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Best DIY ABY Circuit?

Discussion in 'Burnt Fingers DIY Effects' started by rawdatalab, May 29, 2018.

  1. rawdatalab

    rawdatalab TDPRI Member

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    I'd like to build a simple ABY switch to direct output from my pedalboard to either my DAW or my amp. It should have a second switch to allow for both at once, and I don't need LEDs.

    I came across these two schematics. Both look promising, but I can't figure out which is the better build. I've read that the resistors help with popping, but can also suck tone. If not, would the non-resistor schematic benefit from their addition?

    This is the forum that started me with DIY effects (Tillman preamp in an altoids tin!), so I know I've come to the right place. Any assistance would be appreciated. Thanks.

    ABY JM.jpg bestABY.jpg
     
  2. jvin248

    jvin248 Doctor of Teleocity

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  3. Finck

    Finck Tele-Afflicted

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    Resistor helps with the pop when you have a capacitor in the circuit that accumulates energy and releases it when you press the switch, causing noise. Since it's not the case here, I see no need to use the resistor. Anyway, a large resistor, 1M or above, from signal to ground, will not cause serious harm to your tone. Just one, in the input jack.
     
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  4. luckett

    luckett Banned

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    The bottom one will ground the unused output which can reduce noise in some situations, but in this case you're creating a ground loop. It has the potential to create noise, but may not. For your setup, it's best to lift the ground of the unused device, but a ground loop can't be avoided when used in Y mode unless you isolate the grounds.

    Don't put any resistors in it. They will reduce your input impedance significantly, especially in Y mode when you'll have the input impedance of all three devices in parallel.
     
  5. luckett

    luckett Banned

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  6. rawdatalab

    rawdatalab TDPRI Member

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    Thanks as always. So the consensus seems to be to build the first circuit (by JM), but omit the resistors?
     
  7. luckett

    luckett Banned

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    Nobody has said to build the first circuit. It's worse than the second one. Neither is ideal for your application.
     
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