Isolate the Scarlett microphone capture channel (V-487)

deploy/asoundrc

@@ -0,0 +1,27 @@
+# mavmic — the Scarlett Solo 4th Gen microphone alone, for mavwaked.
+#
+# The card's USB capture stream is 4 channels, not 2:
+#
+#   ch1  PCM 01 <- DSP 1 <- Analogue 1   the line/instrument jack
+#   ch2  PCM 02 <- DSP 2 <- Analogue 2   the XLR microphone
+#   ch3  PCM 03 <- Mix C  <- PCM 1       loopback of workstation playback, L
+#   ch4  PCM 04 <- Mix D  <- PCM 2       loopback of workstation playback, R
+#
+# plughw asks ALSA for mono and gets a downmix of all four, so half of what
+# mavwaked scored was whatever the workstation was playing, at unity gain and
+# untouched by the front-panel gain knob. Measured 2026-08-09 with the gain at
+# 0 and a show playing: ch1 rms 0.00000, ch2 0.00002, ch3 0.08834, ch4 0.09045.
+#
+# Air and 48V are named for Line In 2, and both belong to a microphone preamp,
+# so Analogue 2 is the XLR input on this card and Analogue 1 is the jack.
+#
+# This takes slave channel 1 and nothing else. It does not change the card, so
+# the loopback stays available to everything else on the box.
+pcm.mavmic {
+    type plug
+    slave {
+        pcm "hw:CARD=Gen,DEV=0"
+        channels 4
+    }
+    ttable.0.1 1
+}

deploy/mavwaked.service

@@ -32,6 +32,7 @@
 # means out of this unit's own journal, never by guessing.
 #
 #   install: cp to ~/.config/systemd/user/ on workpc
+#            cp ../deploy/asoundrc to ~/.asoundrc on workpc
 #            systemctl --user enable --now mavwaked.service
 
 [Unit]
@@ -46,22 +47,30 @@ After=maven-voice-tunnel.service
 # it returns RMS 0.00004 with its capture switch on and its ALSA volume at the
 # full 496 of 496. That silence is in the hardware, so no flag reaches it.
 #
-# Named CARD=Gen and not card 4, because a USB card number moves when
-# something else is replugged and this daemon must not change ears quietly.
+# mavmic and not plughw:CARD=Gen,DEV=0. deploy/asoundrc defines mavmic and
+# carries the whole reason: the card's capture stream is 4 channels, and two of
+# them are a unity-gain loopback of everything the workstation plays. plughw
+# downmixes all four, so a TV show woke her with the gain knob at 0. Install
+# that file as ~/.asoundrc on workpc or this device does not resolve.
+#
+# Named CARD=Gen inside mavmic and not card 4, because a USB card number moves
+# when something else is replugged and this daemon must not change ears quietly.
 # Not "default" either: that follows whatever pipewire last decided.
 #
-# plughw and not hw. mavwaked asks arecord for 16kHz mono, which is what the
-# whole pipeline is canonical in. Neither microphone offers it, so bare hw
-# dies on "Channels count non available" before a frame is read. plughw puts
-# ALSA's downmix and resampler in front. Any replacement wants the same.
+# mavmic is a plug device and not hw. mavwaked asks arecord for 16kHz mono,
+# which is what the whole pipeline is canonical in. Neither microphone offers
+# it, so bare hw dies on "Channels count non available" before a frame is read.
+# Any replacement wants ALSA's resampler in front the same way.
 #
-# The Scarlett measured RMS 0.003 against 0.14 on the onboard input, so its
-# front-panel gain is the thing to raise if she mishears. That is a knob, not
-# a control ALSA exposes. The two loud devices, the onboard ALC897 and the
-# camera, both clip at peak 1.0 and are worse candidates, not better ones.
+# The mic is on the XLR, which is Analogue 2 on this card and not Analogue 1:
+# Air and 48V are both named for Line In 2 and both belong to a mic preamp.
+# Measured 2026-08-09 through mavmic at 16kHz mono, gain up: rms 0.01826 peak
+# 0.09290 spoken, against a 0.00031 preamp floor, and 0.00002 for the whole
+# stream with a show playing. Front-panel gain is still the thing to raise if
+# she mishears, and it is a knob, not a control ALSA exposes.
 Environment=LD_LIBRARY_PATH=%h/.local/lib
 ExecStart=%h/.local/bin/mavwaked \
-  -device plughw:CARD=Gen,DEV=0 \
+  -device mavmic \
   -addr 127.0.0.1:9100 \
   -lang ru \
   -vad-model %h/.local/share/maven/models/silero_vad.onnx \