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Please explain OHMS.......I don't wanna blow anything up

Discussion in 'Amps and Cabs [BG]' started by Snowdog79, Mar 1, 2003.


  1. Okay.....the concept has been explained to me before, but I'm a little dense and need one more go-around.

    Could someone explain to me how the OHM rating of a cabinet affects how I should hook it up to my amp? Series, parallel, which was gives me maximum volume or maximum headroom? And which way should I not connect things if I don't want unplanned pyrotechnics on stage?

    A general explanation would be great, but here are the specifics of my gear if anyone wants to give me suggestions.......an Eden WT-300 amp (300 watt rating at 4 ohms), one Eden D-210 XLT (350 watts RMS, 8 ohm version), one Eden D-115T (200 watts RMS, 8 ohm version).

    I'd appreciate any advice about coupling this combination together......it's working well, and I'm enjoying it, but I want to make sure I'm getting the most out of my gear while learning a little more about how it works.

    Thanks in advance......

    ~Jeremy
     
  2. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    You can either run one speaker off each output of the WT-300, or you can daisy-chain one cab off the other. Either way, you end up with a total load of 4 ohms on your amp, which is just right for the WT-300.
     
  3. ohms is the essence of all that is natural.
     
  4. And bass is the basis of all that is music :D
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Yep I agree. You've got no problems with your current gear and you're maximising available headroom by running a total 4 ohm load (ie your amp is producing the full 300w). If you ran only one of your cabs, the amp pushes against 8 ohms instead of 4 and produces less watts (I'm guessing about 220W)and therefore less headroom. You'll lose some volume but this is more because you've got less speakers than losing some watts.

    Don't try and add any extra cabinets though, it will drop our impedance below 4 ohms and damage the amp.

    Oh and don't worry about serial/parallell too much unless you plan to delve inside cabs and re-wire things.
     
  6. What happens to the ohm load when running a 4 ohm cab and an 8 ohm cab together, does this muck everything up?
     
  7. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland
    Yes it does. With 8 Ohm and 4 Ohm cabs together, the total Ohms are 2.67... that will definately fry a 4ohm amp.
     
  8. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland
    Ooops, forgot one thing....

    You also have to consider that if you´ve got an 2ohm amp, which will handle the 2.67ohm load, the 4ohm cab will be much louder than the 8ohm one.
     
  9. darkspec

    darkspec

    Jan 2, 2003
    Cleveland Ohio
    Could you run 2 4ohm cabniets (Avatar 212 & 410) on a 4ohm amp (Hartke 3500)? Or should you go with 2 8ohms? Would volume be bad?
     
  10. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland
    No! Here´s what you can do with that amp:

    1. Amp + avatar 212 4 ohm = Good! <- Amp is running at 4 ohms.
    2. Amp + avatar 410 4 ohm = Good! <- Amp is running at 4 ohms
    3. Amp + avatar 212 8 ohm & avatar 410 8 ohm = Good! <- Amp is running at 4 ohms
    4. Amp + avatar 212 OR 410 8 ohm = Good! <- Amp is running at 8 ohms but you won´t get as much volume as with a 4 ohm cab.

    Here´s what you can´t do:
    1. Amp + avatar 212 4 ohm & avatar 410 4 ohm = Boom! = Bad! <- Amp is running at 2 ohms
    2. Amp + avatar 212 4 ohm & avatar 410 8 ohm = Boom! = Bad! <- Amp is running at 2.67 ohms
    3. Amp + avatar 212 8 ohm & avatar 410 4 ohm = Boom! = Bad! <- Amp is running at 2.67 ohms
     
  11. darkspec

    darkspec

    Jan 2, 2003
    Cleveland Ohio
    so with 2 8ohm cabs it will be running at 4 ohms? will it be as loud as running 1 cab at 4 ohms?
     
  12. Ívar Þórólfsson

    Ívar Þórólfsson Mmmmmm... Supporting Member

    Apr 9, 2001
    Kopavogur, Iceland
    Yes, but running two 8ohm cabs will be louder though.

    Why? That´s because in your case you have 6 speakers moving some serious air instead of 2 or 4 speakers.

    I found this out recently when I switched from a 400W combo amp with a 15" speaker, to this 350W setup:

    [​IMG]



    Even though my new rig is 350W compared to my old one 400W, this one moves a whole lot more air!