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4pi build with stands finally realized [message #94409] Sat, 11 September 2021 19:19 Go to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
Started planning and buying parts a year ago, and now it is time to create them. I have spent some time with Sketchup to try different designs. They are made of 21mm plywood with double baffle and additional bracing. Finishing will be bare plywood with Osmo black wax. Internal measures, port dimensions and positioning of drivers are according to original spec. DE250 and JBL2226 drivers will be used. I am showing you pictures from sketchup in this first post. More pictures from the build process will be shared tomorow.
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Re: 4pi build with stands finally realized [message #94414 is a reply to message #94409] Sun, 12 September 2021 12:53 Go to previous messageGo to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
Promised some updates, and here it comes. Decided to finish the stands first. The bottom is made of two layers 21mm birch plywood, and the top is single plate. Top plate is tilted 3 degrees. I used two sheets plywood and it was just enough for speakers and stands.
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Re: 4pi build with stands finally realized [message #94415 is a reply to message #94414] Sun, 12 September 2021 16:57 Go to previous messageGo to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
Building the cabinet.
I wanted flushmonted driver/horn, so I used the router on the outer baffle first. Then I cut out the holes, glued the outer front to the inner and used a copy bit to to make the same cutout on the inner front.
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There was a guide bushing accessory my handheld router, so I made a template for the horn flushmounting. I think I made four versions before I was happy with the fit. The horns were slightly different in size (approximately 1 mm), so I ran them through my router table to make them 100% alike.
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Parts start to come together. I twisted my mind to find a decent way to make the port opening in the baffles flush with the port construction itself. I ended up cutting out a slightly smaller port opening in the baffle, glued the port to the baffle and ran the whole construction face down on my router table with a long copying bit to follow the sides of the inner port. Port opening was finished with a roundover bit to follow the "rounded" design of the speaker and to appear as large as the horn.
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I used masking tape to avoid glue spill. Experience from earlier mistakes taught me that oil or wax dont dont absorbe on those spots. You may have to sand really deep to fix it.
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First sanding of top after side panel assembly. A good start. Side panels were rounded off with a roundover bit with same radius as the plywood thickness. Had to practice on several pieces to find the right router/feeding speed. It is damn easy to get burnmarks. This was done on my routertable to ensure stable feeding and guiding.
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Re: 4pi build with stands finally realized [message #94417 is a reply to message #94415] Mon, 13 September 2021 09:05 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18128
Registered: January 2001
Illuminati (33rd Degree)

Wow, stunning! Excellent work! Those are going to be really great speakers!

Please keep the build pics coming. I can't wait to see them finished.
Re: 4pi build with stands finally realized [message #94420 is a reply to message #94409] Mon, 13 September 2021 16:25 Go to previous messageGo to next message
tom-m is currently offline  tom-m
Messages: 51
Registered: December 2009
Location: Texas
Baron
Yes, very nice! High quality work for sure. I love the birch plywood.
Re: 4pi build with stands finally realized [message #94421 is a reply to message #94415] Mon, 13 September 2021 16:54 Go to previous messageGo to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
More pictures. First round with Osmo black wax just applied. Nice to see the plywood layers highlighted.
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I think this was after second layer black and semi matte clear hardwax. Not dry yet. The bright parts on the sides are light reflections.
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Re: 4pi build with stands finally realized [message #94422 is a reply to message #94420] Mon, 13 September 2021 16:59 Go to previous messageGo to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
Thanks alot. You barely see speakers with plywood finish. Wanted to highlight the endwood, and so far it looks ok.
Re: 4pi build with stands finally realized [message #94423 is a reply to message #94409] Mon, 13 September 2021 17:33 Go to previous messageGo to next message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
This is how I applied damping material. I covered all sided with classic felt damping. This layer is just 7mm thick but has good effect.
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Behind the woofer below the top brace there are two layers more. One sheet with the white stuff which is very airy, and classic foam type on top. So three layers in total behind woofer. Had this laying around from earlier projects, but I believe they will give a good combined effect.
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Added some extra damping on one side as per Waynes description. A sheet with fiberglass will be added under the top brace as recommended.
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Re: 4pi build with stands finally realized [message #94424 is a reply to message #94409] Mon, 13 September 2021 22:09 Go to previous messageGo to next message
grindstone is currently offline  grindstone
Messages: 26
Registered: May 2010
Chancellor
Good box. Thanks for posting. Nice work.
Re: 4pi build with stands finally realized [message #94425 is a reply to message #94424] Tue, 14 September 2021 04:15 Go to previous messageGo to previous message
Roger S. is currently offline  Roger S.
Messages: 10
Registered: September 2021
Location: Norway
Chancellor
Horn mounting. Tight fit, and flush. Made two extra holes on the sides of the horn just to be sure. The horn itself is damped too.
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Filter install. Just enough place for the filter. Speakon 4 pole installed on bottom. I modified the filter for bi-amping to have the option. With four wires in it is also possible to test active crossover and dsp if/when I get the urge.
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2 inches fiberglass insulation mounted under top brace.
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Speakers had to be bolted to the stands before filter/woofer install. Four bolts with rubber gasket between stand and speaker.
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