# TRIO12 Passive Radiator Sub Build



## StillWonderingWhy (Sep 21, 2009)

After some help from Mike and others, I decided on building the CSS TRIO 12 kit for my HT. I'm following the PDF available on their site, with just a few minor modifications. Wood and time have been donated by one of my friends, and he's really helping me out through the woodworking bits.

Anyway, after waiting a few weeks, the TRIO12 finally arrived. Then after waiting a few MORE weeks for my friend with the wood shop to become available, we're finally making some progress. I'm not much of a woodworking guy, so I'm fortunate to have two friends who can help me out with this stuff. I figured you lot would like to see some of the fancy equipment we had available though, so I took a few pictures.

We're starting with 48x96" plywood here, so we started with a panel saw. A lot nicer than working through a 4 foot cut with a circular saw. The rest of the steps are pretty self explanatory looking at the pictures. We decided to change a few of the joints to change what seams would be most visible. The bottom is now fully within the side walls so that the sides won't have a joint before the bottom. The front is on top of the other sides. We used rounded corners for the bracing to add a bit of support. I'm adding pine to the inside corners to increase the surface area for gluing and insure a nice air-tight box. Other than that, it's right out of the plans.

I'm not sure if I want to stain the box or paint it. As per my original plans, I bought primer and silver paint (I have silver L/C/R speakers), but now that I can see the size of this thing I'm not sure I want a big silver box on my floor. Decisions, decisions. If anyone has pictures of a large silver subwoofer I wouldn't mind seeing them.

Hopefully I'll be wrapping up the cutting and doing the gluing and screwing on Sunday. Then I can plug this thing in and see what to expect from the finished product. :hsd: Hopefully I can get this thing working, even if it isn't painted, in time for Thanksgiving to show off a little.

That's all for now!

   

By the way, I'm not in any of these pictures. Maybe I'll do one of me and the sub when it's all done.


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## StillWonderingWhy (Sep 21, 2009)

Made some really good progress this week. Cut out the three openings for the PRs and TRIO12. No fancy jigs, just a jigsaw this time. The speakers are mounting on top of the wood so it's not necessary the cuts be exact. Built the inner brace, which will be screwed into the base and glued elsewhere. Then glued the whole thing together. Spent a few days sanding the thing down to a beautiful smoothness with 80, 100, 150, and 220 grit sandpaper, starting with a belt sander with the 80 and hand sanding the other grits. Also drilled the pilot holes for the PRs and TRIO12, so that concludes the woodworking part of this project.

I'm experimenting with stains right now, but it looks like I'll be using a mix of Minwax Puritan Pine 218 and Red Mahogany 225. I'm laying down the lighter stain first, which brings up the red just a bit. Of course I'm doing it this way because I'm working with the stains I have on hand :whistling:


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## Mike P. (Apr 6, 2007)

The cabinet is looking good. Will you be edge banding the ends of the plywood?


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## StillWonderingWhy (Sep 21, 2009)

I considered it, but it's not in the plans as things stand now. I could always add that later if I hate the look of the edges right?


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## StillWonderingWhy (Sep 21, 2009)

Here's a picture showing a sanded face, one stained with just puritan pine, and one with both puritan pine and red mahogany:
 

A view of the completed staining:
 

And after the first coat of polyurethane:
 

Unfortunately it's raining here, and the drying times are killing my progress. I mounted rubber feet onto the bottom today, and got in the right length mounting screws- black hex bolts. It should be done by the end of the week. Can't wait! :T


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## Mike P. (Apr 6, 2007)

What tuning frequency will you be going with?


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## Binary (Nov 23, 2009)

looks really nice.


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## StillWonderingWhy (Sep 21, 2009)

Mike, I'm following the CSS kit, which has a 22hz tuning frequency. I've never had a tunable sub before (either commercial or sealed) so I'm looking forward to tweaking it. Sounds like 22 should be around where I want though.

Adam, thanks for the encouragement! I'm really pleased how well it's gone for my first project.


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## StillWonderingWhy (Sep 21, 2009)

Done!

Finished the project this afternoon. After finishing up the polyurethane (3 coats) I connected the amp wires and screwed the plate onto the back. It's looking and sounding great.

I used 10 of the 45 gram washers on each PR, giving 450g of weight to each. It sounds nice so far (very tight bass with good reach compared to my other, earlier subs). I'm pleased to see the PRs get a good workout, despite being passive.

 
   

I'll post higher quality pictures (not off my phone) and some dB readings later, once I'm done "breaking it in" :hsd:


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## StillWonderingWhy (Sep 21, 2009)

Since playing the sub a bit I've run into a problem twice. During some intense bass passages (shotgun shots during the beginning of Ratatouille, canon blasts during Pirate of the Caribbean) I've bottomed out the TRIO12. One incredibly loud "pop" noise. I would think I was pushing the subwoofer too hard, but the amp is only 250 watts, and the signal gain is about 50%, with the amp at -15 dB or so. The excursion graphs lead me to believe I should be able to push this thing with all 250 watts without damaging it. What am I missing here? :help:


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## Mike P. (Apr 6, 2007)

A possibility is the amp is clipping. Which amp do you have? Also make sure there are no air leaks between the components and the cabinet.


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## StillWonderingWhy (Sep 21, 2009)

I've got the parts express #300-794. The crossover is set to around 120hz, gain at 50%, bass boost hasn't been tinkered with.

How do I check for air leaks around the components? It's all well screwed in nice and tight, but other than that I haven't taken any steps to prevent leakage.


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## Mike P. (Apr 6, 2007)

Use a closed cell weather striping to seal the sub and PR's to the cabinet. Window weather striping from a hardware store works well.The plate amp should have a gasket if memory seves me correctly.


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## StillWonderingWhy (Sep 21, 2009)

Good news. I did the leak test where you push in a driver (the screw caps on the APRs work great for this) and when I let go I could hear a whistling noise. Turns out I missed a screw on the amp. :duh: Once I put the last one in, the whistle went away. I'd say it now takes about 7-10 seconds for the driver to return to equilibrium after releasing the APRs, so it's pretty air-tight. I'll have to test the subwoofer again and see how it goes.

Mike, I saw you posted db readings from your QUARTET10 subwoofer. Around 100-105db right? I'm just curious for comparison, but would you say you can you more or less turn that up that high and get clean sound? I'd expect a little more capacity from a 12" driver compared to a 10", and I'm just wondering if I should be hearing clipping/popping at half power if everything is working well. I'll get out my db meter next time I fire it up and see if I can hit 100db cleanly, and if not, what volume the popping occurs at. _Hopefully_ putting in that last screw was all it needed.

*Update:* Indeed, correcting the leakage solved my issues! I did some light listening at 90dB and it worked perfectly! Still sounds great, I like the PR feel of the sub. Very tight sounding, but boomy when called for, and I feel it integrates smoothly into my fronts (Polk RM8000T floorstanders).


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## Mike P. (Apr 6, 2007)

Glad to hear you found the problem. Once the sub and PR's suspension loosen up a bit you should get a bit more low end output as well.


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## StillWonderingWhy (Sep 21, 2009)

Got some time to really make sure the sub is working properly now, and it definitely is :bigsmile: Went back over the movie segments that had caused the popping before and pushed it to the volumes I was expecting it to perform at the onset of the project and it handled them dutifully. Then did my standard subwoofer test, which is playing the end of the highway fight scene in Matrix Reloaded (when the two big rigs crash in super slow motion) and that sounded great as well.

So I'm completely satisfied: 10 out of 10. For $200 plus an amp I highly recommend the TRIO12. 250 watts is plenty for me, but I'm sure it works with the BASH300 even better.

And as promised, here are some nicer pictures of the box taken after I put it next to the TV.

And special thanks to Mike for all the help!


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