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293 Views 6 Replies Latest reply: Feb 7, 2012 8:49 PM by jjack972 RSS
sirweesarunch Just Startin'
sirweesarunch
3 posts since
Feb 5, 2012
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Feb 6, 2012 10:03 PM

Spider IV head connectivity to cabinet ..

My 4x12 cabinet is equipped with 4, 8ohm speakers connected in series parallel ...  There are 2 ,  1/4 " mono jacks . Both + sides go to + side of first two speakers , neg- side of those two speakers go to + side of next two speakers , neg side of these speakers return to neg side of 1/4 " Jacks on back of cabinet .. My question is this  Series Parallel wiring compatible with my Spider IV 150 head outputs ????

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  • jjack972 Just Startin'
    jjack972
    83 posts since
    May 16, 2009
    Currently Being Moderated
    Feb 6, 2012 11:47 PM (in response to sirweesarunch)
    Re: Spider IV head connectivity to cabinet ..

    Someone correct me if I am wrong, but from your description it sounds like your cabinet is wired for stereo, and is not a true series / parallel circuit. It is actually two separate series circuits.

     

    If the positive side of one input jack goes to a positive side of one speaker, then the negative from that speaker goes to the positive of the next speaker, then the negative of the second speaker goes back to that same jack, that is a series circuit with two speakers and the impedance of that one circuit would be 16 ohms.

     

    If the speakers are not all tied together, then you have two separate series circuits (cabinet is wired for stereo) and you would have a 16 ohm load at eack 1/4" jack. In this case you could connect your head to the cab, using both the left and the right outputs from the head and both inputs on the cabinet. Although, the cab would sound about 3dB quieter than a cabinet with two 8 ohm loads, which is what the head is designed for.

     

    You can also check out this document for further clarification:

    http://line6.com/support/docs/DOC-3833

    • fflbrgst Power User
      fflbrgst
      1,292 posts since
      Mar 6, 2011
      Currently Being Moderated
      Feb 7, 2012 5:07 AM (in response to jjack972)
      Re: Spider IV head connectivity to cabinet ..

      I agree - it sounds like you have two 16 Ohm circuits (each pair of 8 ohm speakers wired in series).  You can hook these up to the amp with no issues, although volume may notbe as loud/bright as with the correct impedance cabinet.

      • sirweesarunch Just Startin'
        sirweesarunch
        3 posts since
        Feb 5, 2012
        Currently Being Moderated
        Feb 7, 2012 7:01 AM (in response to fflbrgst)
        Re: Spider IV head connectivity to cabinet ..

        I may have left out one connection in my explanation . let me do it again . 2 1/4 inch jacks , both + sides are connected together and run to the + sides of first 2 speakers and those 2 speaker + connections are jumped one to another ..... from the neg. sides of those 2 speakers one wire per neg goes to the next 2 speakers + sides .....   now the 2 final NEG sides of those last 2 speakers are jumped together and travel back to the 1/4 " jacks through one wire and are jumped to both  NEG connections on the 1/4 " jacks .....   I got this schematic from www.shavanomusic.com     they refer to it as series parallel 4 - 8 ohm speakers = 8 ohms total .... I dont know if it matters whether its stereo or mono ?   thanks for the help ...

        • jjack972 Just Startin'
          jjack972
          83 posts since
          May 16, 2009
          Currently Being Moderated
          Feb 7, 2012 3:11 PM (in response to sirweesarunch)
          Re: Spider IV head connectivity to cabinet ..

          Yes that makes a big difference. Your cabinet is wired as a true series / parallel circuit. The total impedance of the cabinet is 8 ohms. The two jacks are wired together, so you wouldn't want to connect both of the outputs of your head to both jacks. Basically it's a one input, one output cab, allowing you to connect another cab to a mono head. You also don't want to just connect one output of the Spider 150 to that cabinet, as that would put an unbalanced load on your head. Probably not what you wanted to hear, sorry.

           

          You could remove the jumpers and turn it into a stereo cabinet as described in my first reply, but you would want to make sure that each speaker can handle at least 40 watts each, so you would have 80 watts power handling capacity per side. That would keep your speakers safe from the 75 watt per side output of the head.

          • sirweesarunch Just Startin'
            sirweesarunch
            3 posts since
            Feb 5, 2012
            Currently Being Moderated
            Feb 7, 2012 8:22 PM (in response to jjack972)
            Re: Spider IV head connectivity to cabinet ..

            JAck , I am so gratefull to have an educated response to my dilema .. Thanks so much for responding ...  It is a minor setback having my wiring incorrect for my amp but now i am armed with the correct knowledge to rectify the problem .. I will remove the jumpers and wire as you mentioned in your first post .. i dont mind a bit losing 3 decibels of volume as this head is Bloody loud as hell anyway ...Ohh ,, in case your curious the speakers are 2 eminence Governors and the other 2 are eminence Wizards .75 watts per speaker .. Again i appreciate the quick response and excellent information ... 

             

             

                                                                                                                                                               John in Socal ..

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