It’s a mix the 80s gated reverb and the fisher k10 stereo (gated), this is an experiment that i did combining a thicker reverb with low frequency, with an impulse response from a 60s spring reverb unit, which brings a movement nice in the mix.
I created this sound that look like a rattlesnake sound thanks to a tambourin and cymbal record. I made repeat those two percussion three times. When one is finish an other one start, and this 3 times. I added between them an effect that end the sound and start a new one.