Haydel says if a double-reed call is hard to blow, the reeds can be trimmed very slightly or simply pushed back toward the end of the call. "This adjustment may also raise the pitch and create an unbalanced call that won't produce a full range of notes," he adds. "To compensate, you may need to push the wedge back slightly to lower the pitch to a comfortable, balanced level."
To add rasp to a double-reed call, Haydel says you should offset the reeds so the tip of the top reed is pushed back 1/16 to 1/32 inch from the tip of the bottom reed. "When tuning any call, always make very slight changes and then reassemble the call and test it," Haydel advises. "It doesn't take much of a change to make a big difference in a call's sound."