Beginner Technical Question

Discussion in 'Amps and Cabs [BG]' started by SonofDadBass, Sep 22, 2005.

  1. SonofDadBass


    Sep 12, 2005
    New Jersey
    a 400w (4ohm) amp connected to

    a 200w (8ohm) cab and
    a 400w cab (8ohm)

    each cab connected to a separate output on the head. (Parallel, would you call it?)

    How many watts would each cab be receiving?

    And here I must give an enormous thanks for all the helpful advice I have received both from my posted questions and from the questions and answers of others here in the forum.

    Take it easy,

  2. winston

    winston Supporting Member

    May 2, 2000
    Berkeley, CA
    Hi, Dan. There is a good link about ohms/impedance in the FAQ sticky at the top of the Amps forum:

    Long story short: cabs of the same impedance (in your case, 8 ohms) will receive the same amount of power. The wattage rating on your cabs is provided by the manufacturer to let you know how much power the cabs can safely handle. This figure has nothing to do with how much power they will draw from your amp--that's entirely dependent on the amp's specs.

    Do be aware, however, that it is possible to damage speakers using wattage well below the mfr. rating if you're clipping the power amp or using a lot of low-end boost. AND many players like feeding their cabs using amps with wattage output well above the cabs' power rating. This can work well as long as you don't turn up the amp too high. HTH.
  3. The amount of power going to each cab will depend on how loud you are playing. When you are as loud as the amp will go without clipping, you'll have 200W going to each speaker.

    When you are standing there quietly between songs, not playing, both speakers will get approximately zero watts.

    No matter how loud you play, both speakers, each being 8 ohms, will always split the power coming from the amp evenly.

    For anyone out there mixing cabs (a 4 and an 8 ohm cab):
    A 4 ohm speaker mixed with an 8 ohm speaker will result in the 4 ohm speaker always getting twice the power of the 8 ohm speaker. Hypothetically with your amp putting out 300W, 200w would go to the 4 ohm cab and 100W would go to the 8 ohm cab.