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Thread: Tweeter and Midrange Level Controls

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    Tweeter and Midrange Level Controls

    This is a general information question from a electronics dummy.

    I'm thinking about my S99 project which is building a 3-way system around the LE14A and wondering about level controls for the tweeters and mids.

    My L110's have controls that act like potentiometers, that is, they rotate freely but the S99 tweeter level controls have three click stops.

    I'm guessing the "click-stop" type control selects different resistor values while the "potentiometer" type is a resistor in and of itself. Am I in the ballpark?

    What are the advantages vs disadvantages of either type?

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    Quote Originally Posted by bedrock602 View Post
    This is a general information question from a electronics dummy.

    I'm thinking about my S99 project which is building a 3-way system around the LE14A and wondering about level controls for the tweeters and mids.

    My L110's have controls that act like potentiometers, that is, they rotate freely but the S99 tweeter level controls have three click stops.

    I'm guessing the "click-stop" type control selects different resistor values while the "potentiometer" type is a resistor in and of itself. Am I in the ballpark?

    What are the advantages vs disadvantages of either type?
    The "potentiometer" type in JBL speakers are actually "L pads." The L indicating two arms of the circuit, one series and one parallel. This, theoretically, provides a constant resistance load across the circuit which a pot cannot. In practice, they are not perfect, but very convenient. They wear out with time - corrode - and have to be cleaned/replaced. The switch type, as you surmised, switch in a specific set of resistors. They are more accurate and last a long time. But, you lose resolution. So, it's a trade-off.

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    Quote Originally Posted by Mannermusic View Post
    The "potentiometer" type in JBL speakers are actually "L pads." The L indicating two arms of the circuit, one series and one parallel. This, theoretically, provides a constant resistance load across the circuit which a pot cannot. In practice, they are not perfect, but very convenient. They wear out with time - corrode - and have to be cleaned/replaced. The switch type, as you surmised, switch in a specific set of resistors. They are more accurate and last a long time. But, you lose resolution. So, it's a trade-off.
    Thank you.

    So "L-Pads" provide more resolution, i.e., better sound?

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    Absolutely not. Just more steps of level adjustment (resolution, in this case, not inherently improving the signal as heard or audio resolving power).
    If, in providing more refinement of adjustment, that improves listening pleasure or better driver level matching, then one could argue that the listening may be improved.
    The already stated caveats apply though, about corrosion build up in both L-pads (a real problem) or switches (also a problem, but often less so).
    Once a setting has been found to be optimal (using whatever criteria is useful to you), hardwiring the values will be an improvement over the long haul.

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    Quote Originally Posted by grumpy View Post
    Absolutely not. Just more steps of level adjustment (resolution, in this case, not inherently improving the signal as heard or audio resolving power).
    If, in providing more refinement of adjustment, that improves listening pleasure or better driver level matching, then one could argue that the listening may be improved.
    The already stated caveats apply though, about corrosion build up in both L-pads (a real problem) or switches (also a problem, but often less so).
    Once a setting has been found to be optimal (using whatever criteria is useful to you), hardwiring the values will be an improvement over the long haul.
    Thank you. That makes perfect sense. I dialed-in the L-Pads on my L110's when I got them a couple of years ago and have not changed their setting since. On my S99 project, I'll figure out a way to listen to them at different levels and choose which sounds best. Once dialed-in, I'll eliminate any unnecessary controls and/or resistors.

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