diff --git a/src/dsp/node_sfilter.rs b/src/dsp/node_sfilter.rs
index 4ed006d..9772b32 100644
--- a/src/dsp/node_sfilter.rs
+++ b/src/dsp/node_sfilter.rs
@@ -88,7 +88,8 @@ impl DspNode for SFilter {
             0 => {
                 for frame in 0..ctx.nframes() {
                     let input = inp.read(frame) as f64;
-                    let freq = (denorm::SFilter::freq(freq, frame) as f64);
+                    let freq = denorm::SFilter::freq(freq, frame) as f64;
+                    let freq = freq.clamp(10.0, 22050.0);
                     out.write(frame,
                         process_1pole_lowpass(
                             input, freq, self.israte, &mut self.z)
@@ -98,7 +99,8 @@ impl DspNode for SFilter {
             1 => {
                 for frame in 0..ctx.nframes() {
                     let input = inp.read(frame) as f64;
-                    let freq = (denorm::SFilter::freq(freq, frame) as f64);
+                    let freq = denorm::SFilter::freq(freq, frame) as f64;
+                    let freq = freq.clamp(10.0, 18000.0);
                     out.write(frame,
                         process_1pole_tpt_lowpass(
                             input, freq, self.israte, &mut self.z)
@@ -108,7 +110,8 @@ impl DspNode for SFilter {
             2 => {
                 for frame in 0..ctx.nframes() {
                     let input = inp.read(frame) as f64;
-                    let freq = (denorm::SFilter::freq(freq, frame) as f64);
+                    let freq = denorm::SFilter::freq(freq, frame) as f64;
+                    let freq = freq.clamp(10.0, 22050.0);
                     out.write(frame,
                         process_1pole_highpass(
                             input, freq, self.israte, &mut self.z, &mut self.y)
@@ -118,7 +121,8 @@ impl DspNode for SFilter {
             3 => {
                 for frame in 0..ctx.nframes() {
                     let input = inp.read(frame) as f64;
-                    let freq = (denorm::SFilter::freq(freq, frame) as f64);
+                    let freq = denorm::SFilter::freq(freq, frame) as f64;
+                    let freq = freq.clamp(10.0, 18000.0);
                     out.write(frame,
                         process_1pole_tpt_highpass(
                             input, freq, self.israte, &mut self.z)