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PostPosted: September 3rd, 2019, 8:47 am 
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I have been making some progress on my first speaker building project for over a decade. I want to "downsize" from the Basszilla and horn setups I have been using, and although I recently have been listening to my old Aria 5R speakers, subwoofers + active crossover, wanted to have a full range speaker to live with in my room. I had been researching various designs from Troel Gravenson and others, looking to get a an efficiency at or above 90dB/1Wm. I ran across a well documented and very well regarded design by Joe Rasmussen in Australia (former colleague of the late Allen Wright). His design is a 2-1/2" way using four (4) 6-1/2" drivers and a 1" dome tweeter mounted in a waveguide.

http://www.customanalogue.com/elsinore/ ... _index.htm

There is a very long project thread (254 page and counting) on DIYAudio.com

https://www.diyaudio.com/forums/multi-w ... hread.html

I have been working on the cabinets over the past couple of weeks, and have been making progress on cutting all the panels and routing out the holes. Having fun with my new Bosch 1/2" router (with fixed & plunge bases), as you can see in the attached. Had to make a template for the rectangular holes in the braces and used a Jasper Jig for the circular cuts. Hope to start assembling the cabinets in the next week or so.

Making the cabinets out of MDF, double layer 1/2" to get the 1" recommended thickness. I ended up making a very stiff torsion box press (i.e. veneer press) for gluing up 2'x4' sheets together maintaining a constant pressure across the entire surface. Based on my cuts, the glueline is tight throughout the entire panel, so successful effort. Actually, I am finding that making tooling to facilitate accurate cutting, routing, and clamping is taking about the almost as much time as working on the speakers. I have made, in addition to the press, an accurate crosscut sled and adjustable router template for the rectangular holes in the braces, as well as tuning up my Bosch contractor's saw.

David


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PostPosted: September 3rd, 2019, 9:05 am 
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David:

Looks like a great project. I know what you mean about the time required to make the fixtures to work with the project. I wound up making 18 fixtures to produce the eggs. It is a lot of work for one time use but without them the job is nearly impossible. Good luck and if things get overwhelming I have a bottle of 18 year old Jameson Reserve I can share.


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PostPosted: September 3rd, 2019, 9:08 am 
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What is the crossover for the speakers. I looked at the link but the crossover design was not clear to me.


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PostPosted: September 3rd, 2019, 9:31 am 
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tomp wrote:
David:

Looks like a great project. I know what you mean about the time required to make the fixtures to work with the project. I wound up making 18 fixtures to produce the eggs. It is a lot of work for one time use but without them the job is nearly impossible. Good luck and if things get overwhelming I have a bottle of 18 year old Jameson Reserve I can share.


Thinking about how to build something in a precise, controlled manner is part of the fun of a project like this. As you well know, not anything to rush into. Your egg speakers could not be done without meticulous planning every step of the way. My project is EASY in comparison.

I could probably use some advice concerning finishing MDF. I want to paint them, and have a Wagner HPLV spray paint rig that I need to learn to use. Otherwise foam rollers. Looking into using wood hardener for the driver cutouts, and multiple coats of shellac for sealing the MDF. Curious on what you did. I am sure that finish will end up taking as much or more time than the cabinet building itself.

David


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PostPosted: September 3rd, 2019, 9:36 am 
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brombo wrote:
What is the crossover for the speakers. I looked at the link but the crossover design was not clear to me.


The crossover is basically 1st order, but with individual driver correction and it takes into account the baffle size in the response. You need to read Joe's discussion. This is a very sophisticated crossover, extensively modeled and tested with the selected drivers.

David


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PostPosted: September 3rd, 2019, 10:58 am 
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The person who painted the eggs with an automotive finish had never worked with MDF before. He discovered that due to the difference in hardness between the MDF and glue lines that no matter how much you sanded there were always ridges that would show because they did not sand at the same rates. He used a polyurethane material that they call "icing" in the trade to cover all the areas having different interfaces. Then he used primer, sanded, color coat, sanded and then several layers of clear coat with sanding in between. Here are two photo of Steve working with the icing at the top of the pyramid where the glue lines are showing and also the egg totally covered with icing. Note that the egg is sitting on top of one of the fixtures I made that allowed Steve to get to all sides by holding the egg in the air by means of the bottom hole that later housed the locating pin for mounting to the pyramid top.


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PostPosted: September 3rd, 2019, 1:04 pm 
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Joined: March 12th, 2013, 11:12 am
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Good quality paintwork is difficult, might be worth calling in an expert painter and writing a check? Or veneer?




David McGown wrote:
tomp wrote:
David:

Looks like a great project. I know what you mean about the time required to make the fixtures to work with the project. I wound up making 18 fixtures to produce the eggs. It is a lot of work for one time use but without them the job is nearly impossible. Good luck and if things get overwhelming I have a bottle of 18 year old Jameson Reserve I can share.


Thinking about how to build something in a precise, controlled manner is part of the fun of a project like this. As you well know, not anything to rush into. Your egg speakers could not be done without meticulous planning every step of the way. My project is EASY in comparison.

I could probably use some advice concerning finishing MDF. I want to paint them, and have a Wagner HPLV spray paint rig that I need to learn to use. Otherwise foam rollers. Looking into using wood hardener for the driver cutouts, and multiple coats of shellac for sealing the MDF. Curious on what you did. I am sure that finish will end up taking as much or more time than the cabinet building itself.

David


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PostPosted: September 3rd, 2019, 1:19 pm 
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Joined: July 8th, 2016, 4:34 pm
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Go to "Parts Express" website and search for "CBT36K" and look at review with heading "Building the CBT36K." That explains in detail how I finished the MDF cabinets of the CBT36K's (pictures included). If doing it again the only change I would make is to get high quality clear shellac and alcohol soluble dyes for shellac. Both are available at the Woodworker's Club in Rockville -

https://woodworkersclub.com/

If you would like to borrow a good Fuji HVLP sprayer let men know (I never used it).


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PostPosted: September 3rd, 2019, 1:32 pm 
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Thanks for the info, I will check that out.

I have a Wagner Flexio HVLP unit that I need to learn to use, my wife picked it up a couple years ago to loan out to a co-worker who couldn't afford one, and it came back unused. So I better learn how to use it.

But I have to get the cabinets built first...

David


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PostPosted: September 3rd, 2019, 1:34 pm 
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My comment is that if you don't have a spray booth spraying is messy. You can just rub on shellac.


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