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Mixing a 4-ohm cab with an 8-ohm cab?

Discussion in 'Amps and Cabs [BG]' started by Skel, Feb 13, 2006.

  1. Skel


    Jun 19, 2005
    Boulder, Colorado
    Sorry if this has been beat to death in previous threads, but I couldn't find this exact scenario. I know the formula for calculating impedance, but if ran a 4-ohm cab and an 8-ohm cab in parallel, and set my amp's impedance to 2 ohms - I'm pretty sure it would be safe for the amplifier(?), but would the result be that the amp just wouldn't drive the cabs quite as hard as they need to be? Put differently, is this (1) safe, and (2) a bad/good idea tone wise?

    Thanks - Skel
  2. barthanatos

    barthanatos Insert witty comment here

    Feb 8, 2006
    South Carolina
    From http://ampeg.com/faq.htm

    Q5) - Can I combine cabinets of different impedances?

    It can be done, but it will cause a mismatch of levels. This is not recommended

    Q6) What is the impedance of an eight ohm cabinet combined with a four ohm cabinet?

    2.7 ohms. This is not recommended

    Sorry I can't offer more than that, but at least it's relevant.
  3. Figjam


    Aug 5, 2003
    Boston, MA
    I think that would be safe, since at 2 ohms you can run two 4 ohm cabs, and an 8 ohm would be fine in its stead. ALthough as mentioned above....
  4. Skel


    Jun 19, 2005
    Boulder, Colorado
    Yea, I think I'll just stick to recommended configurations. Thanks for the quick responses.

  5. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    just to be clear...does your amp say it can run 2 ohm loads? if yes you'll be safe in the "blow up your amp" dept.

    if your amp is mono or dual mono (meaning you can't adjust individual volumes for two speaker outputs) then you will probably have the 4ohm cab over powering (volume wise) the 8ohm cab. still safe, but not might sound the best.
  6. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    If you are running a SS amp that can go to 2 Ohms, it would be fine, but keep in mind that the 4 Ohm will get 2x the power as the 8. On a tube amp, it depends on the amp. Some can handle a slight mismatch, most can handle up to 100% of a mismatch with some loss of power. I run an 4 and 8 on my Mesa 400+, one through the 2 Ohm and one through the 4.
  7. Skel


    Jun 19, 2005
    Boulder, Colorado
    I have an SVT Classic that I just got - it has a 2-ohm setting. I wouldn't want my 4-ohm SVT410-HLF overpowering my 8-ohm Avatar 1X15, but if it's safe at least I could try it just to see if I would like the addition of a 1X15.

  8. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I think the CL could take the mismatch. Put em in the 2 Ohm one. It may or may not sound good. But try it and see. Most tube amps can take a 100% mismatch- a 4 Ohm tap can usually use up to a 2 or 8 Ohm cab.