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Two LAB12s and PVC pipe build.
Two LAB12s and PVC pipe build.
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Old 3rd January 2017, 02:21 AM   #1
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
Default Two LAB12s and PVC pipe build.

Hi Everyone.

First I would like to thank everyone that contributes to diyAudio, and makes all this possible. I learn new things all the time.

A while back I purchased 2 LAB12s, because they seemed to be versatile and well made. They could be used in closed box, bass reflex, T-line, horns and more. I didn't really have a direction for this project, until I picked up this piece of PVC pipe that was being thrown away. Can't beat free!

The PVC pipe is 13 inch diameter x 5 feet. First I simulated a closed box then a bass reflex using Hornresp. The closed box with a driver mounted on each end looked pretty good. I think the Qtc=.69. I'm not sure how to add pictures in the middle of my post, so I will attach them at the bottom. I will post the BR images later.

I figured I would build it sealed first and listen to it for awhile before going ported. So I started cutting rings out of some MDF that I had on hand. I used a router and a Jasper jig to cut them out. I cut two rings for each side that fits inside the pipe, one ring that overlaps the end, and one ring to give the driver a flush mounted look. I used 10-24 hex head screws and T-nuts. Glued the T-nuts using gorilla glue, then chased the threads with a tap. Glued the rings together using wood glue. Then glued the rings to each end using gorilla glue.

I will split the post up so maybe it will make more sense with the pictures.

regards,
Matt
Attached Images
File Type: jpg IMG_0872.jpg (435.7 KB, 394 views)
File Type: jpg IMG_0891.jpg (748.3 KB, 392 views)
File Type: jpg IMG_0892.jpg (673.0 KB, 384 views)
File Type: jpg IMG_0895.jpg (907.9 KB, 377 views)
File Type: jpg IMG_0912.jpg (726.8 KB, 368 views)
File Type: jpg IMG_0948.jpg (668.6 KB, 123 views)
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Old 3rd January 2017, 02:37 AM   #2
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
So I asked my wife for some help getting this thing in the house, and she did, so I think she is okay with it. I put it at the front of the room, where I intend it to go when I'm finished. I was able to do impedance and frequency sweeps using DATS and REW. And here are some more pictures.

Regards,
Matt
Attached Images
File Type: jpg IMG_0976.jpg (605.5 KB, 134 views)
File Type: jpg IMG_0977.jpg (556.8 KB, 113 views)
File Type: jpg IMG_0980.jpg (692.3 KB, 166 views)
File Type: jpg IMG_0893.jpg (405.9 KB, 159 views)
File Type: jpg IMG_0913.jpg (955.7 KB, 86 views)
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Old 3rd January 2017, 03:04 AM   #3
18Hurts is offline 18Hurts  United States
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Join Date: Nov 2010
Really cool sub build,

Even cooler wife--a keeper for sure. Plan on wrapping something around the tube, the greatness of tubes is they are so easy to finish!

Nice job and am looking forward to your readings.
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Old 3rd January 2017, 03:10 AM   #4
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
Here are the Hornresp, DATS, and REW images. Hornresp is pretty amazing it even shows the increase in impedance at about 225hz same as what the DATS measured.

I only simed one driver so the enclosure volume is halved. Hornresp is new to me, so if anyone has any comments or questions please don't hesitate to let me know.

The REW image is with the mic at my seated position and the sub at the front of the room. No other subs are on and no EQ.

Regards,
Matt
Attached Images
File Type: png Hornresp image sealed Input screen.png (18.3 KB, 88 views)
File Type: png Hornresp image sealed Schematic.png (12.7 KB, 71 views)
File Type: png Hornresp image sealed Acoustical Power.png (23.5 KB, 108 views)
File Type: png Hornresp image sealed impedance.png (25.0 KB, 102 views)
File Type: jpg LAB12 PVC Pipe Sealed.jpg (257.7 KB, 70 views)
File Type: png REW In room LAB12 Sealed.png (138.4 KB, 113 views)
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Old 3rd January 2017, 03:23 AM   #5
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
Quote:
Originally Posted by 18Hurts View Post
Really cool sub build,

Even cooler wife--a keeper for sure. Plan on wrapping something around the tube, the greatness of tubes is they are so easy to finish!

Nice job and am looking forward to your readings.
Thanks. And yes she is a keeper. I plan on painting it. I have access to a spray both at a auto body shop. As far as color, I'm leaning toward white pearl, but that changes daily.

Regards,
Matt
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Old 5th January 2017, 02:38 AM   #6
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
I have been listening to the LAB12s sealed for about a week and I like the way they sound, but I think its time to try them in a bass reflex. I am running 2 other bass reflex subwoofers and a large sealed rear chamber bandpass subwoofer in the room currently.

In the sim I used only one driver and one 4" port. In reality two drivers and two 4" ports will be used. I should mention that when I'm done the drivers will be mounted with the cones out.

I picked up the 4" PVC pipe and 90s for the ports, so I guess it's time for the sub to go back out to the garage. I hope my helper is ready for more lifting.

Regards,
Matt
Attached Images
File Type: png LAB12 PVC BR Input.png (12.3 KB, 72 views)
File Type: png LAB12 PVC BR Acoustical.png (21.9 KB, 47 views)
File Type: png LAB12 PVC BR Impedance.png (21.8 KB, 48 views)
File Type: png LAB12 PVC BR schematic.png (9.0 KB, 26 views)
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Old 22nd January 2017, 09:38 PM   #7
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
A little more progress has been made with this project, so thought I would post more pictures. This week I cut the holes for the ports, added some stuffing in the middle of the pipe, and cut the ports to length.
It was too cold in the garage, so I decided to cut the holes in place. The outside diameter of the 4" pvc is 4.5", so I picked up a 4.5" hole saw to cut the holes. Cutting the holes was much harder than I anticipated, what a pain. I used a 12" mitre saw to cut the pvc to length. I started with a longer port length, then cut 1" off at a time, then checking each time with an impedance sweep. I used some modeling clay to temporarily seal the port to the pipe for testing. There is a little more fine tuning needed before I start on the finish. So far I am happy with results.

Regards,
Matt
Attached Images
File Type: jpg IMG_1010.jpg (582.9 KB, 46 views)
File Type: jpg IMG_1012.jpg (676.2 KB, 53 views)
File Type: jpg IMG_1047.jpg (482.1 KB, 55 views)
File Type: jpg IMG_1048.jpg (591.8 KB, 63 views)
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Old 22nd January 2017, 10:21 PM   #8
reloader650 is offline reloader650  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Utah
Here are some of the impedance sweeps.

The first image is a sweep with the port length of 25" and no stuffing.

The second image has the same port length, but with about 1.5 pounds of poly fill in the middle of the pipe away from the ports. Notice the tuning and the impedance peaks are lower.

The third image is after cutting 3" off of each port and 1.5 pounds of poly fill. There is still a little more tuning to do. I may cut 1 more inch off of each port to raise the tuning a little.

Regards,
Matt
Attached Images
File Type: png LAB12 PVC BR 1.png (90.1 KB, 83 views)
File Type: png LAB12 PVC BR 1 Stuffing.png (91.2 KB, 57 views)
File Type: png LAB12 PVC BR 4.png (92.0 KB, 56 views)
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Old 22nd January 2017, 11:42 PM   #9
Don Hills is offline Don Hills  New Zealand
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Join Date: May 2009
Location: New Zealand
Nice. If you finally mount the ports inside the tube, remember to allow for the amount of volume they take up. The tuning will change. Looking at your photos, you could probably leave the ports mounted outside the tube. They'll be hidden behind it.
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Old 23rd January 2017, 12:18 AM   #10
reloader650 is offline reloader650  United States
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Join Date: Apr 2010
Location: Utah
Thanks for your comments Don. Yes I will leave the ports as shown, on the outside and up against the wall. It's not the prettiest subwoofer, but it sounds good. I'm kind of glad it's too cold to work on it in the garage, because I'm enjoying listening to it.

Regards,
Matt
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