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Question about Ohms, 2 cabs with 4 Ohm head

Discussion in 'Amps and Cabs [BG]' started by OneDrop76, Aug 17, 2005.

  1. OneDrop76


    Jul 15, 2005
    Beltsville, MD
    Newbie question, sorry. I currently have an SVT 3 Pro, (4 ohms min) and an 8 ohm Avatar B115H, which I got with the intention of adding a 4x10 later. I was hoping to add an Ampeg 4x10, but most seem to be 4 ohms, or at least the one at the local music shop that I can get used for a song. I know I can just order up an 8 ohm 4x10 from Avatar, but is there any way to rewire a cab to change it from 4 to 8 ohms? Or otherwise run these two cabs simultaneously with my head? Thanks for any help you can offer...
  2. No way to rewire a 4 ohm 4x10 to get an 8 ohm cab.

    You can change the impedence by factor of 4, not a factor of 2.

    Depending on how the current 4 are hooked up you could possibly change it to 1, 16 or 64 ohms. Only 2 of those 3 options are actually available once you know how the current ones are hooked up.

    Given a 4 ohm 2x something cab, the other potential options are 1 or 16 ohms if you hook it up differently. Only one of these options are actually available when you find out how its currently hooked up.

  3. Euphony Penguin

    Euphony Penguin

    Aug 15, 2005
    I use the Ampeg classic series SVT-410HE which is a 4x10 cabinet at 8 ohms. I'd really suggest this one, or the HLF model with the little shelf at the bottom of the cabinet (nice low end sound). But Ampeg makes the only 4x10 i've ever liked out of the numerious ones i've played at my local music stores.

    Ohms works like, 2 16 ohm cabinets equal 8 ohms, 2 8 ohm cabinets equal 4 ohms, 2 4 ohm cabinets equal 2 ohm. One 4 ohms cabinet and one 8 ohm cabinet equal 2.6 ohms. There are a few heads out there that support 2.6 ohms, and very many power amps. As for wiring the cab to change its impedance load, I haven't got a clue.

    To sum it up, I suggest getting a 8 ohm 4x10, I've been using a 4x10 + 1x15 set up for a long while and it gives an awesome loud clear sound.
  4. Thor

    Thor Moderator Staff Member Gold Supporting Member

    N.B. This is true only if everything is connected in
    parallel. Also. with the 4 and 8 ohm cab combination,
    the 4 ohm cab hogs more of the power (wattage)
    available, often resulting in a SPL (Sound Pressure Level)

    Good sensible advice. YMMV. And each cab gets 1/2 the power so it has plenty of bottom from that big fat 15.
  5. chekerbored


    Nov 18, 2004
    I was looking at the Super Redhead, and it's a 4 ohm head, and it says it will support an 8 ohm extension at 400 watts, and a 4 ohm extension cab at 450 watts.

    Now the question. Would it support two 8 ohm cabs? And would it be louder than one 4 ohm cab. (I.E. one 1x15 cab at 4 ohm, or a 1x15 at 8 ohm and a 2x10 at 8 ohm) I remember reading that the more air you were moving helped volume, but i was wondering if that combo would support it.
  6. Thor

    Thor Moderator Staff Member Gold Supporting Member

  7. karrot-x

    karrot-x Banned

    Feb 21, 2004
    Omicron Persei 8
    I'm selling my Ampeg SVT-410 HE, and I live rather close to you. PM if you want more info, it's 8 ohm.