Home Forums GuitarPCB Build Support Sunn T loses a lot of volume when turning up the treble knob.

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  • #14720

    Hi everyone

    When i turn up the treble knob on my sunn model t kit it loses a lot of volume. I triple checked and it’s the right pot and is wired in the right direction. What could be the cause of this?

    #14722
    Billy
    Moderator

    You’re better to post some nice clear in focus pictures of both sides of the pcb and offboard wiring so that we can check and trace it

    There are a few components surrounding the treble pot that could affect it

    #14724

    It’s my first pedal that doesn’t have the pots mounted on the pcb so it’s pretty messy 😅 here’s the schematics

    #14727
    Billy
    Moderator

    All your values look to be correct can’t see R8 and 12

    It may well be the intricacies of this circuit the eq is passive so you cut rather than boost frequency unlikely though

    When you say volume drops is it just when you turn treble up and do you adjust volume to compensate if so does it work

    As you can see from the schematic treble output goes straight to volume input lug 3 and out to your amp via lug 2 or dumped to ground via lug 1 depending on whether you turn it up or down

    You may not get accurate readings with it in circuit but check with no power to the circuit if the volume pot resistances change turn it all the way down and you should have a smaller resistance between lugs 1 and 2 and higher between 2 and 3 and visa versa

    I’ve not built this circuit yet so perhaps one of the guys that has can let you know it’s behaviour

    Barry advises in the build doc controls section to set all eq to the middle and adjust volume etc from there

    #14728
    Barry
    Keymaster

    This is definitely not right.

    Re-flow and give us voltages on all transistors.

    #14731
    wilkie1
    Moderator

    With all tone pots set a mid position. if the vol drops when the TREBLE pot is rotated CW,  I would check the solder connections of TREBLE pot lug 3 and both connections of C9.

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