Me again, when I get my DX7 set up again I'm going to look into that sound... I'd start with the alg. that has all 4 ops. in a stack; set the feedback high (>5) on op.4 and have breath controller wired to output for all ops. but at different sensitivity. Set op.2 to a whole number ratio and op.3 to something uneven. Maybe have one of op.2 thru .4 also output modulated by square wave LFO, rate of which is controlled by breath cont? Just hoping to give you something to jump off from if you don't get the story from the source. Look for results of my hacking in the YAMAHA forum.Tho might take awhile.mn