Swell-delay with a precise peak-time control (lowest tailtime)
delay-time functions the same as the other normal delays, but..
the tailtime is a direct representation of the time (in seconds) the feedback will take to die out, whatever the delaytime. So when you set to control to 30, it will take 30 seconds die out, whether it's at a delaytime of 100ms or 2 seconds..
As it's a "swell" delay, it features two audio-buffers using the exact same timing of writing/reading, but using different feedback times. As one is subtracted by the other, a volume peak in the delay will happen when either one dies out while the other rings on.
As we know both the tailtimes, we can also calculate what the volume-drop will be at the moment of the volume-peak (remaining volume of the signal that hasn't died out yet). So this is internally normalised to input level and goes through a gain stage.
A switch is added so you can have up to 2x gain for the delay, making it up to 2 times the volume of the input level (so watch it!)
As last, an input-attenuator is added to control the dry amount.
Though, I just figured, as the peak is normalised, even though the peak is at the timing set by the lowest tailtime, the duration of the entire delay will be longer, as there can be added quite a lot of gain to get the peak to the right level. This forces the delay to take the long-delay time as extra time after it hits the peak volume. So a tailtime of 3 seconds and one of 7 seconds will create a delay of 10 seconds with a volume peak at 3 seconds. Also, the two tailtimes may not be too close to each other.