# Quartet 12 kit as tower rather than cube?



## jznack

Hello, I'm looking for some input on redoing a CSS Quartet 12 kit: http://www.creativesound.ca/pdf/Quartet12B_Subwoofer_Kit.pdf.

Back story. A couple years ago I got the kit from CSS. It includes a Trio 12 driver and 2 APR 12 passive resonators. The kit is meant to go into a 20" cube. It was my first build and it went alright, but due to time/money constraints I never got around to finishing it the way I wanted. It sounds fine, but it ain't pretty. Now that I have the time and money (and a little more skill) I would like to make a new box from scratch rather than trying to make a silk purse out of a sow's ear, as they say.

Here is a diagram of the home theater area which recently underwent a bit of a transformation. Re-arranged the layout, new seating, new AVR, new Axiom speakers, wall mounted the TV. The last piece of the puzzle is redoing the sub.


































You can see the existing sub build in all it's glory. It currently lives in front of the door on the right.

One of the possible designs I've thought of to help the wife acceptance factor is to make a taller, but more slender tower rather than a big cube. Front facing driver with PR above and below it on the front face. I emailed Bob at CSS to ask his opinion and he said it has been done, but some people don't care for it and to check these forums for more feed back. So here I am. I haven't been able to find anything one way or another. 

Couple questions...

Will the PRs still work properly in this configuration since they are no longer opposed?
Will there be any stability issues with it being taller?
Will it sound worse?

I'd appreciate any and all insights into this. Thank you in advance.

If it's not feasible I still plan on redoing the box, but this time flush mounting the speakers and doing something slightly more artistic/aesthetic.


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## ngjockey

Why not. Don't think you have to worry about the PR's being 180 degrees out of phase because the cabinet has a time delay. Just make them very heavy and consider a plinth or base at the bottom. Like concrete or concrete board or something like that.


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## Mike P.

The PR's will work whether they are opposed or not and it will sound the same. Depending on how high the cabinet is there may be a stability issue, but as mentioned above, nothing that a heavy base can't remedy.


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## jznack

Thanks for the replies thus far. 

Alright, that kind of eliminates the first obstacle. The next is actually designing the thing. 

I plan on using Baltic birch plywood rather than MDF. I used Baltic birch for the current cube and was happy with it, though it did chip a bit when routing. I blame the bit for that though. 

I plan on using 3/4" for the box and then 5/8" for the flush mount cladding on the front. I'm sure I can come up with something to use for the plinth.

For the speaker grills I might try to ape the design of the axioms and use magnets to affix just to keep the look consistent with the other 
speakers. 

For the finish I plan on using a walnut veneer and a dark stain.


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## Mike P.

Sounds good. Just make sure the internal net volume is the same as the original design.


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## jznack

What if the internal volume is a bit larger? Say 110ish instead of the 92 of the recommended cube?

Playing around with some drawings and the enclosure calculator I was thinking 48" tall, 16" wide, and 14" depth I get 110ish.

If I cut it down to the minimums to allow the drivers and amp to just fit (44" tall, 15" wide, 14" deep) I can hit 92.


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## ngjockey

Oh, that's why not.


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## Mike P.

Don't go bigger or you may have issues with the driver bottoming out.


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## jznack

I suppose I could eat up more of the interior space with bracing and bottom weight. 

I can also probably reduce the depth since I think the PRs are a lot shallower than the driver itself. The amp box could line up with one of the PRs rather than directly behind the driver. 

I'll keep playing with it and see if I can get it nailed down at 92 liters net. 

By the way, is there any decent software that will let me play around with box shape graphically? 

I'm still really new at this. I've researched a lot, but still pretty clueless. 

Thanks again for all the help. Really appreciate it.


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## Mike P.

The only box designing I use is the one in my signature, not sure if there's a graphic one out there.


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## ngjockey

http://www.sketchup.com/

It's free.


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## Mike P.

ngjockey said:


> http://www.sketchup.com/
> 
> It's free.


Duh, I knew that. :innocent:


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## jznack

So I'm using the enclosure calculator and sketch up to nail down the design and I'm pretty close.

However, I have one unknown variable, and that's the volume of driver parameter. The difference between 0.1 and 0.2 cubic feet has a pretty substantial impact on the total internal volume.

I've looked, but have been unable to find the volume of the TRIO12 or the APR12. So I'm guesstimating 0.1 x 3. 

There is also the question of the built in SPA500 amp, which I would guess takes up more volume than the driver itself. I can't recall if it is completely sealed or not, so I can't just assume that it's taking up the full 12"x12"x6" of space. Would it be fair to include it as an additional driver?



















I'll put up a sketch up image shortly.


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## jznack

As you can see it's a little tight in there for bracing. I was originally using a single brace going down the center with 6 cut outs in a 2x3 grid. This likely wouldn't work at the bottom due to the closeness of the bottom PR to the amp box. Therefore, I'm thinking of doing a T style brace that would occupy the top 2/3rds. The actual design of the brace will depend on how much volume I have left to fill up once I know what the driver, PRs, and amp will take up.

Either way it will be very close to 92 liters.

Here is the sketchup file in case anyone wants to look at it. subwoofer.skp


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## Mike P.

Contact Bob at CSS for the component displacements, he'll know. With a 12" depth and 44" height you're going to need some kind of a base to stabilize the cabinet from moving.


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## ngjockey

Got a start of an idea for bracing.


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## jznack

Thanks. Fired off an email to Bob. I'll start thinking about the plinth and ways to bottom load it for weight.

How does Axiom keep their towers weighted low and stable without a base?










That Bracing looks pretty good. I was thinking something far more basic. I don't suppose you recorded any sizing data so I could see what the volume is? Otherwise I'll get out the digital measuring tape. 










I'll sketch up what I was thinking of. See what you think.


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## jznack

subwooferbasicbracing.skp


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## ngjockey

Refined it a bit. Designed the braces 3/4" thick and 2" wide (mostly). You can reduce that to 1/2" thick and 1.5" wide. And, yes, that will take some craftmanship and tools. Maybe some rounding.


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## ngjockey

Your design would be simpler.


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## jznack

That's some seriously detailed bracing. I don't think I could pull it off. And I think it might take up too much internal volume. 

I think I will add some front projections though above and below the middle driver to link the front and back. The back spine would be about 3 inches deep, so rather than cut outs I'm thinking drill out some 1 inch holes instead. A lot simpler to build and it will take up a lot less volume.


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## jznack

Just a bit of an update. Since my shop is subzero for the winter (no heat in there) I probably won't start much construction until spring. (Unless I splurge on a furnace). So until then I will work out a detailed plan so when it warms up I will be ready to roll. 

To Do List

Finish drawing out the bracing
Draw up the outer cladding
Draw up a speaker grill
Draw up some cut sheets
Design a plinth of some sort (maybe feet?)

Maybe play around with some alternate designs, like a horizontal tower to go under the tv and center channel. 

Itemize list of materials and tools that will be needed. 

I'll try and post some more later this week.


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## BD55

A horizontal orientation would give you more stability and would mean you don't need to make a heavy plinth. It would be much simpler to make an inert/non-rocking box that way.


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## jznack

My wife may appreciate the horizontal approach as well, though she supports any plan that improves upon the ugly box, as she calls it.


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## jznack

A possible solution to the plinth/stability issue could be a set of spike outriggers like these. 










I've also gotten around to figuring out the internal volume of the components. According to Bob, the original design allocated about 12 liters for bracing and components. By figuring out and subtracting the volume of the bracing, we should be left with the volume of the components.

So if we look at the cut sheet we see this:









(I've labeled each section with a letter.)

The cutsheet assume we're using 3/4" plywood, so if we multiply the dimensions for each section we get the following:

a = 18.5*3*0.75 = 41.625
b = 18.5*3*0.75 = 41.625
c = 12.5*3*0.75 = 28.125
d = 8.875*3*0.75 = 19.96875
e = 8.875*3*0.75 = 19.96875

for a total of 151.3125 cubic inches. When we convert that to Liters we get 2.4795 L, which leaves us about 9.5 liters for the components or about 0.335 cubic feet.

When I feed that back into the enclosure calculator I get 96.548 Liters. to hit the target of 92 Liters internal volume, my bracing should occupy about 4 to 5 Liters which should be totally doable.


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## jznack

I've done some more drafting. This time on a horizontal option. I decided to change up the formula a bit. This time using 1" thick ply and booting the depth from 12 inch to 14 inches.

















































Sketchup file


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## BD55

I hope someone with more practical experience will chime in here, but I think you may have a problem with the small size of the holes in the bracing allowing enough air movement between the driver and PRs.


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## Mike P.

Agreed. 2 inch wide frames is all you need.


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## jznack

Good to know. I was really trying to eat up some internal volume there to get down to 92 liters, hense the 3 inch wide frames. 

I think I will be taking another crack at the vertical tower drawing. I'll try and reduce the height and increase the depth a bit to improve stability. I'll stick to 3/4" as well. 

On a different topic, does anyone have any experience using hide glue in speaker/sub construction?


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## BD55

Another option would be to leave more open space with bracing but close off volume rather than eat at the displacement with thicker bracing like so:









Where the black striped region is a panel closing off that triangular volume.


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## jznack

That's not a bad idea at all. Thanks for the tip.


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## Mike P.

What is hide glue?


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## jznack

Hide glue is made from animal hides.

http://en.wikipedia.org/wiki/Animal_glue

http://www.leevalley.com/us/newsletters/Woodworking/4/6/article2.htm

It's used a lot in furniture making and veneering.


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## Mike P.

Elmers wood glue would be my first choice. That I personally know is excellent for cabinet building.


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## jznack

I actually used Elmers on the first cube cabinet and had no complaints. 

I considered hide glue after researching the building of a Cajon box drum for a drummer friend of mine. Something like this. 










I'm actually kind of liking that finish for the sub itself. And the form factor of it gives me an idea for a tall cube rather than the tall rectangle I've been drawing up thus far.

Hide glue is often used in instrument construction (string instruments, drums, etc) due to having a flexible quality and a tightening effect as it dries and shrinks, pulling the joints together. You can also rework the glue through reheating and cooling.

I figured if it was good enough for a bass drum, that it might be good enough for a bass box. I do wonder though what a strong shock from a sharp bass note would do to it. An open fronted bass drum is going to contend with much different pressures than a sealed subwoofer. A glue and screw would probably be enough to counteract any joint fragility.

Even if I didn't use it for the joints themselves I'd still use it to laminate the outer cladding for the flush mounting and for any veneering.


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## jznack




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## BD55

I think you have a really good idea here. Another configuration (if the driver can handle vertical orientation) you could maybe toy with is down-firing driver with the PRs in the same config. That would give the best configuration from a stability standpoint alone. Not saying I don't like what you've come up with, on the contrary I think it would look great; I just had the thought and wanted to share it.


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## Creative Sound

The driver will work fine down firing.

Carry on.


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## jznack

Actually down firing could be a great option. To flush mount it I would be adding another layer of ply anyway, so that would help push the weight distribution lower as well. The PRs could be set low on the sides as well. 

Alternately, I could front mount both PRs and add a single magnetic grill cover to the front. That could look pretty slick too. 

One thing to check would be for spike placement and whether I could still use a spike outrigger. I don't think there would be any clearance issues. The driver is about 13" giving an inch and a half on either side. I can't find the width of the outriggers, I'll have to fire them an email. They look like they should be able to flank the driver though. Even it they overhung the edge a little bit I think it would probably add to the design.


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## jznack

Maybe a classy bass monolith.


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## Mike P.

If that's your bedroom then you need a serious sub upgrade. :bigsmile:


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## jznack

Sketchup File

Just need outriggers, and cladding.


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## jznack

So I think I'm pretty happy with the design now. I spent some time redoing pretty much everything from scratch just to make sure everything fit properly and that measurements were accurate.

I added the cladding and all the cut outs for the drivers, so it's pretty much ready to turn into a cut sheet. 

The cladding is 1/4 inch on the sides, back and top, and 5/8" on the front and bottom to flush mount the drivers.

I'm still waiting on hearing from the outrigger retailer on dimensions, so I just made a guesstimate. It may be tight around the driver under there.

The grill is pretty close to what I envisioned. It's going to take some more work to build out the frame and get the shape right. I'll also mark out where the magnets will be embedded.

I re-did the bracing entirely and came up with something so simple it might be too stupid. It's basically just 3 squares making a big plus sign. The internal volume works out perfectly with it too.

Here's the sketchup file for those following along.

And a bunch of pictures showing the final design. Other than a few refinements, I think it's done.


































































Thanks again to everyone that has been helping out. With your good ideas and guidance I might actually be able to pull this off. :clap:


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## Mike P.

The bracing is simply and effective, exactly what you need.


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## ngjockey

Never done a down-firing sub but would think you need more space than that underneath.


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## Mike P.

Excellent point. You could get away with 2 inches minimum, 3 inches would be better.


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## jznack

The spikes are 2" long, the outriggers are 1/4" thick, the spikes will sink into the carpet a bit, maybe 3/4". The driver being flush with the base it will be about 1.5" above the carpet. 

If I added on to the base to lift it up another 1.5" would I be at risk of boxing in the driver? Would it suffer from being recessed?

I could limit it to being spacers between the base and the outriggers only. That would leave the front and back open. 

Are there any other trade offs or limitations to doing a down firing setup?


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## Mike P.

There's no problem with the driver being recessed, it's a great idea to give you the required height.


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## Cleaner

Subscribed! Looking forward to this build.


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## steve nn

Subscribed to this one!


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## jznack

Quick update. I've still been playing around with the dimensions a bit to try and make it look a bit sleeker. Taller and more slender basically. It's about 3.5 feet tall and 14 1/4 inches on all sides.










Still working on the plinth. The goal will be to make it appear to be floating above the plinth. 

Still playing with the placement of the PRs. Both on the front, or one on either side either at the top or the bottom.


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