SevenSixTwo - InDIYana 2018 Coax Design

[KEtheredge87]

Hi Everyone,

Like a few others, I've decided to start documenting my build for this year's InDIYana event, and the "Keeping Up With The Joneses" theme. This will be the first 3-way system I have ever designed, as well as the first time I've considered using a coaxial driver. For this competition, the rules dictate the use of 6.5 - 10" woofer(s) <$150 each, paired with a coaxial mid / high frequency driver <$200. The combined driver cost must be under $300, while the cabinet volume must be no more than 2 cubic feet.

I have chosen to compete with the Dayton Esoteric 7" woofer (ES180TiA) and the Celestion FTX0617 6.5" coaxial driver. The Esoteric retails for $139.59 while the Celestion sells for $125.00, bringing my total driver cost to $268.59. My total cabinet volume measures 0.631 ft^3for the Esoteric and a separate 0.407 ft^3 for the coaxial driver, bringing my total internal volume just over 1 ft^3.

While researching the works of Mr. Andrew Jones, I came across the TAD Compact Evolution 1, and was really struck by the design aesthetics. If imitation is the most sincere form of flattery, I must be trying to kiss up a little bit. I chose the outside dimensions of that cabinet (290mm (W) × 524mm (H) × 446mm (D)) as my design space, since I wanted to see what I could do with the same or smaller space, and not spend $24,000 for a pair of speakers in the process! While TAD uses some fancy bi-directional port on the sides of their cabinet, I'm going for a relatively easier to make slot port firing out the front of the cabinet.

As for the project name... I'm a bit of a firearms enthusiast outside of speakers. Since I have a 7 inch woofer, and a ~6 inch coaxial that houses 2 drivers in one, naming this speaker for the 7.62x51mm rifle cartridge seemed like too much fun to ignore!

I have been planning this out out in Autodesk Fusion360 for a couple of months now, and I am excited to start sharing progress with you guys as we get closer to April. I took advantage of the first day ABOVE freezing in Indiana for the last week or so to make some MDF dust in the garage. There's now three glue-ups going in the garage to make 1.25" thick front baffle stock out of 3/4" and 1/2" MDF. I plan to make two final cabinets and one test construction cabinet so that any mistakes (hopefully) get made on the guinea pig cabinet before I screw up the real deals!

Below are a few pictures of the work in progress, and the Fusion 360 renderings of what this might look like come April. I think using a figured curly maple veneer and a tiger brown/orange dye would be an outstanding color combination. We'll see where we end up!

Thanks in advance for following along!

[Wolf]

Interesting!!
Later,
Wolf

[KEtheredge87]

Quick update for the evening... things still look more like a pile of MDF than a speaker cabinet, but we're getting there. I spent the last few days putting my glue-ups together for my 1.25" thick front baffles, and my 1.5" thick rear wall for the Coax / MT section of the cabinet. There was no requirement that my MT section rear wall had to be 1.5" thick, but it just worked out that way while I was fine tuning internal volumes to match what BassBox told me was best.

Anyways... I was only half smart when making these glue-ups. For the front baffles, I made the 1/2" layer of MDF oversize on all sides so I could glue it to the 3/4" layer without worrying about exact alignment. That made it easy to trim away the extra on the router table to make a final size panel. On the MT rear wall glue up, I made both layers the same size, and oversize on all sides, which meant I had spend more effort lining them up nicely during glue-up, and ultimately go back to the table saw for final dimensioning. Next time... I'll do it right and only oversize ONE layer.

The rest of tonight's work was getting all the rabbets cut for the top, bottom, front, and back panels. I had considered mitering these corners, but having a 1.25" front baffle would have required a slightly offset 45 degree miter for just that joint, which wouldn't have worked well with the whole "tape the corners and fold it together" method. Adding these rabbets gives me more surface area for my glue lines, and lets me do easy 1/8" overhangs to get a perfect flush trim with the router later on.

This weekend I will shamelessly be following the template router methods that JavadS was kind enough to document in his Pretty Persuasions project. I'll make a flush cut template for the Celestion FTX0617 and keep gluing up my test cabinet.

Thanks for following along!

[marvin]

Hi Everyone,

Like a few others, I've decided to start documenting my build for this year's InDIYana event, and the "Keeping Up With The Joneses" theme. This will be the first 3-way system I have ever designed, as well as the first time I've considered using a coaxial driver. For this competition, the rules dictate the use of 6.5 - 10" woofer(s) <$150 each, paired with a coaxial mid / high frequency driver <$200. The combined driver cost must be under $300, while the cabinet volume must be no more than 2 cubic feet.

I have chosen to compete with the Dayton Esoteric 7" woofer (ES180TiA) and the Celestion FTX0617 6.5" coaxial driver. The Esoteric retails for $139.59 while the Celestion sells for $125.00, bringing my total driver cost to $268.59. My total cabinet volume measures 0.631 ft^3for the Esoteric and a separate 0.407 ft^3 for the coaxial driver, bringing my total internal volume just over 1 ft^3.

While researching the works of Mr. Andrew Jones, I came across the TAD Compact Evolution 1, and was really struck by the design aesthetics. If imitation is the most sincere form of flattery, I must be trying to kiss up a little bit. I chose the outside dimensions of that cabinet (290mm (W) × 524mm (H) × 446mm (D)) as my design space, since I wanted to see what I could do with the same or smaller space, and not spend $24,000 for a pair of speakers in the process! While TAD uses some fancy bi-directional port on the sides of their cabinet, I'm going for a relatively easier to make slot port firing out the front of the cabinet.

As for the project name... I'm a bit of a firearms enthusiast outside of speakers. Since I have a 7 inch woofer, and a ~6 inch coaxial that houses 2 drivers in one, naming this speaker for the 7.62x51mm rifle cartridge seemed like too much fun to ignore!

I have been planning this out out in Autodesk Fusion360 for a couple of months now, and I am excited to start sharing progress with you guys as we get closer to April. I took advantage of the first day ABOVE freezing in Indiana for the last week or so to make some MDF dust in the garage. There's now three glue-ups going in the garage to make 1.25" thick front baffle stock out of 3/4" and 1/2" MDF. I plan to make two final cabinets and one test construction cabinet so that any mistakes (hopefully) get made on the guinea pig cabinet before I screw up the real deals!

Below are a few pictures of the work in progress, and the Fusion 360 renderings of what this might look like come April. I think using a figured curly maple veneer and a tiger brown/orange dye would be an outstanding color combination. We'll see where we end up!

Thanks in advance for following along!

[ATTACH=CONFIG]n1359099[/ATTACH]

Nice gravity clamps! Subscribed.

[KEtheredge87]

Nice gravity clamps! Subscribed.

Thanks Marvin! Yeah... gravity clamps are the best Back in my solar car days in college we used old lead acid batteries for the same thing. Three cheers for high density materials!

[KEtheredge87]

Hello again everyone,

Today I was able to sketch out the driver and slot port locations on my front baffles, as well as create my flush mounting template for the Celestion driver. Following Javad's handy instructions (Thanks again bud! JavadS) I created a flush mounting template that has just enough room to squeeze the frame into place while having zero play.

Of course, I overcomplicated things... I really wanted to make sure I had the alignment lines on the final template in the right spot. I drew out the center point and lines for vertical, horizontal, and 45 degrees on the first template (but not the second). I spent way more time and mental energy trying to create reference lines on the second template than was needed. Heck, I even brought the driver back into the frame and used 1/4" router bits to make sure I had things evenly spaced all the way around. What dawned on me after I finished the template successfully (good snug fit) was that I could just position the driver where I wanted on the actual baffle, drill two screw holes to secure the driver face down, then attach the template on top of the driver. All of that work just to realize I didn't need to do any of it after all. Oh well. Live and learn!

Tomorrow I plan to cut my baffles for flush mounts and make woofer relief chamfers on the back side. Having a 1.25" baffle makes me think I can get away with one continuous chamfer instead of a series of smaller chamfer notches. That will be a game time decision looking at the mounting hardware and the thickness at those points.

Soon we'll get to actual glue ups and box construction I'm really intrigued to get these boxes to a state where I can tune the slot port. First time I've ever done one. Relying heavily on BassBox Pro for that, so we'll see how close we actually get to the desired tuning!

Thanks for following along!

[marvin]

Great work! Those look like a perfect fit...too perfect--will there be enough room for finish between the speaker driver and the baffle?

[KEtheredge87]

Great work! Those look like a perfect fit. Only concern is will there be enough room for finish between the speaker driver and the baffle?

Thanks Marvin I think there should be enough room. Generally I just put some matte black paint on the MDF in those cavities to blend in with the driver's frame. This time around I have some plans to spray some satin black on these cabinets AFTER the veneer goes on, which would achieve the same effect without an additional painting step afterward.. I will be masking the wholly bejeezus out of the veneered sections too. I don't care how many rolls of delicate painters tape I use! Of course, that's just the plan right now. If I get further and find a roadblock, I may have to re-evaluate that painting plan.

[4thtry]

Very nice project. Look forward to hearing these in April

[KEtheredge87]

Very nice project. Look forward to hearing these in April

Thanks Bill! I'm excited to see your work as well. It's been fun following along! -- Sent from my SM-N900V using Tapatalk

[scottvalentin]

That figured maple will look really cool!! Great work so far Keith, carry on!

[KEtheredge87]

That figured maple will look really cool!! Great work so far Keith, carry on!

Thank you Scott! Another update - inbound!

[KEtheredge87]

Alright everyone, Time for an update on Saturday and Sunday's efforts.

Saturday was spent in CAD and playing with the drivers to make sure I was making the right baffle design choices and confirming my mounting hardware. It's a good thing I checked too. The Celestion FTX0617 is a beefy driver with a big honkin' magnet. The mounting slots it comes with *could* squeak by with a #8 screw, but are really sized for a #10. Also, my stash of black oxide button head machine screws were only 1" long, which wouldn't quite work for my 1.25" thick front baffles. So, off to "The 'Zon", as Gordy calls it I ordered a box of 8-32 x 1.5" and 10-24 x 1.5" black oxide button head machine screws and the appropriate EZ-lok threaded inserts to go with them. The Dayton Esoteric ES180tia woofer can only take 8-32 screws, so I hope things don't look too funny with the smaller screws on the larger diameter driver!

Once the mounting hardware bits were settled, I knew I was going to need to chamfer the inside face of the front baffle to let these drivers breathe, so I trial and error'ed my way into modeling 5/8" x 5/8" (45 deg) chamfers between the mounting holes on the baffle. Again... I'm glad I modeled and thought before cutting wood, as the cabinet design and driver locations only allowed 5/8" chamfers on the sides and top of the Celestion driver. Ii could only squeeze a 1/4" chamfer on the bottom side so that I didn't interfere with the MT chamber bottom panel's glue line at the front baffle.

Sunday was a shop day, taking my hodge-podge of mental and written notes to the garage for a test baffle construction. I used a 1/16" drill bit to pilot the locations for mounting hardware on both drivers. This was done first so that I didn't have to guess where my lines and marks were after the router had cut them away. Then I screwed the FTX0617 coax face down to the baffle so I could line up the flush mounting template and secure it with double sided tape. That method worked well, as I wasn't satisfied I could trust my remaining lines on the template itself.

After all the setup, it was relatively quick work with a flush cutting template bit for the FTX0617's driver recess, and a jasper jig for everything else. Biggest hassle was working around my dust collection hose every time I ran the router in a circle!

For the recesses, I used a 6mm target depth for both drivers. I think this worked out well, as the Esoteric driver sat a bit proud of the baffle without any screws to compress the included gasket, while the Celestion driver sat a bit under the line with no gasket to boost it up.

On the back side of the baffles, I had compassed out some 5/8" OD circles at each 1/16" pilot hole from earlier in the day. This was my reference mark to leave enough uncut material for the threaded inserts to use later. I chucked up my 45 deg chamfer bit and used some scraps with 5/8" and 1/4" lines scribed on them to set my chamfer depth. I added 5/8" chamfers everywhere except the bottom side of the celestion's recess, which got the 1/4" as mentioned above.

Overall, I think the construction method is sound, and should be ready to proceed to the real baffles.

Now the real question... can anybody see where I goofed up?

[Navy Guy]

Somehow I missed this when you first posted. I really like the aesthetics you picked. The Esoteric woofers are amazing so you should have plenty of clean bass.

[KEtheredge87]

Somehow I missed this when you first posted. I really like the aesthetics you picked. The Esoteric woofers are amazing so you should have plenty of clean bass.

Thanks Kerry!

There's been a lot of activity on the forum lately. I figure it's really easy to miss posts when there's so much going on. Before I started this thread I saw your CSS P215 cabinet on Facebook and was really wondering how you guys got that fancy aluminum framing around the walnut veneer side panels. I'm hoping this looks at least half as good as that!