Thanks, Paul; and reassuring to hear that the dynamic range was fine for you.
In this song I'm using delay to hopefully enhance the spaciousness of the reverb (I'm still learning to use both, and I wasn't really satisfied with how I had setup the delay on this song, though it seemed to work well overall in the recording). But what you might be referring to is tremolo, which I'm adding to the held chords (ie when there's no melody movement over them) as if I had a trem bar on my bass.
The song opens with a single note followed by a chord; I then engage the tremolo, and then release it before the next note in the melody, as if I had reached down for the trem bar and gently moved it back and forth a few times.
Is this what you're hearing? I'm guessing it is, as it indeed pulses, and is engaged on all the quiet held chords.
I made several adjustments to the effect, hoping to get it to sound right and not be too overbearing; but it doesn't have the touch that a real trem bar would. I did previously experiment with using an expression pedal to emulate a trem bar, but again it just doesn't have the touch of a real trem bar; and this method seemed to work better for the purposes of this song.