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Pioneer deck question, and HPF capacitor question

Discussion in 'Audio' started by dhcomp, Jul 16, 2003.

  1. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Ok, I finally started a system install on our boat and had a few questions. I have teh pioneer 1400 deck (i know, its the bottom of the line, but someone gave it to me). When i crank it up and there are speakers connected to the internal amp, the screen dims when the bass hits. Is this a lack of power problem? Its in the boat, so i have only used it with the battery power.

    Second question, on 6x9's, if I'm goign to have a sub to put out the low frequencies, what frequency its pretty standard to cross them over at? I know bass blockers are just capacitors, so what capacitors do i need to cross them over at the right point?

    Then what crossover point is recoomended for most subs? Its a JL 12w3. Thanks guys!
     
  2. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I'd cross the subs over at 80Hz for starters......


    A typical "passive" bass blocker is nothing more than a simple capacitor which effectively creates a 6dB/octave crossover slope......that's not very good.

    On subs, the more aggressively you can "shelf off" those frequencies, the better. A 12dB/octave would be OK, 18db or 24dB/octave would be GREAT!

    The problem with the shallow-slope crossovers is that they allow the sub to play too much musical information above the crossover frequency. It makes it easy to "localize" where the sub is positioned, and it makes a mess of your soundstage....it really pulls and smears the sound from the mids (where it belongs) over to the sub.

    Most modern amps have crossovers built in....those are "active" style crossovers, which are also more efficient than those "in line" (passive) filters.


    /forums/images/graemlins/thumb.gif
     
  3. rampage

    rampage 1/2 ton status

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    You can figure out the size of the cap you need and buy your own good quality one.

    f=LRC

    f=freq
    L=inductance of voice coil (should be able to get that from manufacture)
    R=resistance of voice coil (should be 4ohms but you can measure with DVM)
    C=capacitance of course.
     
  4. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Gregg, sorry if i didn't make myself clear, the amp i have has an active crossover for the sub. I need caps to work as bass blockers on some 6x9's. I've done some reserach and will probably get either 47micro farad or 33 micro farad caps, but does the voltage matter? THanks!
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    You'll need to size them properly for the amount of power the amp is potentially going to feed them.....

    Beyond that, just be SURE you understand the cutoff frequency you are selecting and how shallow the slope is.

    If I were you, I'd buy an assortment (if they're cheap enough) so that you could try 100Hz, 120Hz, 150Hz, etc... on those 6x9's.
     

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