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... I wouldn't rely too much on electronics rolloff anymore unless your electronics chain is from the early 90s or sooner....
My old Pioneer did a 1hz sine yesterday, pumping an 18" woofer up en down.:blink:
So even before '90, some amp's were going looow. :bigsmile:
 

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Discussion Starter · #23 · (Edited)
Okay....so let's get started....

I'm sticking with

12 ft3
15 Hz tuned
7.25" port x 35.7"
1200 W


Let me know if I'm posting too many images....This is my first build of any speaker project and I give myself a 6/10 for woodworking skills (don't know if it's me or lack of tools :dontknow: )

Feel free to chime in anytime and let me know good/bad/ugly....I'm not going to win any looks competition with this build. I want it to look 'good enough' so that I can say 'I built that!'.

Today was day 1.... wanted to test cutting the tube, also having a small piece of sonotube would make testing circles and measuring a lot easier).

How to make a straight mark around 24" cube...I used hard plastic edge trimming for the lawn, I had some extra and it worked great!



used clamps to hold it while I measured a few spots around tube and then marked a line all around...you'll notice the ugly edge that I made at the building center...they just gave me a hand saw that i had to manually chop a 12' piece in half! no measuring!



used this tool from dremel.....worked great, remove the black edging and followed the line slowly...




Guess it is easy to see the film that has to be removed from the tube prior to gluing...I HOPE that's the right film...



my homemade attempt at a work area to make me some rounds! I was testing with a jig saw and a dremel (rotozip) type tool and both were awful ....so I did the router jig and worked well. screwed the boards down and everything was level and stable....





tested it out and it worked well....you really do notice that once you remove the film from inside the sonotube that it does change the diameter of your circle. It barely fits into the sonotub with film still there, but without it fits smoothly.



that's it for today....it started to rain and i've decided that all MDF cuts will be done outside....WAAAYYY too much dust inside the garage!
 

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Discussion Starter · #24 · (Edited)
Day 2....was able to to spend some time and got all the major cuts of mdf done. Delivery of driver is a week away so I have to wait to do the bottom cutouts for the driver. But I'm almost done the top brace.

Here's a photo of the top brace. I did 3 layers of mdf 3/4"....2 inside and 1 outside(nothing glued yet). I've got the idea of using the extra pieces from the circle cuts for accents and will use them for feet as well.....will cut to size and route all the straight edges to give it a finished look....




I have two questions for the sonotube 'experts' out there.

1> Maybe I'm paranoid but I'm not a fan of putting insulation on the top brace of the tube, with wind blowing and little fiberglass particles flying around the room to breathe in. Is the insulation a standard requirement or is there a more 'friendlier' approach. I think I saw people put pillows or polyfill?(something that would not affect the volume) but help with the resonance....any thoughts?

2> I'm putting a flare on the top plate. Is a 'donut' flare required on a 7.3" port on the bottom of the port? would it be something that you would do....since I have homemade jig then it would be a harder task to complete but I'd spend the extra effort if it was a must. I was thinking it may be easier to do a brace (since the port is almost 3 feet long) and just flare/brace it at the end (similar to the top but with cutouts)....would that work ok?

thanks...
 

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It doesn't have to be fiberglass - polyester, polypropylene, or any other fiber type will work just as well. Pillows work, but I would only use them if you shove them between the port OD and sonotube ID - do not block the path between the driver and port mouth.

A 7.3" diameter port is a bit undersized for this monster 18" driver, so yeah, I'd flare both the inside and outside if you can.
 

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Hey, have look at my 14.5 hz LLT build from a couple years ago: I've never had a complaint and it's run with a nice Crest Audio amp and no hpf. My friend complained that the bass was too loud (though my wife hasn't :heehee:) and I push it pretty good at times.

I've also never experienced any port chuffing.

You're gonna love it!
 

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Discussion Starter · #29 ·
It doesn't have to be fiberglass - polyester, polypropylene, or any other fiber type will work just as well. Pillows work, but I would only use them if you shove them between the port OD and sonotube ID - do not block the path between the driver and port mouth.
if pillows will work the same then that's great. ikea sells pillows for $2 with following info: Product description
Outer fabric: 100 % polypropylene Pillow filling: Polyester fiber fill....I can buy 3 of them and 'stuff' them under the top brace around the port? Just glue/screw them to the top?
 

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Discussion Starter · #31 · (Edited)
Here's some updates on my status...

Things are going better than I thought they would so far...(ooops don't wanna jinx it!)

1st rule about working with MDF and routing....HOLY DUST!!! I think I've spent as much time cleaning as I have cutting!





I've improved on my cutting of the 'tubes'...I use the plastic as a guide (screwed the plastic to discarded piece)



My donut was the hardest thing to do here....how perfect does it have to be? or will a somewhat 'less than perfect' still help.




I used the scrap piece of woods to make the feet....I predrilled the holes so that I can 'screw-up' into the bottom brace of the sonotube once that part is complete. Made the bottom space 6" high...that should be enough?



I can't complete the bottom brace until I get the driver so all I can do is finish the top and prime the wood for future painting...





That's it for now.....

David
 

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I agree, the donut looks good, and 6" between the baseplate and bottom cap is fine. I would recommend though that perhaps you double or triple up on those legs, as these subs can get quite heavy with multiple layers in the top and bottom cap, a 50lb driver, and all the rest.
 

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Discussion Starter · #34 ·
You can't see in the photos I guess....but the donut is kind of 'lumpy'...I've hand sanded what I could to get it to a 'smooth' ring but there's only so much I can do with it....Also there's not a perfect fit for the port and the donut. Can I use silicone and fill in/smooth out the edges between the port and the donut?

As far as the feet not being strong enough. I was thinking that as well....I PL'd the pieces and have two screws going from the bottom up....It seems 'really' strong for about 150 lbs (I think). They are 5" by 5" 3/4" mdf pieces....but if it looks shaky once complete I will add an additional four similar legs along each edges for a total of 8 feet.
 

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Yes, you can fill in the gaps with silicone, it doesn't need to be perfect. I had to file and sand my port flares by hand and they are fine. Anything resembling a flare will be better off than no flare at all in easing the motion of the air in and out of the port.
 

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Discussion Starter · #36 ·
While I'm waiting for the driver to come I'm thinking about other items for my first build.

My Inuke 3000 uses speakon connectors for speakers. So I was thinking instead of binding posts to use a 4-pole speakon mount...

http://www.neutrik.com/en/speakon/speakon-chassis-connectors/nl4mp-uc

Is this an option? any drawbacks to using them? It states that it's air-tight so I assume it's just one hole to counter sink this into.

Also, this sub will be about 35 feet away from receiver(rca connector for sub out)....Since we're talking about 1200+ watts, should I run a long rca line to the amp right next to the sub? Would it be alright to keep the amp next to receiver and run 35-40ft 12-gauge speaker wire to the sub?

Also, I ordered a minidsp (more toys)....I'm going to pair this monster with my svs pb12 plus. Since the svs is not a passive sub (has its own amp/dsp)....would it still be a good idea to control/manage/benefit having the minidsp control both subs. My receiver also has 2 sub-outs (rca) with Aud. MultEQ XT32....so that will throw another variable in there.....(I'll be using REW....great tool!)..

waiting for the driver is painful....
 

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Hi David, I'm happy to see your build-- I have just settled on nearly the same design for my first build. I located a length of 26" Sonotube and am planning to order my UXL soon (eventual plan is two in 520l tuned to 13 hz--starting with just one). Great to see you figuring everything out a step ahead of me so I can use your thread as a reference guide! :)

It sounded like a 4 week wait for the driver the last time I talked to Mark though (from end of last week)--painful, as you said. How long for yours?
 

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Discussion Starter · #38 ·
It sounded like a 4 week wait for the driver the last time I talked to Mark though (from end of last week)--painful, as you said. How long for yours?
It was a 3 week wait when i ordered....I'm 1/2 way there so hopefully in another 10 days....

Glad to see you're building one as well......my advice so far...cut outside if you can, and get a good circle jig!
 

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Speakon should be fine, may just want to use a soft washer or gasket with it.

A good coaxial cable is shielded, and twisted speaker cables with power running through them reject noise as well. I'd side with the longer speaker cables, shorter coaxial, but do whatever is most convenient in your setup.

Audessy XT32 does a great job, I'd probably just let it handle things. If you are going to use the SVS, make sure you set it to its lowest tune, otherwise you will essentially lose low end from this DIY sub.
 

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Discussion Starter · #40 ·
If you are going to use the SVS, make sure you set it to its lowest tune, otherwise you will essentially lose low end from this DIY sub.
I haven't jumped into the whole dual-sub configs yet, but can I just set the HPF higher on the SVS to say 25hz(30?) so that it won't affect the low end from this sub? again...I'm no expert on how dual-subs play well together....
 
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