Amp set for 2ohm into an 8ohm cab?

Discussion in 'Amps and Cabs [BG]' started by armybass, Aug 19, 2017.


  1. armybass

    armybass Gold Supporting Member

    Jul 19, 2001
    Last night I had my Bassman 100T set to 2ohm output into my 8ohm cab unknowingly. I was not getting any volume or tonal definition. My bass just sounded like mush. It was so obvious that something was wrong I caught it after the first set. Switched to 8 and it sounded great the rest of the night.

    My question to you and gurus is what was actually happening to the amp and cab to make it sound like that? I mean what was the actual electrical definition of what I was doing to cause the amp to sound like that. Was I forcing the amp to work too hard with the resistance it was looking for to offset the power output?

    Just trying to educate myself a wee bit on amp stuff. Thanks for any input?
     
  2. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    using wrong impedance load caused output tubes to operate at incorrect impedance as well. loss power and tone.

    tubes are coupled through a transformer, if you change the load on one side it effects the impedance on the other side according to the ratio its wound to.

    the ratio was wound to a 2ohm load. putting a 8ohm load on it changed the impedance for the tubes.

    switching the 8 ohm load to 8 ohm tap provided the correct ratio for tubes to operate at the correct impedance.
     
    Last edited: Aug 19, 2017
    armybass likes this.
  3. armybass

    armybass Gold Supporting Member

    Jul 19, 2001
    Thank you! I really appreciate the explanation. I certainly hope I did not damage anything, but there was something obviously wrong from the way it sounded. The tone was almost like I had some kind of chorusing, time delay on the bass and it was not responding to turning the volume up and just sounded like awful mush.

    Thank you again for taking the time to explain the science behind it!
     
  4. Yes and for the OP this translates into a lot less power to your speakers. I unknowingly ran an 8 ohm cab from an 4 ohm output on an SVT years ago and definitely noticed the difference, less volume and more distortion.
     
    armybass likes this.
  5. armybass

    armybass Gold Supporting Member

    Jul 19, 2001
    Yes I certainly was getting some distortion from the amp but it was so squashed that is just sounded like all of the life was being sucked out of it. I switched basses at first thinking my preamp battery was dying in my Stingray.
     
    bobyoung53 likes this.
  6. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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