Yet another OHMs question

Discussion in 'Amp Central Station' started by spauldingrules, Oct 14, 2021.

  1. spauldingrules

    spauldingrules Tele-Holic

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    I'm wiring up a 2x12 with 2 8 ohm 25watt greenbacks. I have a solid state 50 watt Marshall head which requires a 4 ohm load minimum. I am NOT trying to maximize volume. What would be safer for my speakers - to wire them parallel at 4 ohms, or series at 16? I'm more concerned about the speakers than the head - it's a backup to my normal 15 watt head with will work fine either way.

    Any input would be greatly appreciated! Thanks!
     
  2. corliss1

    corliss1 Poster Extraordinaire Platinum Supporter

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    The speakers don't know anything about the impedance of what they are connected to - they are only concerned with the wattage.

    If you plan to crank it up, I'd find a different speaker option. If not, go with the 4ohm.
     
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  3. spauldingrules

    spauldingrules Tele-Holic

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    I always thought that on a solid state amp, using a higher or lower impedance affected the output?
     
  4. Telenator

    Telenator Doctor of Teleocity Vendor Member

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    It does. Two speakers at 4 ohms are more efficient than two speakers at 16 ohms.
     
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  5. corliss1

    corliss1 Poster Extraordinaire Platinum Supporter

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    It could, but that doesn't mean the speakers care.

    Output power = RMS voltage squared, divided by ohms. So your power would drop a bit on the 16ohm option.

    I'm always more concerned with wattage in cases like this. If you hook up 50W, plus some distortion, to speakers that can barely handle it, it's likely there will be damage. I guess the 16ohm option could mitigate that a tiny bit, but not enough where I'd recommend it.
     
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  6. NoTeleBob

    NoTeleBob Friend of Leo's

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    With a SS amp, I like things to match. Go for four ohms. Just don't run it flat out (not because of the ohms, but because your amp can push the max your speakers handle).
     
  7. Larry F

    Larry F Doctor of Teleocity Vendor Member

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    When I was 13, one Sunday night, my dad told me that after my bath, he wanted to have a chat. Oh, no, this was the dreaded "talk" that we all get. So I steeled myself and walked into the living room where Dad was waiting for me. I go in, have a seat, and he says, "I think it's time for you to learn Ohm's Law."

    I had been encountering it in my projects, so this was to formalize it.

    A few months later came "the talk." Here's how I remember it.
    Dad: "Well, is there anything you want to know?"
    Me: "Nah, we covered this in biology."
    Dad: "OK, good. Don't do it before you are married."
    Me: "Can I go now?"
     
  8. Paul G.

    Paul G. Friend of Leo's

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    1. SS likes lower impedance, as long as you don't go below the rated minimum.
    2. If you're in parallel and one of your speakers blows open, you won't damage the amp.

    So, in your case, I'd definitely wire them in parallel @4 ohms.

    As long as you're not cranking the amp at high distortion for long periods, your speakers should (no guarantees) hold up. It is usually best practice to have speakers rated at twice the amp's rated power.
     
  9. aging_rocker

    aging_rocker Friend of Leo's

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    4ohms.

    Approach the master volume knob with caution...:twisted:
     
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