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    Zobel Network

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    Pillo69

    Posts : 137
    Join date : 2012-04-11
    Location : Granada (España)

    Zobel Network

    Post by Pillo69 on Wed Oct 18, 2017 6:50 pm

    Hi.
    Does anyone use a zobel at the exit of the ST70?
    What would be the correct CR values?
    Here a calculator that needs values of the speakers, although there are amplifiers that include it from the factory.

    http://diyaudioprojects.com/Technical/Speaker-Zobel/

    Thank you.
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    Peter W.

    Posts : 527
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Zobel Network

    Post by Peter W. on Fri Oct 20, 2017 1:02 pm

    Pillo69 wrote:Hi.
    Does anyone use a zobel at the exit of the ST70?
    What would be the correct CR values?
    Here a calculator that needs values of the speakers, although there are amplifiers that include it from the factory.

    http://diyaudioprojects.com/Technical/Speaker-Zobel/

    Thank you.

    Where:
    Re is the DC Resistance of the driver [ohms]          Can be taken with a standard VOM.
    Le is the Voice coil Inductance of the driver [H]      Needs an LCR meter, or specification from the driver OEM.
    Rz is the calculated Zobel resistor [ohms] and        Will calculate when the values above are input.
    Cz is the calculated Zobel capacitor [F].                 Will calculate when the values above are input.

    Now, VC inductance is usually tiny - use one (1) mH and you should be within the ballpark. The typical driver at rest (resistance) is usually, 4, 6, or 8 oms. Try dropping those values into the calculation and see if they make sense. Then, drop an L-pad vs. resistor into the network and you have some additional control.  

    Yes, I keep an LCR meter - I hadn't thought about this use, however. As a side-bar, I am working with another member here to clone the Dynaco A40 crossover to back-fill earlier resistor/cap crossovers in A25-on-up speakers. Using the OEM values I back-calculated to a crossover point of about 1,700 HZ - and that system uses a small air-core choke of about 0.75mH, and an 8.2uF NP cap with an 8-ohm L-pad. I will measure the VC inductance of the tweeter - that will give me the exact crossover point. But, you get the idea - small changes = significant effects.

    If this effort bears fruit - I will 'show my work' and source the parts for those here. My goal is to make it sufficiently simple that it is the work of a couple of hours if even that.

      Current date/time is Mon Nov 20, 2017 4:16 pm