diff --git a/source/sound/ym2612.c b/source/sound/ym2612.c
index 2832542..d3c05e2 100644
--- a/source/sound/ym2612.c
+++ b/source/sound/ym2612.c
@@ -14,12 +14,13 @@
 **
 ** 2006~2009  Eke-Eke (Genesis Plus GX):
 ** Credits to Nemesis (@spritesmind.net), most of those fixes came from his tests on a Model 1 Sega Mega Drive 
+** More informations here: http://gendev.spritesmind.net/forum/viewtopic.php?t=386
 **
 **  - removed unused multichip support
 **  - added YM2612 Context external access functions
-**  - added LFO phase update in CH3 special mode (Warlock birds, Alladin bug sound)
-**  - fixed internal timers emulation
-**  - added Attack Rate immediate update on register write (Batman & Robin intro)
+**  - implemented LFO phase update in CH3 special mode (Warlock birds, Alladin bug sound)
+**  - improved internal timers emulation
+**  - fixed Attack Rate update in some specific case (Batman & Robin intro)
 **  - fixed EG behavior when Attack Rate is maximal
 **  - fixed EG behavior when SL=0 (Mega Turrican tracks 03,09...) or/and Key ON occurs at minimal attenuation 
 **  - added EG output immediate update on register writes
@@ -29,6 +30,7 @@
 **  - implemented correct SSG-EG emulation (Asterix, Beavis&Butthead, Bubba'n Six & many others)
 **  - adjusted some EG rates
 **  - modified address/data port behavior
+**  - fixed LFO implementation (only 11 bits of precision)
 **
 **  TODO: complete SSG-EG documentation
 **
@@ -582,9 +584,8 @@ typedef struct
   UINT32  eg_timer_add;       /* step of eg_timer */
   UINT32  eg_timer_overflow;  /* envelope generator timer overlfows every 3 samples (on real chip) */
 
-  /* there are 2048 FNUMs that can be generated using FNUM/BLK registers
-        but LFO works with one more bit of a precision so we really need 4096 elements */
-  UINT32  fn_table[4096]; /* fnumber->increment counter */
+  /* there are 2048 FNUMs that can be generated using FNUM/BLK registers */
+  UINT32  fn_table[2048]; /* fnumber->increment counter */
   UINT32  fn_max;         /* max increment (required for calculating phase overflow) */
 
   /* LFO */
@@ -1237,20 +1238,21 @@ INLINE void update_phase_lfo_slot(FM_SLOT *SLOT , INT32 pms, UINT32 block_fnum)
 {
   UINT32 fnum_lfo   = ((block_fnum & 0x7f0) >> 4) * 32 * 8;
   INT32  lfo_fn_table_index_offset = lfo_pm_table[ fnum_lfo + pms + LFO_PM ];
-  
+
   if (lfo_fn_table_index_offset)  /* LFO phase modulation active */
   {
-    block_fnum = block_fnum*2 + lfo_fn_table_index_offset;
+    /* retrieve BLOCK register value */
+    UINT8 blk = (block_fnum >> 11) & 7;
 
-    UINT8 blk = (block_fnum&0x7000) >> 12;
-    UINT32 fn  = block_fnum & 0xfff;
+    /* increase FNUM register value */
+    UINT32 fn  = (block_fnum + lfo_fn_table_index_offset) & 0x7ff;
 
-    /* keyscale code */
-    int kc = (blk<<2) | opn_fktable[fn >> 8];
+    /* recalculate keyscale code */
+    int kc = (blk<<2) | opn_fktable[fn >> 7];
 
-    /* (frequency) phase increment counter */
+    /* recalculate (frequency) phase increment counter */
     int fc = (ym2612.OPN.fn_table[fn]>>(7-blk)) + SLOT->DT[kc];
-      
+
     /* (frequency) phase overflow (credits to Nemesis) */
     if (fc < 0) fc += ym2612.OPN.fn_max;
 
@@ -1266,21 +1268,22 @@ INLINE void update_phase_lfo_slot(FM_SLOT *SLOT , INT32 pms, UINT32 block_fnum)
 INLINE void update_phase_lfo_channel(FM_CH *CH)
 {
   UINT32 block_fnum = CH->block_fnum;
-  
+
   UINT32 fnum_lfo   = ((block_fnum & 0x7f0) >> 4) * 32 * 8;
   INT32  lfo_fn_table_index_offset = lfo_pm_table[ fnum_lfo + CH->pms + LFO_PM ];
 
   if (lfo_fn_table_index_offset)  /* LFO phase modulation active */
   {
-    block_fnum = block_fnum*2 + lfo_fn_table_index_offset;
+    /* retrieve BLOCK register value */
+    UINT8 blk = (block_fnum >> 11) & 7;
 
-    UINT8 blk = (block_fnum&0x7000) >> 12;
-    UINT32 fn  = block_fnum & 0xfff;
-    
-    /* keyscale code */
-    int kc = (blk<<2) | opn_fktable[fn >> 8];
+    /* increase FNUM register value */
+    UINT32 fn  = (block_fnum + lfo_fn_table_index_offset)& 0x7ff;
 
-     /* (frequency) phase increment counter */
+    /* recalculate keyscale code */
+    int kc = (blk<<2) | opn_fktable[fn >> 7];
+
+     /* recalculate (frequency) phase increment counter */
     int fc = (ym2612.OPN.fn_table[fn]>>(7-blk));
 
     /* (frequency) phase overflow (credits to Nemesis) */
@@ -1316,7 +1319,6 @@ INLINE void chan_calc(FM_CH *CH)
 
   UINT32 AM = LFO_AM >> CH->ams;
 
-
   m2 = c1 = c2 = mem = 0;
 
   *CH->mem_connect = CH->mem_value;  /* restore delayed sample (MEM) value to m2 or c2 */
@@ -1356,7 +1358,6 @@ INLINE void chan_calc(FM_CH *CH)
   if( eg_out < ENV_QUIET )    /* SLOT 4 */
     *CH->connect4 += op_calc(CH->SLOT[SLOT4].phase, eg_out, c2);
 
-
   /* store current MEM */
   CH->mem_value = mem;
 
@@ -1631,14 +1632,17 @@ static void OPNSetPres(int pres)
   /* make time tables */
   init_timetables(dt_tab);
 
-  /* there are 2048 FNUMs that can be generated using FNUM/BLK registers
-      but LFO works with one more bit of a precision so we really need 4096 elements */
+  /* there are 2048 FNUMs that can be generated using FNUM/BLK registers */
   /* calculate fnumber -> increment counter table */
-  for(i = 0; i < 4096; i++)
+  for(i = 0; i < 2048; i++)
   {
     /* freq table for octave 7 */
     /* OPN phase increment counter = 20bit */
-    ym2612.OPN.fn_table[i] = (UINT32)( (double)i * 32 * ym2612.OPN.ST.freqbase * (1<<(FREQ_SH-10)) ); /* -10 because chip works with 10.10 fixed point, while we use 16.16 */
+    /* the correct formula is : F-Number = (144 * fnote * 2^20 / M) / 2^(B-1) */
+    /* where sample clock is  M/144 */
+    /* this means the increment value for one clock sample is FNUM * 2^(B-1) = FNUM * 64 for octave 7 */
+    /* we also need to handle the ratio between the chip frequency and the emulated frequency (can be 1.0)  */
+    ym2612.OPN.fn_table[i] = (UINT32)( (double)i * 64 * ym2612.OPN.ST.freqbase * (1<<(FREQ_SH-10)) ); /* -10 because chip works with 10.10 fixed point, while we use 16.16 */
   }
 
   /* maximal frequency is required for Phase overflow calculation, register size is 17 bits (Nemesis) */
@@ -1843,7 +1847,7 @@ INLINE void OPNWriteReg(int r, int v)
           /* keyscale code */
           CH->kcode = (blk<<2) | opn_fktable[fn >> 7];
           /* phase increment counter */
-          CH->fc = ym2612.OPN.fn_table[fn*2]>>(7-blk);
+          CH->fc = ym2612.OPN.fn_table[fn]>>(7-blk);
 
           /* store fnum in clear form for LFO PM calculations */
           CH->block_fnum = (blk<<11) | fn;
@@ -1862,7 +1866,7 @@ INLINE void OPNWriteReg(int r, int v)
             /* keyscale code */
             ym2612.OPN.SL3.kcode[c]= (blk<<2) | opn_fktable[fn >> 7];
             /* phase increment counter */
-            ym2612.OPN.SL3.fc[c] = ym2612.OPN.fn_table[fn*2]>>(7-blk);
+            ym2612.OPN.SL3.fc[c] = ym2612.OPN.fn_table[fn]>>(7-blk);
             ym2612.OPN.SL3.block_fnum[c] = (blk<<11) | fn; //fn;
             ym2612.CH[2].SLOT[SLOT1].Incr=-1;
           }