voltage question to speakers

Discussion in 'AV Receivers' started by StanB, Feb 12, 2006.

  1. StanB

    StanB Agent

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    Is the voltage to my speakers and sub, AC or DC? What is a normal range of voltage with loud music? I have two subs daisy chained. When I turn off one sub it causes the other sub to pop. I put a meter on the sub that I turn off, and when I turn that sub off and I get a 2.5 DC voltage kick sent to the other sub. Is that normal?

    Thanks.
     
  2. Nhoj

    Nhoj Auditioning

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    Hi Stan

    It's AC. Music waveforms are alternating voltages that swing positive and then negative at speeds corresponding to the frequency of the notes involved, at least, by the time your speakers get it. 100hz means 100 up/downs of the voltage. A typical voltage to a tweeter would .01 to 10v on the loud side. A sub woofer would coast at 5-10v with loud peaks and thumps reaching 25 to 40v depending on the capabilities of the amp and the current needs of the speaker. 40 volts is 200 watts into 8 ohms, 400 watts into 4 ohms, 800 watts into 2 ohms. The turn-off thump is a randomly swinging voltage caused by the collapse of the positive and negative rails coming from the power supply. On a polite gizmo, it's muted by grounding or relays. Some components of that thump are changing slowly enough to register as a dc voltage on a meter. DC is a constant unchanging voltage that would not cause the speaker's voice coil to jump, but get hot.
    Turn off the second woofer first, and let its power supply fade away before turning off the first. The thump won't be amplified.

    Cheers

    Nhoj
     
  3. rob-h

    rob-h Second Unit

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    FYI, DC voltage will cause the voice coil to move. Depending on the polarity appled, it will move in or out. Then it will get hot[​IMG]
     
  4. Nhoj

    Nhoj Auditioning

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    Sure, sure... that's how you check a driver's polarity.
    Any change in voltage (ac or dc) will make the cone move, and a .001 hz sine wave will get it just as hot.
     

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