Set DAX RX gain per channel¶
Each DAX RX channel (1–8) has an independent gain control in the DAX Audio applet. Adjusting these lets you match the audio level delivered to digital mode software or other applications receiving DAX audio.
Before you start¶
- AetherSDR must be connected to a FLEX-8600 radio.
- The DAX Audio applet must be open. If it is not visible, click the DAX tray button on the right sidebar to show it.
- DAX must be enabled. If the Enable button shows Disabled, click Enable in the DAX Audio applet before adjusting gain.
- Windows users: AetherSDR does not include a built-in DAX driver on Windows. The DAX Audio applet displays a note: "No built-in DAX driver on Windows. Use TCI, or SmartSDR DAX." DAX works on Windows using FlexRadio's own SmartSDR DAX drivers. All controls in the applet are inert on Windows. For configuration guidance, see Help → Configuring Data Modes.
Steps¶
- Click the DAX tray button on the right sidebar to open the DAX Audio applet.
- Locate the row for the channel you want to adjust: DAX 1: through DAX 8:. The rows visible depend on the connected radio's slice capacity — a radio with fewer slices does not display dead gain sliders for channels beyond its capacity.
- Drag the combined meter/slider for that channel left or right to decrease or increase the RX gain.
- Release the drag. The new value is saved immediately.
Repeat for any other channels that need adjustment.
What each control does¶
| Control | Default | Valid range |
|---|---|---|
| DAX Enable | Starts the DAX audio bridge; emits daxToggled. | Button label is 'Enable'/'Disabled'; master switch for all DAX RX and TX streams. Not built on Windows (#4112). |
| DAX 1 gain+meter | 0.5 | 0.0–1.0 |
| DAX 2 gain+meter | 0.5 | 0.0–1.0 |
| DAX 3 gain+meter | 0.5 | 0.0–1.0 |
| DAX 4 gain+meter | 0.5 | 0.0–1.0 |
| DAX 5 gain+meter | 0.5 | 0.0–1.0 |
| DAX 6 gain+meter | 0.5 | 0.0–1.0 |
| DAX 7 gain+meter | 0.5 | 0.0–1.0 |
| DAX 8 gain+meter | 0.5 | 0.0–1.0 |
| TX gain+meter | 0.5 | 0.0–1.0 |
| Windows note | On Windows builds the applet shows only the note 'No built-in DAX driver on Windows. Use TCI, or SmartSDR DAX.' (#4112). | Windows has no built-in DAX bridge (no kernel-mode audio driver); all other controls are omitted and their setters are null-guarded. |
DAX Enable: A toggle button labeled Disabled or Enabled that serves as the master switch for all DAX RX and TX streams. Click to toggle. When enabled, the button text changes to Enabled; when disabled, it shows Disabled. The setting is persisted as AutoStartDAX.
Each RX gain+meter is a combined level meter and gain slider. The background bar shows the smoothed post-fader signal level in real time. The vertical thumb line marks the current gain position. Dragging the thumb emits the new gain and persists it immediately. RX meter levels use exponential smoothing with a fast attack and slow decay, so level peaks appear quickly and fall more gradually.
Each slider has an accessibility name set to "DAX RX 1 gain", "DAX RX 2 gain", "DAX RX 3 gain" through "DAX RX 8 gain" respectively for screen reader support.
The slice assignment indicator to the left of each slider (showing either — or Slice A–Slice H) is read-only and reflects which slice is currently routed to that DAX channel.
Tips¶
- The level meter fill reflects post-fader output level — that is, the incoming audio multiplied by the current gain. Moving the slider gives immediate visual feedback on the effective output.
- Gain values are stored as two-decimal-place floats (for example,
0.75). They are restored fromDaxRxGain1–DaxRxGain8each time AetherSDR starts. - If a channel shows — in the slice assignment indicator, no slice is routed to it and the meter will show no activity regardless of the gain setting.
- Rows for DAX channels beyond the connected radio's slice capacity are hidden entirely. For example, a radio with 4 slices shows only DAX channels 1–4. TX gain remains available on all radios.
- On Linux, the DAX audio bridge uses a native PipeWire stream source path, reducing RX latency from approximately 400 ms to approximately 200 ms compared to the previous PulseAudio client.
Troubleshooting¶
- The meter shows no activity even though gain is set above 0.0 — Check the slice assignment indicator for that row. If it shows —, no slice is assigned to that DAX channel. Assign a slice to the channel in your radio configuration, then verify the Enable button shows Enabled.
- Gain resets to 0.5 after restart — The setting was not saved. Confirm the drag completed before closing AetherSDR. The save occurs on release of the slider.
- DAX Enable button does nothing on Windows — This is expected. AetherSDR includes no built-in DAX driver on Windows. Use FlexRadio's SmartSDR DAX drivers instead.
- Some DAX channel rows are missing — This is normal when the connected radio has fewer slices than the maximum. For example, a radio with 4 slices displays only DAX channels 1–4. The hidden rows have no effect on the remaining channels.