My DIY cab project what problems do i have to look out for ?

Discussion in 'Amps and Cabs [BG]' started by lewibassist, Jan 28, 2005.

  1. Hiya i am currently building a bass cab for my A.S level tech major project. I am basing the design around the same sizes as a Aguilar GS-112 and i have a Eminence Delta 12 at 8 ohms to put in there. I have no experience with cab building and i wounder if there any problems i will come up against. I tried to match the aguilar speaker as close as i could so i can avoid the math side of the building. I tried my best to match the port hole size up as accurate as possible. Would it matter where the ports were just as long as they the right size ?. Any tips you can give me on anythin to with cab building will be much appreciated :)
  2. CrackBass


    Aug 10, 2004
    hey man, you can't avoid the math. you might get lucky but odds are you won't have a cab living up to it's potetial. buy the speaker sytems book at radio shack for like ten bucks. it's not really that hard to figure out for the type of box you're building. use 3/4" plywood for material, preforably voidless cabinetgrade. (although for a cab that size you might get by with 1/2") ports can be placed almost anywhere but they need to be the right size and length. pvc can work well on the cheap side. you might want to get some help with your basic carpentry skills if this is your first endevour.

    design first! then start building.

    good luck
  3. Hey cheers for the reply. I have a pic of the progres its coming together pretty well.


    I will have to get one of those books. I am also confused about how to connect the speaker to a jack input. Do i need anyhtin inbetween the speaker and the jack input ?
  4. CrackBass


    Aug 10, 2004
    if you are going to run a tweeter the you will need a crossover. if you are going to run just the 12 then you can run straight to the jack.
  5. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
  6. CrackBass


    Aug 10, 2004
    oh another thing. since you have constructed the cab already, you can use some baffling material such a fiberglass insulation or a variety of other things to "adjust" the airspace. the book will explain it.
  7. The cab is only screwed together its only temperary. So if i need to make any adjustmants it can be easily done. Ive heard that some cabs can rattle and make unwanted noises. How can i stop this from happening ?. And what are the main reasons for the noises to happen ?
  8. CrackBass


    Aug 10, 2004
    you need to make sure everything is glued together solid and then caulked from the inside, also what kind of joints do you have on your corners. that is where your cab will come apart if not properly constructed. if you put it together right your cab should not rattle.
  9. Sundogue


    Apr 26, 2001
    Wausau, WI
    Make sure when you finish it up that you glue and screw it together. Also, you should use some 1x1 strips to also glue and screw in place for reinforcement of all joints.

    You might also want to employ cross bracing which will minimize the panels from resonating too much.
  10. Nice looking cab. From my limited experience in modifying my own cabs I can tell you that internal bracing can add a great deal of clarity.
  11. Thanks for all the help guys. I will be glueing and screwing the sides together. I will be using basic but joints as my carpentary skills are very limited.
  12. Petebass


    Dec 22, 2002
    QLD Australia
    To get the best out of the Delta 12, it like a cab that has an internal volume of 3.443cu.ft (97.5litres), and the box needs to be tuned/ported to 52Hz.

    Seeing you've already built the cab, and from the pic it looks smaller than 3.4cu.ft, we'll need to recalculate the tuning to suit. What are the dimensions of the cab?
  13. jondog


    Mar 14, 2002
    NYC metro area
    The picture looks nice. If you're doing this for a class, I would think learning the math would be a good idea - it's probably not a class designed to teach you how to reverse engineer existing products (unless you go to Behringer Tech) :)
  14. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    You aren't going to get a good result copying the port dimensions of the Aguilar cab when you are using a different speaker, the Delta 12. Their t/s parameters aren't the same at all.

    You can't avoid doing the math if you want this to turn out well.
  15. The dimensions of the cab are 14"H x 19"W x 18"D hope this helps. I am doing this for an A.S level tech project.
  16. Ports work best when they are at least one port diameter away from any obstruction (cabinet walls, speaker). If you add damping material make sure you don't block the ports.
  17. Petebass


    Dec 22, 2002
    QLD Australia
    That makes it a 77 litre cab (2.719cu.ft). I suggest you tune it to 55Hz.

    I see you've already cut 2 holes for ports. They look like they're about 3" in diameter. How's my guess?

    If they are, you'll need to get some tubing and make them 2.4' in length to get 55Hz. At the moment the cab is tuned at about 66Hz, too high bass.
  18. Spector_Ray


    Aug 8, 2004
    Don't use fiberglass insulation because of it's tendencies to break apart and with the bass frequencies and airflow, that insulation will rattle apart to nothing in short order. What I would suggest you use is Polyfil material. It's the type of filling used to make pillows and such. It can be bought at any fabric store as well as your Wal-Marts and the like.
  19. Petebass


    Dec 22, 2002
    QLD Australia
    Before we get too much into acoustic stuffing, I forgot to mention that the cab won't need any. Sorry guys. The whole thing started when I incorrectly announced the box size to be 90 litres. It turns out my T/S paramater data was incorrect (Bgavin if you're reading this, your spreadsheet needs some fixing. I think Eminence may have changed the speaker a bit).

    After fixing them, the correct cab size turns out to be 44 litres (1.56cu.f) at 51Hz, so the existing cab is actually a bit to large. For this driver, the larger cab didn't really affect the overall performance and with the adjusting the tuning, should be OK as is.
  20. Scott D

    Scott D

    Apr 21, 2003
    Minneapolis, MN

    Polyfill is only really used in a sealed enclosure.