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Stuffed t-line to flatten midrange resonant freq impedance peak near xo cut off

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  • Stuffed t-line to flatten midrange resonant freq impedance peak near xo cut off

    I was wondering if a heavily stuffed tapered transmission line could be used to flatten the resonance impedance peak enough that you could simplify things and do away with impedance compensation components in the xover where resonance would be near the cut off frequency. Any experience in using a t-line in this way?

    Also, when stuffing to the point of flattening the impedance spike, will the t-line ultimately behave more like a sealed enclosure with a roll off closer to 12 dB/oct on the bottom end because the terminus output is essentially zero with the amount of stuffing needed to knock down the impedance spike?

    Nice to drop in again. I haven’t posted since sometime around 2009/2010.

  • #2
    in a double peak vented t-line you definitely reduce the secondary peak down to where there is a single peak and the single peak is reduced as well. The resonate frequency also drops a bit. Whether or not you need impedance compensation is a separate discussion
    John H

    Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower


    • #3
      Gotta think that with enough stuffing you just end up with an aperiodic cabinet.


      • #4
        Can't get rid of the primary resonance completely. However you don't necessarily need a compensation network. Most times you can design the crossover such that the impedance peak is taken care of by proper component selection. There are always exceptions of course.
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.


        • #5
          I would imagine that despite the cabinet construction, there will always be an impedance spike that would need to be managed on a component basis. I'm sure some of the guys that are crossover wizards would know more about driver impedance and cabinet design than myself though.


          • #6
            I like the idea. What frequency are you trying to dampen? I would worry that the stuffing will dissipate the wave if it is too high frequency. I suspect that no reflected wave = no impedance correction.


            • #7
              I have several TB W4 1337 titanium drivers sitting around I would like to put to good use. Measured Fs is 73hz.


              • #8
                I think a 73 Hz wave should travel through the stuffing pretty well. You will probably need to experiment with both stuffing density and line length to get something close to the desired result. Hopefully, you have some way to measure the impedance.