Running amp at 2.67 ohms?

Discussion in 'Amps and Cabs [BG]' started by FunkSlap89, Jan 4, 2006.

  1. FunkSlap89


    Apr 26, 2005
    Albany, NY
    This can be achieved by using one 4 ohm cab and one 8 ohm cab. If my amp isn't rated at this level, but is rated at minimum 2 ohms (safely... Genz Benz), than can i run it at 2.67? All this resistance stuff is really complicated... :confused:
  2. haujobb


    Dec 16, 2004
  3. +1
  4. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Yes, but the 4 ohm speaker will probably get much more of the load. I say probably because it depends on the effeciency of the cabs.

    Solid state amps don't care as long as you do not go below the minimum, in your case 2 ohms. Tube amps care more.

    And to clarify, it isn't resistance, it is impedance ;)
  5. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Resistance is futile :)

    To think about sensitivity, as mentioned above, both cabs run at the same voltage, not the same wattage. The 4-Ohm cab runs at twice the wattage of the 8-Ohm cab in this configuration.

    The reason for thinking about this, is that if the two cabs have a significant loudness mismatch, then you might as well leave the quieter one home, and reduce the thermal load on your amp.

    But, if you have both speakers on hand, then there is nothing like a listening test to determine if the loudness contributed by the extra speaker is worth transporting it.
  6. Fixed ;)
  7. Le Basseur

    Le Basseur

    Mar 26, 2002
    The "2,67 Ohms" issue is exactly what my rig looks like right now.
    My Yamaha BBT500 (D-class digital amp head) goes through a EBS 410 (4 Ohms) as a top and a DIY T115 Epifani clone (8 Ohms) as a bottom.Due to the impedance mismatch AND the different sensitivity,the EBS cab plays louder than the Epi clone,while the second gives that "rumble sensation" or "velvet bottom" in a rather refined manner,without being boomy,hard-to-EQ and overly-present.It's a great combination sound-wise and it works fine no matter if heard from close proximity or 30 meters away,in the audience. :hyper:
  8. Slink


    Dec 27, 2005
    Food for thought! If your 4ohm cab has say 2-12's and your 8ohm cab has 1-12 then each speaker will draw the same amount of power from your amp.
  9. ^^Smart ass! :D

    That's pretty smart.. so that means you won't get a weird sound because one speaker goes faster than the other.
  10. FunkSlap89


    Apr 26, 2005
    Albany, NY
    so, now my question is... is it ok to have unequal power distribution to the speakers? Will it make them sound any different than usual? thanks for the replies, btw...
  11. haujobb


    Dec 16, 2004
    They can't move faster than the other, a change in the speed of cone movement would be a change in frequency.
  12. It's O.K. - perhaps you'll get a bit of a volume mismatch. Just do it and see if you like it. I find that there are so many variables (given numbers of drivers, surface area, etc) that the only way you'll know is by trying it. You're not going to hurt anything running at 2.67 ohms.

  13. Fuzzbass

    Fuzzbass P5 with overdrive Gold Supporting Member

    I sometimes run a 4-ohm 3x10 and an 8-ohm 1x15 together. The cabs sound nicely balanced: when I put the 1x15 on top I hear it better, when I put the 3x10 on top I hear that one better. No change in tone (aside from the fact that the fifteen and tens are now blended together).
  14. hasbeen

    hasbeen Commercial User

    Sep 23, 2004
    Vice President, KMC/JAM USA: Distributor of Ashdown amplification
    official Genz Benz response:

    You have no worries. Our amps are tested below 2 ohms and won't even breath heavy.
  15. Different? No, but all other things being equal, the 4ohm cab will be louder because it's getting more power than the 8ohm cab.
  16. FunkSlap89


    Apr 26, 2005
    Albany, NY
    yeah, I've heard that! It really is a great feature... why rate an amp at 2 ohms if it can't pull the load? I love this amp btw, it has killer tone! :bassist:

    thanks for the replies everyone. I think i'll just get a 4 ohm cab to get the extra power. :cool:

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