Build Thread - SMJ Equilateral Subwoofer

[theSven]

The journey continues for the theater with a new project to replace the subwoofers that were in use now that the new SMJ CC has been successfully launched. The sono tube subwoofer setup was my very first DIY project that I had done, and it had a grand 10 year run. Wanting a better center channel for the theater, I knew this bridge would come and I would either cross or figure out how to retro fit the tube. I chose to go with something new that would match what is currently in place, and modernize the build.

This is my fourth project with SMJ Audio, and with every project the processes and technology evolve. That is something I really enjoy, innovation! Steve is always raising the bar for the designs and making these projects a reality for me. From the Calliope which was love at first listen and the 100% wife approval factor rating, the new baffle design for the Ardent D's, the gasket seal on the center channel along with crossover art and fitting it all into the cabinet in an elegant fashion. The builds evolve and who doesn't love evolution?

The subwoofer of choice for this project is the CSS SDX12 XBL2 12". I took advantage of the last sale for Black Firday thanks to technodanvan who shared the sale that was going on. The sub is a monster as Steve has shared with me, I've only seen photos from Parts Express. The photos below clearly depict this sub could be used for an anchor.







I will let Steve upload some images of the cabinet design. The colors discussed match what has been done already, the Bamboo and the dark lords favorite color... Black 😅. The plan is to build two cabinets that will reside on each side of the center channel.

Looking forward to the new year for this project and all the fun to come along with another DIY build!

[technodanvan]

Mmm...love me some CSS subwoofers! How many did you get?

[JonMarsh]

The journey continues for the theater with a new project to replace the subwoofers that were in use now that the new SMJ CC has been successfully launched. The sono tube subwoofer setup was my very first DIY project that I had done, and it had a grand 10 year run. Wanting a better center channel for the theater, I knew this bridge would come and I would either cross or figure out how to retro fit the tube. I chose to go with something new that would match what is currently in place, and modernize the build.

This is my fourth project with SMJ Audio, and with every project the processes and technology evolve. That is something I really enjoy, innovation! Steve is always raising the bar for the designs and making these projects a reality for me. From the Calliope which was love at first listen and the 100% wife approval factor rating, the new baffle design for the Ardent D's, the gasket seal on the center channel along with crossover art and fitting it all into the cabinet in an elegant fashion. The builds evolve and who doesn't love evolution?

The subwoofer of choice for this project is the CSS SDX12 XBL2 12". I took advantage of the last sale for Black Firday thanks to technodanvan who shared the sale that was going on. The sub is a monster as Steve has shared with me, I've only seen photos from Parts Express. The photos below clearly depict this sub could be used for an anchor.







I will let Steve upload some images of the cabinet design. The colors discussed match what has been done already, the Bamboo and the dark lords favorite color... Black 😅. The plan is to build two cabinets that will reside on each side of the center channel.

Looking forward to the new year for this project and all the fun to come along with another DIY build!

Um, Steve, one question for you, when you say the could be used as an anchor, did you have in mind a traditional VA lake motorboat, or something more like the ships supported at the Suffolk Naval Base, which I believe you lived close to at one time? I mean, you might need two or three of these for a typical aircraft carrier, right?

[Steve Manning]

Um, Steve, one question for you, when you say the could be used as an anchor, did you have in mind a traditional VA lake motorboat, or something more like the ships supported at the Suffolk Naval Base, which I believe you lived close to at one time? I mean, you might need two or three of these for a typical aircraft carrier, right?

Even though we will have a pair of them they might be a tad small for an aircraft carrier.

[theSven]

Mmm...love me some CSS subwoofers! How many did you get?

2 for this project.

[Steve Manning]

Well as Sven alluded to, we have some pictures of the intended design.

At this point I'm looking at the external cabinet being bamboo with the internal bracing Baltic Birch.

[JonMarsh]

Does CSS provide for having a bracing support at the rear of the magnet assembly?

[technodanvan]

Does CSS provide for having a bracing support at the rear of the magnet assembly?

Not unless they updated the SDX12 since I got mine. Judging from the pics Sven posted I'm thinking no such updates have been implemented.

[Steve Manning]

Does CSS provide for having a bracing support at the rear of the magnet assembly?

What are you thinking it should be supported?

[technodanvan]

He has a sub...maybe it was a Peerless?...that is a fair bit heavier than the SDX12 and has some bolt holes on the rear to brace the frame and support the magnet with the cabinet.

[Steve Manning]

Materials have started arriving for the subs as well as a couple of other projects.

Some 18mm Baltic Birch ......



As well as some 1/2" & 3/4" moisture resistant MDF

[theSven]

This is going to be a fun project with images of the pieces being machined on the CNC!

[Steve Manning]

Well with some nice weather for a change I got the shop opened up and made some sawdust.



Initial break down of the full sheets I did with the track saw




Was then able to break down into finial size parts with the table saw.





These pieces will be glued into 3 layer slabs for machining.

Also got additional material delivered ..... pin block maple and some bamboo.

[JonMarsh]

I'm jealous of Steve's shop and this project for Sven- I have one or two of the CSS SDX10, but the SDX12 is a monster of an achievement IMO, and I am in a very Dickens sort of mood for this project- "Great Expectations"

[Steve Manning]

Performing what Jon calls slow work ..... turning heavy boards into very heavy boards.

Making 2 1/4" thick slabs for the cabinet side panels.

[JonMarsh]

Performing what Jon calls slow work ..... turning heavy boards into very heavy boards.

One of my favorite things to contemplate!

[theSven]

This is exciting to see the wood start to take shape and sawdust to follow in due time. Will these go onto the CNC for shaping?

[Steve Manning]

This is exciting to see the wood start to take shape and sawdust to follow in due time. Will these go onto the CNC for shaping?

Yep, these will be shaped on the CNC

This roughing pass will take around 15 minutes



This finishing pass around 30 minutes. What appears to be a solid blue are actually lines 0.050" apart.



Hopefully we end up with something that looks like this.

[Steve Manning]

With the weather being nice, I opened up the shop doors and got some chips flying.

Started machining some of the side panels. This is roughing out the curved profile





After the finishing pass was completed



With the exception of removing the tabs, a finished panel.

[theSven]

That panel came out great! How much does it weigh? I find that becoming one of my favorite questions for the builds. That way I can keep training at the gym to make sure I can lift these cabinets 😂. I'm also curious how long it took to make the panel, <6 hours? I imagine all the back and forth at a slower speed takes time to achieve such perfection.

[Steve Manning]

That panel came out great! How much does it weigh? I find that becoming one of my favorite questions for the builds. That way I can keep training at the gym to make sure I can lift these cabinets 😂. I'm also curious how long it took to make the panel, <6 hours? I imagine all the back and forth at a slower speed takes time to achieve such perfection.

I'll have to pull out the scales and see. Though I expect these subs will be giving you CC a run for the money!

As for machine time, not too bad. Actual cutting time was about an hour. It's the setup, tool changes and what not that adds a bunch extra to the process. Having an automatic tool changer would be a game changer for something like this .... one can but dream.

[Steve Manning]

Well to answer the question, the blank panels weigh just over 26lbs each ..... yep these will be stout!

Progress continues despite life's alternative ideas. The two side blank panels are machined for both subs and one of the front baffles came off the CNC this afternoon. I plan on doing a test fit with the woofer tomorrow.

I had taken a picture of all 4 panels but for some reason it was blank when I looked at it.



The front baffle ....

[letiennam]

I guess the finished product weighs more than me. The side walls are so thick, they're going to be very sturdy

[JonMarsh]

"Sturdy".... a true understatement!

"Beautiful" is another word that comes to mind...

Of course, beautiful is as beautiful does, and this CSS 12" driver is a beaut!

Moving them around will not be trivial... something I'm thinking about more with current and pending projects.

[theSven]

I'm thinking furniture blankets, dolly with air tires, straps, and pads to move these cabinets around... Install the woofer after the cabinets make it to the theater room. I'm very much looking forward to having bass for the movies again later this year.

[Steve Manning]

Well things hit a bit of a speed bump when I test fit the woofer into the baffle. It didn't fit .... at all! I've found over time that for the most part drivers match manufactures drawings reasonably well. Any issues I find is in the required depth for the flange to fit flush. I checked that since I have the drivers on hand and adjusted the CAD and CAM files accordingly. Well imagine my surprise when I discovered the driver was too large in diameter, by 3/16"!!!!

So .... most of Friday was spent trying to figure what happened and if I could salvage the baffle which had turned out rather nice. What I discovered was CSS Audio has updated their SDX12 drivers, but not the drawings to go with them.

The pictures on both CSS and Parts Express reflect the older model ....



This is what's shipping now .....




After determining what happened I looked into how to fix it. My conclusion due to the fact that the baffle is curved as well as having a radius on the edge of the driver opening is that I will have to make a new baffle.

So for those looking at buying any CSS drivers be aware their drawings are questionable!

[theSven]

How do we get feedback to the manufacturer to update their info? That is frustrating and makes a few four letter words come to mind.

[Steve Manning]

How do we get feedback to the manufacturer to update their info? That is frustrating and makes a few four letter words come to mind.

I contacted CSS Audio via email and they said they were working on the drawings. Of course one has to wonder how you modify the driver without already having an updated drawing? Next time your out in Michigan you should stop by and give them a WTF!

I plan on sending an email to PE to let them know they should put a warning up on their site letting folks know the CSS drawings are screwed up.

[Steve Manning]

Email sent to PE.

[JonMarsh]

How do we get feedback to the manufacturer to update their info? That is frustrating and makes a few four letter words come to mind.

Only a few?

Well, this has happened to me in the far past, so I pretty much always have a habit of working off my own measurements of the drivers (in more ways than one) but one really ought to be able to work from the published data...

[theSven]

Trying to be modest and professional in the responses... Of course I had to re-type that response multiple times to be constructive.

[Steve Manning]

Well I contacted PE and heard back from them this morning. They were unaware of the issue and will be updating the website.

[Steve Manning]

After putting the baffle issue aside for a few days and working on other things, like starting on drawings for Jim's Ardent D build, I let the back of the noggin chew on the problem to see if I could come up with anything.

Following the mantra of not throwing away your cutoffs until the project is finished, I was able to use some scrap material to establish more or less a new reference location for the CNC to work from.

Cutting a piece 2" wide and setting the baffle against it I was able to define my reference location in 3 axis just as I did before making the original cuts.









I was able to get lucky enough to be within a few thousandth of an inch and was able to mill out the required material for a nice fit of the woofer.

[theSven]

Steve Manning That is some true engineering work there to make the baffle wider without having to redo the whole panel! I'm glad that PE is updating their site to let customers know too. Sounds like marketing got ahead of product at CSS and pushed product to fast. That's a common problem in my world with software vendors.

[JonMarsh]

Bravo, bravo!!

[Steve Manning]

Thanks gents .... a small update .... had to put a 30 degree bevel on the sides of all the panels. Somebody thought it would be fun to add all these crazy angles?

[JonMarsh]

Thanks gents .... a small update .... had to put a 30 degree bevel on the sides of all the panels. Somebody thought it would be fun to add all these crazy angles?

Was that your idea or Steves? If you had four sides, it would hae been easier- but not as neat looking!

[JonMarsh]

Well things hit a bit of a speed bump when I test fit the woofer into the baffle. It didn't fit .... at all! I've found over time that for the most part drivers match manufactures drawings reasonably well. Any issues I find is in the required depth for the flange to fit flush. I checked that since I have the drivers on hand and adjusted the CAD and CAM files accordingly. Well imagine my surprise when I discovered the driver was too large in diameter, by 3/16"!!!!

So .... most of Friday was spent trying to figure what happened and if I could salvage the baffle which had turned out rather nice. What I discovered was CSS Audio has updated their SDX12 drivers, but not the drawings to go with them.

The pictures on both CSS and Parts Express reflect the older model ....



This is what's shipping now .....




After determining what happened I looked into how to fix it. My conclusion due to the fact that the baffle is curved as well as having a radius on the edge of the driver opening is that I will have to make a new baffle.

So for those looking at buying any CSS drivers be aware their drawings are questionable!

I still think this is a really great looking driver, and well designed for the application. too bad about details like this creating problems

[Steve Manning]

Things are underway for the next phase of the build ..... internal bracing. Got the CAM files done over the last few days and got some Baltic Birch cut today for machining parts.





This stuff is a lot easier to move around compared to that MDF!

On a side note, I thought it might make sense to mount the cabinet feet using 3/8-16 bolts rather than the typical 1/4-20. I put in an order to Rampa and was rather shocked at the size of their 3/8-16 inserts compared to the EZ Lock inserts I've used in the past. Case in point ....

[theSven]

Those are some nice looking inserts that look like it will not strip out getting put in. Good find on that brand and I hope they install like butter, melt in smooth.

[JonMarsh]

Rampa are my favorite, but then my normal use case isn't typical either. I'm using either M4 or M6, depending on the application. Bought lots of them. Size the entry hole correctly, and they install well, lock in solid, and no guessing about the correct depth, due to the lip design.

But, you won't find them at a big box store.

But then, there's a lot of good stuff you won't find at a big box store...

[Steve Manning]

Had a productive day machining internal Baltic Birch brace parts.













I'll need to do a little sanding on the parts to knock off some fuzz on the edges.

[JonMarsh]

Slick! Great progress!

[Steve Manning]

Well to go along with those new threaded inserts, I ordered some feet to match what Sven has on his center channel.







These beasties weigh over pound each!

[Steve Manning]

Work has also been progressing on the internal bracing.

There has been a considerable amount of time marking locations for mortises for the loose tenon joints.









Once all the mortise were cut it was time for a dry fit.













Got lucky and everything fit as intended and is pretty much nice and square.

A few more pieces to add both top and bottom for completion. Looks like each brace assembly has 51 domino's when all is said and done. Looks like I need to put in an order for some more.

[theSven]

This is really taking shape now! The excitement keeps building as the build progresses.

[JonMarsh]

Work has also been progressing on the internal bracing.

There has been a considerable amount of time marking locations for mortises for the loose tenon joints.









Once all the mortise were cut it was time for a dry fit.













Got lucky and everything fit as intended and is pretty much nice and square.

A few more pieces to add both top and bottom for completion. Looks like each brace assembly has 51 domino's when all is said and done. Looks like I need to put in an order for some more.

That's why I always order extra on small important bits, like threaded inserts!


looking real good, Steve!