diff --git a/source/cart_hw/datel.c b/source/cart_hw/datel.c
index 8faab21..4989b51 100644
--- a/source/cart_hw/datel.c
+++ b/source/cart_hw/datel.c
@@ -21,9 +21,8 @@
 
 #include "shared.h"
 
-#define TYPE_AR   0x01
-#define TYPE_PRO1 0x02
-#define TYPE_PRO2 0x03
+#define TYPE_PRO1 0x12
+#define TYPE_PRO2 0x22
 
 static struct
 {
diff --git a/source/gx/config.c b/source/gx/config.c
index 46e23a0..a3a9e98 100644
--- a/source/gx/config.c
+++ b/source/gx/config.c
@@ -71,6 +71,7 @@ void config_default(void)
   config.hq_fm          = 1;
   config.psgBoostNoise  = 0;
   config.filter         = 1;
+  config.lp_range       = 50;
   config.low_freq       = 880;
   config.high_freq      = 5000;
   config.lg             = 1.0;
diff --git a/source/gx/config.h b/source/gx/config.h
index 5c00934..5a4a378 100644
--- a/source/gx/config.h
+++ b/source/gx/config.h
@@ -36,8 +36,9 @@ typedef struct
   int32 psg_preamp;
   int32 fm_preamp;
   uint8 filter;
-  uint16 low_freq;
-  uint16 high_freq;
+  int16 lp_range;
+  int16 low_freq;
+  int16 high_freq;
   float lg;
   float mg;
   float hg;
diff --git a/source/gx/gui/legal.c b/source/gx/gui/legal.c
index e435676..4684576 100644
--- a/source/gx/gui/legal.c
+++ b/source/gx/gui/legal.c
@@ -36,7 +36,6 @@
 void legal ()
 {
   int ypos = 56;
-
   gxClearScreen((GXColor)BLACK);
 
   FONT_writeCenter ("DISCLAIMER",22,0,640,ypos,(GXColor)WHITE);
diff --git a/source/gx/gui/menu.c b/source/gx/gui/menu.c
index 70eae48..1ad2550 100644
--- a/source/gx/gui/menu.c
+++ b/source/gx/gui/menu.c
@@ -224,11 +224,11 @@ static gui_item items_audio[10] =
   {NULL,NULL,"PSG Volume: 2.50",        "Adjust SN76489 output level",  52,132,276,48},
   {NULL,NULL,"FM Volume: 1.00",         "Adjust YM2612 output level",   52,132,276,48},
   {NULL,NULL,"Filtering: 3-BAND EQ",    "Setup Audio filtering",        52,132,276,48},
-  {NULL,NULL,"Low Freq: 200 Hz",   "Adjust EQ Low Band Frequency", 52,132,276,48},
-  {NULL,NULL,"High Freq: 20000 Hz","Adjust EQ High Band Frequency",52,132,276,48},
   {NULL,NULL,"Low Gain: 1.00",          "Adjust EQ Low Band Gain",      52,132,276,48},
-  {NULL,NULL,"Middle Gain: 1.00",       "Adjust EQ Middle Band Gain",   52,132,276,48},
+  {NULL,NULL,"Mid Gain: 1.00",          "Adjust EQ Middle Band Gain",   52,132,276,48},
   {NULL,NULL,"High Gain: 1.00",         "Adjust EQ High BandGain",      52,132,276,48},
+  {NULL,NULL,"Low Freq: 200 Hz",        "Adjust EQ Low Band Frequency", 52,132,276,48},
+  {NULL,NULL,"High Freq: 20000 Hz",     "Adjust EQ High Band Frequency",52,132,276,48}
 };
 
 /* System options menu */
@@ -700,8 +700,8 @@ static void soundmenu ()
   int ret, quit = 0;
   gui_menu *m = &menu_audio;
   gui_item *items = m->items;
-  float psg_volume = (double)config.psg_preamp/100.0;
-  float fm_volume = (double)config.fm_preamp/100.0;
+  float psg_volume = (float)config.psg_preamp/100.0;
+  float fm_volume = (float)config.fm_preamp/100.0;
 
   sprintf (items[0].text, "High-Quality FM: %s", config.hq_fm ? "ON":"OFF");
   sprintf (items[1].text, "PSG Noise Boost: %s", config.psgBoostNoise ? "ON":"OFF");
@@ -710,18 +710,29 @@ static void soundmenu ()
   if (config.filter == 2) sprintf (items[4].text, "Filtering: 3-BAND EQ");
   else if (config.filter == 1) sprintf (items[4].text, "Filtering: LOW PASS");
   else sprintf (items[4].text, "Filtering: OFF");
-  sprintf (items[5].text, "Low Freq: %d", config.low_freq);
-  sprintf (items[6].text, "High Freq: %d", config.high_freq);
-  sprintf (items[7].text, "Low Gain: %1.2f", config.lg);
-  sprintf (items[8].text, "Middle Gain: %1.2f", config.mg);
-  sprintf (items[9].text, "High Gain: %1.2f", config.hg);
+  if (config.filter == 2)
+  {
+    sprintf (items[5].text, "Low Gain: %1.2f", config.lg);
+    strcpy (items[5].comment, "Adjust EQ Low Band Gain");
+    sprintf (items[6].text, "Middle Gain: %1.2f", config.mg);
+    sprintf (items[7].text, "High Gain: %1.2f", config.hg);
+    sprintf (items[8].text, "Low Freq: %d", config.low_freq);
+    sprintf (items[9].text, "High Freq: %d", config.high_freq);
+  }
+  else if (config.filter == 1)
+  {
+    sprintf (items[5].text, "Low-Pass Rate: %d %%", config.lp_range);
+    strcpy (items[5].comment, "Adjust Low Pass filter");
+  }
 
   GUI_InitMenu(m);
 
-  if (config.filter < 2)
-    m->max_items  = 5;
-  else
+  if (config.filter == 1)
+    m->max_items  = 6;
+  else if (config.filter == 2)
     m->max_items  = 10;
+  else
+    m->max_items  = 5;
 
   GUI_SlideMenuTitle(m,strlen("Audio "));
 
@@ -761,7 +772,7 @@ static void soundmenu ()
 
       case 3:
         GUI_OptionBox(m,0,"FM Volume",(void *)&fm_volume,0.01,0.0,5.0,0);
-        sprintf (items[3].text, "FM Volume: %1.2f", (double)config.fm_preamp/100.0);
+        sprintf (items[3].text, "FM Volume: %1.2f", fm_volume);
         config.fm_preamp = (int)(fm_volume * 100.0);
         break;
 
@@ -769,56 +780,71 @@ static void soundmenu ()
         config.filter ++;
         if (config.filter > 2) config.filter = 0;
         if (config.filter == 2)
-          sprintf (items[4].text, "Filtering: 3-BAND EQ");
-        else if (config.filter == 1)
-          sprintf (items[4].text, "Filtering: LOW PASS");
-        else
-          sprintf (items[4].text, "Filtering: OFF");
-
-        if (config.filter < 2)
         {
-          /* reset menu selection */
-          m->offset     = 1;
-          m->selected   = 3;
-          m->max_items  = 5;
+          m->max_items  = 10;
+          sprintf (items[4].text, "Filtering: 3-BAND EQ");
+          sprintf (items[5].text, "Low Gain: %1.2f", config.lg);
+          strcpy (items[5].comment, "Adjust EQ Low Band Gain");
+          sprintf (items[6].text, "Middle Gain: %1.2f", config.mg);
+          sprintf (items[7].text, "High Gain: %1.2f", config.hg);
+          sprintf (items[8].text, "Low Freq: %d", config.low_freq);
+          sprintf (items[9].text, "High Freq: %d", config.high_freq);
+        }
+        else if (config.filter == 1)
+        {
+          m->max_items  = 6;
+          sprintf (items[4].text, "Filtering: LOW PASS");
+          sprintf (items[5].text, "Low-Pass Rate: %d %%", config.lp_range);
+          strcpy (items[5].comment, "Adjust Low Pass filter");
         }
         else
         {
-          /* enable items */
-          m->max_items  = 10;
+          sprintf (items[4].text, "Filtering: OFF");
+          m->max_items  = 5;
+          m->offset = 1;
+          m->selected = 3;
+        }
 
-          /* intialize EQ */
+        /* reintialize EQ */
+        audio_set_equalizer();
+
+        break;
+
+      case 5:
+        if (config.filter == 1)
+        {
+          GUI_OptionBox(m,0,"Low-Pass Rate",(void *)&config.lp_range,1,0,100,1);
+          sprintf (items[5].text, "Low-Pass Rate: %d %%", config.lp_range);
+        }
+        else
+        {
+          GUI_OptionBox(m,0,"Low Gain",(void *)&config.lg,0.01,0.0,2.0,0);
+          sprintf (items[5].text, "Low Gain: %1.2f", config.lg);
           audio_set_equalizer();
         }
         break;
 
-      case 5:
-        GUI_OptionBox(m,0,"Low Frequency",(void *)&config.low_freq,10,0,config.high_freq,1);
-        sprintf (items[5].text, "Low Freq: %d", config.low_freq);
-        audio_set_equalizer();
-        break;
-
       case 6:
-        GUI_OptionBox(m,0,"High Frequency",(void *)&config.high_freq,100,config.low_freq,30000,1);
-        sprintf (items[6].text, "High Freq: %d", config.high_freq);
+        GUI_OptionBox(m,0,"Middle Gain",(void *)&config.mg,0.01,0.0,2.0,0);
+        sprintf (items[6].text, "Middle Gain: %1.2f", config.mg);
         audio_set_equalizer();
         break;
 
       case 7:
-        GUI_OptionBox(m,0,"Low Gain",(void *)&config.lg,0.01,0.0,2.0,0);
-        sprintf (items[7].text, "Low Gain: %1.2f", config.lg);
+        GUI_OptionBox(m,0,"High Gain",(void *)&config.hg,0.01,0.0,2.0,0);
+        sprintf (items[7].text, "High Gain: %1.2f", config.hg);
         audio_set_equalizer();
         break;
 
       case 8:
-        GUI_OptionBox(m,0,"Middle Gain",(void *)&config.mg,0.01,0.0,2.0,0);
-        sprintf (items[8].text, "Middle Gain: %1.2f", config.mg);
+        GUI_OptionBox(m,0,"Low Frequency",(void *)&config.low_freq,10,0,config.high_freq,1);
+        sprintf (items[8].text, "Low Freq: %d", config.low_freq);
         audio_set_equalizer();
         break;
 
       case 9:
-        GUI_OptionBox(m,0,"High Gain",(void *)&config.hg,0.01,0.0,2.0,0);
-        sprintf (items[9].text, "High Gain: %1.2f", config.hg);
+        GUI_OptionBox(m,0,"High Frequency",(void *)&config.high_freq,100,config.low_freq,30000,1);
+        sprintf (items[9].text, "High Freq: %d", config.high_freq);
         audio_set_equalizer();
         break;
 
diff --git a/source/gx/osd.h b/source/gx/osd.h
index b61cf46..fa125e7 100644
--- a/source/gx/osd.h
+++ b/source/gx/osd.h
@@ -33,9 +33,9 @@
 #define SK_UPMEM      "/genplus/sk2chip.bin"
 
 #ifdef HW_RVL
-#define VERSION "version 1.4.0W"
+#define VERSION "version 1.3.XW"
 #else
-#define VERSION "version 1.4.0G"
+#define VERSION "version 1.3.XG"
 #endif
 
 /* globals */
diff --git a/source/system.c b/source/system.c
index ab2a13d..dffe89a 100644
--- a/source/system.c
+++ b/source/system.c
@@ -54,14 +54,19 @@ void audio_set_equalizer(void)
 /****************************************************************
  * AUDIO stream update
  ****************************************************************/
-static int ll, rr;
+static int llp,rrp;
+
 void audio_update (int size)
 {
-  int i;
-  int l, r;
-  int psg_preamp = config.psg_preamp;
-  int fm_preamp  = config.fm_preamp;
-  int filter = config.filter;
+  int i, l, r;
+  int ll = llp;
+  int rr = rrp;
+
+  int psg_preamp    = config.psg_preamp;
+  int fm_preamp     = config.fm_preamp;
+  int filter        = config.filter;
+  uint32 factora    = (config.lp_range << 16) / 100;
+  uint32 factorb    = 0x10000 - factora;
 
   int16 *fm[2] = {snd.fm.buffer[0],snd.fm.buffer[1]};
   int16 *psg = snd.psg.buffer;
@@ -97,10 +102,10 @@ void audio_update (int size)
     if (filter & 1)
     {
       /* single-pole low-pass filter (6 dB/octave) */
-      l = (ll + l) >> 1;
-      r = (rr + r) >> 1;
-      ll = l;
-      rr = r;
+      ll = (ll>>16)*factorb + l*factora;
+      rr = (rr>>16)*factorb + r*factora;
+      l = ll >> 16;
+      r = rr >> 16;
     }
     else if (filter & 2)
     {
@@ -124,6 +129,10 @@ void audio_update (int size)
     *sb++ = l;
 #endif
   }
+
+  /* save delayed samples */
+  llp = ll;
+  rrp = rr;
 }
 
 /****************************************************************
diff --git a/source/system.h b/source/system.h
index ddbd2b4..0c53d77 100644
--- a/source/system.h
+++ b/source/system.h
@@ -85,6 +85,7 @@ extern uint32 count_z80;
 extern uint32 line_z80;
 extern int32 current_z80;
 extern uint8 system_hw;
+extern uint32 count_z80;
 
 /* Function prototypes */
 extern int audio_init (int rate);