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Quick ohm matching ques

Discussion in 'Amps and Cabs [BG]' started by squire_pwr, Jan 4, 2004.

  1. squire_pwr


    Apr 15, 2003
    San Diego, CA.
    I think I know the answer to this, but I don't want to break anything.

    Can I run a 4 ohm head through an 8 ohm cab?

    I won't run it loud (so even though I think it's an issue, it won't be one effecting my decision at the moment), just want to see what the head sounds like in my bedroom. Thanks.
  2. amos


    Oct 23, 2003
    SE Portland Oregon
    definitely search before posting technical questions but your amp puts out ohm loads while the cab is rated at a specific ohm.

    but to answer your question, yes, you can use an 8 ohm cab with your head. in fact you can use two 8 ohm cabs (producing a 4 ohm load on your amp)
  3. notanaggie

    notanaggie Guest

    Sep 30, 2003
    One possible issue if it is tube type, (doesn't sound like it is tho) higher loads increase voltages in the power section and can stress things.

    Pshycho Bass Guy described it in a post reply a while back. Don't remember which, look for other ohms questions.
  4. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    The general rule for a solid state amp is "equal or higher". The minimum impedance is usually written in big letters somewhere on the amp. It's safe to go higher, but not lower. Lower will fry the amp. There are some exceptions to this rule, but generally it applies to most solid state amps.

    The general rule for tube amps is anywhere between 50 and 200 percent of the rated impedance. So for instance if your amp wants to see 8 ohms, you could go anywhere between 4 and 16, but 2 ohms would be too low. This rule applies specifically to push-pull amps, and it specifically doesn't apply to class A tube amps. But I don't know of too many class A tube bass amps (at least not modern ones).
  5. squire_pwr


    Apr 15, 2003
    San Diego, CA.
    Cool. Thanks a lot guys! That's an interesting thing about tube amps tho, nonsqtr. Had no idea! But yeah, I'm pretty sure it's a solid state (old peavey head, not sure the model), so now all I need to do is find an unshielded cable and I'm good to go. :)

    oh. new question (too simple for a new thread). Would it be ok to use a shielded cable for amp -> cab? For bedroom volumes? :) thanks!
  6. Use a speaker cable to go from amp to cab.