In a previous post (BOSS FW-3 Mods) I told how I did some basic mods to a BOSS FW-3 Wah pedal, which is basically a Cry Baby design with a potentiometer for varying the Q.
For the capacitor that controls the sweep range (C12), I chose a value of 0,022uF, to give the effect a very personal lower sweep range. I found it problematic in some situations, because the effectiveness of the variable band pass filter as a musical device is very dependent on the color of the signal that it encounters at its input. For instance, if I am using the brigde pickup in an already bright sounding guitar (tele or strat), playing high pitch notes, a low frequency sweep will let the sound almost without volume at the low end of the range. The same happens in the opposite situation – high sweep range with dark sounding pickups, or lower notes.
So, in order to have an all terrain wah effect, I have put a switch for alternating between three different values:
- 5nF – higher frequencies sweep range
- 10nF – the original one
- 20nF – lower frequencies sweep range
Given the behavior of a DPDT on-on-on switch, you can get those three values and their corresponding sweep range values (see https://www.electrosmash.com/crybaby-gcb-95) using three 10nF capacitors, this way:
Other values can be chosen, of course, to obtain more radical or subtle changes. For instance, with 10nF in the center, 56nF at right and 4.7nF on top you get:
- 3.2nF – very high range, good for a very bright guitar and higher notes
- 10nF – original sweep range
- 66nF – very low sweep, suitable for a bass guitar
The real life device, as built for this project:
As I mentioned in the previous post (BOSS FW-3 Mods), this pedal, apart from being a tank, has space enough inside for storing all the money I have. In this picture you can see how the DPDT switch fits inside the case:
In the main PCB, the cables from the switch are soldered instead of the original capacitor:
And the final result from the outside (the scratches and dents were already there, they are natural relic as this pedal has more than 20 years):
If you have any advice about the execution of the project, or simply have tried it, or in case you had any problem, please let me know in the comments below.