ft in sqsum that eventually turns around, raise srate to 441000 and it goes away


;; FM(e^x)=PM(e^x):
(define* (fmpmex beg dur freq amp)
  (let* ((start (seconds->samples beg))
         (end (+ start (seconds->samples dur)))
	 (fm-carrier (make-oscil freq))
	 (pm-carrier (make-oscil freq))
	 (ampf (make-env '(0 0 1 1 10 1 11 0) :scaler amp :duration dur))
	 (sumex 0.0))
     (do ((i start (+ i 1))
          (x 0.0 (+ x .0001)))
         ((= i end))
       (let ((vol (env ampf))
            (ex (exp x)))
  