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Need help from and DIY cab builders...

Discussion in 'Amps and Cabs [BG]' started by haujobb, Apr 17, 2005.


  1. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    I'm looking at building my own set of cabs, for a bottom I've been looking at different speakers in a 2x15 cab. It seems that the best setup is a pair of Eminence Kappa 15LF's, they go the lowest - -3 point of 47Hz - and have to highest Sensitivity - averages around 104 DB's.

    The thing that bugs me is that I'm getting these specs out of a pair of drivers that cost less than $150 each when drivers costing twice as much arent even comparing. Is it possible that I've made a typo somewhere or do these specs seem reasonable.

    BTW I'm using WinISD Beta, the Alpha version wouldn't run on my computer for more than 5 minutes at a time...
     
  2. Sidecar666

    Sidecar666

    Mar 27, 2004
    The type/construction of the enclosure and room you play in has alot to do with the depth and feel of bass. Just because a speaker lists a certain frequency response, doesn't mean it will hit that frequency. Plus, it doesn't mean it will sound good, either!
     
  3. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
  4. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    From what I see, I'd say they average 95db sensitivity. There is a big hump at 2k where they approach 104db but that's it; at 40hz or so they are lower yet. That's based on the graphs published at the Eminence site.
     
  5. illidian

    illidian

    Jul 2, 2004
    You probably don't want that big hump of a 9dB increase.

    Make the cab bigger, that should help.
     
  6. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    I was going by the graph generated by WinISD using two drivers in a 10 cu ft box with a tuning of 45 Hz...
     
  7. WinISD Alpha shows 99db and -3 db of 41hz. Something is wrong with that program you're using. Maybe the parameters are off.

    I want to clarify that there is a Kappa 15lf and a Kappa Pro 15lf, the latter of which is cast frame and is in the Avatar cabs.
     
  8. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    Was that for one or two drivers? What box size and port tuning did you use?
     
  9. Why does WinISD show such cracked out graphs for some drivers? Like if you put in the TS specs for Deltalite 2515's it shows you need a 46cu ft box tuned to 31hz....
     
  10. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    That's the correct cab size for 2 of those speakers in the "Optimal Flat alignment". WinISD beta defaults to that alignment automatically. It gives a -3dB point of 28Hz.

    It was spaced out figures like that that made me go buy books and learn how to calculate these things myself. The cab volume is based on formulas and tables that are based on the speakers Thielle Small parameters. Once I understood it all, it turns out that some speakers do indeed need some wierdo sized cabs.

    These same drivers in the SBB4 alignment would have a cab that's half the size. The -3dB point will be higher though, 36Hz. the 10" deltalites are pretty good, but I'm not a fan of the 12's or 15's. They're better suited for PA.

    Back to the Kappa 15LF's - WinISD beta will tell you 4.6cu.ft per driver, tuned to 41Hz and -3dB at 43Hz (Optimal Flat alignment). Personally I'd go 3.62cu'ft per driver tuned to 39Hz for a -3dB point of 47Hz (SBB4 alignment). You won't notice the missing 3Hz, the cab will be much smaller, and SBB4 has a much better transient response (is faster at reproducing notes). It also has better excursion characteristics when pushed hard.
     
  11. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    I have 2 Kappa 15 LF drivers loaded in 3.62 cubic ft (SBB4 alignment). They rock on lows. Pretty shy on the highs and upper mids so you'll need something else to fill in the gaps... They sound much better than they're cost would lead you to believe.
     
  12. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    yeah they don't do anything above 1.5K. A typical tweeter (if you use one) will cut in at 3K so you might have a gap in the freq response. Wether or not it's a problem depends on a lot of things - the player's preference, wether or not there's another cab taking those frequencies. A midrange driver is another possibe solution.

    You gotta love the tweak factor with DIY :)
     
  13. 2 drivers, 10cu ft., 45 hz.
     
  14. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    Hmmmmmmm, maybe I'll take another crack at the Alpha version, if that fails can anyone name some other programs that work good?
     
  15. Funkengrooven

    Funkengrooven Turn it down? You gotta be nuts!!

    I have the winISD beta version that runs very well.
    email me off list and I'll send it to you. or I can post if if someone will clue me as to how....

    The parameters for building your own cabinets are as follows.

    1, ) What size are you willing and ABLE to carry that includes what kind of vehicle you have available. a great cabinet that you cannot move is useless

    2,) How many and what type of speakers you want to use.
    I prefer JBL 15's and 18's ( :hyper: JBL Fanatic!!) but that is just me, I would never own an Eminence.

    3,) how skilled are you (or your buddies) at wood working. Designing a cabinet you can't build is also useless.

    4,) How much time and money are you willing to invest.
    in wood, drivers, tools, fasteners (nails, glue, screws etc.) accessories (like corners, edging, grill cloth/frames etc.)

    At this point and any forseeable point I only play through my own cabinets (with only one exception and that was someone elses home built cabinet, they did a fine job too) . I can send out pictures if you like and am willing to help you through any rough spots.

    Take your time and measure 3 or 4 times before you put saw to wood and you will have a kick-ass cabinet.
     
  16. My spread sheet has the math for SBB4, QB3, Flat alignments already worked out.

    It is a simple matter to sort the spread sheet by box volume, F3, or whatever thrills you. Once sorted, you can make a determination as to what will suit your needs for size and tuning. You can plug these drivers into WinISD if you want to see graphs.

    I can tell you right now that 10 cubic feet is a monster to move around.
     
  17. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    I'm starting to get some normal numbers out of WinISD, still I'm getting better graphs from a Kappa 15LF than a Kappa Pro 15LF. Am I doing something wrong or is this correct?
     
  18. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    If you mean you're getting the LF to go lower than the Pro, yep that's correct. You're probably assuming the Pro speaker should be "better", and it probably is for PA which is what a lot of raw drivers are made for. The Pro goes a lot higher (4K) than the LF (1.5K) and has a higher sensitivity. However for bass, the LF seems a better choice.
     
  19. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    So I'm thinking I'm gonna go with two Kappa 15LF in an 8 cu. ft. ported box. I realise that that is a huge box, but I'm still young, I have alot of helpers and I've always been a firm believer that you need a big box for big bass...
     
  20. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Have you considered 2 seperate cabs? One of these days you're going to have to move it without help, and probably up a couple of flights of narrow stairs with drunks in the way.