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4 or 8 ohm confusion!

Discussion in 'Amps and Cabs [BG]' started by jimstick, Feb 26, 2001.

  1. jimstick


    Dec 8, 2000
    Hello, I am considering getting a Trace AH150SM, I have a Trace 1518(1 x 15 cab 300 watts) The AH150SM has a 4 ohm output impedance(150 watts). The cab is 8 ohms. Would it be safe to run just the one 8 ohm cab. or do I need two 8 ohm cabs. Also,is 150 WattsRMS loud enough. I play in a loud rock band and I like to have some headroom.
  2. Gabu


    Jan 2, 2001
    Lake Elsinore, CA
    You can run a 8 ohm cab in a 4 ohm jack. It will reduce your volume a bit.

    I was using 2 100 watt heads, one into a 1x15 and the other into a 4x8 .. It was not loud enough to keep up with my drummer and guitarist at the same time. I ended up selling them and buying a 600 watt Carvin Cyclops. THAT is loud enough.
  3. kcm


    Jun 17, 2000
    Woking, Surrey.
    Recommend if you can go for an 8ohm 4x10 with your 1x15 which will make the amp run at optimum output. I use this setup at my rehearsal studio and have used it onstage and it really kicks despite the amp only being 150wts. From what I understand one speaker runs at the ohms stated (8) but if you add another you have to half it, half of 8 being 4 which is the minimum for your amp. Ideal!!

    Not a techie but I'm sure this is how it goes!!
  4. AssMan


    Dec 2, 2000
    Minnesota, USA
    you can run 2 8ohms cabs, 1 4ohms cab, or 1 8ohms cab. Your amp says it puts out 150 watts at 4ohms right? If you run a single 8 ohms cab it should put out around 100 watts. What the 4ohms label on your amp means that 4ohms is biggest load it can handle. The lower the ohms resistance level the more stress it puts on the amp, and more power is produced. You wont get more power out of amp if you run lower than it says it can, well you will but the amp burn out from too much stress pretty quickly. Some amps nowadays have a protect circuit and will shut if the ohms load is too low. Ohms work backwards. The lower the number the louder it will be. But if you run two 8ohms cabs you will have more sound output because you have more speakers driving the sound. More speakers=more sound output=louder overall sound. It's like lifting something. It's easier when you have 8 weak people, than if you have 4 stronger people. They both can get the job done but the weaker people can do it more efficiently with effort than the stronger people can. Less effort=better performance and longer life. Bottom line, 1 8ohms cab will work fine and will not hurt your amp at all. also when add another cab of the same impedance (or Ohms value) your total ohms value is divided in half. 2 8ohms=4ohms. 2 4ohms cabs = 2. There are 16ohms cabs out there but those are usually used with guitars. The ones I listed are the cabs you'll most likely deal with.
  5. jimstick


    Dec 8, 2000
    Thanks guys, you answered all my questions! Love your username, ASSMAN cometh!!!

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