diff --git a/tests/node_sfilter.rs b/tests/node_sfilter.rs
new file mode 100644
index 0000000..1cf0a24
--- /dev/null
+++ b/tests/node_sfilter.rs
@@ -0,0 +1,55 @@
+mod common;
+use common::*;
+
+#[test]
+fn check_node_sfilter_compare() {
+    let (node_conf, mut node_exec) = new_node_engine();
+    let mut matrix = Matrix::new(node_conf, 3, 3);
+
+    let noise = NodeId::Noise(0);
+    let sf    = NodeId::SFilter(0);
+    let out   = NodeId::Out(0);
+    matrix.place(0, 0, Cell::empty(noise)
+                       .out(None, None, noise.out("sig")));
+    matrix.place(0, 1, Cell::empty(sf)
+                       .input(sf.inp("inp"), None, None)
+                       .out(None, None, sf.out("sig")));
+    matrix.place(0, 2, Cell::empty(out)
+                       .input(out.inp("ch1"), None, None));
+    matrix.place(1, 1, Cell::empty(noise)
+                       .out(None, None, noise.out("sig")));
+    matrix.place(1, 2, Cell::empty(out)
+                       .input(out.inp("ch2"), None, None));
+    pset_d(&mut matrix, sf, "freq", 100.0);
+    matrix.sync().unwrap();
+
+    let ta = std::time::Instant::now();
+    let (out_l, out_r) = run_for_ms(&mut node_exec, 10000.0);
+    let ta = std::time::Instant::now().duration_since(ta);
+    println!("ta1 Elapsed: {:?}", ta);
+
+    save_wav("check_noise_sfilt_in.wav", &out_r);
+    save_wav("check_noise_sfilt1.wav", &out_l);
+
+//    let fft = run_and_get_fft4096(&mut node_exec, 5, 1000.0);
+//    for (fq, lvl) in fft {
+//        println!("{:5}: {}", fq, lvl);
+//    }
+
+    pset_s(&mut matrix, sf, "ftype", 1);
+
+    let ta = std::time::Instant::now();
+    let (out_l, _) = run_for_ms(&mut node_exec, 10000.0);
+    save_wav("check_noise_sfilt2.wav", &out_l);
+    let ta = std::time::Instant::now().duration_since(ta);
+    println!("ta2 Elapsed: {:?}", ta);
+
+    let fft = run_and_get_fft4096(&mut node_exec, 5, 1000.0);
+    for (fq, lvl) in fft {
+        println!("{:5}: {}", fq, lvl);
+    }
+
+//    let fft = run_and_get_fft4096(&mut node_exec, 50, 1000.0);
+//    assert!(fft.len() == 0);
+    assert!(false);
+}