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Old 12th March 2013, 11:25 AM   #21
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No, I think that's too small with high resonant frequency, bell curve type and high Qtc. A bigger one is better. Look at the Qtc instead that you need to start. To help you, look at the Qtc color picture from this French website. (1) First you chose Qtc, (2) second the calculations gives you the ideal internal volume for your loudspeaker.
Enceinte accoustique close

If you want you can use the software bellow, for that matter.
WinISD - LinearTeam
UniBox by Kristian Ougaard UniBox - Unified Box Model for Loudspeaker Design
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Old 12th March 2013, 03:40 PM   #22
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You can make the sub enclosure of the bass reflex type having either shorter ports and a less diameter, like the ones you posted the link, but in this case it's good you know that some high speed air shuffle will make some noise at higher SPL output. No problem at comfortable listening levels. You can design them to the side or back out from direct listening position.
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Old 12th March 2013, 05:00 PM   #23
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Shorter ports such as this SVS PB12 subwoofer??
I imagine a properly tuned 15" woofer would eat most 12" subs for breakfest.
Perhaps 2-3 ports?SVS PB12-PLUS 12 2300W Ported Subwoofer (Black Oak) - $1,849.00 ...
Clearly its a compact sub, only 25 long , 19" high

Last edited by Kingnoob; 12th March 2013 at 05:20 PM.
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Old 12th March 2013, 05:56 PM   #24
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No, no. Think like this. Suppose you are going with a ported system (BR). Then if you are using the ports you linked on post #13, shorter ports will give you a smaller diameter, with 3x ports large like those in your post #23 you will have several meters in length for such a FB in this case (post #2).

Let's say for the same alignment (VB = 130.5 L/FB = 16.9 Hz) that you buy a Precision Port 3" Flared Port Tube Kit
you need to use a 11" to 1ft in lenght. That's why you should manufacture your own tube/port with mx. length permited by max speaker dimension, so that diameter can be maximum (1 or two ports) for the same tunning frequency.
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Last edited by Inductor; 12th March 2013 at 06:20 PM. Reason: alignment
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Old 12th March 2013, 06:30 PM   #25
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Let's make another alignment case.
STEREO INTEGRITY HT 15, VB = 130.5 L, FB = 20.0 Hz
Using this port Precision Port 4" Flared Port Tube Kit 268-352 you will need about 14" to 15" because it's 4" diameter (constraints) and the tunning frequency is 20Hz.
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File Type: jpg STEREO INTEGRITY HT 15, VB = 130.5 L, FB = 20.0 Hz.jpg (90.6 KB, 69 views)
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Old 12th March 2013, 06:49 PM   #26
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Quote:
Originally Posted by Inductor View Post
Let's make another alignment case.
STEREO INTEGRITY HT 15, VB = 130.5 L, FB = 20.0 Hz
Using this port Precision Port 4" Flared Port Tube Kit 268-352 you will need about 14" to 15" because it's 4" diameter (constraints) and the tunning frequency is 20Hz.
why does Stereo integrity suggest tuning freq 22hz?
I am still rather confused to tuning ported subs

Last edited by Kingnoob; 12th March 2013 at 07:07 PM.
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Old 12th March 2013, 08:41 PM   #27
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default tuning freq on win scp was also about 21.9-22 hz bizzarre
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Old 13th March 2013, 01:53 AM   #28
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Quote:
Originally Posted by Kingnoob View Post
why does Stereo integrity suggest tuning freq 22hz?
I am still rather confused to tuning ported subs
I don't know, but certainly it's a bad alignment.
5ft = 141.58L
As they say Ported = 5 ft^3 tuned to 22 Hz For 5ft you will need a 20Hz tunning. Again that's relative, after you are in the process you might change tunning as you like. But if you do not simulate before you build I am sure you will build or attract a... disaster. Also very important, the alignments for car are completely different from alignments in room or audiophile because of many variables. A room gain can be between 0.5-2dB/octave@200Hz and in a car being between 8 and 11dB, just as a crude idea.

There's nothing confusing after you start using the simulation software I linked twice for you on post #6 and post #21. They have variables for port dimensions
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Old 13th March 2013, 04:13 AM   #29
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Quote:
Originally Posted by Inductor View Post
I don't know, but certainly it's a bad alignment.
5ft = 141.58L
As they say Ported = 5 ft^3 tuned to 22 Hz For 5ft you will need a 20Hz tunning. Again that's relative, after you are in the process you might change tunning as you like. But if you do not simulate before you build I am sure you will build or attract a... disaster. Also very important, the alignments for car are completely different from alignments in room or audiophile because of many variables. A room gain can be between 0.5-2dB/octave@200Hz and in a car being between 8 and 11dB, just as a crude idea.

There's nothing confusing after you start using the simulation software I linked twice for you on post #6 and post #21. They have variables for port dimensions
+1 I AGREE
Confused me also & didn't make since I swore those spec's didn't make any since.
Tuning above FS didn't make since to me... cuz Sub falls off below FS.
so 18-16 hertz wud be best for tuning....

Is ported better in a small room? Or sealed 12.5' x 13' room

Last edited by Kingnoob; 13th March 2013 at 04:32 AM.
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Old 13th March 2013, 11:53 AM   #30
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I don't know, I can not predict that. You can go perhaps to the next chapter on room acoustics and calculators. You can read, test and simulate I guess.
By the way when you mention your room you forget the most important measurement the height of the room. Also important are the type of construction and sound absorption materials like windows and carpets in percentage of the area/side. Example: a sound studio is different from a bathroom.
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