Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

head question

Discussion in 'Amps and Cabs [BG]' started by spalka621, Jan 13, 2006.


  1. spalka621

    spalka621

    Jul 26, 2005
    Sioux Falls, SD
    How many watts would a amp thats rated at 180 rms, such as a Electric Blue 180 Amplifier Head, put through a 8 ohm cab.
     
  2. Thor

    Thor Moderator Staff Member Gold Supporting Member

    The Ashdown manufacturer specs found online at Musicians
    Friend, Same Day and zZounds all use the same PDF file.

    I can't see any Ohm rating info in any of the specs available.
    Just a claim of 180 watts RMS.

    It does note that the minimum impedance is 4 ohms.
    If the Amp produces 180 watts at 4 ohms, which is
    likely, we can apply
    Ohm's Law (P(ower) = I^2(Currrent) xR(esistance )
    and V(oltage) = I(Current) x R(esistance)

    and derive 180 = I^2 x 4 I then = 6.70 and
    Voltage is 26.8 volts (V=IR).

    Substituting an 8 ohm load
    (26.8 = Ix8) we find the new current is I = 3.35.
    Then the Power of the new circuit is P = I^2 x R
    or P = 11.2225 x 8 or 89.78 watts.

    Note how this is not readily revealed in the specifications
    somehow.

    Be aware that how loud this amp is will depend on the
    sensitivity of the speaker the amp is connected to.

    Ohm's Law is covered in the FAQ's if you have a further interest.
     
  3. spalka621

    spalka621

    Jul 26, 2005
    Sioux Falls, SD
    okay thNKS FOR THE INFO I WAS JUST CONFUSED ABOUT WHAT RMS MEANT