Wiring a 4x12 cab

Discussion in 'Cabinets & Speakers' started by hasic, Oct 16, 2010.

  1. hasic

    hasic New Member

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    So, I just got a new 4x12 cab and 4 V30 16 ohm speakers. Now this is the first time I'm actually looking inside a cab so I really have no idea how to wire it all together. All I know is that the amp head only handles 4 or 8 ohm, so was thinking about wiring it in parallel to end up with 4 ohms.

    I am very unsure about this now, but I've attached a couple of pictures of how it looks so you can use them to make some drawings of the wires.

    My problem is that I'm not very good with electronic stuff and I cant really read schematics even though I've been trying to find out how to do it since yesterday. Could really appreciate some help here.


    PS; Don't mind the cables that are on the picture, they are just there because I was messing around without actually knowing what to do.
     

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  2. JohnH

    JohnH Well-Known Member

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    You are on the right track - all in parallel will give you 4 Ohms out of 4 x 16 Ohm speakers. See the second diagram on this link:

    Wiring a 4 X 12 Speaker cabinet

    It shows two jack also, but just omit one if you wish
     
  3. hasic

    hasic New Member

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    Thanks, but I've already been looking on that page. Problem is I dont know how to use what I see on the schematic practially, if you know what I mean. For example, I'm not sure on what connector to put the first cable, and I have no idea how to go from there either.
     
  4. JohnH

    JohnH Well-Known Member

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  5. JohnH

    JohnH Well-Known Member

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  6. hasic

    hasic New Member

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    Thank you John, the first one you posted was easy to understand. I've got the speakers wired now, just got a few more questions and I'm done. I've got two "minus" cables and two "plus" cables that are supposed to go into the jackplate (?), and the jackplate has got 4 connectors, two at each side but I dont see which side is the plus side. One of the sides are on the input for 4 ohms, is this the "plus" side?

    Question 2 - Stupid question but just worrying since its my first expensive amp and don't want to mess anything up. Running a 50 watt head through a 4x12 cab with V30's in it cant harm the cab or head if impedance is matched, right?

    Question 3 - I've got two inputs on my head for cabs, does it matter which one I pick? Also, there is a input next to those two saying D.T? What is this?
     
  7. JohnH

    JohnH Well-Known Member

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    Q1 - can you post a photo of your jack socket?
    Q2 - no problem, even one V30 can handle that
    Q3 - what is the head? I dont know what DT would stand for
     
  8. hasic

    hasic New Member

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    Posting the pictures now. One picture on the back side of the head, inluciding the two inputs and one D.T Input. Second picture is of the jackplate on the inside with the four connectors, two for each input. Third picture is of the jackplate on the back side.
     

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  9. hasic

    hasic New Member

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    Anyone feel confident to let me know which side of the jack plate is actually the + side?
     
  10. Adwex

    Adwex New Member

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    I'm not sure.
    First, you must be sure that all speakers are 16 ohms each.

    There is a plus terminal and a minus terminal on both sides, you will be using all 4 terminals. The jackplate circuitry allows either a parallel/parallel connection between the 4 speakers (4 ohms total), or a series/parallel connection between the 4 speakers (16 ohms total).

    On each side, you will wire from the + on the jackplate to the + on the top speaker, then, from the - on the jackplate to the - on the top speaker.

    Then, you will wire from the other + terminal on the top speaker, to the + terminal on the bottom speaker. Then you will wire from the - terminal on the top speaker to the - terminal on the bottom speaker. The top and bottom speakers will now be wired together in parallel, resulting in a total of 8 ohms.

    Do the same for the other pair of speakers on the other side, using the other two terminals on the jackplate.

    The circuitry in the jackplate connects the two halves of the cab in parallel for the 4 ohm jack, and series for the 16 ohm jack...assuming the switch is set for Mono. This is the standard factory config for a late model Marshall 4x12.

    Since your amp only handles 4 or 8, you will be using ONLY the 4 ohm input...with the switch set to Mono.

    NEVER USE THE 16 OHM INPUT.

    Somebody check my work, make sure I got it right.
     
  11. hasic

    hasic New Member

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    Thank you, Adwex, this cleared up alot. I've done this and I'm almost ready to get my 2204 running for the first time. The only problem remaining is that I can't find any + or - marks on the jackplate. There are 2 connectors on the left side, and this is where the 4 ohm input is aswell, and two connectors on the right side, next to the 16 ohm input. But as I said, I can't find any + or - marks at all on the jackplate.

    Edit: Does anyone maybe have the same jackplate that I'm using that could just point out two terminals are positive and which aren't, from left to right? Becuase unfortunately I don't have any tools for measuring or testing.
     
  12. Adwex

    Adwex New Member

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    I'm not sure.
    Actually, it doesn't really matter which terminal is + or - to make the system work. You've got a 50/50 shot at getting it correct, but if you choose wrong, it only means that all the pluses become minuses and vice versa...no harm done, just keep consistent from side to side to prevent phase cancellation, otherwise while one pair of cones are moving out, the other pair of cones will be moving in...you probably won't like the sound.

    Hopefully someone can chime in and tell you which is which.
     
    Last edited: Oct 16, 2010
  13. Adwex

    Adwex New Member

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    Just to be complete...
    The Mono/Stereo switch separates the two halves of the cab, so that each pair of speakers is independent from the other pair. Since each pair is wired in parallel, the total for each side is 8 ohms.
     
  14. Adwex

    Adwex New Member

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    I'm not sure.
    The jack labelled "DT" is most likely actually "DI", which usually stands for "direct input". This jack is used to "go direct" into a board or recorder.
     
  15. hasic

    hasic New Member

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    Thank you very much, it seems to be working well now!
     

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