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Series / Parallel switching for Speaker Cabinet

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  • Series / Parallel switching for Speaker Cabinet

    Hi,

    I have a 2 x 12 speaker cab that is 16 ohms. It is two 8 ohm speakers in series. I use it with an Engl Ironball that has a 16 ohm output.

    I also want to use the cab with an amp that only has 4 and 8 ohm outputs. Putting the two 8 ohms in parallel will give me 4 ohms.

    So, I can re-wire for impedence matching for either amp, but not both.

    I've tried to sketch out the wiring for a switch to flip from one mode to the other.....can anyone confirm if this is correct? And does it matter whether the tip or ring of the speaker cable goes to positive on the speaker?

    Click image for larger version

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    Thanks,
    Andy

  • #2
    Re: Series / Parallel switching for Speaker Cabinet

    This doesn't look right to me, but maybe I'm just not following your diagram correctly. HERE (7th from top) is a diagram for a DPDT switch to achieve 16 or 4 ohms (8 ohms isn't available with this configuration). Switch boxes are available for sale that are pre-wired.

    Regarding "And does it matter whether the tip or ring of the speaker cable goes to positive on the speaker?" .....If you are using this cab as a stand alone only, the importance is that both speakers are wired +/- the same to eliminate phase cancelling. If you plan on using this cab with another, tip is +, barrel is -. So, best to wire tip to +.

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    • #3
      Re: Series / Parallel switching for Speaker Cabinet

      The way to switch two speakers between series and parallel, is exactly the same as how to switch a humbucker between series & parallel. Use the Duncan diagram and pretend one speakers wire is +black and -white, and the other speaker is +red & -green. Use a slightly heavier duty switch, however.

      Click image for larger version

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      Last edited by ArtieToo; 06-17-2019, 08:33 PM.

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      • #4
        Re: Series / Parallel switching for Speaker Cabinet

        What kind of switch should one use?

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        • #5
          Re: Series / Parallel switching for Speaker Cabinet

          Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

          https://www.tubesandmore.com/product...lay-monostereo


          Last edited by Darg1911; 06-21-2019, 05:37 AM.

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          • #6
            Re: Series / Parallel switching for Speaker Cabinet

            Originally posted by Darg1911 View Post
            Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

            https://www.tubesandmore.com/product...lay-monostereo


            Originally posted by IM4Tone View Post
            This doesn't look right to me, but maybe I'm just not following your diagram correctly. HERE (7th from top) is a diagram for a DPDT switch to achieve 16 or 4 ohms (8 ohms isn't available with this configuration). Switch boxes are available for sale that are pre-wired.
            Exactly!

            Comment


            • #7
              Re: Series / Parallel switching for Speaker Cabinet

              Originally posted by Dave Locher View Post
              What kind of switch should one use?
              Simple DPDT on-on. But, obviously, rated for the power. A typical AC power switch would be more than sufficient.

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              • #8
                Re: Series / Parallel switching for Speaker Cabinet

                So long as the impedance of the cab is greater than the impedance of the amp you can use it.

                If you wire the cab at 16 ohms you can use it with 4,8, & 16 ohm amp outs

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                • #9
                  Re: Series / Parallel switching for Speaker Cabinet

                  Originally posted by Darg1911 View Post
                  Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

                  https://www.tubesandmore.com/product...lay-monostereo


                  this is just giving you one (2 speakers together) load at 16 ohms or 2 individual loads (2 speakers in stereo) at 8 ohms each

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                  • #10
                    Re: Series / Parallel switching for Speaker Cabinet

                    Originally posted by regan View Post
                    this is just giving you one (2 speakers together) load at 16 ohms or 2 individual loads (2 speakers in stereo) at 8 ohms each
                    It's 4 ohms mono on the left top jack.

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                    • #11
                      Re: Series / Parallel switching for Speaker Cabinet

                      Oh so it is,I missed that sorry

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                      • #12
                        Re: Series / Parallel switching for Speaker Cabinet

                        Originally posted by regan View Post
                        So long as the impedance of the cab is greater than the impedance of the amp you can use it.

                        If you wire the cab at 16 ohms you can use it with 4,8, & 16 ohm amp outs
                        This is only true with solid state power amps.
                        Oh no.....


                        Oh Yeah!

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                        • #13
                          Re: Series / Parallel switching for Speaker Cabinet

                          Originally posted by PFDarkside View Post
                          This is only true with solid state power amps.
                          Nope, It's quite OK

                          https://mesa-boogie.imgix.net/media/...d%20Hookup.pdf

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                          • #14
                            Re: Series / Parallel switching for Speaker Cabinet

                            Originally posted by regan View Post
                            You’ll notice in the documentation that it states at maximum a doubling of load impedance is ok. (4 ohm amp and 16 ohm speaker is not OK). For solid state this is ok.

                            Also, I’d trust this advice for manufacturers that explicitly mention you can mismatch impedance. Not all amps are built with the robustness of Mesa Boogies.
                            Oh no.....


                            Oh Yeah!

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