1. Signal Chain: In a typical guitar rig, the signal chain usually goes from the guitar to the wah pedal, followed by distortion or overdrive pedals, and then other effects pedals (such as modulation, delay, and reverb). Placing the wah pedal before the distortion/overdrive allows you to modify the incoming signal before it gets distorted.
2. Wah Effect on Distorted Signal: When you place the wah pedal after the distortion, the wah effect gets applied to the already distorted signal. This can result in a "muddy" or unclear wah sound since the distortion can mask the subtle frequency changes created by the wah pedal.
3. Wah Control over Distortion: Placing the wah pedal before the distortion gives you more control over how the distortion affects the wah sound. You can use the wah to shape the distorted tone by emphasizing certain frequencies or creating more dramatic sweeps.
4. Feedback and Noise Reduction: Placing the wah pedal before the distortion can also help reduce noise and feedback issues. Some fuzz and distortion pedals can amplify any noise or feedback if placed after the wah. Having the wah before the distortion allows you to better control the level of feedback you hear.
Remember, this is a general recommendation, and your preferences may vary depending on the specific pedals you are using and the sound you are trying to achieve. Experimenting with different pedal placements is an essential part of finding your personalized guitar tone.