чтобы закрыть эту тему, помещу ещё ответ с техподдержки данлопа:
Sorry for the confusion, but I believe I see what the problem is. The “slapback” settings in the manual are not written correctly. The proper way to get a slapback tone is to set the delay and regen pot to about the 9 o’clock position. The pedal will not go into self-oscillation with these parameters set.