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larger Class D amps

Discussion in 'Electronic Basics' started by [email protected], Aug 23, 2007.

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  1. Guest

  2. Bob Eld

    Bob Eld Guest

  3. Guest

    Ok, thanks.

    Wait a minute... the TPA3001D1 is mono, huh, meaning I'll need 2 to
    power 2 speakers... so that's 40W already... and wait, Class D is ~90%
    efficient, vs. ~50% for class AB, right? So this will sound a bit
    like an 80W Class AB system, right? (rounding the 90% to 100% to make
    the math easier to do in my head)

    And if I power 4 speakers, that's 80W consumed, sounding like 160W of
    Class AB, right?

  4. Nobody

    Nobody Guest

    Wrong. Amplifiers are rated by the amount of power they deliver, not the
    amount which they consume. A 40W class AB will consume ~80W and deliver
    40W; a 40W class D will consume ~40W and deliver 40W.

    If amplifiers were rated according to consumption, everyone would be
    selling "1kW" amplifiers consisting of an 8W IC amp and a 1kW power
    resistor ;)
  5. Ninja

    Ninja Guest

    If I'm not mistaken, audio amps are usually rated by output power rather
    than input power. A 40 watt amp delivers 40 watts to the speakers
    (neglecting speaker impedance as it affects the output power), whether it
    class D, class A or anything in between. Ninty percent efficiency vs. 50%
    will save you some heat sinks and power supply capacity, but it won't give
    more output power.
  6. PhattyMo

    PhattyMo Guest

  7. Eeyore

    Eeyore Guest


    Amplifier ratings are OUTPUT power not INPUT power, so efficiency is irrelevant to how loud they go.

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