Joe X
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Posts posted by Joe X
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Port area is too low.
dual 4.5" aero ports with length of 18.8 in would give acceptable results, the box would spec as follows:
Fb = 32,341 Hz
Vb = 3,707 ft^3
Also I would do a dual layer baffle and some vertical crossbracing
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The box you have right now is huge, especially for the power that you're running. What exactly do you feel is lacking with your current box? What vehicle is it in and how are the subs/port laid out?
its an 02 focus hatchback. port back subs fire up. i just feel for the power im running it should hit harder. its not alot louder than the 1 aq 15 i was running b4 in a 6 cube box tuned to 32hz.
To complement what has already been pointed out I would compare:
1) the Port area/Vb from you old box with the new.
2) port and sub firing direction. Same??
ALSO your electrical should easily take the doubled power. Wiring and all.
Having said that HDC3 subs loose a lot their steam low tuned, probably you will be interested to see this:
http://www.stevemeadedesigns.com/board/topic/131804-box-size/page__view__findpost__p__1853199
35-38 Hz will make them louder most likely.
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Well, the maximum dims to install the box and your budget are necessary to provide suggestions.
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With a driver displacement of 0.15 (estimanted) cubic feet and dismissing your bracing which you don't provide measurements this would work:
Enclosure Specifications:
Fb = 30,012 Hz
Vb = 1,979 ft^3
Subwoofer Mounting = Front Mounted
External Height = 15 in
External Width = 31 in
External Depth = 14 in
Port Width = 2 in
L Port Internal Assembly Parts:
Front to Back = 10 1/2 x 13 1/2
Extension = 22 1/2 x 13 1/2
If you let me know the missing information I could get more accurate. Two inch port width can work.
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^^^odd, I see the HDC graph as being "better."
Right, very "SQ"
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OP so for a 36Hz tune the box would be like this:
Enclosure Specifications:
Fb = 36 Hz
Vb = 4 ft^3
Subwoofer Mounting = Front Mounted
External Height = 17 in
External Width = 32,15 in
External Depth = 20 in
Port Width = 4 in
Cut List:
* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.
External Enclosure Parts:
Front & Back = 32 1/8 x 17
Left & Right Sides = 18 1/2 x 15 1/2
Top & Bottom = 32 1/8 x 18 1/2
L Port Internal Assembly Parts:
Front to Back = 14 1/2 x 15 1/2
Extension = 3 11/16 x 15 1/2
Honestly the 33Hz tuning is fine for the SDC2.5 but tuning is slso a quesion of taste so there are both options.
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If nothing else moving the port to the top of the side could reduce the potential load.
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Ok since I don't know where you got at, im just going to show you what I was going post to before the dims mess, so a dual layer baffle surface and a 33hz tuning should give you something very close to this:
Enclosure Specifications:
Fb = 33,029 Hz
Vb = 6,465 ft^3
Subwoofer Mounting = Flush Mounted
External Height = 22,5 in
External Width = 41,5 in
External Depth = 18,25 in (because of the double baffle)
Port Width = 3 7/8 in
2 x Front & Back (3 parts) = 41 1/2 x 22 1/2
L Port Internal Assembly Parts:
Front to Back = 12 1/8 x 21
Extension = 3 7/16 x 21
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Here is the response plot if the aq sdc 2.5 4cuft@33Hz:
The HDC315 behaves very differently than this sub in the same box:
With the typical gain dip just above tuning frequency so 33Hz is bad for the HDC3 on 4 cuft but not so for the sd2.5.
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Ok so for a SSD 18 Fi recommends this:
Ported box: 6-10 cuft @ 33Hz
Driver displacement for that sub = 0.22 cuft.
Assuming you are giving internal dimensions and with the port you specify your box specs as follows:
Fb = 26,952 Hz
Vb = 6,305 ft^3
Port Area/Vb = 9,993
So you are tuned low and port area is low.
Recommendation is as follows use a double layer baffle, change port width to 4 in, and retune to 33Hz. If you like that I will let you know the size of the pieces of wood you are missing to make the L port.
That sounds perfect to me, although, are you sure about the 26hz? I used the torres calculator and double checked it, comes out to 33hz.
I just realized my measurments were off,
the box is 17.5inches tall once the 3/4'' mdf is accounted for.Also, Bear in mind the port is on the side that is 21inches tall. however, I think i've got it figured out. My box is actually 6.95 cuft. and the port can be 3.7inches wide and 30 inches long
I think you may be confusing external dimensions and internal dimensions measure the external dimensions on the box (yes add 0.75 to the depth because the baffle is not installed) and then substract 1.5 inches to each one and those are you internal dimensions, the INTERNAL height is the height of the port.
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Ok so for a SSD 18 Fi recommends this:
Ported box: 6-10 cuft @ 33Hz
Driver displacement for that sub = 0.22 cuft.
Assuming you are giving internal dimensions and with the port you specify your box specs as follows:
Fb = 26,952 Hz
Vb = 6,305 ft^3
Port Area/Vb = 9,993
So you are tuned low and port area is low.
Recommendation is as follows use a double layer baffle, change port width to 4 in, and retune to 33Hz. If you like that I will let you know the size of the pieces of wood you are missing to make the L port.
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I was just wondering, you are really doing a slanted box right?? asking because you mention ease of build as an issue.
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yeah im just going to have to use 6" aeros. i mean thats the only way.
In that case you could do as follows, ports are still top mounted:
Enclosure Specifications:
Fb = 33,236 Hz
Vb = 6,447 ft^3
Subwoofer Mounting = Flush Mounted
External Height = 24 in
External Width = 48 in
External Depth = 14,5 in
Cut List:
* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.
External Enclosure Parts:
2 x Front & Back (3 parts) = 48 x 24
Left & Right Sides = 12 1/4 x 22 1/2
Top & Bottom = 48 x 12 1/4
Port Quantity and Dimensions:
Number of Ports = 2
Aero Port Diameter = 6
Aero Port Length = 17
Try to install the ports far from each other an from the walls. The design calls for flush mounted subs, it's a good idea to perform it due to the way they are going to be installed.
Also note that some (mainly front to back) crossbracing would be beneficial.
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airspeed wont decrease as you are doubling your air volume at the common point of the port.
Dividing the common point increases port surface area and changes calcuations vs common port. Common port is more efficient, just put some rounded corners in there and a V shaped piece at the bottom to optimize it.
Ok friction losses decrease on the center duct, the V shaped piece will align the flow and avoid some turbulence but nothing more. Probably no big deal but still will tune differently than the standard port. I am guessing it will tune higher.
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Xmax is specified as one way and in the linear BL region so to speak "usable" region. Which to choose don't depend solely on this.
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I tried getting the Torres calculated download on my computer but it wouldn't download for the life of me. If you wanna send me a suggestion I would appreciate any advice, and I'm gonna try downloading it again tonight.
Yes, I just need the maximum dimensions he has to work with and will work something out, if you can run the Torres you can verify what I put out or design something and I could tell you if see any issues.
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if turbulence is a concern for you, consider doing kerfs on any bends you have and the openings of the port/s
The pic was just a crude effort to explain how its possible to do one port in center of two subs.
Yes you can smooth turbulence and I guess it can be done succesfully is just that aispeed lowers on the center duct and therefore the standard tuning equation would be inaccurate by some margin, I would just love to see some analytics for that situation.
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K if took a box with this design and separated the chambers and where the ports meet, I will be good? I use the Torres Calculator (as best I can). It's given me the manufactors desired tuning and airspace.:
Pretend there is some MDF in the middle of the box dividing it. That is an old design.
If the center divider cuts the port as well it would be a standard L port, port up, when possible (when you have enough width) is best to have ports and subs on the same face.
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Yeah, I have seen those but because the air speed lowers on the common center duct an there's a lot of turbulence on the T I think the standard equation will not predict accurately tuning and I expect lower sound quality on such port design, to me just placing a center divider there makes things more predictable.
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Just post your dims on your build thread.
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Yes 2 chambrs - 2 ports for the reasons explained. I have not seen equations to model port tuning for a 2 chamber single center port design.
As for a single chamber center slot port it can be easily done IF the port does not turn.
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This thread will be out soon so decide what will you be using and post a build thread, from there I can calculate your box or you can use the Torres calculator, My vote goes to Fi easily from those two.
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If you do separate chambers you will need two ports, is a bit harder to build and and a larger box but because drivers can't load each other (due to individual tolerances) some energy is saved and some better sound quality is achieved, some people use separate chambers because of this, at least one kicker box design document also support the use of separate chambers. The center divider provides some "natural" bracing also.
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I think I'm just gonna tell him sealed or a ported enclosure. I'll play with 4th order with my own equipment for practice once I decide to build. I'll stick to the 2cuft @32hz see how that works otherwise I'll build him a sealed. Thanks for the help
If you want a design suggestion for a 2 cuft I can provide it or you can use the Torres calculator.
the box is 17.5inches tall once the 3/4'' mdf is accounted for.
help with first time "REAL" box in 240sx hatch
in Subwoofers / Enclosures
Posted · Edited by Joe X
It all depends on what you can fit you need an internal net volume (Vb) around 3 cubic feet for those subs, so here is a design suggestion for those settings I have added a double baffle (top face) on those dims:
Enclosure Specifications:
Fb = 34 Hz
Vb = 3 ft^3
Subwoofer Mounting = Flush Mounted
External Height = 13 in
External Width = 26 1/4 in
External Depth = 25 in
Port Quantity and Dimensions:
Number of Ports = 2
Aero Port Diameter = 4
Aero Port Length = 16,591 in, 16 9/16 in
Vertical crossbracing is recommended as well. You can play around those dims with the Torres so see what you come up with.
In this suggestion the ports go fully inside the box.