diff --git a/src/hw.accel.a b/src/hw.accel.a
old mode 100644
new mode 100755
index 9906c4456..2fca68c4c
--- a/src/hw.accel.a
+++ b/src/hw.accel.a
@@ -118,13 +118,15 @@ EX_3MHZMASK     =    $C0     ; 3.6Mhz
 
 ; FASTChip
 fc_lock         =    $C06A
-FC_UNLOCK       =    $6A     ; write 4 times
-FC_LOCK         =    $A6
 fc_enable       =    $C06B
 fc_config       =    $C06E
 fc_data         =    $C06F
+FC_UNLOCK       =    $6A     ; write 4 times
+FC_LOCK         =    $A6
 FC_1MHZ         =    9
 FC_ON           =    40      ; doco says 16.6Mhz
+FC_SPKR         =    2
+FC_HIFI         =    4
 
 ; TransWarp I
 ; may overlap with paddle trigger
@@ -213,6 +215,19 @@ build_setspeed
          rts
 
 build_addon
+         lda   #FC_UNLOCK            ; change Fastchip speaker setting to 'HIFI'
+         sta   fc_lock               ; (improves sound on most games)
+         sta   fc_lock               ; (setting reverts on power cycle)
+         sta   fc_lock
+         sta   fc_lock
+         sta   fc_enable
+         lda   #FC_SPKR
+         sta   fc_config
+         lda   #FC_HIFI
+         sta   fc_data
+         lda   #FC_LOCK
+         sta   fc_lock
+
          lda   #<addon
          ldy   #>addon
          ldx   #(end_addon-addon)