diff --git a/drivers/vga-nextgen/vga.c b/drivers/vga-nextgen/vga.c
index 3e3f45f..c0da82b 100644
--- a/drivers/vga-nextgen/vga.c
+++ b/drivers/vga-nextgen/vga.c
@@ -116,7 +116,8 @@ inline static void sound_callback() {
             adlib_cycles_per_vga = 0;
         }
         sum_adlib_samples += adlibgensample_ch(adlib_cycles_per_vga);
-        out += (int16_t)(sum_adlib_samples >> adlib_divider);
+        register uint8_t d = adlib_divider;
+        out += (int16_t)(sum_adlib_samples >> d);
         if (adlib_cycles_per_vga == 0) {
             sum_adlib_samples = 0;
         }
@@ -132,21 +133,24 @@ inline static void sound_callback() {
             last_dss_sample = dss_sample();
             dss_cycles_per_vga = 0;
         }
-        out += dss_divider > 8 ?
-            ((int16_t)last_dss_sample - (int16_t)0x0080) >> (dss_divider - 8):
-            ((int16_t)last_dss_sample - (int16_t)0x0080) << (8 - dss_divider); // 8 unsigned on LPT1 mix to signed 16
+        register uint8_t d = dss_divider;
+        out += d > 8 ?
+            ((int16_t)last_dss_sample - (int16_t)0x0080) >> (d - 8):
+            ((int16_t)last_dss_sample - (int16_t)0x0080) << (8 - d); // 8 unsigned on LPT1 mix to signed 16
     }
 #endif
 #ifdef COVOX
-    if (is_covox_on) {
-        out += covox_divider > 8 ?
-            ((int16_t)true_covox - (int16_t)0x0080) >> (covox_divider - 8):
-            ((int16_t)true_covox - (int16_t)0x0080) << (8 - covox_divider); // 8 unsigned on LPT2 mix to signed 16
+    if (is_covox_on && true_covox) {
+        register uint8_t d = covox_divider;
+        out += d > 8 ?
+            ((int16_t)true_covox - (int16_t)0x0080) >> (d - 8):
+            ((int16_t)true_covox - (int16_t)0x0080) << (8 - d); // 8 unsigned on LPT2 mix to signed 16
     }
 #endif
 #ifdef TANDY3V
     if (is_tandy3v_on) {
-        out += sn76489_sample() >> tandy3v_divider; // already signed 16
+        register uint8_t d = tandy3v_divider;
+        out += sn76489_sample() >> d; // already signed 16
     }
 #endif
 #ifdef CMS
@@ -163,10 +167,10 @@ inline static void sound_callback() {
     out_l = out;
     out_r = out;
 #endif
-    register uint8_t r_rivider = snd_divider; // TODO: tume up divider per channel
-    register uint8_t l_rivider = snd_divider;
-    pwm_set_gpio_level(PWM_PIN0,(int16_t)((int32_t)out_r + 0x8000L) >> r_rivider); // Право signed 16 to unsigned 16
-    pwm_set_gpio_level(PWM_PIN1,(int16_t)((int32_t)out_l + 0x8000L) >> l_rivider); // Лево  signed 16 to unsigned 16
+    register uint8_t r_divider = snd_divider; // TODO: tume up divider per channel
+    register uint8_t l_divider = snd_divider;
+    pwm_set_gpio_level(PWM_PIN0,(uint16_t)((int32_t)out_r + 0x8000L) >> r_divider); // Право signed 16 to unsigned 16
+    pwm_set_gpio_level(PWM_PIN1,(uint16_t)((int32_t)out_l + 0x8000L) >> l_divider); // Лево  signed 16 to unsigned 16
 }
 #endif
 
diff --git a/src/audio/adlib.c b/src/audio/adlib.c
index d72049b..735ea39 100644
--- a/src/audio/adlib.c
+++ b/src/audio/adlib.c
@@ -22,7 +22,7 @@
 
 #include <stdint.h>
 #include <stdio.h>
-
+#include <stdbool.h>
 
 //static double samprateadjust = 1.0;
 //static uint8_t optable[0x16] = { 0, 0, 0, 1, 1, 1, 255, 255, 0, 0, 0, 1, 1, 1, 255, 255, 0, 0, 0, 1, 1, 1 };
@@ -106,9 +106,11 @@ static uint8_t adlibdidattack[9], adlibpercussion = 0, adlibstatus = 0;
 
 static uint16_t adlibport = 0x388;
 
+extern volatile bool is_adlib_on;
 
 void outadlib ( uint16_t portnum, uint8_t value )
 {
+	if (!is_adlib_on) return;
 	if (portnum == adlibport) {
 		adlibaddr = value;
 		return;
@@ -153,6 +155,7 @@ void outadlib ( uint16_t portnum, uint8_t value )
 
 uint8_t inadlib ( uint16_t portnum )
 {
+	if (!is_adlib_on) return 0;
 	if (!adlibregmem[4])
 		adlibstatus = 0;
 	else
@@ -231,6 +234,7 @@ static inline void tickadlib_ch ( uint16_t curchan )
 
 void tickadlib ( void )
 {
+	if (!is_adlib_on) return;
 	for (int curchan = 0; curchan < 9; curchan++) {
 		tickadlib_ch(curchan);
 	}
diff --git a/src/manager.c b/src/manager.c
index ce31755..a4f799d 100644
--- a/src/manager.c
+++ b/src/manager.c
@@ -37,7 +37,7 @@ volatile uint8_t cms_divider = 12;
 volatile uint8_t dss_divider = 0;
 volatile uint8_t adlib_divider = 0;
 volatile uint8_t tandy3v_divider = 0;
-volatile uint8_t covox_divider = 9;
+volatile uint8_t covox_divider = 0;
 
 volatile bool is_xms_on = false;
 volatile bool is_ems_on = true;