Help With a Certain Kind of Sound in Many of the Groups

I've come across quite a few of these. Some I managed to get past by luck, others I gave up. I'm not sure what settings are making this sound.

The one I'm currently on is Group 12, 6 of 6. The sound I'm talking about is the bell-like ringing quality. Not the delay, but the clear high, full tones. I keep flipping from pulse to make the sound clearer and saw to make it fuller, which then needs a filter to make it smooth, which lowers the tone, so I open the filter back up and go back to pulse...

The effect seems to be related to increasing up the filter delay time? Is that because I'm actually hearing a slowly descending cutoff and thinking I hear ringing dying away? No sound like this was covered in the lessons that I can find.