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Ohm question.....

Discussion in 'Amps and Cabs [BG]' started by Sparker, Mar 27, 2013.


  1. Sparker

    Sparker

    Jan 13, 2010
    OK I admit that I just don't get it.....:help:

    I am wanting to build up to a head and single 4x10 cab rig, but I want to use my Acoustic B100 1-15" 4 Ohm speaker output to start with. What do I need to look for (4 or 8 ohms) in order to hook up to the B100 for now and later a new bass head TBD later.

    Thanks in advance!!!
     
  2. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
  3. Sparker

    Sparker

    Jan 13, 2010
    Yes.... and another question has come to mind. Which are more readily available? 4 ohms or 8 ohms 4-10" cabs

    Thanks!!
     
  4. tbirdsp

    tbirdsp

    Sep 18, 2012
    Omaha, NE
    Jim Carr - that amp is an oddball in that the external speaker jack is connected in SERIES to the internal 4 ohm speaker - not parallel.
     
  5. Sparker

    Sparker

    Jan 13, 2010
    any thoughts on a 4-10" cab that could work without damaging the amp

    Any ideas are appreciated

    Thanks!
     
  6. IF you want to use an extension cab with your combo get a 4 ohm 410. The extension jack is series so with the internal and extension the total load will be 8 ohms (THIS is true with GC Acoustic combos ONLY as far I know). If you want to disconnect the internal speaker a 4 ohm or 8 ohm cab will work (8 ohm will let you add a second cab).
     
  7. tbirdsp

    tbirdsp

    Sep 18, 2012
    Omaha, NE
    You can pretty much hook anything up to the B100 and not damage it because the external jack is wired in series. In this configuration you would ADD the impedance loads of the speakers together - so the internal one is 4 and if you add another 4 ohm it would be an 8 ohm load. This is actually going to reduce the output power of the amp (to probably 75~80watts), but because of the increased speaker area it might be louder anyway. Now adding an 8 ohm cab to the B100 isn't going to hurt anything, but then the load is going to be 12 ohms, significantly reducing the output of the amp IMHO.

    MOST heads are set up so the speaker jacks are wired in PARALLEL. In this configuration two 4 ohm cabs would equal a load of 2 ohms - not good if the amp is rated for a 4 ohm minimum (most are). The usual setup would be to run a single 8 ohm cab with the head, then you can add another 8 ohm cab later to get to a 4 ohm load.

    Basically you really need a 4 ohm cab to be any good as an extension cab with the B100 - but it would be better to get an 8 ohm cab in case you want to expand your new rig with another cab in the future. Personally I would just keep saving until you can afford to by a new head of your choice and an 8 ohm cab. Use the B100 as it is.
     
  8. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    +1

    Combos are, IMHO, a trap. :scowl: :spit:
     
  9. +1 keep saving and trade the combo in.

    Or get a 8 ohm cab and rewire it to 2 ohms temporarily. I don't like 4x10's so make it a 2x15 that uses 4 ohm speakers. By the time you stack that lot up you'll be hell on wheels.
     

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