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Thread: 4410 network question

  1. #1
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    4410 network question

    Hi!

    I am still trying to fully understand the 4410 network and to implement it without attenuators.

    All I intend to do is to copy the 0 dB setting for mid and high frequency with fixed L-pads using resistors.

    1) Since the highest setting on the original attenuators is "+1" attenuating it by 1dB would result in "0" setting, right?

    Mid frequency: there is a pre - attenuation with a 1.2 Ohm resistor. Using an online L-Pad calculator this would translate into ca. -1.5 dB (assuming 8 Ohm impedance).

    So my question is: is this correct and is it correct to attenuate it by 1 dB more to copy the "0" setting of the original 4410?
    Using the L-pad calculator this would give 2 Ohm in series and 24 Ohm in parallel.

    2) What I wrote above should theoretically apply if the attenuators were common (adjustable) L-pads. I do not fully understand the schematic. It looks as if the terminals normally going to ground or "-" are interconnected between the LP1 and LP2. Is this correct or is the schematic wrong?

    Sorry if this sounds too complicated...

    To sum it up: which resistor values would you use to imitate the "0" setting of the originals?

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    Thanks!

    Marc

  2. #2
    Administrator Robh3606's Avatar
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    Just use the 4410A schematic and you should be fine. This is retooled no attenuators set-up "flat".

    Rob
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    "I could be arguing in my spare time"

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    Hi, Rob!

    Thanks for your advice.

    I am aware of the 4410a network.

    It is much more complex and I would like to use my existing components.

    Basically it should be a quite easy calculation to answer for someone more knowledgeable than me.

    Anyone with an idea if my approach is more or less correct?

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    I do basically know how to do this.

    Was just looking for a confirmation for this specific case (where I wanted to combine the pre - resistor and L-pad setting into one serial / parallel).

    Terminal 1 normally goes to ground. Is this a mistake in the original 4410 schematic?

    Thanks,

    Marc

  6. #6
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    Grounding an Lpad?? GOOGLE How to Wire an Lpad


    Don't try to combine//meld the functions of the fixed pad ( R2 + R3 in the mid section ) with the function of its variable Lpad.

    Merging the two Lpads ( which have other LC components located between them ) requires a redesign of all midrange LC values to maintain the proper curves. ( I'm confident that redesign is beyond your capabilities ).

    Stick with simply substituting some fixed resistors for the 2 variable LPads.


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    I apologize if my words were confusing or even annoying.

    I will follow your advice and put the fixed pads where LP1 / LP2 are.

    By "ground" I only meant that the other end of the parallel resistor connects to "-", just like R3 does.

    So please could you confirm that I connect the new fixed pad at itīs position exactly like R2 / R3 (the schematic is confusing because it shows the "1" terminals connected to nothing but each other)?

    May I use 8 Ohm for calculation?

    This would give a new additional fixed pad (midrange) of 0.9 Ohm in series and 66 Ohm parallel.

    One last "thank you"

  8. #8
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    Quote Originally Posted by dub View Post
    I apologize if my words were confusing or even annoying.

    I will follow your advice and put the fixed pads where LP1 / LP2 are.

    By "ground" I only meant that the other end of the parallel resistor connects to "-", just like R3 does.

    So please could you confirm that I connect the new fixed pad at itīs position exactly like R2 / R3 (the schematic is confusing because it shows the "1" terminals connected to nothing but each other)?

    May I use 8 Ohm for calculation?

    This would give a new additional fixed pad (midrange) of 0.9 Ohm in series and 66 Ohm parallel.

    One last "thank you"
    Yes, connect the replacement ( fixed ) Lpad in the same arrangement as R2 / R3 .

    The variable LPads are 8 ohm types // so yes, you can use online calculators to get the substitute resistor values.

    Your calculation method is dependent on the panel markings being accurate (its anyone's guess if they are ) .
    ( Mind you, resistors are cheap enough, so you could simply buy enough to cover off 3 different amounts of attenuation. )

    A more direct method is to;

    Arrive at the values needed by turning the knob(s) of the variable LPad to where the speaker sounds balanced // ( then after cutting the wires leading to the 2 variable LPads ) measure the resistance between pins 3 + 2 , then 2 + 1, to arrive at the needed values of the replacement resistors.

    The resistor equaling ( measurement ) 3+2 is the series resistor while the resistor equaling 2+1 is the parallel resistor.

    Review the whole substitution process from one of the many links found by Google ( that I've already previously provided ).

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    Great. That helps me a lot.

    At least it confirms that my basic understanding of wiring is correct. I will implement another fixed pad.

    The point is that I donīt have the L-pads and I am not intending to buy some just to measure. Otherwise I would gladly just do that. That is the only reason why I was trying to calculate

    I am using the layout of my existing N80T network (that does not have variable ones) which is almost identical to the 4410. I have certainly adjusted all caps and inductors (checked their resistances, too) to 4410 values.

    If you had to calculate only, which value would you use for impedance? I was considering 8 Ohms because I read that the 58450 L-pads were nominally 8 Ohms.

  10. #10
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    This is the right answer for obtaining the results closest to flat response. Even more exacting would be to measure the acoustic output with FFT software such as REW or SpectraFoo at the desired listening / measurement location, set the controls to the curve required at the location ( a meter from the baffle on axis will be different from a chair five meters away 15 degrees off axis ) then isolate the L-pads and make your resistance measurements.


    Quote Originally Posted by Earl K View Post
    Yes, connect the replacement ( fixed ) Lpad in the same arrangement as R2 / R3 .

    ...

    A more direct method is to;

    Arrive at the values needed by turning the knob(s) of the variable LPad to where the speaker sounds balanced // ( then after cutting the wires leading to the 2 variable LPads ) measure the resistance between pins 3 + 2 , then 2 + 1, to arrive at the needed values of the replacement resistors.

    The resistor equaling ( measurement ) 3+2 is the series resistor while the resistor equaling 2+1 is the parallel resistor.
    ...

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  11. #11
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by dub View Post
    I am using the layout of my existing N80T network (that does not have variable ones) which is almost identical to the 4410. I have certainly adjusted all caps and inductors (checked their resistances, too) to 4410 values.
    You may want to emulate the L80T3 network. The L80T is the worst JBL 3-way I've ever owned. I converted mine to T3 networks and still have very little love for them—compared to L112, 4412A, and L96.


    FWIW, here's a shot of the N80T (left) and T3:


    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  12. #12
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    Weird,

    We don't know what speakers the OP actually owns and what he's trying to accomplish with these modifications ( from the get-go, I assumed he had a pair of 4410's ).




    PS ( EDIT )

    Okay, finally some background info on what this is all about.

    Read Dub's ( Marc ), 2 year-old thread about modifying his JBL L80T speakers

    From all accounts ( BMWCCA//Phils along with SeaWolfs testimonials ) gives the opinion that the L80T speakers sorely lack the magic of the Pro 4410 monitor ( even though they share the same components and have pretty similar crossover values and layouts ).
    - So it looks like this is all about Marc's desire to find a way to get the same magic ( of the 4410 )out of his L80T's.

    ( Some conjecture is ). that magic may come from the extra resistive damping that the N4410 has right before the Mid + HF driver in the form of variable padding.

    I return to my initial thoughts to recreate the 4410 network layout ( making all LCR values identical while omitting the variable LPad ) and then adding 2 fixed resistors ( ie; fixed LPad ) located right at the driver and after the existing network ( for both the mid & tweeter sections ) .

    Marc, simply use an online pad calculator ( set for 8 ohms ) to arrive at the needed resistor values ( 1 db, 1.5 db, 2 db, 2.5 db ) . Resistors are cheap, so buy a whole bunch of the many available values ( as suggested by the pad calculator ).

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