diff --git a/files/apf.dsp b/files/apf.dsp
new file mode 100644
index 0000000..b551de1
--- /dev/null
+++ b/files/apf.dsp
@@ -0,0 +1,7 @@
+// import Standard Faust library
+// https://github.com/grame-cncm/faustlibraries/
+import("stdfaust.lib");
+
+// (t, g) = give: delay in samples, feedback gain 0-1
+apf(del, g, x) = x : (+ : _ <: @(del-1), *(g)) ~ *(-g) : mem, _ : + : _;
+process = _ * .1 <: apf(100, .5);