1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
     
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

2x12 dimension help

Discussion in 'Amps and Cabs [BG]' started by cosmicpimp2, Jan 16, 2012.


  1. So I've been researching for about a week now to make a 2x12 cab with eminence delta 12lfa. i have two and i was thinking of going off the avatar cab dimension or mesa boogie since its close. I like the mesa sound prob the most. I wanna make this an open thread to throw around ideas for a solid 2x12 vented with a ceramic speaker. just some general dimensions. the vents always get me cause i get confused how deep and big to make them. I'm a skilled carpenter but not so good at understanding the math of speakers. I figured maybe this could help people that can make the cabs but don't know all the exact specs
     
  2. BrBss

    BrBss Supporting Member

    Jul 9, 2010
    Albuquerque NM
  3. I've been using winISD a lot. But I've played many cabs that sound good that doesn't follow those dimensions.
     
  4. I'm trying to just get a thread of what people have built and found to sound good with 2x12's. All the math in the world doesn't matter to me if it sounds bad
     
  5. BrBss

    BrBss Supporting Member

    Jul 9, 2010
    Albuquerque NM
    The math was developed for a reason. Without math, its a guessing game. Good luck with that.
     
  6. Passinwind

    Passinwind I am Passinwind and some of you are not. Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    WinISD works with whatever dimensions you feed it, not just by suggesting standard alignments. Try using it to understand why those various cabs that you like sound the way they do. ;)
     
  7. See that I can work with! Like the mesa cabs I can't find the info for the speakers. I'd like to build a cab that's a bit closer to that sound with the delta's. It's been a headache punching numbers without a really solid answer I'm comfortable with. I could punch in a wrong number here or there and screw it all up. I've got about 10 pages of hand written notes to get around where I want. But each cab could differ an inch here or there to change the sound
     
  8. qts

    qts

    May 15, 2006
    Ijmuiden-holland
    In the past Bgavin, a member of this forum help me with a 1x12 configuration with this driver.
    It'll will be difficult for me to explain the steps you need to take according WINISD or an other box calculater program, but to spoon feet you, :smug: each driver needs 69liter netto (2.4cft) and a 1x102mm (4'') pvc pipe, 65 mm long
    I hope some of the experts will chim in
     
  9. Matthijs

    Matthijs

    Jul 3, 2006
    Amsterdam
    Did you have a look at the cabinet suggestions on the eminence site? I think they might be a good starting point for modeling somehting in winisd. Most of the time they have a selection of smaller and bigger cabinets worked out for a speaker. You could compare those dimensions and the specs to the Mesa sound, choose the model that's closest to the mesa and start adapting from there. Don't know if there will be a 2*12 cabinet in their list, but you can double up the dimensions before you enter them in winisd.
     
  10. Remember that the Avatar has a shelf port and the Mesa has 3 triangle ports.
     
  11. BogeyBass

    BogeyBass

    Sep 14, 2010
    good suggestion lets look at that Cab design PDF. after playing around with the driver in WinIsd, Eminence suggested setup for med vented cab sounds
    good.

    Vb of 2.5 cubic ft and tuned to a Fb of 50hz

    Eminence suggest using Round 2x4" ports,
    shelf ports and triangle ports are garbage to me, and i agree with the round port choice. placing evenly spaced 4" ports closely to the driver can end up giving you a wide box.
    I prefer 4 evenly spaced 3" ports placed close to the driver, because with 4 ports you can use more smaller more convenient sizes. And still get a decent port velocity that 2 larger ports would give you. aside from a few other reasons I dont care to discuss.

    I hate boxes that are too small for heads, if i remember a rack is 19" wide and with 1/2 ply case would be about 20"

    so i went with 20" wide, then for height to get a aesthetically pleasing ratio used the good old Golden Ratio. look it up, it works so well. But yet so many ugly cabinets fail to use it. anyhoo

    so 20" wide 32" 3/8 tall for a true vertical alignment, not some annoying squat looking thing with horrible offset drivers trying to make it smaller. Depending on how much baffle setback you want for a grill and the thickness of your wood. the depth will give you the final size, to give you the needed airspace.

    Shooting for 2 separate compartments for each woofer will help keep up with standing waves and will make the 4 ports dedicated to each driver more accurate. And add a good brace to the center of the cabinet. blah blah blah with 1/2 inch of set back and 1/2 inch front and rear baffle. I decided 18.5 inches of depth.

    So if you measure the actual internal measurement of one of the compartments at 15" x 19" x 17" you get 2.8 cubic feet.

    subtract the volume of the driver, bracing and ports you should be around the recommended 2.5 cubic feet.

    4 x 3" ports with a correction factor for a single flared end should be 9.5 inches in length to get you close to 50hz
    I think i went higher to 51hz for error factor so real world tune should be around 49 to 52 hz both 1to 2hz above or below the drivers Fs.......cool. I dont care to argue about tuning,

    Eminence actually tunes below Fs for this driver, Except for the med cabinet is tuned higher most likely for power handling, but not to high which would make it boomy and annoying in such a small airspace of 2.5

    [​IMG]

    basic drawing, i hate thin looking goober cabinets, so with 1/2" or 12mm ply, you simply add another 1/2 x1/2 layer to the inner edges of the cabinet to give it a beefy 1inch look, plus it will add supporting edge all the way around the front baffle.

    this is a incomplete drawing obviously, not showing bracing or the 2 separate compartments.
    the LFA's are going to need Hf drivers, no point in trying to wedge them into this cabinet, it is purely dedicated to having enough volume for the LF drivers and to provide very accurate symetrical evenly spaced ports for each driver. A simple HF box can be added later and contain the realated drivers and crossovers.
     
  12. Matthijs

    Matthijs

    Jul 3, 2006
    Amsterdam
    That post must win a prize for the most helpfull post ever!

    Just one point: it is advisable to base dimensions on prime numbers, to prevent similar distances within the box and thus similar standing waves. Common is d:w:h = 3:5:7 but other combinations can be used too (5:7:11 or 2:3:5). Not as esthetically pleasing as the golden rule, or 2:1 though.
     
  13. qts

    qts

    May 15, 2006
    Ijmuiden-holland
    Why so many vents? sinds this driver is well to 140 watts before exeeding xmax, vent mach is 0.10.
    Is one pipe not enough?
     
  14. BogeyBass

    BogeyBass

    Sep 14, 2010
    with the back panel removed gut shot of some suggested braces and showing ports and compartments.

    [​IMG]

    little more detail showing beefy 1" false front

    [​IMG]

    all done with tolex and fabric grill, white piping around the grill edges would look hot.

    [​IMG]

    forget all that ugly junk, use nice tolex, fabric grill and piping like this, whatever colors you want

    [​IMG]
     
  15. Matthijs

    Matthijs

    Jul 3, 2006
    Amsterdam
    O.K. now you're just showing off.

    Slow day at work?
     
  16. BogeyBass

    BogeyBass

    Sep 14, 2010

    ;) yah can you tell I am bored, i have not played around with sketch up for awhile figured this was a perfect chance.

    likewise i think you might want to set the front baffle back a little more than 1/2.

    Since you might use 1/2 thick wood for the grill frame.
    covered in grill cloth, the grill would stick out a bit.

    I like the grill to be really close to the edge with a tiny setback so maybe add a 1/4 inch so the grill dont end up sticking out.

    and the grill frame will most likely cover the ports a little, so you just cut little circle whoop a doos in the frame so it dont obstruct the ports. once covered in cloth you will never know.

    I was going to make a thread for a generic 2x12 and 2x15 form factor in the future, so it looks like the 2x12 is done.
    But I did make this drawing today specifically for CosmicPimp2 and the Delta LFA driver.

    [​IMG]
     
  17. will33

    will33

    May 22, 2006
    austin,tx
    Keep in mind WinISD models the driver/box interaction, which happens mainly below 200hz or so, it's tayloring the lowend behaviour. The rest of the sound depends on the drivers response curve/distortion characteristics further up. The box won't have an effect on this. You use the drivers datasheet above 200hz and your box model below 200hz and meld them together to see what it will sound like.

    In other words, Bogeybasses instructions will give you a fine box for your drivers. It will perform quite well, but won't sound exactly like a Mesa.
     
  18. wow thanks for the info. I was kinda expecting the typical do more research answer but you never know when someone will help you out. The dimensions I came up with were almost the same just a hair bigger. I'm still in the learning process and reading like crazy. I'm def a lot more comfortable now cause my specs weren't way off from that. I didn't want to punch in a wrong number and really screw up things. Thanks BogeyBass, that is one of the most helpful answers I've ever seen
     
  19. If i make a non venting cabinet, i mean, all closed cabinet. That will damage final sound?
     
  20. will33

    will33

    May 22, 2006
    austin,tx
    The delta12LF isn't really designed for sealed cabinets. In general, a sealed box means less output and power handling in the bass. Some like that "tone" better than the big bass ported cabinets. For example, the most popular bass cab ever, the Ampeg 810, is a sealed cabinet. You get around the lower power handling and bass output by using lots of speakers.

    Very general statements here. Each design is it's own thing and should be viewed as such.
     

Share This Page