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building a custom cabinet

Discussion in 'Amps and Cabs [BG]' started by Discrepancy, Jan 26, 2005.


  1. Im going to be building a custom cabinet soon. Its going to look like a traffic light (my bands name is Green Means Go!). Im using 3 15" speakers, and its going to be powered by my Fender BXR200 head. A friend of mine suggested to have one output on the head to go a 4 ohm speaker, and the second output to power 2 8 ohm speakers. Will this work? Any suggestions on what type of wood to use? Any advice you can give would be great. Thanks.
     
  2. I believe your Fender head supports a minimum load of 4 ohms. The wiring you've suggested would leave you with a load LOWER than what that amp can handle.
    Now you can wire TWO-4 ohm speakers in series (gives you 8 ohms), then wire that combination parallel with an 8 ohm speaker, which in turn would leave you with 4 ohms. Or you could connect the 8 ohm series combo to one amp output, and the other 8 ohm speaker to the second amp output. It's basically the same, as the amp's outputs are wired parallel.

    Please read the information at this site. You'll find it down the page in a section named "oddball configurations"..
    http://www.colomar.com/Shavano/spkr_wiring.html

    There is so much more to building a cab that will sound right. The box has to be built according to the speaker's specifications, and tuned accordingly.
    But if you do try it, build it out of 3/4" plywood. Search around the web.. You'll find some ideas

    Mag...
     
  3. If I do the first thing you suggested (2 4 ohms and one 8), would it use 1 output on my amp, or will it still require 2 outputs.
     
  4. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    You could wire it either way.

    But I really gotta tell you, this cab design is not a great idea.

    First off, it's gonna be very heavy. Most 2x15's will dang near give you a hernia. A 3x15 is going to be no fun at all to move around.

    Stairs? Good luck.

    Second, the odd impedence layout will result in the speakers being unevenly powered. The two 4 ohm speakers will recieve half the wattage from your amp, and the one 8 ohm speaker will recieve the other half.

    If you absolutely MUST have a 3x15 cabinet, the best way to do it would be to get an amp that will handle a 2 ohm load. Then you can use 3 8 ohm speakers wired in parallel, yielding a 2.67 ohm load. Each speaker will get 1/3 of the amps power.

    If you've got to stick with your current amp, I'd consider making a 2x15 that looks like a 3x15. Most 2x15 cabs are plenty loud, you can use 2 8 ohm speakers wired in parallel for a 4 ohm load, it'll be cheaper, and it'll be quite a bit lighter. With the added height that the 3x15 look will require, the cab will probably need to be unusually shallow front-to-back to maintain the proper cabinet volume; this depends on the speakers' required cabinet volume and tuning. Different speakers require different sized cabs and tunings to sound good. The problem with an extremely shallow cab is that it becomes difficult to construct the proper vents to achieve the required tuning; it also may be a problem in that it may be too shallow to set your amp on top.

    So overall, it's just not a real good idea to design speaker cabinets based solely on looks. If you're concerned about sound quality at all, the function must dictate the form. You cannot just throw some speakers into a box. The internal dimensions and vent size and length must be correct for the particular speaker being used. There are lots and lots of different 15's out there, and each one has different requirements. If you build a cab that looks like a stop light, with no regard to proper cabinet design, it's probably going to sound about as good as a stop light.
     
  5. What about 3 16 ohm speakers? Would that work well?
    What will the result of the uneven power be if I used the 2 4ohms and the one 8.

    This is something I really want to do, but I only want to do it if it will sound good.
     
  6. msquared

    msquared

    Sep 19, 2004
    Kansas City
    To get around the ohms problem, you could build it with two active drivers and a resonant cone. You might have to go to 10s or 12s to do this, but it'll be less of a problem to move around and if you do 10s there's no reason you can't get a PA stand for it and paint the stand yellow. Check partsexpress.com for some gear.

    Or else just find a really lightweight 15 and build it so that the 15 isn't hooked up and has a sealed chamber that's just deep enough for the speaker itself. You'll keep the looks but get more cabinet space.

    Very cool idea by the way.
     
  7. msquard you gave me an idea.

    I'd have 2 cabs in one, a 2 x 15 for gigs and use the 1 x 15 for practice. That would eliminate the ohms problem and make things simple.

    Anyone have suggestions on good speakers?

    Thanks again.
     
  8. snake

    snake

    Jul 21, 2004
    Aurora. CO
    I agree with Discrepancy, I certainly would'nt want to have move that MoFo. Breaking them up would be great idea. Even three single fifteens would work. Maybe paint the cabinets the colors you wanted.
     
  9. I was gonna have 3 of the round speaker grills that just cover the speaker, and paint them in their respective colors. I'll have casters or something to move it.
     
  10. what about three twelves instead of three 15's, cheaper and lighter, plus if your using that many cabs, why use 15's. Also, there is some free windows software for calculating speaker port sizes based on a whole pile of variables, it's pretty cool software, http://www.linearteam.dk/ check it out,
     
  11. popinfresh

    popinfresh

    Dec 23, 2004
    Melbourne, Aus
    If your just painting the grill. Go with 2x15's and just make three circles in the grill IMO. 3x15 would be an ass to move. And you won't need 3x15's for gigs. Perhaps look at adding one or two smaller speakers in there so you don't sound a mess on stage? Or just go with 12's.
     
  12. IvanMike

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

    Nov 10, 2002
    Middletown CT, USA
    3 16 ohm speakers will give ya 5.33 ohms. if i did one cab like that it would be a 3x10.

    if used 3 cabs i'd go with compact 1x12's like bergie, bag end, epi, or other ones in that smaller size. 3 of them should have a lot of low end
     
  13. What do you mean by "sound a mess on stage"? Would 2 15" sound bad?
     
  14. popinfresh

    popinfresh

    Dec 23, 2004
    Melbourne, Aus
    Some 2x15" rigs can sound bad, ok, most do. Some people get real nice sounds from them, some people just have no clarity in their tone, it's all just lows/low mids with barely any highs. With no clarity, it just sounds messy. With 3x15's, i imagine it would be worse... Shouldn't be too bad if you get good 15's.
     
  15. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    Why not get that cab you WANT, based on how it SOUNDS, and then put a painted grillecloth on it?

    i.e. If you like the way 8-10s sound, it shouldnt be hard to take the grillecloth off of it, paint your stoplight on it, and then put it back on. Then you would have the look you want, and no one would have any idea what speakers are under there anyway.

    Besides, if you paint a whole cabinet red, green, and yellow, you are gonna feel mighty stupid if you end up in another band, or this band changes it's name.

    Can you imagine showing up to a jazz audition with a rig like that? :smug: