The key to the tube call is flexibility at the reed area...the way to start off is to take and look at the distance across the area where the reed will lie...usually 1" or 1 -1/16" .... then take your reed and lay it where there is no tension at all. Then put your O-ring on with just enough force to create the quarter moon shape. That should get you started...you can experiment as to the looseness some like their reeds loose...I mean really loose, some leave them in the way I described above then cut tiny notches on either side next to the inner wall no more then 3/32" tall, this allows the reed to flap a hair for rasp....just do not put your reed on to where it is so tight you can't even run it...pappy
