You can think of the Mix control as the volume of the first repeat relative to the dry signal, and the Feedback control as the rate of the volume decrease of each successive repeat.
Feedback at 100% means each successive repeat is the same volume as the one before it so you get infinite repeats.
Feedback at 0% means you get only one repeat (the 2nd repeat being 0% of the volume of the first repeat), etc.
Thanks.
I'm always intrigued how players such as Vai can have what would seem to be a very washed out delay setting yet his main signal doesn't seem to really get washed out.
There are different tricks that can accomplish this along with the standard controls.............