diff --git a/src/dsp/mod.rs b/src/dsp/mod.rs
index 724682c..fdc11a6 100644
--- a/src/dsp/mod.rs
+++ b/src/dsp/mod.rs
@@ -582,7 +582,7 @@ macro_rules! node_list {
             sfilter => SFilter UIType::Generic UICategory::Signal
                (0  inp   n_id      d_id  r_id   f_def stp_d -1.0, 1.0, 0.0)
                (1 freq  n_pit      d_pit r_fq  f_freq  stp_d -1.0, 0.5647131, 1000.0)
-               (2  res   n_id      d_id  r_id   f_def stp_d 0.0, 0.99, 0.5)
+               (2  res   n_id      d_id  r_id   f_def stp_d 0.0, 1.0, 0.5)
                {3 0 ftype setting(8) fa_sfilter_type 0 12}
                [0 sig],
             test => Test UIType::Generic UICategory::IOUtil
diff --git a/src/dsp/node_sfilter.rs b/src/dsp/node_sfilter.rs
index 029f586..324eff9 100644
--- a/src/dsp/node_sfilter.rs
+++ b/src/dsp/node_sfilter.rs
@@ -127,6 +127,18 @@ macro_rules! process_filter_fun {
             $out.write(frame, s as f32);
         }
     } };
+    ($nframes: expr, $inp: expr, $out: ident, $freq: ident, $res: ident,
+     $maxres: expr, $input: ident, $maxfreq: expr, $block: block) => { {
+        for frame in 0..$nframes {
+            let $input = $inp.read(frame) as f64;
+            let $freq  = denorm::SFilter::freq($freq, frame) as f64;
+            let $freq  = $freq.clamp(1.0, $maxfreq);
+            let $res   = denorm::SFilter::res($res, frame) as f64;
+            let $res   = $res.clamp(0.0, $maxres);
+            let s = $block;
+            $out.write(frame, s as f32);
+        }
+    } };
     ($nframes: expr, $inp: expr, $out: ident, $freq: ident,
      $input: ident, $maxfreq: expr, $block: block) => { {
         for frame in 0..$nframes {
@@ -245,7 +257,7 @@ impl DspNode for SFilter {
             },
             8 => { // Simper SVF Low Pass
                 process_filter_fun!(
-                    ctx.nframes(), inp, out, freq, res, input, 22000.0, {
+                    ctx.nframes(), inp, out, freq, res, 1.0, input, 22000.0, {
                         let (low, _band, _high) =
                             process_simper_svf(
                                 input, freq, res, self.israte,
diff --git a/tests/node_sfilter.rs b/tests/node_sfilter.rs
index 5bb9a3f..aec0842 100644
--- a/tests/node_sfilter.rs
+++ b/tests/node_sfilter.rs
@@ -563,7 +563,7 @@ fn check_node_sfilter_simpersvf_lowpass() {
         avg_fft_freqs(10.0, &[
             500, 700, 900, 1000, 1500, 2000, 3000, 4000, 12000
         ], &fft[..]), vec![
-            (0, 20), (500, 20), (700, 50), (900, 110), (1000, 40),
+            (0, 20), (500, 20), (700, 50), (900, 120), (1000, 50),
             (1500, 10), (2000, 0), (3000, 0), (4000, 0)
         ]);
 
@@ -593,8 +593,8 @@ fn check_node_sfilter_simpersvf_lowpass() {
         avg_fft_freqs(4.0, &[
             100, 500, 1000, 2000, 3500, 4000, 5000, 6000, 8000, 12000
         ], &fft[..]), vec![
-            (0, 24), (100, 16), (500, 20), (1000, 20), (2000, 36), (3500, 132),
-            (4000, 80), (5000, 20), (6000, 8), (8000, 0)
+            (0, 24), (100, 16), (500, 20), (1000, 20), (2000, 36), (3500, 144),
+            (4000, 88), (5000, 20), (6000, 8), (8000, 0)
         ]);
 
     // Low Pass Simper SVF @ 4000Hz RES=0.0
@@ -635,7 +635,7 @@ fn check_node_sfilter_simpersvf_lowpass() {
     let fft = fft_with_freq_res_type(&mut matrix, &mut node_exec, 8, 0.0, 1.0);
     assert_eq!(
         avg_fft_freqs(4.0, &[1, 5, 10, 100, 1000, 4000, 12000, 22050, 22051], &fft[..]), vec![
-            (0, 56), (1, 0), (5, 0), (10, 0), (100, 0), (1000, 0),
+            (0, 60), (1, 0), (5, 0), (10, 0), (100, 0), (1000, 0),
             (4000, 0), (12000, 0), (22050, 0)
         ]);
 }