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MFW-15 sealed (x4) - Page 2

post #31 of 102
4/21/12 at 10:47am
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BK 5000 series II five channel amp rated at 145 into four ohms, one channel per box.
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post #32 of 102
4/21/12 at 12:23pm
Looks like, what, about 2.5 cubes per box internal? Total guestimate. I'd throw some pillows in there; 145RMS each ain't much. In a 3 cubes sealed box with 225RMS, that driver doesn't reach xmax until 7hz, iirc.
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post #33 of 102
4/21/12 at 3:53pm
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Just a hair over 4.1 cubic ft without accounting for the space taken by the driver. I modeled it with WinISD and came up with 3.5 ft^3 as about optimum, considering the power I'm throwing at them. Using actual volume, WinISD says xMax at 25hz (assuming 84300 Pa air pressure in Albuquerque).
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post #34 of 102
4/21/12 at 3:54pm
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Day Four.
Stack of baffles cut out of the Chinese birch plywood.

 

IMG_0302.jpg


Edited by petew - 6/16/12 at 12:16pm
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post #35 of 102
4/21/12 at 3:55pm
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We've got voids. This ain't Baltic birch!

 

IMG_0303.jpg


Edited by petew - 6/16/12 at 12:17pm
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post #36 of 102
4/21/12 at 3:56pm
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Set up to route the hole for the terminal cup. I've never used the Jasper jig before. Note safety gear.

 

IMG_0304.jpg


Edited by petew - 6/16/12 at 12:17pm
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post #37 of 102
4/21/12 at 3:56pm
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Closeup showing the locating pin for the Jasper jig.

 

IMG_0305.jpg


Edited by petew - 6/16/12 at 12:18pm
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post #38 of 102
4/21/12 at 3:58pm
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I drilled the pilot hole with an 1/8" brad point bit. I just loosened the drill chuck and left the bit in the hole to act as the pin. The screw keeps the cutoff piece from breaking loose and spinning.

 

IMG_0311.jpg


Edited by petew - 6/16/12 at 12:18pm
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post #39 of 102
4/21/12 at 3:59pm
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I clamped a piece of a solid core door to the table saw to back up the router cuts. The plywood scraps hold the baffle in place, with one clamp in the corner for insurance.

 

IMG_0313.jpg


Edited by petew - 6/16/12 at 12:19pm
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post #40 of 102
4/21/12 at 4:00pm
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Now for the front baffles. First find the center of the panel.

 

IMG_0307.jpg


Edited by petew - 6/16/12 at 12:20pm
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post #41 of 102
4/21/12 at 4:01pm
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Then strike lines perpendicular to the edges and running through the center.

 

IMG_0314.jpg


Edited by petew - 6/16/12 at 12:20pm
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post #42 of 102
4/21/12 at 4:02pm
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Align the driver with the center lines and mark all eight holes.

 

IMG_0315.jpg


Edited by petew - 6/16/12 at 12:21pm
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post #43 of 102
4/21/12 at 4:02pm
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Routing out the hole. Two drywall screws hold the cutoff this time.

 

IMG_0316.jpg


Edited by petew - 6/16/12 at 12:21pm
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post #44 of 102
4/21/12 at 4:04pm
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Test fit. It Fits! I didn't take a pic of drilling the mounting holes. I just drilled 1/4" holes on the marks I made earlier. I'll press (and glue) tee nuts into the baffles later.

 

IMG_0317.jpg


Edited by petew - 6/16/12 at 12:22pm
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post #45 of 102
4/21/12 at 4:04pm
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Everything is cut. Tanner thinks he should get dinner but it's too early. Tanner always wants something to eat.

 

IMG_0318.jpg


Edited by petew - 6/16/12 at 12:22pm
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post #46 of 102
4/21/12 at 5:09pm
Quote:
Originally Posted by petew View Post

Everything is cut. Tanner thinks he should get dinner but it's too early. Tanner always wants something to eat.

Is that Tanner's "Dogcave" under the workbench?
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post #47 of 102
4/21/12 at 5:19pm
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edited - the link in the previous post got broken by blu-ray dot com.  Apparently they killed any pictures on their site that were referenced from avsforum.

 

Yup that's the dogcave. You can see the "chin mark" on the bottom of the door. Bentley's cave is under the other end of the bench.


Edited by petew - 12/16/12 at 7:14am
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post #48 of 102
4/21/12 at 5:42pm
Always nice to read a well documented build. Especially when the builder has time to actually work through the project.

Thanks for sharing.
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post #49 of 102
4/21/12 at 6:59pm
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One more this evening. I pressed all the tee nuts into the baffles. Hopefully the adhesive will hold.  

 

**update 6/16/12 - the tee nuts from Home Depot are crap and the barbs snapped off on two when I installed the drivers.  Lesson 1: use better quality hardware from Parts Express.  Lesson 2: Locktite Power Grab is not that good.  Use PL Premium, or Gorilla polyurethane glue instead.

 

IMG_0323.jpg

 

IMG_0324.jpg

And now for a...


Edited by petew - 6/16/12 at 12:26pm
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post #50 of 102
4/22/12 at 9:08pm
Quote:
Originally Posted by petew View Post

Just a hair over 4.1 cubic ft without accounting for the space taken by the driver. I modeled it with WinISD and came up with 3.5 ft^3 as about optimum, considering the power I'm throwing at them. Using actual volume, WinISD says xMax at 25hz (assuming 84300 Pa air pressure in Albuquerque).

Very cool. They looked significantly smaller with the driver situated in them, and not a cube from the photo perspectives, so I was thinking it was 20x20x15. I'm glad I was totally off.

With that high frequency of an xmax at full tilt, are you planning on applying a HPF in the 20s? What's your objective, response and extension-wise?
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post #51 of 102
4/23/12 at 5:16am
Thread Starter 
I think I'll install some blocks to decrease volume some and bring xmax down to about 20hz. What is a good number to use for the volume of the driver?

I hope to EQ relatively flat down to the low twenties. I have a Behringer BFD but I really want to get a miniDSP.
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post #52 of 102
4/24/12 at 7:22am
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Clean up the rabbit joints. I started with the palm sander but ended up using the belt sander.

 

IMG_0334.jpg


Edited by petew - 6/16/12 at 12:26pm
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post #53 of 102
4/24/12 at 7:23am
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Roundover.

 

IMG_0336.jpg


Next up - gluing the front and rear baffles in place.


Edited by petew - 6/16/12 at 12:27pm
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post #54 of 102
5/15/12 at 8:31am
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Here's the baffles being glued on. I did both back and front at the same time.

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post #55 of 102
5/15/12 at 8:33am
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Closeup showing how the baffle relates to the corner braces. The screws that hold the driver just clear the braces (that was luck, not planning).
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post #56 of 102
5/15/12 at 8:43am
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I marked the back baffle and applied a liberal helping of glue. Then set the box down on the baffle. More glue to the box for the top baffle, then align everything and clamp 'er down. I cleaned up the excess glue with water and a sponge.
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post #57 of 102
5/15/12 at 8:44am
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I guess I forgot to shoot pics of running a router with a flush trim bit around the baffles to cut them flush to the sides. After that I sanded the boxes with 100 grit paper on the orbital sander.
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post #58 of 102
5/15/12 at 8:45am
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I applied some simple feet to the subs to hold me over until I decide how to finish the subs. I didn't want to scrape up the cabinet bottoms.

The plywood piece is my gauge block to help me get things placed consistently.
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post #59 of 102
5/15/12 at 8:48am
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I soldered the wires to the terminal cups. Then crimped on the lug connectors for the speaker. The terminal cups get attached with coarse thread screws.

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post #60 of 102
5/15/12 at 8:50am
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I ran the machine screws into the tee nuts to be sure they were clear of glue and crud.

In spite of doing that, I still spun out two tee nuts. The tee nuts were really thin and the barbs snapped right off. Note to self, buy better quality hardware next time.
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