Closed Thread
Results 1 to 10 of 10

Reload Thread: 4th order port/chamber question

  1. #1
    Beatin''s Avatar
    Beatin' is offline CarAudio.com Elite



    Join Date
    Nov 2012
    Location
    MI
    Posts
    986
    Post Thanks / Like
    Mentioned
    2 Post(s)

    4th order port/chamber question

    is it possible to have the front chamber also be it's own port?

    Let's take a 1.66 cube chamber with the ID of 6.5in x 15.5in x 28.5in

    Let's say the port opening is 6.5x15.5 and the chamber/port is 28.5 deep. winISD shows that such a chamber will be ported to about 66.25hz.

    Is this possible? Does this actually work without a dedicated port? What if you put the 6.5x15.5 opening on the side of the chamber length-wise that goes to 28.5in, will the port still work?



    All day I'm clippin'
    voltage be dippin'
    I don't give a damn,
    cause my trunk always hittin'!

    creating a proper sound wave. Step one, turn it up until clipping. Step two, done.




  2. #2
    SounDrive's Avatar
    SounDrive is offline SounDrive RCA



    Join Date
    Apr 2013
    Location
    Lebanon & Knoxville, TN
    Posts
    1,928
    Post Thanks / Like
    Mentioned
    2 Post(s)

    Re: 4th order port/chamber question

    Doesn't sound right. You don't want a sub to be directly in front of a port, ever.



    Owner, SounDrive Custom RCAs (and other cables)

    Find us on Facebook!

  3. #3
    Beatin''s Avatar
    Beatin' is offline CarAudio.com Elite

    Threadstarter


    Join Date
    Nov 2012
    Location
    MI
    Posts
    986
    Post Thanks / Like
    Mentioned
    2 Post(s)

    Re: 4th order port/chamber question

    Quote Originally Posted by Tenacious. View Post
    Doesn't sound right. You don't want a sub to be directly in front of a port, ever.
    The chamber IS the port. I think it's called a "clamshell".



    All day I'm clippin'
    voltage be dippin'
    I don't give a damn,
    cause my trunk always hittin'!

    creating a proper sound wave. Step one, turn it up until clipping. Step two, done.

  4. #4
    bbeljefe's Avatar
    bbeljefe is offline Premium Member bbeljefe is a Supporting Member of the forum!



    Join Date
    Jul 2013
    Location
    Shreveport, LA
    Posts
    1,788
    Post Thanks / Like
    Mentioned
    21 Post(s)

    Re: 4th order port/chamber question

    As was mentioned, it isn't useful to have a speaker load directly into a port. Likewise, it isn't useful to have a port that exceeds the piston area of your driver(s). In this case, since the drivers are also loaded into Fb, there is no danger of damage but... there will also be no appreciable benefit.

    That said, it will change the tuning of the cabinet but only as much as, say, repositioning the cabinet in the cabin of the vehicle.

    You should refigure Fb and use a port that's about 25% of the piston area you have. Or, ~16 sq in per cubic foot of airspace.

    The exception to that rule is the wave transmission line, in which the enclosure is essentially one long port that equals the Sd of the driver(s).




  5. #5
    SounDrive's Avatar
    SounDrive is offline SounDrive RCA



    Join Date
    Apr 2013
    Location
    Lebanon & Knoxville, TN
    Posts
    1,928
    Post Thanks / Like
    Mentioned
    2 Post(s)

    Re: 4th order port/chamber question

    Quote Originally Posted by bbeljefe View Post
    As was mentioned, it isn't useful to have a speaker load directly into a port. Likewise, it isn't useful to have a port that exceeds the piston area of your driver(s). In this case, since the drivers are also loaded into Fb, there is no danger of damage but... there will also be no appreciable benefit.

    That said, it will change the tuning of the cabinet but only as much as, say, repositioning the cabinet in the cabin of the vehicle.

    You should refigure Fb and use a port that's about 25% of the piston area you have. Or, ~16 sq in per cubic foot of airspace.

    The exception to that rule is the wave transmission line, in which the enclosure is essentially one long port that equals the Sd of the driver(s).
    I've always heard to start with around half of the cone area of the drivers for port area being used when making a 4th order, but I'm not sure how accurate of a figure that is, but I believe it's what Ranger was using and he hit some pretty impressive numbers and had pretty good response, too.

    ---------- Post added at 10:55 AM ---------- Previous post was at 10:55 AM ----------

    Quote Originally Posted by bbeljefe View Post
    As was mentioned, it isn't useful to have a speaker load directly into a port. Likewise, it isn't useful to have a port that exceeds the piston area of your driver(s). In this case, since the drivers are also loaded into Fb, there is no danger of damage but... there will also be no appreciable benefit.

    That said, it will change the tuning of the cabinet but only as much as, say, repositioning the cabinet in the cabin of the vehicle.

    You should refigure Fb and use a port that's about 25% of the piston area you have. Or, ~16 sq in per cubic foot of airspace.

    The exception to that rule is the wave transmission line, in which the enclosure is essentially one long port that equals the Sd of the driver(s).
    I've always heard to start with around half of the cone area of the drivers for port area being used when making a 4th order, but I'm not sure how accurate of a figure that is, but I believe it's what Ranger was using and he hit some pretty impressive numbers and had pretty good response, too.



    Owner, SounDrive Custom RCAs (and other cables)

    Find us on Facebook!

  6. #6
    Buck's Avatar
    Buck is offline always low Buck is a Supporting Member of the forum!



    Join Date
    May 2008
    Location
    Nashville
    Posts
    18,378
    Post Thanks / Like
    Mentioned
    254 Post(s)

    Re: 4th order port/chamber question

    Quote Originally Posted by bbeljefe View Post
    As was mentioned, it isn't useful to have a speaker load directly into a port. Likewise, it isn't useful to have a port that exceeds the piston area of your driver(s). In this case, since the drivers are also loaded into Fb, there is no danger of damage but... there will also be no appreciable benefit.

    That said, it will change the tuning of the cabinet but only as much as, say, repositioning the cabinet in the cabin of the vehicle.

    You should refigure Fb and use a port that's about 25% of the piston area you have. Or, ~16 sq in per cubic foot of airspace.

    The exception to that rule is the wave transmission line, in which the enclosure is essentially one long port that equals the Sd of the driver(s).
    T-line's aren't exactly Sd, they can be bigger. They have to be at least Sd so no loading/pressurization occurs. For a 4th order you don't want to exceed your piston area in most cases (not even close), more like 1/2 total Sd.



    Alpine - ASE (local) - Batcap - C&D Tech - CT Sounds - DC - eD - Excessive Amperage - Rainbow

  7. #7
    Beatin''s Avatar
    Beatin' is offline CarAudio.com Elite

    Threadstarter


    Join Date
    Nov 2012
    Location
    MI
    Posts
    986
    Post Thanks / Like
    Mentioned
    2 Post(s)

    Re: 4th order port/chamber question

    So it's better to just port the chamber properly with a 6 inch round port for example?



    All day I'm clippin'
    voltage be dippin'
    I don't give a damn,
    cause my trunk always hittin'!

    creating a proper sound wave. Step one, turn it up until clipping. Step two, done.

  8. #8
    Buck's Avatar
    Buck is offline always low Buck is a Supporting Member of the forum!



    Join Date
    May 2008
    Location
    Nashville
    Posts
    18,378
    Post Thanks / Like
    Mentioned
    254 Post(s)

    Re: 4th order port/chamber question

    Quote Originally Posted by Beatin' View Post
    So it's better to just port the chamber properly with a 6 inch round port for example?
    Yes. With a port like that, it's sealed. That chamber does resonate according to 1/4 wave but it would be really high where it wouldn't effect the subs, it'd have to be really deep.

    For a "port", you have to have separate airspace based on what you were saying because only with the combo of the air and port does the tuning work correctly.



    Alpine - ASE (local) - Batcap - C&D Tech - CT Sounds - DC - eD - Excessive Amperage - Rainbow

  9. #9
    bbeljefe's Avatar
    bbeljefe is offline Premium Member bbeljefe is a Supporting Member of the forum!



    Join Date
    Jul 2013
    Location
    Shreveport, LA
    Posts
    1,788
    Post Thanks / Like
    Mentioned
    21 Post(s)

    Re: 4th order port/chamber question

    Agreed, but in the interest of brevity I didn't go into a dissertation on t-lines. But actually, some driver loading is beneficial in some instances, depending on the compliance of the driver and to keep it from exceeding xmax.

    T-lines are about as varied as personalities.




  10. #10
    bbeljefe's Avatar
    bbeljefe is offline Premium Member bbeljefe is a Supporting Member of the forum!



    Join Date
    Jul 2013
    Location
    Shreveport, LA
    Posts
    1,788
    Post Thanks / Like
    Mentioned
    21 Post(s)

    Re: 4th order port/chamber question

    [QUOTE=Tenacious.;8453495]I've always heard to start with around half of the cone area of the drivers for port area being used when making a 4th order, but I'm not sure how accurate of a figure that is, but I believe it's what Ranger was using and he hit some pretty impressive numbers and had pretty good response, too.[COLOR="Silver"]

    ---------- Post added at 10:55 AM ---------- Previous post was at 10:55 AM ----------

    Depends on the power and the displacement of the driver's cone.




Closed Thread

Similar Threads

  1. 2 sa 12's 4th order port
    By ryanrj828 in forum Enclosure Design & Construction Help
    Replies: 7
    Last Post: 08-10-2013, 09:57 AM
  2. 4th order bandpass ported chamber question
    By DFW40 in forum Enclosure Design & Construction Help
    Replies: 5
    Last Post: 12-31-2012, 01:53 AM
  3. Need help with 4th order ported thru arm rest
    By sacking74 in forum Enclosure Design & Construction Help
    Replies: 3
    Last Post: 04-06-2010, 12:01 AM
  4. 4th order port question
    By oldschoolboomer in forum Enclosure Design & Construction Help
    Replies: 22
    Last Post: 06-01-2009, 03:43 PM
  5. 3 subs ported or 2 4th order jbl's
    By FOSGATE JOE in forum Subwoofers
    Replies: 14
    Last Post: 11-01-2006, 09:51 AM

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may post attachments
  • You may edit your posts
1e2 Forum