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Thread: Modeling networks

  1. #1
    jim henderson
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    Modeling networks

    I’m trying to model the 4344 MKII network’s MF section so I can see the effects of any component changes. I took the forum’s advice and got a student/demo copy of PSpice and entered the network schematic and the 2123H’s equivalent circuit. (I couldn’t find an L-Pad in the component library so I used two 8-ohm resistors and set the top one to 0.1 and the bottom one to 0.9 to get 90% full scale.) Does this look right?
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  2. #2
    jim henderson
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    Here's the graph:
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  3. #3
    jim henderson
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    Now I’d like to model the HF section of the 4430/4435 network. There are generally few T/S parameters published for compression driver/horn pairs. The 2426 spec only has Re and BI. What do I use for an equivalent circuit?

    I’m not an Electronic Engineer, so I may be missing some fundamental concepts here.

  4. #4
    Administrator Robh3606's Avatar
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    Hello Jim

    Take a look at the Pi speaker site. Wayne Parham uses Aimspice. If you down load his Crossover Document I think he has what you are looking for. Basically what the motor breaks down into LRC.

    Spice model:

    ! tweeter virtual circuit (JBL 2426)
    ! voice coil reactance
    R4 6 10 3.3
    L4 10 11 0.1mH
    ! mechanical reactance (on 2370)
    C6 11 12 30uF
    L6 11 12 3mH
    R6 11 12 100
    C7 12 13 15uF
    L7 12 13 1.5mH
    R7 12 13 100
    C8 13 0 7.5uF
    L8 13 0 0.75mH
    R8 13 0 100
    R9 11 0 20
    C9 11 0 80uF

    http://www.pispeakers.com/contents.html

    This is out of context you should look at the whole document,

    Where did you get the Pspice??

    Rob

  5. #5
    jim henderson
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    Here's the one I used http://www.ee.mtu.edu/faculty/rzulin...ce/80dlabe.exe

    Here's another that I downloaded but haven't used yet http://www-ferp.ucsd.edu/najmabadi/C...E/91pspstu.exe

    This looks like an alternate source http://www.cadencepcb.com/products/d...t/91pspstu.exe

  6. #6
    Administrator Robh3606's Avatar
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    Thanks hope Waynes document helps you out.

    Rob

  7. #7
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    Originally posted by jim henderson
    Now I’d like to model the HF section of the 4430/4435 network. What do I use for an equivalent circuit?
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  9. #9
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    Re: Modeling networks

    Originally posted by jim henderson
    I couldn’t find an L-Pad in the component library so I used two 8-ohm resistors and set the top one to 0.1 and the bottom one to 0.9 to get 90% full scale.
    For some reason that doesn't sound right, but I could be wrong. You might want to measure the poles of an actual L-Pad or just leave the L-Pad out of the circuit.

  10. #10
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    Here is what I get measuring an L-Pad.
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    Hi Giskard

    Great Info !

    If you reduce that speaker load to 6.0 ohms , what do you get as a variation of resistance values as measured between pins 1 & 3 ?

    ( I do need to buy an 8 ohm Lpad sometime so I can answer these questions myself ).

    Thanks <. Earl K

  12. #12
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    Hello Earl,

    Measuring a 6.2 ohm resistor yields a variance of 7.4 ohms with L-Pad closed to 6.2 ohms with L-Pad wide open. Maximum resistance occurs roughly between the 9 o'clock and 11 o'clock position where the resistance is 8.8 ohms. Setting the L-Pad right at 12 o'clock yields an 8.0 ohm load (3 to 1) with the "series" resistor portion of the L-Pad being 3.6 ohms (2 to 3) and the "parallel" resistor portion of the L-Pad being 17.0 ohms (2 to 1).

    *****

    For this particular L-Pad (JBL 58450) when series (3 to 2) is x then parallel (2 to 1) is y.

    x =~ 1.0 ohms y =~ 29.2 ohms knob =~ 3 o'clock position
    x =~ 2.0 ohms y =~ 24.2 ohms knob =~ 2 o'clock position
    x =~ 3.0 ohms y =~ 20.0 ohms knob =~ 1 o'clock position
    x =~ 4.0 ohms y =~ 14.6 ohms knob =~ 11 o'clock position
    x =~ 5.0 ohms y =~ 9.4 ohms knob =~ 10 o'clock position
    x =~ 6.0 ohms y =~ 4.8 ohms knob =~ 9 o'clock position
    x =~ 7.0 ohms y =~ 0.2 ohms knob =~ 7 o'clock position

    Anyway...


    Last edited by 4313B; 10-23-2003 at 01:08 PM.

  13. #13
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    Thumbs up

    Thanks !!

    - Good to know .

    <> Earl K

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