Guitar effects chain with Pure Data

I’ve been asked recently to make patch that would let the user edit the effects chain in Pd. It’s like a patch bay for guitar effects. This is currently limited to 4 effects, but it’s working quite well and it’s glitch-free (you can change the sequence of effects without any audio dropout or noise of any kind). It can easily be modified to increase the number of effects (I could do it upon request).

Effects chain/patch bay for guitar effects made with Pd

As you can see in the picture above, the sequence of effects can be changed using the (rather crude…) GUI. You’ll need to select the effect you want to move using the cursor of the slider, and then click on the “Move up” button. Effects can be renamed by clicking in the symbol boxes on the right, typing text, and hitting Return. Each effect can be bypassed using the toggle box connected to it. There’s definitely room for improvement, especially with respect to the GUI, but well, it works :). Please note that a unique continuous signal is assumed (you cannot split the signal into two or more parallel paths).

Some key objects used in this patch are part of the [iemmatrix] package that comes with Pd-extended to manipulate matrices. It was developped at IEM (Institut für Elektronische Musik und Akustik, in Graz, Austria)

You can download the patch here. There’s no audio sample as all effects used in the effects chain are available in previous posts.

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7 Responses to Guitar effects chain with Pure Data

  1. Roy Cohen says:

    I downloaded your code and im a bit confused. When you check in the squares the bypass turns on or off. And what does bypass exactly do? (i know it sounds obvious but im really really new to this and want to make sure I understand whats going on)

    • Hi Roy, the bypass button channels the incoming sound either through the effect, or around it. If the toggle is checked the sound goes through the effect and gets processed. If unchecked it “bypasses” it, and the output is identical to the input. It works just like the on/off button on a pedal.

  2. Jay Bordas says:

    Hi, I just downloaded your patch which is great, but I can’t figure out where is received the “s~ adc” signal…

    • Hi Jay,
      All the routing of the audio happens inside the GUI subpatch. Right-click on it to open it and see the guts. All the [s~ ] and [r~ ] objects in the patch communicate with other send and receive objects in the GUI subpatch.

  3. Pedal_Workshop says:

    Pierre… all this dsp pedal stuff is fascinating. Opens up a whole new world to the guitarist. Now the questions, is it possible to use, lets say, an arduino or even the Raspi as the trigger to select the effects instead of using the GUI (btw, I am a hardware guy not a programmer…sadly)? I guess what I am looking for is a smaller version of what you have built. Four momentary stomp switches (since that is the limit of the chain) to enable or disable the desired effect?

    • Hi, I’m not really sure I understand you question. Pd can be controlled by an Arduino using “pduino” (see my posts about this), so this patch can definitely be triggered by for or more switches.

  4. luizmello says:

    Great, I’m starting with Pd and your patches helps me to discover new sounds with this tool.
    Thanks for sharing it

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