Looks like you can get the most precise control on the Digitech so I would start there. Set the EQ flat on your amp and uke. Like Booli said, boost the LOW LEVEL a bit on the Digi EQ and then sweep the LOW FREQ until your feedback goes crazy (you want to find where it's living before you try and get rid of it - otherwise you might completely miss the right frequency). Then turn the LOW LEVEL down until the feedback is manageable. Odds are the feedback range is going to be somewhere in the 180-300hz spectrum. But each uke is different.
I completely agree with this Brad. I was searching for articles to explain, or videos to demo how to do this kind of thing, but everything I came up with was highly technical and/or involved calculus equations with lots of charts and graphs that made even my patience exhausted from way too much detail, even for me.
RANE has lots of great technical articles about audio on their site. Most of it aimed towards either designers of gear or those doing this 'work', in the trenches for their daily bread.
Further, Brad, the way you've described this method here is excellent and better than I could have said it myself.
In my mind, I am trying to distill from the encyclopedic explanation, and for me, that is sometimes very difficult to do, since my head is usually in that space, and I'm not always able to explain it for folks new to this.
I've got 'notch filter', 'reverse-bandpass filter' and things like 'Q' and 'Q-curves' going on my head, which interferes with me being able to explain without lots of visual aids and audio demos.
Sometimes I feel like 'I've seen to much' and that has poisoned me for being able to speak about certain topics with others in a succinct and concise manner, so I am grateful that you have said it the way you did. Kudos brother!
Thanks Hippie Guy & Booli appreciate your expert advise , will have a play tomorrow .
Sure thing. Please report back and let us know how you make out.