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  • Dual 12" + 2" Comp designs

    been working on a couple dual 12 cabinets with a 2" comp. using the B&C ME60 horn w/ either a B&C or Selenium driver. the 12" i am not sure of just yet. I was thinking the daytons for a cheap version or a B&C for an expensive option. I'll just change the depth of the port according to what driver i use. the cabinet is net 3.9 cuft before any blocking and driver displacements.
    Attached Files

  • #2
    Re: Dual 12" + 2" Comp designs

    well i guess i can't post the other design.

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    • #3
      Re: Dual 12" + 2" Comp designs

      alright, uploaded as an image.
      Attached Files

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      • #4
        Re: Dual 12" + 2" Comp designs

        Are those ports I see directly behind the drivers? I thought I read this was not a good location for ports.

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        • #5
          Re: Dual 12" + 2" Comp designs

          Originally posted by Randy L View Post
          Are those ports I see directly behind the drivers? I thought I read this was not a good location for ports.
          i always thought the same. then i did a lot of reading. this cabinet will be crossed at 100hz.

          http://forum.speakerplans.com/reflex...opic45906.html

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          • #6
            Re: Dual 12" + 2" Comp designs

            Originally posted by scottcameron View Post
            been working on a couple dual 12 cabinets with a 2" comp. using the B&C ME60 horn w/ either a B&C or Selenium driver. the 12" i am not sure of just yet. I was thinking the daytons for a cheap version or a B&C for an expensive option. I'll just change the depth of the port according to what driver i use. the cabinet is net 3.9 cuft before any blocking and driver displacements.
            That looks sweet. I'd be tempted to use triangular vents from the front panel though, rather than vents in the rear. The material for the triangular vents can serve as additional bracing for those large side panels, which should in turn improve the bass response.
            Brian Steele
            www.diysubwoofers.org

            Comment


            • #7
              Re: Dual 12" + 2" Comp designs

              n00bs...

              Those things on the jack are NL4s with metal flanges.

              The vents are vertical slots on either side of the drivers. Their placement looks fine, and it looks like there's enough port area, but round vents are superior to any other shape for allowing the lowest tune with the least air noise.

              What's the cabinet's trapezoid angle? Does this correspond in any way to the horizontal dispersion of the horn? I recommend a square 60x40 horn flare so that the horn can be rotated to convert the cabinet for standalone or arrayed operation. (40 degree horizontal pattern for 'arrayed', 60 for standalone).
              Best Regards,

              Rory Buszka

              Taterworks Audio

              "The work of the individual still remains the spark which moves mankind ahead, even more than teamwork." - Igor I. Sikorsky

              If it works, but you don't know why it works, then you haven't done any engineering.

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              • #8
                Re: Dual 12" + 2" Comp designs

                Originally posted by Randy L View Post
                Are those ports I see directly behind the drivers? I thought I read this was not a good location for ports.
                It's not. Mids and highs will escape through the ports, and that's a recipe for trouble. And lose the trapezoid shape. It serves no purpose except to encourage splayed multiple cabs, which should not be done. This explains why:

                http://homepage.mac.com/randyhyde/we...udioStuff.html
                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

                Comment


                • #9
                  Re: Dual 12" + 2" Comp designs

                  If the cabinet is being crossed at 100hz why do you have ports anyways? I guess you can tune it real high like 80hz or something if you want, but you can/should do that on the baffle.

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                  • #10
                    Re: Dual 12" + 2" Comp designs

                    Originally posted by billfitzmaurice View Post
                    It's not. Mids and highs will escape through the ports, and that's a recipe for trouble. And lose the trapezoid shape. It serves no purpose except to encourage splayed multiple cabs, which should not be done. This explains why:

                    http://homepage.mac.com/randyhyde/we...udioStuff.html
                    Agreed on the port location, but he is using a 60x40 nominal coverage horn, which will almost certainly require more than 1 cab per side on larger outdoor gigs. Since this is a rather high spl category combination, I didnt perceive it as being a small hall only type cab (pardon the a$$umptions). So the trap design may be required (any smaller coverage and I'd say its a must).

                    Make sure you check the driver volume displacement, that horn will take up a huge amount of space (mine take close to 1 1/2 cubic feet with the driver attached), and will completely change your cabinet needs.

                    Comment


                    • #11
                      Re: Dual 12" + 2" Comp designs

                      Originally posted by BElstro View Post
                      Agreed on the port location, but he is using a 60x40 nominal coverage horn, which will almost certainly require more than 1 cab per side on larger outdoor gigs. Since this is a rather high spl category combination, I didnt perceive it as being a small hall only type cab (pardon the a$$umptions). So the trap design may be required (any smaller coverage and I'd say its a must).
                      If you have overlapping coverage, and all CD horns do, there will be comb filtering. When you place cabs side by side the midrange dispersion will be halved. Both those concerns are solved with vertically array cabs. In cases where extremely wide dispersion is required, as in wider than 120 degrees, the cabs can be rotated to different axis, creating an axial array.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

                      Comment


                      • #12
                        Re: Dual 12" + 2" Comp designs

                        the first cabinet has an angle of 15 degrees and 2-2"x9" ports on either side of the horn. i have seen and read about guys running a 20 degree to help eliminate comb filting in the 12s when 2 cabinets are placed side by side. i am here to learn as are the majority. the second cabinet sports the same angles but is rear ported, drivers are flush mounted, and the baffles roll around at the sides. i would like to roll the lower 12 off first.

                        i have read a ton of arguments on the rear porting idea. mostly opinions on both sides. i have also looked at and read into the whole line array concept. can be a lot of money involved and it seems no design will ever be perfect. i looked into this design a while back.
                        http://www.forsburg.com/pages/products-setup.html. so how can this work.

                        i am looking for a top cabinet design i can use as a single in smaller places and double them up when outside.

                        Comment


                        • #13
                          Re: Dual 12" + 2" Comp designs

                          Using multiple HF sources in nearly any other form than a line source is a disaster, don't do it.

                          Comment


                          • #14
                            Re: Dual 12" + 2" Comp designs

                            Originally posted by billfitzmaurice View Post
                            If you have overlapping coverage, and all CD horns do, there will be comb filtering. When you place cabs side by side the midrange dispersion will be halved. Both those concerns are solved with vertically array cabs. In cases where extremely wide dispersion is required, as in wider than 120 degrees, the cabs can be rotated to different axis, creating an axial array.
                            Wasnt arguing that there would be no comb filtering, but that it would be more convenient to splay them with trap cabs than with 'square' cabs. Scottcameron is correct in saying there is no perfect solution, and with proper placement the effects can be minimized. For his situation I think he's on the right track without mortgaging the house and car. I also agree on the rotatable horn suggestion, for arraying the cabs a 40deg horizontal is much nicer to work with.

                            I'm no expert on port placement (seems like your caveat emptor), but it seems to me that many times the mic's can be directly behind, or very close to directly so much that rear porting may cause unneeded feedback due to the proximity of the VC to the port. Mine are within 2 feet of the mic sometimes, and I can see a 2dB difference making or breaking my mix. I think we would need to measure a loudspeaker (better to use the one that is modeled) and see if the HF is directional out of the vented pole enough to warrant any kind of concern (I did try and read the spkrplns pages, but it seemed more opinionated than based upon real world measurement). I'm also all for tuning the box to its capability, instead of tuning to a certain frequency.... propriety is just that.... it limits the use of the cab to a sub/top combo only. A HP on an EC will limit the response just fine when used with subs.

                            Comment


                            • #15
                              Re: Dual 12" + 2" Comp designs

                              Originally posted by BElstro View Post
                              Wasnt arguing that there would be no comb filtering, but that it would be more convenient to splay them with trap cabs than with 'square' cabs.
                              I can only assume that you did not look at the link I posted. Splaying doesn't work. If one must use cabs side by side, and the only reason to do so is a low ceiling, they should be cross-fired.
                              it seems to me that many times the mic's can be directly behind, or very close to directly so much that rear porting may cause unneeded feedback due to the proximity of the VC to the port.
                              If the port is properly placed, so that the cone is not visible through it, no mids or highs will escape the port and rear mounting makes no difference, as the low frequencies which emanate from a port are omni-directional, and will be equally loud in front of or behind the speaker irrespective of front or rear placement.
                              www.billfitzmaurice.com
                              www.billfitzmaurice.info/forum

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