Most store-bought Wahs sound unimpressive, and cost $150 or more. I thought I could do better. I bought a $20 Wah pedal, and decided to spend $50 upgrading it. I took pictures as I went along, so you can see for yourself. I did some .mp3s too. If you have a dead Wah or volume pedal, you can do something similar. I owned a Wah pedal briefly, about 20 years ago. It was useless. So I don't know much about Wah, but I know what I like.

Most Wah pedals use the same inductor and 2-transistor design (Morley have loads of different designs). Component values do change the tone, this is well documented. Inductors are mysterious, they do have a big effect, but the rest is just switching resistors and caps (No Mr. Teese! Stop while you still can!). Transistor selection matters too.