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How off can my zobel be with good results

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  • How off can my zobel be with good results

    I want to recycle a zobel but the component properties are slightly off.

    I need 10 uf cap and 10 ohm resistor

    But I HAVE a 6.8 uf cap and a 12.5 resistor.

    Too far off; worth recylcling or should I buy the new components?

    thanks

  • #2
    Re: How off can my zobel be with good results

    I'd think that the capacitor you have, which is 32% below the value you need, and the resistor you have, which is 25% larger in value than you need, are both more than "slightly" off. The values you have may work out okay depending on what you want and how much their errors degrade the expected performance, but if it were me, I'd buy the proper-valued components.
    Paul

    Originally posted by jhw View Post
    I want to recycle a zobel but the component properties are slightly off.

    I need 10 uf cap and 10 ohm resistor

    But I HAVE a 6.8 uf cap and a 12.5 resistor.

    Too far off; worth recylcling or should I buy the new components?

    thanks

    Comment


    • #3
      Re: How off can my zobel be with good results

      It will be off. How much? You need to run (measure) an impedance curve to find out.
      Last edited by ; 11-26-2008, 10:15 PM.

      Comment


      • #4
        Re: How off can my zobel be with good results

        Originally posted by jhw View Post
        I want to recycle a zobel but the component properties are slightly off.

        I need 10 uf cap and 10 ohm resistor

        But I HAVE a 6.8 uf cap and a 12.5 resistor.

        Too far off; worth recylcling or should I buy the new components?

        thanks


        Tell me your driver. If it's almost any Dayton model (or even quite a few others - as long as I have F/Z data for them) I'll check it for you in a sim.

        Chris

        Comment


        • #5
          Re: How off can my zobel be with good results

          Originally posted by Chris Roemer View Post
          Tell me your driver. If it's almost any Dayton model (or even quite a few others - as long as I have F/Z data for them) I'll check it for you in a sim.

          Chris
          Dynavox LW6004PMR 6-1/2" Woofer 295-605
          Thanks

          Comment


          • #6
            Re: How off can my zobel be with good results

            Originally posted by jhw View Post
            Dynavox LW6004PMR 6-1/2" Woofer 295-605
            Thanks

            Here's the deal:

            That driver (which I'D call a nominal 6 ohm, rather than 8) hits a minima of 5.5 ohms at 250 Hz. It rises steadily to 20 ohms at 10 kHz.
            Any of these Zobels won't affect the minima of 5.5n @ 250 Hz, at all.
            Listing resistor ohms, cap uF, resultant ohms @ 900 Hz, 3kHz, & 10kHz:

            (what you have won't do much, but it's better than none at all)
            12.5n + 6.8uF: 6.8n, 7.9n, 8.9n, - so, still steadily rising, but rate is < half

            what you think you need isn't too much better, but it IS a little better
            10n + 10uF: 6.5n, 6.9n, 7.7n, - still rising, but closer to only 1/3 as much

            10n + 6uF: nearly flat at 8.1n +/-0.4 from 1.4kHz up
            8n + 8uF: nearly flat at 7.0n +/-0.4 from 800 Hz up
            7n + 14uF: nearly flat at 6.0n +/-0.4 from 110 Hz up
            6n + 18uF: nearly flat at 5.4n +/-0.4 from 140 Hz up

            If I were using 2 in parallel, I'd have to go with the 10ohm + 6uF, which for two in parallel would be 5 ohms + 12uF, but it would keep my load at approx. 4 ohms to keep an amp happy.

            For a single driver, I'd go with a 7 ohm resistor + 14uF cap for a fairly flat 6 ohm load. A "textbook" XO would be best calc'd at a 6 ohm load.

            Chris

            Comment

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