diff --git a/src/trx-server/src/config.rs b/src/trx-server/src/config.rs
index 83daaf1..e50c48c 100644
--- a/src/trx-server/src/config.rs
+++ b/src/trx-server/src/config.rs
@@ -331,6 +331,8 @@ pub struct SdrConfig {
     pub sample_rate: u32,
     /// Hardware IF filter bandwidth (Hz).
     pub bandwidth: u32,
+    /// WFM deemphasis time constant in microseconds (50 or 75).
+    pub wfm_deemphasis_us: u32,
     /// SDR tunes this many Hz below the dial frequency to keep signal off DC.
     pub center_offset_hz: i64,
     /// Gain configuration.
@@ -344,6 +346,7 @@ impl Default for SdrConfig {
         Self {
             sample_rate: 1_920_000,
             bandwidth: 1_500_000,
+            wfm_deemphasis_us: 50,
             center_offset_hz: 100_000,
             gain: SdrGainConfig::default(),
             channels: Vec::new(),
diff --git a/src/trx-server/src/main.rs b/src/trx-server/src/main.rs
index 66bff84..5002166 100644
--- a/src/trx-server/src/main.rs
+++ b/src/trx-server/src/main.rs
@@ -316,6 +316,7 @@ fn build_sdr_rig_from_instance(
         rig_cfg.audio.sample_rate,
         rig_cfg.audio.channels as usize,
         rig_cfg.audio.frame_duration_ms,
+        rig_cfg.sdr.wfm_deemphasis_us,
         Freq {
             hz: rig_cfg.rig.initial_freq_hz,
         },
diff --git a/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs b/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
index ad82b32..927884c 100644
--- a/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
+++ b/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
@@ -296,6 +296,15 @@ pub struct ChannelDsp {
 }
 
 impl ChannelDsp {
+    pub fn set_channel_if_hz(&mut self, channel_if_hz: f64) {
+        self.channel_if_hz = channel_if_hz;
+        self.mixer_phase_inc = if self.sdr_sample_rate == 0 {
+            0.0
+        } else {
+            2.0 * std::f64::consts::PI * channel_if_hz / self.sdr_sample_rate as f64
+        };
+    }
+
     fn pipeline_rates(
         mode: &RigMode,
         sdr_sample_rate: u32,
diff --git a/src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs b/src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs
index 774a2d0..abedbde 100644
--- a/src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs
+++ b/src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs
@@ -73,6 +73,7 @@ impl SoapySdrRig {
         audio_sample_rate: u32,
         audio_channels: usize,
         frame_duration_ms: u16,
+        wfm_deemphasis_us: u32,
         initial_freq: Freq,
         initial_mode: RigMode,
         sdr_sample_rate: u32,
@@ -113,7 +114,7 @@ impl SoapySdrRig {
             audio_sample_rate,
             audio_channels,
             frame_duration_ms,
-            75,
+            wfm_deemphasis_us,
             channels,
         );
 
@@ -180,7 +181,7 @@ impl SoapySdrRig {
             center_offset_hz,
             center_hz: hardware_center_hz,
             retune_cmd,
-            wfm_deemphasis_us: 75,
+            wfm_deemphasis_us,
         })
     }
 
@@ -196,6 +197,7 @@ impl SoapySdrRig {
             48_000,
             1,
             20,
+            50,
             Freq { hz: 144_300_000 },
             RigMode::USB,
             1_920_000,
@@ -266,6 +268,11 @@ impl RigCat for SoapySdrRig {
                     *cmd = Some(hardware_hz as f64);
                 }
             }
+
+            if let Some(dsp_arc) = self.pipeline.channel_dsps.get(self.primary_channel_idx) {
+                let channel_if_hz = (self.freq.hz as i64 - self.center_hz) as f64;
+                dsp_arc.lock().unwrap().set_channel_if_hz(channel_if_hz);
+            }
             Ok(())
         })
     }
@@ -280,6 +287,10 @@ impl RigCat for SoapySdrRig {
             if let Ok(mut cmd) = self.retune_cmd.lock() {
                 *cmd = Some(self.center_hz as f64);
             }
+            if let Some(dsp_arc) = self.pipeline.channel_dsps.get(self.primary_channel_idx) {
+                let channel_if_hz = (self.freq.hz as i64 - self.center_hz) as f64;
+                dsp_arc.lock().unwrap().set_channel_if_hz(channel_if_hz);
+            }
             Ok(())
         })
     }