A delay is a loop, and loops have a gain
The short answer from the manual: lower FDBK and/or THD. Too much signal is being fed back into the delay module, so the delay signal grows instead of decaying.
The longer answer explains why it happens at settings that seemed fine on the last song.
A delay takes its own output and feeds it back to its own input. Whether that loop decays or grows comes down to one number: how much of the signal survives each trip around it. Below 100 percent, each repeat is quieter than the last and the tail dies. At 100 percent it sustains forever. Above 100 percent, every repeat is louder than the last, and what started as an echo turns into a screech.
FDBK is the obvious control for that number. It is not the only thing in the loop.
Why THD pushes it over the edge
The THD knob is a machine-learning model of a Sony reel-to-reel machine. Real tape does two things to a signal, and both raise loop gain:
It saturates. Saturation is not a level change, it is a shape change: it invents harmonics that were not there before. Those new frequencies go around the loop too, get saturated again, and invent more. Energy is being added, not just recirculated.
It compresses. Tape squashes peaks and lifts the quiet parts. That is exactly what you want for glue, and exactly what keeps a dying tail alive: the repeats that should be fading away are getting pulled back up every pass.
So FDBK at 60 percent with THD at zero can decay perfectly while FDBK at 60 with THD high sustains forever. Nothing is broken. You added gain to the loop.
There is one more reason to watch it: the tape circuit sounds best when nothing is clipping. If the input or output meters go red, the signal is exceeding 0 dBFS inside the plugin, and that clipping is its own distortion adding its own harmonics to the loop.
Why it screeches at one pitch
Pure runaway is a roar. A screech at a specific note means something in the loop is louder at that frequency than the rest.
Usually it is an EQ boost. A 6 dB boost at 3 kHz means the loop gain at 3 kHz is 6 dB higher than everywhere else, so that band crosses unity first and takes off while the rest of the signal is still decaying. Resonant boosts with a narrow Q are the worst offenders.
The practical rule for anything inside a feedback path: cut, do not boost. Cutting mud at 300 Hz makes long delays cleaner and lowers loop gain at the same time. Boosting air at 12 kHz does the opposite.
Getting long tails without losing control
If you want very long delays with high feedback, the plugin has a purpose-built answer: switch the gate to HARD mode.
Hard gating uses the Headroom Preservation Engine, which clears residual tail artifacts once the source drops below the gate threshold. The important part for this problem: it stops older, undecayed repeats from re-entering the delay. Energy that would otherwise keep circulating is removed, so you can run feedback high and still have the tail behave.
It also restores headroom, which is what usually stops long delays turning into mud. If a hard gate sounds too abrupt, raise SPACE: gating happens before the Depth module, so the diffusion smooths the edge the gate leaves behind.
When it is already screaming
In order:
- Pull FDBK down. It is the direct control on loop gain and it acts immediately.
- Pull THD down. If lowering FDBK alone fixed it but you liked the old feedback amount, this is the knob that was really at fault.
- Check the meters. Red on input or output means clipping inside the plugin. Lower Input, and raise Output to make up the level.
- Look at your EQ for boosts, especially narrow ones. Turn them into cuts elsewhere.
- Switch the gate to HARD if you want to keep the long tail.
- Check your DAW routing. If Clarity Delay is on a send, make sure that send's output is not finding its way back into the same send. That is a feedback loop outside the plugin, and no knob inside it will fix it.
Still runs away at settings that look sensible? Email support with a screenshot of the plugin and how it is routed.