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Three 8 ohm cabs?

Discussion in 'Amps and Cabs [BG]' started by crud19, Feb 10, 2004.

  1. crud19


    Sep 26, 2001
    I would like to run two Ampeg 1x15 cabs and one Ampeg 4x8 cab with my SVT-CL. All three cabs are 8 ohms. Two questions: Will this adversely affect my amp? If not, should I have it set for 4 ohm or 2 ohm output? Thanks in advance for the advice.
  2. MascisMan


    Nov 21, 2003
    Dallas, Tx
    I would think the total impedance load would be 2.6 ohms but Im not sure....if this is the case then you would want your amp set to 2 ohms.
  3. crud19


    Sep 26, 2001
    I guess since I would be running two of the cabs in parallel (with a speaker y-cable), it would be like running a 4 ohm cab and an 8 ohm cab. I just don't want to blow anything up.
  4. metron


    Sep 12, 2003
    Why dont you just use two cabs instead of three? What I would do is get two 4 ohm cabs so that you could use one if you wanted to and then combine two for a total impedance of 2 ohms. If you have all 8 ohm cabs you wont be able to use only one with the head you have. More versatility that way.
  5. crud19


    Sep 26, 2001
    Well, I already have three 8 ohm cabs, and I like them. Plus, smaller, 8 ohm cabs are easier to move around and fit into a van. (as opposed to two 2x15s or 8x10s)
  6. kmacleish


    Nov 19, 2003
    Atlanta, GA
    The impedance would be 8/3 = 2.666666 . . . . ohms.

    Your Ampeg should be set up for 2 ohm output.

    And using two 4 ohm cabs would seem to be a better solution, giving you the versatility of a smaller or bigger rig, and a bit more power per cab, although 150 watts per cabinet is still not really enough to get good performance out of many cabinets. It would be (only slightly) better than the 100 watts per cabinet you are looking at now.
  7. Boozy


    Apr 29, 2002
    Kelowna BC, Canada
    You should still be able to run an 8 ohm cab with your head, you're head would probably just not put out as much power.

    You're cabs dictate how many ohms your head runs at.

    plug one 8 ohm cab in = head runs at 8 ohms
    plug two 8 ohm cabs in = head runs at 4 ohms
    plug three 8 ohm cabs in = head runs at 2.6* ohms
    plug four 8 ohm cabs in = head runs at 2 ohms

    From what I have read, as long as your cabinet in capable of running at 2 ohms, it will have no problem running at 2.6* ohms.

    You would be better off having maybe one 4 ohm 4x8 and two 8 ohm 1x15's (same as a 4 ohm 2x15) that way the 4x8 and 2x15 would get equal power and would therefore be of more equal volume.

    I'm just not sure if your amp will divide its power equally to each out put or evenly umung your cabs... I guess you could split your two 1x15's into one output (daisy chain or y-splitter), and plug the 4x8 into the other output... if the 2-15's seem way louder than the 4x8, switch things around and see if it sounds better.

    If you just daisy chained them all from the same 2 ohm output, I would think each 8 ohm cabinet should get equal power.

    Oh yeah,having a head that can run at 2 ohms really makes a guy want 4 ohm cabs. One 8 ohm cab alone will be too weak in most cases so you will need to carry two of those cabs around in order to have a 4 ohm load anyways. Now if one of those cabs was 4 ohms, atleast you could use one cab and still be able to get loud.

    I dunno..
  8. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Keeping in mind that the value of impedance assigned to any cabinet is a nominal value, that the nominal impedance for a 1x15 and a 4x8 probably occur at different frequencies, that a bass string generates many frequencies simultaneously and that any cab's actual impedance varies widely with frequency, I don't think that you really need to worry about it.

    I'd set the impedance selector at 2 ohms, plug in your three cabinets (any way you can) and have a great time!

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