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Boss DD-7 Modding advice - Effects loop

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  • Boss DD-7 Modding advice - Effects loop

    Hi everyone,

    I've been tinkering with some mods on a Boss DD-3, replacing the direct out jack with a normally closed stereo jack (effects loop mod). This mod essentially lets you add any effect (flanger, chorus, etc.) to the signal chain (using a TRS Y-cable), applying it only on the repeats.

    Having worked on a Boss DD-7 recently (internal Tap Tempo mod), I'm attempting to do the same mod, replacing one of the stereo jacks. The circuit is very different from the DD-3 of course, but I'm hoping I can feed in the additional effects loop somewhere in the signal path.

    On the DD-3, I inserted the additional loop at point 12 on the schematic (attached), just before the "Effect Level" controls.

    On the DD-7, would it be possible to break one of the ribbon cable connections to the VR board, to insert the additional loop? Schematic attached.

    I'm not too familiar with reading complicated schematics, and I wonder if the new design of the DD-7 makes this mod possible at all. Would be a really fun mod if it works though, and I'd be happy to share the final result!

    Click image for larger version

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  • #2
    The VR board does not have any audio signal present. Each pot has a common DC reference voltage _DVREF and the DC level output from each pot is used by the processor to alter each parameter. So, the proposed modification will not work - you will only be intercepting the E.LEVEL control voltage. As this will also be blocked by DC blocking capacitors in your FX pedals, the processor will be missing a control voltage and quite probably this will cause an error condition and stop the pedal from working.


    • #3
      Hey Mick,
      thanks for your reply! I thought I had read somewhere that this might be problematic, but your explanation really helped making sense of it.
      It's probably safe to conclude that this mod doesn't work for the DD-7, or at the very least not in the same way as on the DD-3.