fix for the internal DAC

highest available cutoff frequency pre-calculating depending on sample rate
copych · Feb 1, 2023 · 508e2b7 · 508e2b7
1 parent 4018859
commit 508e2b7
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Showing 3 changed files with 6 additions and 4 deletions.
diff --git a/config.h b/config.h
@@ -7,7 +7,7 @@
 //#define DEBUG_JUKEBOX
 //#define DEBUG_FX
 
-//#define USE_INTERNAL_DAC      // use this for testing, SOUND QUALITY SACRIFICED: 8BIT STEREO
+#define USE_INTERNAL_DAC      // use this for testing, SOUND QUALITY SACRIFICED: 8BIT STEREO
 //#define NO_PSRAM              // if you don't have PSRAM on your board, then use this define, but REVERB AND DELAY'D BE SACRIFICED, SMALL DRUM KIT SAMPLES USED 
 
 #define MIDI_ON               // use this option if you want to operate by MIDI
@@ -19,7 +19,7 @@
 #define MIN_CUTOFF_FREQ 250.0f
 
 #ifdef USE_INTERNAL_DAC
-#define SAMPLE_RATE     22050 // price for increasing this value is less delay time
+#define SAMPLE_RATE     44100 // price for increasing this value is less delay time
 #else
 #define SAMPLE_RATE     44100
 #endif

diff --git a/rosic_TeeBeeFilter.h b/rosic_TeeBeeFilter.h
@@ -154,6 +154,7 @@ class TeeBeeFilter
     float resonanceSkewed;     // mapped resonance parameter to make it behave more musical
     float sampleRate;          // the sample rate in Hz
     float twoPiOverSampleRate; // 2*PI/sampleRate
+    float highLimit;           // highest cutoff freq allowing stable behaviour
     float compens;             // drive gain correction
     float bias;                 // reso bias compensation
     int    mode;                // the selected filter-mode

diff --git a/rosic_TeeBeeFilter.ino b/rosic_TeeBeeFilter.ino
@@ -36,6 +36,7 @@ void TeeBeeFilter::SetSampleRate(float newSampleRate)
   if( newSampleRate > 0.0 )
     sampleRate = newSampleRate;
   twoPiOverSampleRate = 2.0*PI/sampleRate;
+  highLimit = sampleRate / 4.18f;
   feedbackHighpass.setSampleRate(newSampleRate);
   calculateCoefficientsExact();
 }
@@ -84,8 +85,8 @@ inline void TeeBeeFilter::SetCutoff(float newCutoff, bool updateCoefficients)
   {
     if ( newCutoff < 200.0f ) // an absolute floor for the cutoff frequency - tweakable
       cutoff = 200.0f;
-    else if ( newCutoff > 10550.0f )
-      cutoff = 10550.0f;
+    else if ( newCutoff > highLimit ) // seems to be stable with the current settings, higher values may lead to nan, +inf or -inf during processing
+      cutoff = highLimit;
     else
       cutoff = newCutoff;