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Tweeter sensitivity confusion .........

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  • Tweeter sensitivity confusion .........

    a friend gave me a speaker to play around with for fun.

    It has a small 5" woofer, and 2 1" dome tweeters wires in series, with a 3.3uf cap and a 4 ohm resistor after the cap.

    POSITIVE ------3.3 Cap---4ohm Resistor-----4ohm tweeter------4ohm tweeter----- NEGATIVE

    What I wrote above all in series.
    My question is, if I remove one of the tweeters, and only use one, but put a 4 ohm resistor in the 2nd tweeters place, will I be getting the same basic sensitivity? (or very close)

    Tying the leads together and bypassing the 2nd tweeter, will throw off the crossover obviously and it made the first tweeter a good bit too loud also.
    Identical tweeters.
    And this is a dipole surround speaker, but otherwise, sounds fairly decent and normal.

  • #2
    Series wiring vs a single are the same sensitivity. Being a 1st order xover, the Fc will shift when changing to 8 ohms from 12 ohms. You will actually cut the output further with swapping for a resistor, but the net xover Fc will be close to the same.

    Later,
    Wolf
    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
    "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

    *InDIYana event website*

    Photobucket pages:
    http://photobucket.com/Wolf-Speakers_and_more

    My blog/writeups/thoughts here at PE:
    http://techtalk.parts-express.com/blog.php?u=4102

    Comment


    • #3
      Originally posted by Wolf View Post
      Series wiring vs a single are the same sensitivity. Being a 1st order xover, the Fc will shift when changing to 8 ohms from 12 ohms. You will actually cut the output further with swapping for a resistor, but the net xover Fc will be close to the same.

      Later,
      Wolf

      Okay cool, could not get my brain in gear! So instead of say 2 tweeters at about 85db each,(guestimations..) and combined equal 88db, now the single one will net 88db just by itself.

      oops forgot to add it is a 2nd order, it DOES have a coil also!

      Comment


      • #4
        Then while the Fc of the xover won't change, the Q of the filter will, and FR will shift a bit.

        Later,
        Wolf
        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

        *InDIYana event website*

        Photobucket pages:
        http://photobucket.com/Wolf-Speakers_and_more

        My blog/writeups/thoughts here at PE:
        http://techtalk.parts-express.com/blog.php?u=4102

        Comment


        • #5
          Here's my method (which I think SHOULD yield equivalent results)?
          I took the .zma data (for a single 4ohm tweeter - actually used 275-035 (neo) ) and doubled the values (to sim a pair in series).
          Then I took that series z-file and simmed it (using the orig. f-file) with a 4ohm resistor and 3.3uF cap in series. I did NOT add a shunt coil (2nd order) 'cause you haven't mentioned a value.
          Then I simmed just bypassing (jumpering) the 2nd tweeter by using the orig. f/z data files (so . . . half the z, but same .frd - since a pair in series should have the same sensitivity as a single) along with the series 4ohm and 3.3uF.

          When going from the series pair (orig.) to just a single tweeter, the output looks to drop an ave. of about -4dB. I THINK that's because the 4ohm series resistance has a greater effect on the 4ohm "load" (single tweeter) than on the 8ohm load (series tweeter pair).
          In order to match the output of the tweeter pair (when using just a single), I had to change the series resistor from 4 to 2ohms (half), and double the cap from 3.3 to 6.6uF - which kinda makes sense in a way.

          This does NOT seem to correlate w/the OP's findings though. Maybe 'cause in reality he's got a 2nd order filter?

          Comment


          • #6
            Chris Roemer
            I will actually try 4 methods today and take SPL levels, with Both pairs, a single tweeter, leads of 2nd bypassed, and with single with 4 ohm in place of 2nd tweeter and single with 2 ohms in place of 2nd tweeter.

            I put the tweeters impedance graph, not sure that will change anything, but I used "4 ohms" as a guestimate.
            1" Dome, with Ferrofluid, I checked since I had to remove the dome to get a "Dent" out of it from behind.

            FYI< it is crossed at 2khz according to manufacturers specs. Did not measure coil yet.

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