"Sump Basin" Subwoofer - MacGyver style - Page 2 - AVS Forum
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post #31 of 56 Old 12-12-2012, 06:31 PM - Thread Starter
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I will find a place for the stuff! I just used some expanding foam in it as well!
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imagic - he's right, you have to use duct tape or it isn't a true MacGyver style subwoofer. biggrin.gif
Excellent thread, true DIY ingenuity here.

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post #32 of 56 Old 12-12-2012, 06:46 PM - Thread Starter
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Here's what's happening right now - foam is setting, should help seal the vents and maybe even dampen the sound a bit, who knows. If this sounds great, I'll be trying the poured cement trick to make this a 'final' design. I still need to sand the end of the tube to try and smooth it a bit. I'm not pushing my luck on this, there's plenty of spare port velocity. I'll be listening within the hour, very psyched to check out 16hz with 8db of extra oomph.


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post #33 of 56 Old 12-12-2012, 07:12 PM - Thread Starter
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Ok. Holy cr**. Or whatever the usual first response is. Wow.

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post #34 of 56 Old 12-12-2012, 07:46 PM
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Haha, nice first response.

The great stuff is closed cell foam though so it's not doing anything but taking up space and acting as a glue.
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post #35 of 56 Old 12-12-2012, 09:15 PM - Thread Starter
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If nothing else it could (slightly help) break up some standing waves. Probably does nothing. Its main purpose is to act as an adhesive and sealant, for sure. The fact that it becomes rigid when dry and is very lightweight is why I used it.
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Haha, nice first response.
The great stuff is closed cell foam though so it's not doing anything but taking up space and acting as a glue.

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post #36 of 56 Old 12-13-2012, 12:57 PM - Thread Starter
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Listening last night and this morning has been revelatory. I have zero doubt about the LLT concept's effectiveness. My current tuning is set at 17hz - the design allows port extenders to be added for lower tuning. A pair of 24" 'extension' tubes will give me a 12 hz tune, I'll be trying that out tonight after I head back to Home Depot once again. My thinking is to put the tubes in for HT duty, take them out for music listening sessions (unless the music explicitly demands the ability to play that low). I'm psyched. Bass is scary loud, visceral, tight, low, clean. Exactly the sound I was looking for.


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post #37 of 56 Old 12-13-2012, 05:32 PM
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I'm interested in you impression of the difference between the 2 tunings. I'm leaning toward 12hz for my next build. The extension tubes is a great idea too.
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post #38 of 56 Old 12-13-2012, 05:55 PM
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That is some massive gain on the vented setup. biggrin.gif what about using a port plug in one of them instead of extensions? Not sure how it will model but worth a try.
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post #39 of 56 Old 12-13-2012, 06:24 PM - Thread Starter
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The port plug models terribly - at 12 hz vent mach is .57 versus extension tubes mach .14 - at the current 17hz tune it's mach .10
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That is some massive gain on the vented setup. biggrin.gif what about using a port plug in one of them instead of extensions? Not sure how it will model but worth a try.

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post #40 of 56 Old 12-14-2012, 05:23 AM
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Nice work imagic.

One thing you might experiment with since PVC is so cheap is flaring the diameter of the piping. Say going from 2"(or whatever your currently using) pipe up to 4" or 6" with an adapter on the last segment(s) which should slow down the air velocity at exit. IDK how to model or predict its behavior, but should be a fun cheap exercise.......
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post #41 of 56 Old 12-14-2012, 06:02 AM - Thread Starter
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That's going to happen today. I'm using dual 3" tubes as ports. I have my eye on a part that looks cool and should do that job rather well.
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Nice work imagic.
One thing you might experiment with since PVC is so cheap is flaring the diameter of the piping. Say going from 2"(or whatever your currently using) pipe up to 4" or 6" with an adapter on the last segment(s) which should slow down the air velocity at exit. IDK how to model or predict its behavior, but should be a fun cheap exercise.......

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post #42 of 56 Old 12-14-2012, 06:27 AM
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Excellent.

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post #43 of 56 Old 12-15-2012, 11:35 AM
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post #44 of 56 Old 01-01-2013, 10:27 AM - Thread Starter
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So it is: We enter 2013 and the sump basins are going strong. They survived the 'Small NE GTG' - one of my concerns was durability, especially in transport. No issues. It's nice to have heard them side-by-side with several 18" heavy-hitters. Considering the modest power and displacement, I couldn't be more pleased with the price/performance.

They are so good, I have zero inclination to upgrade. Bass is 'perfect' in my modest listening room.

As the spring GTG approaches, I am considering building a couple dipole arrays that I can mount to a pair of sump basins and create full-range speakers. Something really powerful, lightweight and keeping with the MacGyver theme - made with parts bought at Home Depot.

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post #45 of 56 Old 01-01-2013, 04:50 PM
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I am going to build a pair of these over the next week or so. What is your final setup? What I need if I am following your build correctly is 4 sump basins, 4 24" x 3" sections of PVC, 2 12" Sony subwoofers from Walmart, a can of great stuff, and some duct putty for all the joints. Of course a few screws and other odd and ends.
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post #46 of 56 Old 01-02-2013, 08:12 AM - Thread Starter
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Cool! Yup you got it. My final setup is 4 sump basins, 1 in each corner of the system. Power comes from a Crown XTi-2002. I run pairs on each channel - parallel for a 2 ohm load. EQ has a slope of 6 db/octave. I have not found a need for a HPF, the sub seems to self-limit.

The other things you'll need - somethig to act as leg - I used long screws with rubber caps on the ends but the ideal is probably sofa legs or door stops. You'll also need 3" PVC couplers to terminate the ports, and finally some sort of sealant for the port's exit - I happened to use 'outdoor double-sided tape' to create the seal. I could just as well have used Silicone, epoxy, plumbers tape... just about anything that makes the joint between the pipe and the basin airtight. If you are lucky, you can probably achieve the seal with a careful cut and a tight fit, but I was not able to achieve that.

You'll also need something to use as legs - the ideal is Sofas legs but I'm just using long screws.

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I am going to build a pair of these over the next week or so. What is your final setup? What I need if I am following your build correctly is 4 sump basins, 4 24" x 3" sections of PVC, 2 12" Sony subwoofers from Walmart, a can of great stuff, and some duct putty for all the joints. Of course a few screws and other odd and ends.

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post #47 of 56 Old 01-02-2013, 09:17 AM
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Ok, thanks. Did you mount the 3" coupler into the sump basin and then attach the 24" section of PVC into that?
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post #48 of 56 Old 01-02-2013, 09:36 AM - Thread Starter
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^^^ The way I did it, I first attached the coupler to the tube - you could glue it, but it sticks tight if you hammer it on. With the basin's bottom facing up, I inserted the tube until the coupler made contact. At that point I sealed it and sprayed the foam. The point of the foam is to bond the tubes to the side-walls of the basin, and perhaps to diffract some standing waves that would have bounced off the (flat) bottom. What's important is that you not manipulate the tubes once the foam is applied, until it cures. Seal the port before applying foam. Once the foam cures you're good to go. I used one can of 'large gap' good stuff per sump basin sub.

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post #49 of 56 Old 01-02-2013, 09:47 AM
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What is the ID and OD of the flange on these? Is it possible that they take an 18 mounted directly to the basin?

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #50 of 56 Old 01-02-2013, 09:56 AM - Thread Starter
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An 18" is a no-go with my design - you get 15.75" ID with the narrower 'bottom' - I'm relying on the flange to connect the two basins. A 15" would work and I intend to try such a build soon. Flipping it probably does give you an 18" opening, not sure about that, I need to go measure one at the store. Definitely curious. The main issue is that there isn't that much air space - 2.5 cubic feet per basin.

A dual-opposed 15" implementation could be a real winner - especially with an economical, lightweight 15" like the Polk MoMo.
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What is the ID and OD of the flange on these? Is it possible that they take an 18 mounted directly to the basin?

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post #51 of 56 Old 01-06-2013, 02:26 PM
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Well I was hoping to get started on this project today. I went to Lowe's and their sump basins are made differently than these, very flimsy. I'll try to get back out and go to a Home Depot and see what they have.
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post #52 of 56 Old 01-06-2013, 02:41 PM - Thread Starter
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That's correct what Lowes carries is totally unsuitable.
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Well I was hoping to get started on this project today. I went to Lowe's and their sump basins are made differently than these, very flimsy. I'll try to get back out and go to a Home Depot and see what they have.

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post #53 of 56 Old 01-09-2013, 01:48 PM
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Ok, finally had some time today to go in search of these sump basins. The only ones that the Home Depot had were huge and had 4" holes in the side. They said they don't carry the smaller ones and were able to find one in a store about 150 miles away. I went everywhere in town that I could think of and nobody had them. The larger ones that Home Depot had would easily hold 18's, I guess you could use a fiberglass body kit and cover the area where the hole is.
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post #54 of 56 Old 01-09-2013, 02:08 PM - Thread Starter
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I looked at the huge basins as well. That hole on the side, I'm thinking it could be used to install a port. I have to go check those out. Sorry if it seems like a wild goose chase. I found that some Home Depot stores have no clue what they are, and you have to spot them in the upper shelves. My local Home Depot seems to have plenty, always in stock.
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Ok, finally had some time today to go in search of these sump basins. The only ones that the Home Depot had were huge and had 4" holes in the side. They said they don't carry the smaller ones and were able to find one in a store about 150 miles away. I went everywhere in town that I could think of and nobody had them. The larger ones that Home Depot had would easily hold 18's, I guess you could use a fiberglass body kit and cover the area where the hole is.

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post #55 of 56 Old 01-09-2013, 02:16 PM
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Wow what a cool idea. And thanks for the duct seal tip. Never thought to use it to seal drivers in place. I have some I've used to smooth the airflow around magnets and such. But never thought to use it for what it's actually meant for biggrin.gif
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post #56 of 56 Old 01-09-2013, 06:17 PM
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I wondered if you could put a port there. They are 18"x30".
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