)))
         ((or (c-g?)
	      (= i end)))
       (set! y (+ x (* index (sin y))))

       (let ((result (* amp (sin y)))
             (sum 0.0))
	 (do ((n 1 (+ n 1))) 
             ((= n iters)) 
           (set! sum (+ sum (/ (* 2.0 
			          (bes-jn n (* index n))
			          (sin (* n x)))
			    (* n index)))))
	 (outb i (* amp sum))
         (outc i (- sum (sin (+ y pha1))))
         (outa i (* amp (sin (+ y pha1))))))))

(with-sound (:channels 3 :statistics #t :clipped #f) (feedbk 0 1 100 1.0 0