Making my dad a surprise sub/present and could use some input. - Page 2 - AVS Forum
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post #31 of 39 Old 05-03-2013, 09:32 AM - Thread Starter
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Originally Posted by lennon_68 View Post

Yeah, I think it's well within reason. Looking at the PE page for the Bash 300W (in the Q&A section) I found that the amp has a high pass at 17.7hz. They weren't sure what order it was but even if it's 1st order it looks pretty good. Dual 3" ports at 20" each would be better but that's a lot of extra volume.

Ok so I wasn't too far off saying 15hz. The 17.7 will work just fine for this setup I think. Should I do dual 3's? How much bigger do I need to make the internal volume to compensate for the volume displaced by the ports?
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post #32 of 39 Old 05-03-2013, 09:57 AM
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Originally Posted by skeeter99 View Post

Ok so I wasn't too far off saying 15hz. The 17.7 will work just fine for this setup I think. Should I do dual 3's? How much bigger do I need to make the internal volume to compensate for the volume displaced by the ports?

Ignore what I said about extra volume, the dual 3" ports don't really take up that much more volume... Just using the internal volume of the ports the single 4" port would be .12 cuft and the dual 3" ports (@20" long) would be .16 cuft. That's not really accurate though you'd need the external diameter to get the real volume displaced.
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post #33 of 39 Old 05-03-2013, 10:00 AM - Thread Starter
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Originally Posted by lennon_68 View Post

Ignore what I said about extra volume, the dual 3" ports don't really take up that much more volume... Just using the internal volume of the ports the single 4" port would be .12 cuft and the dual 3" ports (@20" long) would be .16 cuft. That's not really accurate though you'd need the external diameter to get the real volume displaced.

Ok just wanted to make sure. So basically 4.25" cubic feet. I'll get some 3" pipes and get-er-done! Thanks for the help! UPS has the package out for delivery now to my house so it should be on the front porch when I get home. We'll see if I get any building done this weekend though. Its supposed to be high 70's, low 80's here which will be the nicest its been all year. Pretty sure I'm gonna have to be outside most of the weekend smile.gif

Scott
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post #34 of 39 Old 05-03-2013, 12:57 PM
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Originally Posted by skeeter99 View Post

Ok just wanted to make sure. So basically 4.25" cubic feet. I'll get some 3" pipes and get-er-done! Thanks for the help! UPS has the package out for delivery now to my house so it should be on the front porch when I get home. We'll see if I get any building done this weekend though. Its supposed to be high 70's, low 80's here which will be the nicest its been all year. Pretty sure I'm gonna have to be outside most of the weekend smile.gif

Scott

Yes 4.25 ft3 with a pair of 3" x 20" ports or a single 4" x 17" port. The 3" ports will have about 3 m/s lower port velocity. Tuning point is 20hz..
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post #35 of 39 Old 05-03-2013, 01:51 PM - Thread Starter
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Yes 4.25 ft3 with a pair of 3" x 20" ports or a single 4" x 17" port. The 3" ports will have about 3 m/s lower port velocity. Tuning point is 20hz..

Perfect, that sounds exactly what I want to do (with the dual 3"). Maybe I'll play around in Sketchup this weekend for the first time and try to get the cabinet drawn out on there ...

Thanks for all the help, I'll update once I have more info!

Scott
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post #36 of 39 Old 05-17-2013, 07:19 PM - Thread Starter
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Ok I'm going to start cutting tomorrow, finally! I'm building the bottom which will house the driver and the dual 3" ports as a double baffle. I came up with 16" W x 24" deep x 24.75" tall (to account for the double .75" bottom baffle) to get the 4.75 ft^3 required. Here's what I came up with for my cut list:

Front and Back: 16" wide x 24.75" tall
Sides: 22.5" deep x 22.5" tall (I'm fully insetting both sides)
Top and Bottom: 16" wide x 22.5" deep plus 1 extra panel on the bottom so three total panels in this config
Base: 16" wide x 22.5" deep

I'm building the standard box with the sub and ports firing down with the plate amp on the back. I'll build 3" stands to set the main box up off the base. How do the cuts look? Once I get them done putting the actual box together goes pretty quick.

Thanks for all the help!

Scott
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post #37 of 39 Old 05-20-2013, 09:27 AM - Thread Starter
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Got all the panels cut and the box all put together except the baffle for the driver and ports. I glued it up so its 1-1/2" as I wanted to have plenty of meat for the driver to bolt to. I'm not using wood screws, I'm going to glue in some nice T-Nuts and bolt that sucker in there. No chance it'll come out! Gonna walk across the street to Lowes at lunch and pick up the nuts and bolts. Tonight is my son's 11th bday so I probably won't be able to get anything done tonight but hopefully by the end of the week it'll be up and running!

Scott
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post #38 of 39 Old 05-20-2013, 10:37 AM
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Originally Posted by skeeter99 View Post

Got all the panels cut and the box all put together except the baffle for the driver and ports. I glued it up so its 1-1/2" as I wanted to have plenty of meat for the driver to bolt to. I'm not using wood screws, I'm going to glue in some nice T-Nuts and bolt that sucker in there. No chance it'll come out! Gonna walk across the street to Lowes at lunch and pick up the nuts and bolts. Tonight is my son's 11th bday so I probably won't be able to get anything done tonight but hopefully by the end of the week it'll be up and running!

Scott

I was wondering how this was going. Sounds like it's coming together finally. Any build pics? How was the build process (run into any snags)?
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post #39 of 39 Old 05-20-2013, 11:27 AM - Thread Starter
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I did run into a couple little snags yesterday as I was cutting out the driver relief. I did my outside measurement of the driver starting at the 1" mark on the tape measure (so I didn't have to worry about the clip adding in anything) then measured all the way to the other side and read it at 13-1/2". I think to myself, that seem big for a 12" driver but oh well so I wrote it down as the outside cutout relief diameter to be 13-1/2" NOT the 12-1/2" it should have been. Here's the result:



Well since its firing down you won't be able to see it at all so I'm not too concerned about it. Then as I'm doing the cut through with my Jasper Jig I realize that my 1/4" bit isn't long enough with the throw of my Bosch plunge router because of the 1-1/2" baffle. DOH! I had already made a couple passes so I had a pretty good mark of where the cutout needed to be so I drilled a pilot hole with the drill press and used my jig saw and had no problems at that point. The cut came out very well and the driver fits in there perfectly.



Time to go walk over to Lowes now and get some hardware!

Scott
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