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Need help choosing capacitors

Discussion in 'General Electronics Discussion' started by Vytaz, Apr 6, 2016.

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  1. Vytaz

    Vytaz

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    Apr 6, 2016
    Hello everyone, i decided to make my own boombox and i got stuck at choosing what capacitors i need to use for my tweeters and woofers to keep them safe from failing, how to calculate how much uF is needed ? For now what ive gathered:
    2x skytek 6'5 PP mid woofer 200w 8ohm
    2x Hifi 40w tweeter 8ohm
    Amp tda7492p 50w+50w
    24v power supply
    And if you have any suggestions please feel free to share, thanks!
     
  2. dorke

    dorke

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    Jun 20, 2015
    Welcome to EP.
    The issue of choosing capacitors has much more issues related than "keeping them safe"...
    What are your design goals in terms of RMS power?
    You see a 24V PS will not get you very far...
    can you calculate what power you can get with it?
    Hint :a lot less than you think ;)
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I calculate a max of 288W into 8Ω in bridged configuration

    however that would be for square waves - for music it would be closer to 200W but that assumes 100% efficiency and would have no headroom.
     
  4. dorke

    dorke

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    Jun 20, 2015
    Steve,How so?
    Must be the late hour (mine or yours);)
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    you're correct, I calculated for 48 volts. Divide my numbers by 4.

    or use speakers with half the impedance.

    oops
     
  6. Vytaz

    Vytaz

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    Apr 6, 2016
    So ineed less power? Sorry im a complete newbie to this so i need to cover alot of ground haha
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
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    Jan 21, 2010
    No, you'll need a higher voltage and/or bridge connected amplifiers and/or lower impedance speakers.

    capacitors are not an answer.
     
  8. dorke

    dorke

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    Jun 20, 2015
    Yes like all newbies have to.
    But seriously,
    Try and calculate the max power you can achieve with a 24V power supply and assume you have an 8 ohm speaker.
    This is the very basic and essential understanding of Power Amplifiers.
    Show how you did that .
    Don't be shy,we all learned (and still do) mostly from our mistakes;)
     
    Last edited: Apr 7, 2016
  9. Vytaz

    Vytaz

    3
    0
    Apr 6, 2016
    Thanks, i remember reading somewhere that my amp has two amplifier chips so i guess its already bridged so ineed to find a 24v non bridged amplifiers, must they be mono or bridgable amps are mono only? By the way how did you get the 48v in total? I could not find much information how to calculate the total voltage, although ive counted 280w total power required just for the speakers. Thanks guys for pointing out my mistakes and showing me what i need to know.
     
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