i can confirm the issue with the KarplusRings.sc engine knocking out the sound output with bpf_res set to 0, and if you do the reverse (bring bpf_res to the max of 4 with the bpf_freq very high) there can be some really sustained noise that may or may not require a reboot to clear out (watch out for speakers/headphones).
there are probably other solutions, but for me one quick way to deal with this is to edit the min/max values for bpf_freq and bpf_res in scripts using the KarplusRings.sc engine to tame the white noise that excites the resonator. here are the values that seem safe so far:
cs.BPF_FREQ = cs.new(100,9000,'lin',0,0.5,")
cs.BPF_RES = cs.new(0.05,2.5,'lin',0,0.5,")