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post #1 of 71 Old 02-09-2013, 10:20 AM - Thread Starter
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Hey everyone, I created a thread a few months ago looking for some help and it kinda died out.

I have an RF-83 system currently without a sub. I was looking at greeting a PB-13 ultra and when checking it out on the forums people were saying that for that price point I midaswell build my own.

In the original thread I got a recommendation of using a UXL-18 (from beast, who I'm sure will chime in tongue.gif). They are currently out of stock. Do you think I should wait for them to get back in stock of do you think there's a better option?

The room it will be going in is 19ftx14ftx9ft.

The space I have for the sub is 30in deep x 30inch wide x any height. The width could go as wide as 40 inches. I'm hoping to get something around 2ftx2ftx2ft.

I'm planning on building the enclosure out of mdf and veneering it. I plan on flush mounting the speaker. I would assume I'm going to need to use 1 inch mdf. 1" mdf is a bit difficult to find, so am I better off gluing 2 1/2 mdf sheets (I've heard gluing 1/4" and 3/4", is there a difference)? Also, for the inner piece of the flush mount (basically the part the sub will actually mount to), should I cut the hole out and leave the rest of the mdf so it would be like an entire second layer on the front, or is it ok to just cut it into a 3-4 inch thick ring and gluing it up (not sure how much sense this makes)?

Last question, what do you guys recommend doing for the bottom/feet?
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post #2 of 71 Old 02-10-2013, 01:22 PM - Thread Starter
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Forgot to add, it's used mainly for music, then gaming, then tv and movie watching
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post #3 of 71 Old 02-10-2013, 01:34 PM
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What's your budget?

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post #4 of 71 Old 02-10-2013, 02:41 PM - Thread Starter
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I was originally going to go with a PB-13 ultra.

I'm hoping to not spend more than 1000 on the driver/amp but could go higher.

I don't have enough space for multiple subs though so I'm trying to get the most bang for my buck out of a single sub
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post #5 of 71 Old 02-10-2013, 02:53 PM
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Quote:
Originally Posted by hotsho111 View Post

I was originally going to go with a PB-13 ultra.

I'm hoping to not spend more than 1000 on the driver/amp but could go higher.

I don't have enough space for multiple subs though so I'm trying to get the most bang for my buck out of a single sub

Well the PB13 is almost 2k is it not?

With it's dimensions of 22.5x 20.5x 27 you could get real close to a DO setup without a much larger enclosure. 24x24x27 would net you around 3.5 per driver that would lend nicely to a pair of SI's. Pick up 2 D4's and wire them for a final 4 ohm load. Snag an EP4000 to power them with 900 watts per channel. I'm too lazy to model it, but I'm betting it would easily hold it's own against the Ultra with a similar footprint, and all for a whopping 750 bucks or so.

A single LMS would also work nicely in a smaller enclosure with a bunch o power.

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post #6 of 71 Old 02-10-2013, 03:03 PM - Thread Starter
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They are around 2k but can be found for cheaper sometimes. I was planning on spending around 1000 but I'd go higher if it gets me more bang for my buck.

I was planning on using an ep4000 for power.

You'd take the dual D4's versus a single UXL-18?
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post #7 of 71 Old 02-10-2013, 03:11 PM
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Well the UXL 18 is a wicked driver so it's kind of splitting hairs. You can buy 2 SI's for less than one UXL, so that's something to consider as well. There are certainly arguments for either. I'm merely offering an additional suggestion as you mentioned the UXL is out of stock.

As far are the cab is concerned. Either cg BB or 3/4" MDF will suffice. You don't need 1" thick. Pick up some 3/4" and build a double front baffle. You can then countersink the driver as you wish.

Here's an example.

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post #8 of 71 Old 02-10-2013, 03:24 PM - Thread Starter
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Thanks. Good to know 3/4 should be good enough
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post #9 of 71 Old 02-10-2013, 03:57 PM
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Quote:
Originally Posted by hotsho111 View Post

Thanks. Good to know 3/4 should be good enough

Trust me, if it will suffice for a cab over 5', it will work for you. biggrin.gif

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post #10 of 71 Old 02-10-2013, 07:04 PM - Thread Starter
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That's impressive.

I'm not in a big rush, so if I can get more out of a uxl-18 than something else I may wait for it.

Looking around online I'm trying to see if I should go with a 6 or 9 cubic foot box (assuming I use a uxl).

It looks like a 9cubic foot box would be 25inx25inx25in tuned to 18hz. It would require a 2.5inch x18inch port size with a 36" port length.

The 6 cubic foot box would be 22inx22inx22in tuned to 20hz and would require a 2.5 inch by 15 inch port with a 37" port length.

It looks like they both hit xmax around 13.5hz.

Is the benefit of tuning at 18hz significantly better than going with a slightly smaller box? Would the dimensions need to be adjusted a bit to accommodate for the port and bracing?
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post #11 of 71 Old 02-11-2013, 02:20 PM - Thread Starter
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Quick question when determining the volume of the box. To get it I assume it is measuring internal dimensions (so if it's 24x24x24 with 1" mdf, it would technically be 22x22x22). How is the port/port length taken into account?

I'm gonna try and start working up a design for the UXL-18
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post #12 of 71 Old 02-11-2013, 02:31 PM
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Quote:
Originally Posted by hotsho111 View Post

Quick question when determining the volume of the box. To get it I assume it is measuring internal dimensions (so if it's 24x24x24 with 1" mdf, it would technically be 22x22x22). How is the port/port length taken into account?

I'm gonna try and start working up a design for the UXL-18

Try using this. It's pretty handy.
http://www.hometheatershack.com/forums/enclosure-volume-calculator/#axzz2Kd0ZRoOV
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post #13 of 71 Old 02-11-2013, 02:58 PM - Thread Starter
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Wow, that's amazing. Thanks!
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post #14 of 71 Old 02-12-2013, 09:23 PM - Thread Starter
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So, using that calculator with a 24"x24"x27" case, a 2.5"x18"35" inch port size and a single 24"x24"x3/4" brace with 5"x5" square cutouts came out to 6.353 cubic feet without the driver (no idea what the volume of the driver is).

Does that seem right? Would I need more/less bracing for a box that size?

I've been messing with WinISD but I'm not sure what I'm looking for.

Anyone with more experience have any suggestions about what tuning/port size I should go with with a 9 cubic foot box (using external dimensions and not including any internal bracing, the port, or the driver)?
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post #15 of 71 Old 02-18-2013, 05:58 PM - Thread Starter
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Bumping this up, hoping someone with more knowledge than me can help run the numbers
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post #16 of 71 Old 02-18-2013, 06:24 PM
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I would use more then a single shelf brace for a high powered sub that size... You dont have to use full shelf braces either, it can just be interlocking strips of wood or dowels, which will save area and wood.



What tune are you aiming for? I'm showing a 2.5" x 18" x 42" port for a 20hz tune in 6.3 ft3. 18hz tune is 53.5" long. A 2.5" x 12" x 35" would get you 18hz in 6.3 ft3, and still have more cross area then a 6" round port. I like the Ultimax 15 in this box, even with the 1 db hump at 40hz.

I'm running the numbers with 24.75 x 24 x 27 using .75 material (the extra .75 is for your double thick baffle). The port dimensions should be 13.5 x 3.25 x 34.25 for 1502 in3, giving you 6.85 ft3 before bracing.
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post #17 of 71 Old 02-18-2013, 06:36 PM - Thread Starter
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I was hoping to get into the teens. I'm not sure if there is a sweet spot to shoot for in terms of tuning though. I'm sure there is a point of diminishing returns.

I'm hovering around a 9-9.7 cubic foot box (using external dimensions). I haven't quite figured out the exact dimensions to use yet. Would bracing have a significant effect on the tune?

Once I get a more solid idea of dimensions I'll draw something up and post it back up here to see if it needs more bracing
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post #18 of 71 Old 02-18-2013, 06:41 PM
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Well if you're at 9 ft3, the port dimensions I gave will tune you to 15hz. The lengths start to get pretty crazy if you go lower.
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post #19 of 71 Old 02-18-2013, 07:21 PM - Thread Starter
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It's 9ft3 using external dimensions, ~3ft is removed if you take into account the port and bracing (right?).

Which port dimensions would give the 15hz tune?
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post #20 of 71 Old 02-18-2013, 07:27 PM
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A 2.5" x 12" x 35" port will tune you to 15hz in 9 ft3. For calculating the port volume you have to include the material thickness, so 3.25" x 13.5" x 33.5" for 1470 in3, or about 0.85 ft3 taken up by the port.
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post #21 of 71 Old 02-18-2013, 07:34 PM - Thread Starter
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Is that tune for a 9ft3 external volume?

Is the port considered part of the total internal volume or is it subtracted from it?

Using the (simple) example I used before with a 9 ft3 external volume came out to ~6.3 ft3 internal volume taking into account some bracing and subtracting the port size.

Would that still be able to get to 15hz?

Sorry for all the questions
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post #22 of 71 Old 02-18-2013, 07:53 PM
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Alright, we only talk about internal volume around here so there's no confusion wink.gif Re-read post #16, as that is talking about your external dimensions and the internal volume/port tuning.

You're going to need a port that's over 50" long to get 15hz in 6.2ft3 internal. So a 2.5" x 12" x 53" port will take up 2260 in3 volume, and your 24.75 x 24 x 27" box is at 6.4 ft3 after accounting for the port.

It might be a good idea to increase the cabinet depth a couple inches
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post #23 of 71 Old 02-18-2013, 08:07 PM - Thread Starter
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I should be able to increase the external dimensions to 25x25x30 (30in is about as far as I can go on depth, 28in is a bit more comfortable)
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post #24 of 71 Old 02-18-2013, 08:18 PM
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That will work better. You can make the port about 43.5" long with the bigger box for a 15hz tune. So the port would run all the way across the bottom, and angle about half way up the back of your box.
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post #25 of 71 Old 02-18-2013, 08:28 PM
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Something else you could do instead of building a slot is use PVC pipe with 90 degree elbows

http://www.lowes.com/pd_23361-1814-PVC+00304++1000_0__?productId=3132791

http://www.lowes.com/ProductDisplay?partNumber=87671-1814-PVC+07300++1000&langId=-1&storeId=10151&productId=3581470&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1

Four 3" ports would equal a 6" port. Same length 43.5" for all four ports. This would use about 1/3 less airspace then the slot port.
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post #26 of 71 Old 02-18-2013, 08:34 PM - Thread Starter
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What is the tune with the 25x25x28 box? I'm trying to see how much of a gain it is/if it's worth it, as it's gonna be pretty tight on space
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post #27 of 71 Old 02-18-2013, 09:09 PM
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Quote:
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What is the tune with the 25x25x28 box? I'm trying to see how much of a gain it is/if it's worth it, as it's gonna be pretty tight on space

With the 43.5" port you'll be just under 16hz.
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post #28 of 71 Old 02-18-2013, 09:20 PM - Thread Starter
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I think I might whip up a design with cylinder ports and one with a slotted port. To clarify, to get the same effect of the 2.5"x12"x43.5" slotted port I would need 4 3"x43.5" cylinder ports? How big would the cylinder ports need to be to use 3 (instead of 4)

Also, about the tuning, with the 25x25x28 box the tuning would be around 16hz and with the 25x25x30 it would be around 15hz?

Thanks again for humoring me....
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post #29 of 71 Old 02-18-2013, 09:53 PM
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Quote:
Originally Posted by hotsho111 View Post

I think I might whip up a design with cylinder ports and one with a slotted port. To clarify, to get the same effect of the 2.5"x12"x43.5" slotted port I would need 4 3"x43.5" cylinder ports? How big would the cylinder ports need to be to use 3 (instead of 4)

Yes. Three ports would need to be about 32". I wouldn't recommend dropping your port area that much.

Also, about the tuning, with the 25x25x28 box the tuning would be around 16hz and with the 25x25x30 it would be around 15hz?

Yes again

Thanks again for humoring me....

You'll get a hair deeper tuning with the round ports, because they use less cabin volume.
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post #30 of 71 Old 02-18-2013, 10:03 PM - Thread Starter
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Thanks, that all makes sense, but what do you mean three ports would need to be 32"? If 4 ports need to be 43.5" (with 3" port) wouldn't using 3 ports require them to be bigger/longer?

I'll start whipping up a few front cab designs and see what looks best
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