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Thread: STC Preamp bypass switch - and tone pot - issue

  1. #1
    Junior Member
    Join Date
    Jan 2015
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    4

    Default STC Preamp bypass switch - and tone pot - issue

    Hi there,
    Recently, I installed a bypass switch (DPDT) on my active Jazz Bass with SD basslines and STC2 preamp. I got the instructions from SD forum: http://www.seymourduncan.com/blog/ti...e-stc-preamps/
    It worked, exept the BIG volume loss when balance at center (like PU's out of phase). The PU's to balance pot connection is correct. Also I installed a "tone" pot that simply have no effect on my passive tone.
    Any suggestion or feedback?

  2. #2
    Funkfingers
    Guest

    Default Re: STC Preamp bypass switch - and tone pot - issue

    Need to see photographs of your actual wiring before hazarding any comment.

    With traditional VVT Jazz Bass controls, it is normal for there to be a "notch" sound whenever one pickup is set for full output and the other is partially rolled off. This is a direct consequence if how the two pickups are adjusted relative to the strings. It is usually judged by ear.

    With a balance control in circuit, there is no guarantee that the centre detented position on the pot provides exactly fifty fifty volume mixing. Your pickup adjustments could mean that the balance control centre position sits in one of the two "notch" positions where the sound would be expected to be honky.

    Of course, it is possible that one of your pickups is faulty. More likely is untidy soldering of the pickups to the balance pot.

  3. #3
    Junior Member
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    Jan 2015
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    4

    Default Re: STC Preamp bypass switch - and tone pot - issue

    Click image for larger version. 

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    Hi, thanks for your reply here's two photos of the wiring. Again I should say that in active mode the balance pot provites a great balance between the two PUs. When in passive mode there not a simple "notch"; it's rather a BIG volume attenuation making the center position useless. Not to mention the tone pot that just doesn't work: acts more as a "Producer Switch" as Lee Sklar have once said

    Quote Originally Posted by Funkfingers View Post
    Need to see photographs of your actual wiring before hazarding any comment.

    With traditional VVT Jazz Bass controls, it is normal for there to be a "notch" sound whenever one pickup is set for full output and the other is partially rolled off. This is a direct consequence if how the two pickups are adjusted relative to the strings. It is usually judged by ear.

    With a balance control in circuit, there is no guarantee that the centre detented position on the pot provides exactly fifty fifty volume mixing. Your pickup adjustments could mean that the balance control centre position sits in one of the two "notch" positions where the sound would be expected to be honky.

    Of course, it is possible that one of your pickups is faulty. More likely is untidy soldering of the pickups to the balance pot.

  4. #4
    Junior Member
    Join Date
    Feb 2019
    Posts
    1

    Default Re: STC Preamp bypass switch - and tone pot - issue

    Hi, I'm having the exact same problem - was this ever resolved? Thanks!

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