--- a/src/DSP/SVFilter.cpp
+++ b/src/DSP/SVFilter.cpp
@@ -102,6 +102,7 @@ SVFilter::response SVFilter::computeResponse(int type,

 void SVFilter::computefiltercoefs(void)
 {
+    //printf("compute coeff (%f, %f, %d)\n", freq, q, stages);
     par.f = freq / samplerate_f * 4.0f;
     if(par.f > 0.99999f)
         par.f = 0.99999f;
@@ -125,7 +126,7 @@ void SVFilter::setfreq(float frequency)
     bool nyquistthresh = (abovenq ^ oldabovenq);

     //if the frequency is changed fast, it needs interpolation
-    if((rap > 3.0f) || nyquistthresh) { //(now, filter and coefficients backup)
+    if(true || (rap > 3.0f) || nyquistthresh) { //(now, filter and coefficients backup)
         if(!firsttime)
             needsinterpolation = true;
         ipar = par;
@@ -168,7 +169,7 @@ void SVFilter::setstages(int stages_)
     computefiltercoefs();
 }

-void SVFilter::singlefilterout(float *smp, fstage &x, parameters &par)
+void SVFilter::singlefilterout(float *smp, fstage &x, parameters &par, parameters &par2)
 {
     float *out = NULL;
     switch(type) {
@@ -189,10 +190,16 @@ void SVFilter::singlefilterout(float *smp, fstage &x, parameters &par)
             warnx("Impossible SVFilter type encountered [%d]", type);
     }

+    //printf("delta q = %f\n", (par.q-par2.q)/buffersize_f);
+    //printf("delta f = %f\n", (par.f-par2.f)/buffersize_f);
     for(int i = 0; i < buffersize; ++i) {
-        x.low   = x.low + par.f * x.band;
-        x.high  = par.q_sqrt * smp[i] - x.low - par.q * x.band;
-        x.band  = par.f * x.high + x.band;
+        const float t     = i/buffersize_f;
+        const float par_f = (1-t)*par.f + t*par2.f;
+        const float par_q = (1-t)*par.q + t*par2.q;
+        const float par_q_sqrt = sqrtf(par_q);
+        x.low   = x.low + par_f * x.band;
+        x.high  = par_q_sqrt * smp[i] - x.low - par_q * x.band;
+        x.band  = par_f * x.high + x.band;
         x.notch = x.high + x.low;
         smp[i]  = *out;
     }
@@ -211,6 +218,8 @@ void SVFilter::singlefilterout(float *smp, fstage &x, parameters &par)

 void SVFilter::filterout(float *smp)
 {
+    //printf("SVFilter::filterout\n");
+#if 0
     for(int i = 0; i < stages + 1; ++i)
         singlefilterout(smp, st[i], par);

@@ -227,6 +236,15 @@ void SVFilter::filterout(float *smp)
         }
         needsinterpolation = false;
     }
+#endif
+    if(needsinterpolation) {
+        //printf("interpolating...\n");
+        for(int i = 0; i < stages + 1; ++i)
+            singlefilterout(smp, st[i], ipar, par);
+        needsinterpolation = false;
+    } else
+        for(int i = 0; i < stages + 1; ++i)
+            singlefilterout(smp, st[i], par, par);

     for(int i = 0; i < buffersize; ++i)
         smp[i] *= outgain;
diff --git a/src/DSP/SVFilter.h b/src/DSP/SVFilter.h
index 7cb7e989..57e82494 100644
--- a/src/DSP/SVFilter.h
+++ b/src/DSP/SVFilter.h
@@ -56,7 +56,7 @@ class SVFilter:public Filter
             float f, q, q_sqrt;
         } par, ipar;

-        void singlefilterout(float *smp, fstage &x, parameters &par);
+        void singlefilterout(float *smp, fstage &x, parameters &par, parameters &);
         void computefiltercoefs(void);
         int   type;    // The type of the filter (LPF1,HPF1,LPF2,HPF2...)
         int   stages;  // how many times the filter is applied (0->1,1->2,etc.)