Are you sure it's a WAH? To my mind, "wah" is a modulation in the contour of the frequencies being produced- you can "wah" any amp by turning the "tone" knob up or down, whereas most devices located where that triangle are technically tremolo (modulation in the frequency of the pitch of the note or notes.)
Just to confuse the issue, what is often called "tremolo" on amps is actually vibrato- a modulation in the VOLUME of the pitch or note.