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Discussion Starter · #1 · (Edited)
Single 8" in vented cabinet - Finished!

About halfway done with this one - the box is together and the components work, so all that's left is the finishing. It's a single 8" Dayton QT210-4 in a 40-litre box, tuned at 35 hz. I'm working with ⅝" particle board.

The optimal box size for this driver works well for me. The sharp cut-off below 35 is what I want - this isn't going to be a room-shaker, I just want it to fill in below where my 5" mains leave off. They're self-powered, so I went with a self-powered sub as well.

At 20" high (plus the 1¼" from the particle board), it just fits under my desk. I went with four vents instead of just one for aesthetic reasons. Does anyone think I'm going to need cross-bracing for 100 watts?

The current finishing plans are to round off the corners and then paint it black to match the mains. I've been testing on scraps to work out how to get the finish to look good, I suspect it's going to involve a lot of filling and sanding.

I don't have a measurement mic handy, but by ear, it sounds about how the plot predicted. Lots of power between 60 and 40, and then it's almost gone by 30. It fits in quite nicely with my mains, and manages to hide under my desk in the process.
 

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Are all of the walls doubled up with the 5/8" PBoard? If so I wouldn't see a need for much bracing. If it were my build, and all the walls were 1 1/4", I would just throw mabey two 1" dowel rod braces in there attached to each side wall. Even with the enclosure glued up it could still easily be done by drilling 4 holes to attach the braces to the walls with wood screws, and try to squeez a little glue in between if you want for added measure. The screw heads will be covered by your enclosures finish, especially if they are countersunk, and filled. Be sure to pre-drill the holes in the dowels if you go that route as well. This will prevent them from splitting when the screws go in. Hope this helps, and its a good looking little sub so far! :D
 

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Discussion Starter · #5 ·
The port tubes are "1½ inch" schedule 40 drain pipe, which has an actual ID of 1.6". They each project into the box 9¾", for a total length of 10¾. I've attached a diagram of all the relevant measurements.

All the sides are single sheets of particle board, the only place where they're double-thickness is where the ports attach to the box. I'll have to do some thinking on how to cross-brace, if you're suggesting dowel braces for a double-thick box, that sounds to me like a single-thick box would need a full brace or two.
 

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Discussion Starter · #7 ·
Indeed it is the Dayton. It's the 100-watt version, which is underpowered for the driver (which maxes out at 150 watts RMS), but seemed to be the best match I could find. While testing, I don't think I ever turned it up over half, and it's currently sitting at about 1/4 power.

WinISD gave the airspeed through the vents at a max of mach 0.02. I suppose I could have used 2" vents and lowered that even further, but then I would have needed 19" long vents in a box only 15" deep. Adding elbows and such to make them fit and keep the ends clear of the sides would have been problematic with four vents in a small box.
 

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Discussion Starter · #8 ·
Apologies for double-posting, but here's some progress. After a lot of sanding, filling, sanding, priming, sanding, and priming yet again, the first top coat is on and drying. I'm starting to see why veneer is such a popular finishing option. Here it is primed, the eventual finish will be a gloss black.
 

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Discussion Starter · #9 ·
And it's finished! I'm still not happy with how the non-rounded corners came out, my next build will definitely have a different finish on it. This was a lot of work to get even close to right. (It's by no means perfect, there are a lot of little defects when you look at it up close.) I like the chromed socket-head bolts on the back of the box, if I had a better-looking driver, I'd happily use them around the front and show it off.

It makes a cute little system with my mains, I didn't know they were going to end up the same height. All three speakers are happily hanging out at about a quarter of full power, which is plenty. My computer is running in single-digit percentages of volume output and it's a comfortable listening volume.

So... Anyone in the Seattle area have a measurement mic I can use? I'd love to see the box's frequency response.
 

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