GT Threshold Sound.

Going to the beach on Saturday. First time out with my new GT.
In the "All Metal Mode" when I set the threshold at a just audible level it is very choppy or raspy not a smooth tone. I have to raise the threshold to a higher level before it smooths out. In "Discriminate Mode" it is smoother at just audible. Is this normal or is there smoothing I am missing?

Thanks in advance for any info.