Ohm help please

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by 6Tones, Oct 7, 2004.


  1. 6Tones

    6Tones Supporting Member

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    My VHT amp internal speaker is 8ohm,and I want to run a 16ohm extension cab with it,the amps selector switch is 4,8,16 ohms, what should I set it too?
    Also what if I used a 8ohm extension cab,would I set the ohm selector switch rating to 4?
    Thanks in advance!
     
  2. John Phillips

    John Phillips Member

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    If the internal speaker is 8-ohm, and the extension is 16, the total impedance is 5.33 ohms - assuming the sockets are in parallel, which in most amps they are.

    This is a safe mismatch from either the 4 or 8 ohm settings (it 'sounds' closer to 4, but actually it's a 33% mismatch from either if you work it out!). Try both and see which sounds better. If you can't tell any difference, it probably doesn't matter at all either way. If I had to pick, I'd probably go for 4 since mismatching fractionally upward is a little less hard on the tubes than downward. Also, it may be worth mentioning that 2/3 of the power will go to the 8-ohm speaker and only 1/3 to the 16-ohm extension cab.

    If you're using an 8-ohm extension cab, set the amp to 4, yes. The power is divided equally between the internal and external speakers.
     
  3. 6Tones

    6Tones Supporting Member

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    Ok Ill go with the 4ohm setting.
    Thanks John!
     
  4. J.T.

    J.T. Supporting Member

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    Is the 16 ohm cab a 2x12 ? It might be easier to re-wire the 2x12 for 8ohms that paired with the internal 8 ohms will give you 4 ohms total with out a mismatch
     
  5. 6Tones

    6Tones Supporting Member

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    No its a 1x12 16 ohm extension cab:p
     

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