diff --git a/scripts/start-synth.sh b/scripts/start-synth.sh
index 677f3dc..2024aea 100755
--- a/scripts/start-synth.sh
+++ b/scripts/start-synth.sh
@@ -64,13 +64,18 @@ fi
 if [ "$MODE" = "onboard" ] || [ "$MODE" = "i2s" ]; then
     info "Mode: Onboard audio (PMIC headphone / line out on JMISC)"
     AUDIO_OPTS=(-audiooutdev 0 -inchannels 0 -outchannels 1)
-    # Apply ALSA UCM HiFi verb to configure DSP routing (required for audio)
-    if command -v alsaucm &>/dev/null; then
-        alsaucm -c hw:0 set _verb HiFi 2>/dev/null && \
-            info "  UCM HiFi verb applied" || \
-            info "  UCM HiFi verb failed"
+    # Configure ALSA mixer for onboard audio (jack detection broken, set manually)
+    if command -v amixer &>/dev/null; then
+        amixer -c 0 cset name='RX_MACRO RX0 MUX' AIF1_PB 2>/dev/null
+        amixer -c 0 cset name='RX_MACRO RX1 MUX' AIF1_PB 2>/dev/null
+        amixer -c 0 cset name='RX_CODEC_DMA_RX_0 Audio Mixer MultiMedia1' 1 2>/dev/null
+        amixer -c 0 cset name='RX INT0_1 INTERP' 'RX INT0_1 MIX1' 2>/dev/null
+        amixer -c 0 cset name='RX INT1_1 INTERP' 'RX INT1_1 MIX1' 2>/dev/null
+        amixer -c 0 cset name='RX INT0_1 MIX1 INP0' RX0 2>/dev/null
+        amixer -c 0 cset name='RX INT1_1 MIX1 INP0' RX1 2>/dev/null
+        info "  ALSA mixer configured for onboard audio"
     else
-        info "  alsaucm not found — skipping UCM config"
+        info "  amixer not found — skipping mixer config"
     fi
 fi