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Opinions on cab design

Discussion in 'Amps and Cabs [BG]' started by Skorzen, Dec 19, 2002.

  1. Skorzen


    Mar 15, 2002
    Springfield MA
    I put to gether this design for a cab, and was wondering what the people out there with more expirience thought about it. Ideas, criticism whatever. I used WinISD to get the numbers.
  2. Skorzen


    Mar 15, 2002
    Springfield MA
    Here is the plot generated by WinISD

  3. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    sounds HEAVY
  4. Skorzen


    Mar 15, 2002
    Springfield MA
    Yeah true, I was planning on putting it os casters, but I don't think it would way as much as a 6 or 8 10. But as always I could be wrong.
  5. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Looks pretty cool to me, but I think Id probably go with a seperate cab for the mid drivers.

  6. Skorzen


    Mar 15, 2002
    Springfield MA
    Fixed a couple misprints in the plans added depth specs ect.. See first post.
  7. geshel


    Oct 2, 2001
    Given a quick look, I'd say you'll need more vent area on the bottom cab. 1" is going to be too narrow and will probably start huffing and interfering with the resonance when those 12s get moving.

    I just plugged the latest specs from the Eminence website into WinISD, and I get a pretty different curve for the Deltas. If you used the specs that came in the WinISD database, I've found they're usually out of date.

    Would you put any high-pass filter on the Betas? They won't handle any power below 60Hz in that arrangement (if you get the WinISD PRO beta, it'll plot max power handling / sound pressure given excursion limitations).
  8. That would be the first thing I'd add would be a high pass on the 8's.
  9. My only suggestion would be the width. If you do decide to stack it, it'd look incongruous.

    here are the dimensions of some popular 410's
    25"W X 25"H X 16.5"D
    SWR (GIII):
    23"W x 25.25"H x 18.375"D
    Eden XLT (and T's for width):
    23"W x 23"H x 18.5"D
    Ampeg (HLF):
    24W x 30 x 19
    Ampeg (HE)
    24W x 25 x 16
    Aguilar (GS)
    22.50"W x 28.25"H x 16.625"D

    Overall, i love the design, especially the low shelf!

    Good luck and KEEP US INFORMED!:)
  10. oh, and if you plan on keeping it one cab, making a rock back cab (think: ampeg 810) would make it moch more managable.

    Good luck!
  11. First, consider splitting the cab. You will find this amount of weight and sheer size (10.2+ cubic feet) is terrible to move. If you make this out of 3/4" MDF, the empty cab without bracking will weigh 100+ pounds. I figure 29 square feet of material just for the panels. Bracing is extra, as will be interior walls. Figure 48 pounds for 4 drivers, grille, metal hardware, port material. You are looking at 200 pounds.

    Stairs are not your friend.


    A passive crossover will still work with a connecting cable between the two cabs. If you are bi-amping a Speakon with pair #1 for the Lows and pair #2 for the Highs will work fine.

    The Delta 12LF is a high Qts (0.42) driver similar to the Magnum 15LF. Tuning the cab accurately will be your primary concern. I used the latest numbers from Eminence (PDF) and got quite a different result. Eminence has entirely revamped their driver line, and the WinISD database is all but useless. I keep all the Eminence data in my spread sheet, including a date when entered.

    Optimal flat response is 3.28 cubic feet at 43 Hz, with f3 at 42 Hz. Optimal SBB4 transient response (tight bass) is 2.29 cubic feet at 45 Hz, f3 at 48 Hz.

    Group delay numbers are 12msec for SBB4 and 16 msec for Flat.
  12. Skorzen


    Mar 15, 2002
    Springfield MA
    Thanks for the input, I was planning on putting some kind of crossover in there, but have not bee able to find much info on them. If any of you know of somewhere I can get some basic info on design ect that would be great. also I was looking at some prefab crossovers and was wondering if the power ratings on them were more ridged? I know alot of people contend that you should supply a speaker with 2X it's rated rms, and was wondering if that was safe with a crossover? It seemed to like it would not be, but I don't really know much about the subject so input is appreciated.
  13. Skorzen


    Mar 15, 2002
    Springfield MA
    one other thing, how hard would it be to add an L pad to a prefab crossover? and how would it be done?
  14. geshel


    Oct 2, 2001
    You could probably put a simple first-order high-pass on there, which would just be a capacitor in series with the two 8s. Here's a chart:


    that gives simple values. It should work fine, you don't have to be too exact. Oh, I see the high-pass table doesn't go down very low. The good thing is for first-order (6dB / octave), you can just scale the capacitor values appropriately. A 250Hz filter cap would be twice as large (OK, it goes the other direction :) ) as the 500Hz one.

    You might just want to crossover the 8s up a bit higher, and make their box sealed. It'll keep things simpler and maybe sound better. I'll semi-arbitrarily pick 250Hz - if you want to change it you should be able to figure out the new values given the info here.

    So, a simple high-pass on the Betas (4 ohms together, right?) at 250Hz would be 160uF. You'll need NON-POLARIZED electrolytic capacitors for this. They are here


    on Parts Express's web page. You can use a 150uF (will raise the freq. slightly) or get two 80s and put them in parallel with each other (piggyback them - capacitors add in parallel, inductors add in series).

    You could get a pre-made subwoofer crossover set, (about $32 at PE), but most of that cost (the inductors) is for the low-pass, and I don't think you should put a low-pass on the Deltas, at least initially - I'd just leave them full-range.

    PE only seems to have one high-power mono 4-ohm L-pad


    You can wire this in between the crossover and the Betas, if you want level control on them. But, with the Deltas covering full-range too that will have a somewhat interesting effect (it'll really be more of a bass control, as it'll adjust the level of things above 250Hz to those below). I wouldn't recommend an L-pad for this - I'd use amp EQ instead. If you do use an L-pad it should come with wiring instructions - or they might have some on the PE web page.

    Oh, as for power ratings on crossovers. Even when you use an amp that's rated at 2x the RMS of the speakers, you're not using all that power most of the time. So, you probably don't need x-overs that handle that much power. Those caps at PE are rated at 100v, which they say is good to about 200w. That should be sufficient in that situation.
  15. Buy one from Eminence.

    Link to Eminence Crossovers

    It is a waste of your time and money playing around with building one. Unless you know the exact impedance at the crossover point, you will incorrectly terminate the crossover.
  16. geshel


    Oct 2, 2001
    Too bad they don't have any 4-ohm models :(

    (and for those curious, you don't want to hook a 4-ohm load up to an 8-ohm crossover, the result is like having 18" wheels on one side of your car and 12" wheels on the other side. . . :) )
  17. Skorzen


    Mar 15, 2002
    Springfield MA
    Thanks fo the input info on the crossover is very helpful thanks. Something I was thinking about was bouilding a smaller cab that was essentially half of the origional plan, and if this works well build a second for the final product. This would give me 8 ohm loads so I could use the eminence crossover. Despite the two 8 ohm speakers, with the crossover would the impedence for the cab still be 8 ohms?
  18. geshel


    Oct 2, 2001
    If you split the signal (if you hook the Delta to the "low pass" outputs and the Beta to the "high pass" output of the crossover), yes the total load is still 8 ohms with two 8-ohm drivers.

    You know, I didn't think of that when I recommended you not put a low-pass on the Deltas, sorry. That would put them in parallel with th Betas at higher frequencies, reducing the load to 2 ohms in places most likely. !! :(

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