Correct Waveform.astype()

madarrays/waveform.py

@@ -757,7 +757,8 @@ class Waveform(MadArray):
             if np.issubdtype(dtype, np.floating):
                 int_range = src_iinfo.max - src_iinfo.min + 1
                 zero = src_iinfo.min + int_range // 2
-                y = (super().astype(np.float64) - zero) / (int_range // 2)
+                y = ((super(type(y), y).astype(np.float64) - zero)
+                     / (int_range // 2))
                 y.clip(min_value=-1, max_value=1-np.finfo(dtype).eps)
                 y = y.astype(dtype)