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Old 23rd November 2002, 09:43 PM   #1
Ilianh is offline Ilianh  Canada
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Default 8" subwoofer

Ive been calculating this vented subwoofer using a 8" driver in Winisd

I want to keep the box as small as possible, the problem is winisd doesent take into account if the box has damping or not. Some other apps like JBL speakershop pro take it into acount, but im not sure how precise it is or how it will affect the box fs and the vent calculations... any ideas?

I would prefer doing it into winisd, it has better vent info and calculations
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Old 23rd November 2002, 10:37 PM   #2
f4ier is offline f4ier  Australia
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Have you tried winISD Pro? Enclosure quality factors are found under the "Advanced ->" button.

This thread might interest you

Also try Unibox and Subwoofer Simulator .

//----------
Taken from the Adire Audio version of LspCAD:

QA that is the Q-value due to damping materials in the box. The range of QA is 3-100. A box with moderate lining has a QA of about 30. A heavily stuffed box can have a QA of 3.

If the box is completely stuffed with damping material, the QA will decrease, but also will the virtual box volume increase with about 20% i.e. the driver unit will experience a larger box than Vb.

Stuffing -- Qa:
100% -- 3
50% -- 7
0% -- 15-30
//----------


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Old 23rd November 2002, 10:55 PM   #3
Ilianh is offline Ilianh  Canada
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Thanks for the reply,
well here, JBL speaker shop pro defines damping as
minimal, normal or heavy how do i work with that? in knowing how much poly fill to add or something...

that doesent help much, or is precision here basicly irrelevant?

because with this woofer, i get a 2 cuft box with normal damping...
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Old 23rd November 2002, 11:34 PM   #4
f4ier is offline f4ier  Australia
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Calculating the effects of fiberfill to a certain accuracy is actually possible, but acquiring the necessary data to fill in the equations is next to impossible. If memory serves me well, you'd need things like the number of fibers, compliance, mass, aerodynamic drag coefficients etc. This is why existing software settle for approximations.

Measuring the sub's performance while taking/adding more fiberfill is the best way. The next best thing is to design boxes based on someone else's measurements (keeping in mind of course the type of material and environmental conditions at the time the measurements were taken).

Google search for "Make a small box act like a larger one with polyester fiberfill" by Tom Nousaine. The page is currently unavailable, but if you click on the Cached link, the page should load with all the tables of measurements.

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Old 24th November 2002, 06:11 AM   #5
Ilianh is offline Ilianh  Canada
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ok, welli calculated evrything and started the project at 7:30 pm... finished at 11:30 pm...the glue isnt even totaly dry yet lucky me i had evrything i needed at home, as proper vents and conectors and stuff for the XO

i still have to cover it with something, maybe some veneer.

i tested it... and whoa.... this thing sounds awsome(with the mid/tweeter speaker not shown on pic, it usualy stays on top of the sub woofer),
about the best ive heard yet,
the system will have 2 woofers like this one and 1 mid/tweeter speaker on top of each woofer,

thats a rear/side pic of the sub, the front is not seen here
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File Type: jpg woofer.jpg (36.3 KB, 329 views)
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Old 25th November 2002, 04:15 AM   #6
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Man, not bad for 3 Hours! Does the bass have much extension? What type of Driver is it? I have several (read like 4 or 6!) 8" drivers sitting around and will probably test them on my sonotube thats slowly coming together. Usually I find 8" 'ers sound fine on music, but can be lacking on movies, however you do have quite a large volume there.
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Old 25th November 2002, 12:13 PM   #7
Ilianh is offline Ilianh  Canada
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heh, yhea
4 hours actualy.. but im lucky to have the needed tools.
the finishing will probably take longer... depending on what i choose...
yhea 8" drivers are really good for music.
its a driver i bought for very cheap in some surplus store, but its very good...measured it and did the box. 2 cuft is massive... one thing im worried about, i used a 2" port diameter, tuned at same fs as driver, and its around 1.8 inch long (not sure.. gotta check.. at school now) theoriticaly its fine, what im worried about is it's surface,

i'll maybe try to use 2 2" ports for a larger ports surface (you can see on the pic that this was my original plan)
gonna post more later
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Old 25th November 2002, 02:00 PM   #8
Ilianh is offline Ilianh  Canada
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i just read in one of my books that the port surface should be atleats 5 times smaller than the woofer`s cone surface.. how accurate is that.. and why is it that way?

is bigger better? or "size doesent matter, its how you use it that matters"
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