panel thickness and a vacuum adapter. Leave just enough material so you can break the cutout free.

http://www.homedepot.com/p/Bosch-3-Hood-Dust-Extraction-Kit-for-MR23-Series-Routers-RA1177AT/205412363?cm_mmc=Shopping|G|Base|PLA|D25T|PowerTools&gclid=CJD4y873tdQCFQ-BaQod8FwCLQ&gclsrc=aw.ds

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That's a good idea.  If the router is leaving "just enough material" to break the cutout free, the vacuum attachment becomes unnecessary, as the sawdust remains outside of the cabinet.  I could then use a utility knife to cut the remaining material, without exposing the woofer to sawdust.  Am I missing something?

 

Thank you @USNRET.  That's just the kind of suggestion I'm looking for. 

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8 minutes ago, USNRET said:

After posting I thought about how a circle template device would work with the vacuum plate.

 

I've never used one of those.  The width of the cabinet is ~ 8.5".  How would/could I attach a template device?  The router bit would need to get right against the inside edges of the sides.

 

Another problem regarding a router occurs to me.  The remnants of the broken binding posts stick up above the surface.  I'd need to grind them below the surface to use the router.

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I use this on my Dewalt cut out tool, many different circle guides both bought and made. You will need to remove the binding post and have a hole in the center of the circle for the pivot pin.
 

Circle guide.gif

Dewaly cutt off.jpg

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7 minutes ago, USNRET said:

I use this on my Dewalt cut out tool, many different circle guides both bought and made.
 

Circle guide.gif

Dewaly cutt off.jpg

 

I must be dense.  

 

How would that work with the bit right against the sides of an 8.5" wide surface?  Intuitively, I see how it would work on a flat surface much larger than the circle being cut, but I don't see how it could work in this situation.  Plus, a circle won't work if the access panel can permit the removal of the woofer.  The opening must be ~ 7.5" wide.  I'm looking at a rectangular opening ~ 7.5" x 8.0" with rounded corners.

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My mistake, I thought round. My first idea would be to draw the shape you need on computer, print, trace to scrap material, cut out, smooth any defects, attach to sub and use that as a guide for router.

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You can cut an access like this one using just a straight piece of wood with a couple clamps or finishing nails. Lay your piece of wood as a straight edge that the router base will ride against. This means the distance from the cutting bit to the edge of the tool is where the straight edge is. It can be clamped in place or nailed in place. Just make sure the nails are small and you don't fully nail them in. They are just to hold it long enough to make the cut and then be removed. You will be making one cut at a time.

 

Another option would be to use a circular saw and make two passes all the way across the cabinet above and below the woofer. You are going to make a panel that runs all the way across the back of the cabinet, using the side panels as your supports and where the panel will screw in. An alternative would be to router this panel out and only cut half the depth on the side panels so you can make a dado joint on the ends. I hope this make sense. If you would like to discuss further, message me with your phone number.

subaccess.jpg

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Now I see, said the blind man.  I could cut the opening into a larger piece of scrap material, which is then temporarily attached to the cabinet to act as a guide for the router.  Using 1/4" material would make it unnecessary to grind away the remnants of the binding posts; the router would be outside of the posts.

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13 minutes ago, Wardsweb said:

You can cut an access like this one using just a straight piece of wood with a couple clamps or finishing nails. Lay your piece of wood as a straight edge that the router base will ride against. This means the distance from the cutting bit to the edge of the tool is where the straight edge is. It can be clamped in place or nailed in place. Just make sure the nails are small and you don't fully nail them in. They are just to hold it long enough to make the cut and then be removed. You will be making one cut at a time.

 

Another option would be to use a circular saw and make two passes all the way across the cabinet above and below the woofer. You are going to make a panel that runs all the way across the back of the cabinet, using the side panels as your supports and where the panel will screw in. An alternative would be to router this panel out and only cut half the depth on the side panels so you can make a dado joint on the ends. I hope this make sense. If you would like to discuss further, message me with your phone number.

subaccess.jpg

 

That photo shows one of my perceived dilemmas.  The square opening doesn't appear to be large enough to deliver the driver without an episiotomy.  Furthermore, how would I get at the screws attaching the woofer?  Perhaps replacing the broken binding posts and permitting woofer removal in the future is too ambitious.

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I've got a Paslode nail gun that can shoot tiny brads to hold the guide temporarily in place.  The tiny holes are easily filled.  If you look closely at the cabinet on the left in the original photo you can see where just such a nail hole was filled.

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