Audio probe and zero point DD

[scotheath]

I guess I should have asked this a couple days back but thought I'd better before boxing this thing up. As I went through all the components at one point the sound went from a tone( I used my ipod with a tone generator app instead of strumming) too a feed back kinda squeal coming out of the caps, and was affected by the feedback pot. So a couple things is that normal or should it just be a tone not affected by the pots, 2nd what position should the pots be in ? All on or off ? The pedal has 3 pots. Delay feedback and level
Sorry I posted this with my previous question but think it might of gotten overlooked
I was previously having problem with the feedback pot not working but after going through it seemed to work, but am curious about noise coming through as stated above