Passive tone into a Thumb system

Discussion in 'Pickups & Electronics [BG]' started by bajerovaquero, Mar 5, 2014.


  1. bajerovaquero

    bajerovaquero

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    Hello
    I´m installing a used Warwick Thumb pickups and preamp in another instrument.
    It has 4 holes so I was wondering about adding a passive tone to fill the 4th hole. Makes a lot of sense because you cant shape the tone in passive mode anyway...

    Is this a straight operation I mean hot to 250k pot with capacitor and ground?
    Let me know if it would work or the extra resistor will interact with the active system.

    Thanks
     
  2. line6man

    line6man

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    Some Warwicks have active pickups. If that's the case, you will want a lower value pot.
     
  3. RobbieK

    RobbieK

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    ^ true dat.

    also, some people like to run a passive tone pot from the bypass switch so it only kicks in when the bass is switched to passive mode.
     
  4. bajerovaquero

    bajerovaquero

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    Thanks for your responses! I appreciate

    Here is the wiring diagram:
    [​IMG]

    There are pots of 500 100 and 25k ....
    I¨m going to wire first a 500k pot between hot and jack and listen what happens if not work then a 50K

    Also I got some 250k dpdt pot so could you provide some schematic RobbieK?


    Thanks
     
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  6. line6man

    line6man

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    The pickups are clearly stated to be active. This means you should use a 25k tone pot. (Or 50k, to taste.) Additionally, you may want to try higher capacitances than would typically be used for passive pickups, because the frequency cutoff point of a tone control is partly dependent on signal impedance. 0.1uF is a good place to start.

    Note that tone controls behave a bit differently with buffered signals than when they are allowed to interact with the impedance of a coil.

    For a tone control that is only in the circuit in passive mode, use this diagram:
    [​IMG]
     
  7. JP Morin

    JP Morin

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    the thumb pre already have a preamp bypass build-in. a "passive tone knob" would be useful but I'd use the fourth hole for something else... or plug it with a non used dummy knob or switch... May be a EMG afterburner in it, or a drive circuit ??
     

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