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Topic: Any designs or suggestions for a ported 12" speaker cabinet? |
Jack Stoner
From:
Kansas City, MO
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Posted 15 Jan 2015 6:30 am |
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I'm considering building a ported speaker cabinet for an Eminence EPS-12C speaker. Anyone have a working ported cabinet or dimensions?
Thanks in advance. |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 15 Jan 2015 8:08 am
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I can't seem to load an EV design, Jack. If you're interested, I can E-mail it to you.
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Les Cargill
From:
Oklahoma City, Ok, USA
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Posted 15 Jan 2015 10:12 am
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Have you discovered WinISD? You add the Thiele-Small parameters for the driver you want to use to a database. You select that speaker, hit a button and it calculates the optimum enclosure size for you.
It then gives you a "box"; each of the three lengths to make this enclosure. You can trade off length,width and depth and it'll adjust the others for you. You can also enter the volume of a smaller enclosure and it'll estimate the frequency response.
If you'd like, I'll run it on the Eminence EPS-12C if I can find the T/S params and report back. It'll be a few hours.
"Optimum" means the "best bass"; the volume that has the most linear transfer function - is-minimum-phase, if you will. |
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Bill Moore
From:
Manchester, Michigan
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Posted 15 Jan 2015 11:49 am
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Jack, I have a pair of cabinets, made by Sonic, sealed, with a slot type port at the bottom. These cabs will add a lot to the bass, using the same speaker. I've tried this cab and open back cabs, and you get much more bass with the ported cab. They measure 18" tall, 14" wide and 12" deep. There is some fiberglass insulation inside and the speaker mounts from the front. The slot on the bottom is 1 1/2" tall. As you can see, this is probably the smallest cab that can be used with a 12" speaker. I don't think it would matter if you added an inch or two to the dimensions. Here is a picture:
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Jack Stoner
From:
Kansas City, MO
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Posted 15 Jan 2015 12:13 pm
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| Thanks, Bill. That is close to what I want. I'll have to consider how much that 1 1/2" X 14" will convert to a couple round or square port holes. |
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Les Cargill
From:
Oklahoma City, Ok, USA
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Posted 16 Jan 2015 7:03 pm
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Jack, WinISD says 14"x14"x9.26" with two 2" circular ports of 0.80 inches would be twice the optimum volume ( 1.050 cu. ft. instead of the calculated 0.525 ) should work. I don't think there is a design for 0.525 cu. ft that will hold that speaker.
http://www.linearteam.dk/?pageid=winisd for the software. http://www.usspeaker.com/Eps12c-1.htm for the T/S parameters.
I'd put the ports in back. And I believe that if you use 3/4" plywood, that's close enough to 0.80". If not, you can usually find PVC about that internal diameter. |
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Jack Stoner
From:
Kansas City, MO
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Posted 17 Jan 2015 3:21 am
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Thanks Les. That really helps.
I've read in a JBL speaker design manual that the ports can be anywhere. |
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Tommy Boswell
From:
Virginia, USA
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Posted 17 Jan 2015 7:12 am
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Jack,
If you build this, please let us know how it works. I'd be tempted to build one myself.
Should the speaker be front-mounted or back-mounted? Since the internal volume is critical, that has to be part of the design, right? |
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Les Cargill
From:
Oklahoma City, Ok, USA
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Posted 17 Jan 2015 12:40 pm
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| Jack Stoner wrote: |
Thanks Les. That really helps.
I've read in a JBL speaker design manual that the ports can be anywhere. |
The only problem with ports in the back is that you have to keep away from walls a bit.
I am still not 100% sure that the thickness of the box material counts for port length - the boxes I built used a 3" long port, and that included the box thickness. I am pretty sure that the box material does count, but I'm still looking.
I really can't recommend WinISD enough - it helps in buying gear, too - if a box is too small, you can at least kind of tell. For bass, I bought a pair of (2006 vintage) 400W G&K 1x15" boxes mostly based on the size of the box and number of ports - assuming an Eminence Delta, that was close to the right size. They don't make that one any more.
This is slightly less important for steel/Telecaster than bass or PA. |
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