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Old 31st December 2002, 07:04 PM   #1
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Default Another newbie asking help from the masters...

Hi,

I decided to build new boxes for my home-theater with speakers my local store holds. According to specs it can be used in car applications as in home as well. Things is, when I try plot a box with WinIsd it gives me a small box perfect for a car but way too small for home. This is the speaker : http://www.maxspeakers.net/products/caliber/index.html

Just click on "MaxCaliber specifications" The speaker I want to use is the 12" 4ohm model CA-1275/4. If you click on the model number you have the response curves. If someone could help me get something at least 36" high still with good response it would be great!

Thank you!
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Old 31st December 2002, 08:48 PM   #2
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Your subs has a VAS of 68 liters, so all your box designs are going to be less than that or the woofer will think it's in free-air. The biggest sealed box I got had a Q of .5 and was 45 liters, 1.6 cu. ft. I don't know how to calculate the different alignments for a ported box but all the ported box volumes I got were around 30 or 25 liters, 1.0 cu. ft..

If you want to build a 36" tall box it will have to be pretty thin or a strange shape. Which brings me to ask; Why would you want a big box?
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Old 31st December 2002, 09:07 PM   #3
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Have you ever seen home boxes with a 12" woofer, a 5" midrange and a tweeter in a 22" high box? lol shouldn't be very pretty. Now what I could do is 1 chamber for the sub and another one for the rest. But wouldn't this affect the response of the woofer?
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Old 31st December 2002, 09:09 PM   #4
halojoy is offline halojoy  Sweden
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Default My calculation with WinIsd

Vas=68lit Fs=29Hz Qts=0.32
Gives: 17.5 lit / Qtc=0.707
30 lit gives Qtc=0.57
I use this online ISD:
http://www.ljudia.se/se/teknik/isd/
the first one is sealed, closed boxes, the second basreflex
-------------------------------------------------------
I would only be glad if a driver can be happy in a small box.
You can put a stand of some sort to get it up from floor.
-----------------------
The relation between Qts/Fs indicates it is more suited for a bassreflex, vented.
32/29 is almost 1.0 (I disregard the decimal comma; (multiply Qts with 100))
And that is typical for a Woofer suited for Vented box.

Those good for sealed have more like up to 2.0; or above 1.5
Example: Qts=0.50 Fs=25; and 50/25=2.0

Of course you can use it in Closed box, nevertheless
----------------------------------------------------------------

Optimum bassreflex for this 12" is, according to program
Vb=31.66 liter, gives Fb=36.75

I guess other can fill in with more views on this driver.

/halo
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Old 31st December 2002, 09:36 PM   #5
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Yep I want it to be ported. Those results are the ones I got from winIsd too. I think what I will do is build 2 sub-woofers and two other bookshelf sized speakers. Is it a good idea?
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Old 31st December 2002, 10:27 PM   #6
halojoy is offline halojoy  Sweden
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Quote:
Originally posted by DPW666
Yep I want it to be ported. Those results are the ones I got from winIsd too. I think what I will do is build 2 sub-woofers and two other bookshelf sized speakers. Is it a good idea?
Do you mean to use both subs, in same stereo system.
Or will you use those 2 subs in two different stereo systems.
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Old 31st December 2002, 11:19 PM   #7
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in the same system. Like if I had the fullrange boxes but with the subs separated
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Old 1st January 2003, 12:18 AM   #8
Ron E is offline Ron E  United States
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This speaker has a stiff suspension (low Vas) and it is probably intended for car audio use. Lucky for you, there is no hard rule for how large a box you can put a speaker in or how low you can tune.

Since you are wiling to give it some extra volume, there is no reason you can't use a so-called EBS (Extended Bass Shelf) enclosure. EBS alignments can have very good transient response. These have a larger box and lower tuning than the standard vanilla enclosure sized you get from a limited program like WinISD (which has a lot of dumb errors, BTW, so don't trust it). A good program, if you have Excel 2000, is the spreadsheet Unibox, by Kristian Ougaard.

In a pinch, WinISD Pro alpha will work. It has fewer errors than regular WinISD beta, but it still has a few. Vented box excursion was wrong, last I checked and there were a couple other things.

Back to the subject, a box 60Liters tuned to 28Hz gives a nice response shape and decent power handling, and your MaxSPL would be 110+dB from ~30Hz on up, which is decent. You will want to use at least a 4" port x 17.5" long, and a larger diameter (and longer) port or even a PR would be better.

You say you want a 36" tall enclosure, make your box 36" by whatever width and depth gives you the volume you want. If this results in a shape too skinny, who says you need to use all the box volume? Make a solid shelf halfway up, you will want to brace the cabinet anyway.

Have fun.
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Old 1st January 2003, 04:54 AM   #9
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Yeah this speakers is primarly intended for car use. My brother is using one of them in his car with a box he made and it sounds damn fine with a good amp. At first he was driving it with a cheapo 300watt pioneer amp and it sounded like sh*t. Then we tried with an amp more powerfull I don't remember the name but this time we were impressed. I think I'll go with with the box suggested on the site. 2 feet cubic at 34hz. Anyway for the price they are, even if I miss my shot it still won't be a big mess up. They are only 100$ CDN wich is about 65$ US.

Thanks for the suggestions! Keep them coming I still have 2 days before I can buy everything. Ho yes HAPPY NEW YEAR!
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Old 1st January 2003, 03:37 PM   #10
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Except for Ron E, everyone in this thread is far too concerned with WinISD's Optimal Enclosure recommendation.

I found WinISD all right for it's charting function. You are under no obligation whatsoever to use it's Optimal Enclosure.

As Thiele and Small, (of Thiele-Small parameters fame), pointed out, the ported box has a large number of perfectly satisfactory variations from the Optimal Enclosure Size. And WinISD's Optimal Enclosure Size is not the same as theirs, anyway.

I would put your woofer into a box that is 2.0 cu ft and tuned to 30 Hz. Below is a chart of your woofer in such a box and the "perfect" woofer designed for that box. Your woofer is in red, the "perfect woofer" is in green. Not much difference, is there?

I would include a 10% extra volume to account for the space your woofer takes up, the space the port takes up, and any bracing you might use. Such a box can have the following dimensions, (using 3/4" building material):

38" high
14" wide
10 3/8" deep

It should be pointed out that even a 10% difference in box size varies the response very little. Don't get concerned about finding exact percentages of volume things take up. You have plenty of room.

Make sure all joints are dealed up with silicone or construction adhesive. No leaks allowed.

A 3" diameter port should be 8 1/2" long. It might create port noise. A 3" diameter port with flares from Parts Express or Madisound would be better. Add an inch to the length. A 4" diameter port won't need flares, and should be 15 1/2" long. Noisewise, a 3" dia port with flares equals a 4' dia port without flares.

http://www.partsexpress.com/webpage....up_ID=143&so=2

www.madisound.com Catalog-Miscellaneous-Accessories.html

Your vent can be facing the front, back, top or sides. Even the bottom, if you use stands. You can use elbows, if the vent is too long to fit in the box. The vent opening inside the box should be clear of any obstruction or stuffing. You should put about an inch or so of stuffing around the inside walls of the box. Do not fill-that is a no-no for ported enclosures.

Good luck!!
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