diff --git a/include/dsd.h b/include/dsd.h
index 2490cb7..c9db9d9 100644
--- a/include/dsd.h
+++ b/include/dsd.h
@@ -1342,6 +1342,8 @@ void lpf(dsd_state * state, short * input, int len);
 void hpf(dsd_state * state, short * input, int len);
 void pbf(dsd_state * state, short * input, int len);
 void nf(dsd_state * state, short * input, int len);
+void hpf_dL(dsd_state * state, short * input, int len);
+void hpf_dR(dsd_state * state, short * input, int len);
 //from: https://github.com/NedSimao/FilteringLibrary
 void LPFilter_Init(LPFilter *filter, float cutoffFreqHz, float sampleTimeS);
 float LPFilter_Update(LPFilter *filter, float v_in);
diff --git a/src/3.c b/src/3.c
index f9470e4..e104993 100644
--- a/src/3.c
+++ b/src/3.c
@@ -479,10 +479,10 @@ void init_audio_filters (dsd_state * state)
   HPFilter_Init(&state->HRCFilter, 960, (float)1/(float)48000);
 
 	//left and right variants for stereo output testing on digital voice samples
-  LPFilter_Init(&state->RCFilterL, 960, (float)1/(float)48000);
-  HPFilter_Init(&state->HRCFilterL, 960, (float)1/(float)48000);
-  LPFilter_Init(&state->RCFilterR, 960, (float)1/(float)48000);
-  HPFilter_Init(&state->HRCFilterR, 960, (float)1/(float)48000);
+  LPFilter_Init(&state->RCFilterL, 960, (float)1/(float)16000);
+  HPFilter_Init(&state->HRCFilterL, 960, (float)1/(float)16000);
+  LPFilter_Init(&state->RCFilterR, 960, (float)1/(float)16000);
+  HPFilter_Init(&state->HRCFilterR, 960, (float)1/(float)16000);
 
 	//PBFilter_Init(PBFilter *filter, float HPF_cutoffFreqHz, float LPF_cutoffFreqHz, float sampleTimeS);
 	//NOTCHFilter_Init(NOTCHFilter *filter, float centerFreqHz, float notchWidthHz, float sampleTimeS);
@@ -522,6 +522,30 @@ void hpf(dsd_state * state, short * input, int len)
 	}
 }
 
+//hpf digital left
+void hpf_dL(dsd_state * state, short * input, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+	{
+		// fprintf (stderr, "\n in: %05d", input[i]);
+		input[i] = HPFilter_Update(&state->HRCFilterL, input[i]);
+		// fprintf (stderr, "\n out: %05d", input[i]);
+	}
+}
+
+//hpf digital right
+void hpf_dR(dsd_state * state, short * input, int len)
+{
+  int i;
+  for (i = 0; i < len; i++)
+	{
+		// fprintf (stderr, "\n in: %05d", input[i]);
+		input[i] = HPFilter_Update(&state->HRCFilterR, input[i]);
+		// fprintf (stderr, "\n out: %05d", input[i]);
+	}
+}
+
 //nf
 void nf(dsd_state * state, short * input, int len)
 {
diff --git a/src/dsd_audio.c b/src/dsd_audio.c
index bef22e7..c035d4b 100644
--- a/src/dsd_audio.c
+++ b/src/dsd_audio.c
@@ -306,9 +306,6 @@ processAudio (dsd_opts * opts, dsd_state * state)
               *state->audio_out_float_buf_p = -32768.0F;
             }
           *state->audio_out_buf_p = (short) *state->audio_out_float_buf_p;
-          //hpf
-          if (opts->use_hpf_d == 1)
-            *state->audio_out_float_buf_p = HPFilter_Update(&state->HRCFilterL, *state->audio_out_float_buf_p);
           //tap the pointer here and store the short upsample buffer samples
           state->s_lu[n] = (short) *state->audio_out_float_buf_p;
           state->audio_out_buf_p++;
@@ -329,9 +326,6 @@ processAudio (dsd_opts * opts, dsd_state * state)
               *state->audio_out_temp_buf_p = -32768.0F;
             }
           *state->audio_out_buf_p = (short) *state->audio_out_temp_buf_p;
-          //hpf
-          if (opts->use_hpf_d == 1)
-            *state->audio_out_float_buf_p = HPFilter_Update(&state->HRCFilterL, *state->audio_out_float_buf_p);
           //tap the pointer here and store the short buffer samples
           state->s_l[n] = (short) *state->audio_out_temp_buf_p;
           //debug
@@ -459,9 +453,6 @@ processAudioR (dsd_opts * opts, dsd_state * state)
               *state->audio_out_float_buf_pR = -32768.0F;
             }
           *state->audio_out_buf_pR = (short) *state->audio_out_float_buf_pR;
-          //hpf
-          if (opts->use_hpf_d == 1)
-            *state->audio_out_float_buf_pR = HPFilter_Update(&state->HRCFilterR, *state->audio_out_float_buf_pR);
           //tap the pointer here and store the short upsample buffer samples
           state->s_ru[n] = (short) *state->audio_out_float_buf_pR;
           state->audio_out_buf_pR++;
@@ -482,9 +473,6 @@ processAudioR (dsd_opts * opts, dsd_state * state)
               *state->audio_out_temp_buf_pR = -32768.0F;
             }
           *state->audio_out_buf_pR = (short) *state->audio_out_temp_buf_pR;
-          //hpf
-          if (opts->use_hpf_d == 1)
-            *state->audio_out_float_buf_pR = HPFilter_Update(&state->HRCFilterR, *state->audio_out_float_buf_pR);
           //tap the pointer here and store the short buffer samples
           state->s_r[n] = (short) *state->audio_out_temp_buf_pR;
           state->audio_out_buf_pR++;
diff --git a/src/dsd_audio2.c b/src/dsd_audio2.c
index ce5ba51..21a9723 100644
--- a/src/dsd_audio2.c
+++ b/src/dsd_audio2.c
@@ -951,6 +951,18 @@ void playSynthesizedVoiceSS3 (dsd_opts * opts, dsd_state * state)
   if (state->tg_hold != 0 && state->tg_hold == TGL) encL = 0;
   if (state->tg_hold != 0 && state->tg_hold == TGR) encR = 0;
 
+  //test hpf
+  if (opts->use_hpf_d == 1)
+  {
+    hpf_dL(state, state->s_l4[0], 160);
+    hpf_dL(state, state->s_l4[1], 160);
+    hpf_dL(state, state->s_l4[2], 160);
+
+    hpf_dR(state, state->s_r4[0], 160);
+    hpf_dR(state, state->s_r4[1], 160);
+    hpf_dR(state, state->s_r4[2], 160);
+  }
+
   //interleave left and right channels from the short storage area
   for (i = 0; i < 160; i++)
   {