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  1. #1
    New Member
    Join Date
    Jul 2007
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    San Francisco, CA
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    2

    Daisy-chaining speakers, power unmatched

    Hi all,
    tech question: What happens if I have a mono amp that gives 700 watts at 4 ohms, and I have 2 speakers, both 8 ohms, one rated for 300 watts and one for 400? I know that they will offer 4 ohms resistance, but what happens to the power handling if I crank up the amp? Will the two speakers "figure it out" and absorb 300 and 400 watts respectively, or will the "weak" speaker blow up? Question two, does anybody know where I can learn more, book or website?
    Thanks!

  2. #2
    OK, when you connect 2 speakers in series, the impedances are added together, so you get 16 ohms, not 4. 4 would be in parallel, which what I assume you mean.

    Power, measured in Watts, is actually a measurement of the heat dissapated by the speaker's voice coil when work is done. This work is the movement back and forth due to current flowing through it and the electrical properties of the coil itself.

    Your amp will generate a voltage which, when turned all the way up, will cause current to flow through the speaker enough to cause 700 watts worth of heat. That is the theory.

    When you connect 2 or more speakers in parallel the formula is:


    1
    ZTotal = _________________
    1 1 1
    ____ + ____ + _____
    Z1 Z2 Z3

    If all the speakers have the same Z:

    Ztotal = Z of one speaker / the number of speakers. In this case the current will be the same in all the speakers. the power will also be divided up evenly, since the voltage and current are the same. ( Power + voltage times current). Each speaker in your arrangement in your question would dissapate 350 watts. The speaker rated at 300 Watts will probably fry. Sorry. Daisy chaining (series circuit) would work if your amp can work at 16 ohms.
    Last edited by penniesfromheaven; 2nd Jul 2007 at 22:18. Reason: spaces in formula are wrong
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  3. #3
    Sorry, the spaces came out wrong in the formula. I'll try it a different way:

    Ztotal = 1 / (1/Z1 + 1/Z2 + 1/Z3...)
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  4. #4
    Really it depends what rating you quoted. if it was an RMS rating, yu won't blow it up unless you run a sine wave at max volume for an extended period of time, music tends to be a lot more dynamic, with peaks and valleys, so your RMS rating of 300 watts may indicate peak ratings that are much higher, your speakers may be fine. ultimately you shuoldn't push any system that hard (you'd be using up any and all headroom)....

    for the average gig, it would probably be fine. if you are doing a DJ thing and playing pre-recorded music all night it may be different (pre-recorded music is a lot more static in it's level peaks than live bands) but agian, if you have the mixer sending a wicked hot signal to your amp and it's cranked, you've got problems more than an unmatched set of speakers.

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