The following are the specs for a sub box i've found. Is it possible to find what frequency they are tuned for? If so, could someone do that for me and post it?
Two 4"x4" Round Port Tubes
Dimensions: 16.5"(W) x 12"(H) x 14 3/4"(D)
Mounting Depth: 6 1/2"
Diameter of hole: 11"
Total air space: 1.20 Cubic Ft.
THANKS GUYS
Replies (7)
swez on 12/29/2004 18:56:09
Yes, it's possible to get a pretty close number on the tuning specs you can expect from this box.
What is the length of each port?
Swez
danielm87 on 12/29/2004 21:48:59
The ports are 4 inches in diameter and 4 inches deep.
I guess those people like simplicity.
Thanks for the help Swez. Barely missed ya in the chat room, i tried to answer the Bat Call earlier, but i had to run to church with the folks.
/```*Daniel*```\
swez on 12/30/2004 05:51:34
Hummm, the larger the diameter of the port, the longer it has to be. Especially in a small enclosure.
Ran your numbers in a port caluculator and noted that this box, with that size port diameter, your PTF (Port Tuned Freq.) is closer to 52 Hz. Not good! It would be better to plug the ports and run this one as a sealed box, depending on the sub used.
Note: Have a look at your sub while playing some good low tracks. Chances are good that this sub will sound fine at upper bass frequencies, but as the notes get lower, the cone will "unload" (suspension will lose control) and sound pretty bad at <45 Hz.
Swez
PS Is this a ported or Bandpass enclosure?
danielm87 on 12/30/2004 08:52:45
Wow, thats a shock. I had a box from the same company with those ports, and my subs sounded terrible in there, like you said, only 45-55 Hz sounded good in that box, otherwise it was distorted like crazy.
Its a BP enclosure.
Daniel
Victor on 12/30/2004 10:02:14
you can tune the ports to a lower freq... wonder how.. ?
I cant say by how many Hz exactly ( it depends on the length of the straws and the volume they occupy ) but the tuning shall definitely be lower..
I have tried this and it works.. some of you may have read this on some web sites too..
stuff the ports with straws ( drinking plastic straws ) such that 1" or more of the straws remain out side the ports. this way you will actually increase the length the air travels in the ports .. and in turn tune the port to a lower frequency..you can try pulling and pushing the bunch of straws in and out so that u can tune it to the kind of sound you like..
Try it..
Victor...
danielm87 on 12/30/2004 10:16:28
hmm, very interesting. I'm gonna run down to wal-mart and grab a few packs of straws and try it out on one of my boxes.
Thanks Vic.
swez on 12/30/2004 10:38:48
Interesting idea... a pile of soda straws for port tuning. Am wondering if port velosity will be high enough to make the straws whistle?
You can use PVC piping to lengthen the ports both inside and outside the box you have mentioned. That will drop your PTF to a lower frequency and make the subs sound better at lower frequencies.
I ran some numbers and it looks like a pair of 10" long port inserts will get you down to 35 Hz. If you pull the original ports and inset new ones, (4.0" ) make sure to allow a min of 4" from the adjacent wall inside the box.
Or, if you just use the ports as is, and slide a PVC insert into them, will need to know the actual I.D. of the pipe used to recalculate the proper length. As we go smaller in ID, the pipe length needed will also decrease as we go lower in PTF.
Swez
Two 4"x4" Round Port Tubes
Dimensions: 16.5"(W) x 12"(H) x 14 3/4"(D)
Mounting Depth: 6 1/2"
Diameter of hole: 11"
Total air space: 1.20 Cubic Ft.
THANKS GUYS
Replies (7)
swez on 12/29/2004 18:56:09
Yes, it's possible to get a pretty close number on the tuning specs you can expect from this box.
What is the length of each port?
Swez
danielm87 on 12/29/2004 21:48:59
The ports are 4 inches in diameter and 4 inches deep.
I guess those people like simplicity.
Thanks for the help Swez. Barely missed ya in the chat room, i tried to answer the Bat Call earlier, but i had to run to church with the folks.
/```*Daniel*```\
swez on 12/30/2004 05:51:34
Hummm, the larger the diameter of the port, the longer it has to be. Especially in a small enclosure.
Ran your numbers in a port caluculator and noted that this box, with that size port diameter, your PTF (Port Tuned Freq.) is closer to 52 Hz. Not good! It would be better to plug the ports and run this one as a sealed box, depending on the sub used.
Note: Have a look at your sub while playing some good low tracks. Chances are good that this sub will sound fine at upper bass frequencies, but as the notes get lower, the cone will "unload" (suspension will lose control) and sound pretty bad at <45 Hz.
Swez
PS Is this a ported or Bandpass enclosure?
danielm87 on 12/30/2004 08:52:45
Wow, thats a shock. I had a box from the same company with those ports, and my subs sounded terrible in there, like you said, only 45-55 Hz sounded good in that box, otherwise it was distorted like crazy.
Its a BP enclosure.
Daniel
Victor on 12/30/2004 10:02:14
you can tune the ports to a lower freq... wonder how.. ?
I cant say by how many Hz exactly ( it depends on the length of the straws and the volume they occupy ) but the tuning shall definitely be lower..
I have tried this and it works.. some of you may have read this on some web sites too..
stuff the ports with straws ( drinking plastic straws ) such that 1" or more of the straws remain out side the ports. this way you will actually increase the length the air travels in the ports .. and in turn tune the port to a lower frequency..you can try pulling and pushing the bunch of straws in and out so that u can tune it to the kind of sound you like..
Try it..
Victor...
danielm87 on 12/30/2004 10:16:28
hmm, very interesting. I'm gonna run down to wal-mart and grab a few packs of straws and try it out on one of my boxes.
Thanks Vic.
swez on 12/30/2004 10:38:48
Interesting idea... a pile of soda straws for port tuning. Am wondering if port velosity will be high enough to make the straws whistle?
You can use PVC piping to lengthen the ports both inside and outside the box you have mentioned. That will drop your PTF to a lower frequency and make the subs sound better at lower frequencies.
I ran some numbers and it looks like a pair of 10" long port inserts will get you down to 35 Hz. If you pull the original ports and inset new ones, (4.0" ) make sure to allow a min of 4" from the adjacent wall inside the box.
Or, if you just use the ports as is, and slide a PVC insert into them, will need to know the actual I.D. of the pipe used to recalculate the proper length. As we go smaller in ID, the pipe length needed will also decrease as we go lower in PTF.
Swez
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