Selecting an audio source
Applies to: Pearl Mini, Pearl Nexus
The audio that's coming from the connected HDMI video sources (HDMI-A and HDMI-B) is automatically used as the default audio source for the HDMI-A and HDMI-B channels. You can choose different audio sources for a channel using the Admin panel and do things like adjust the input gain.
Select your audio sources from connected video sources (SDI, HDMI, USB video UVC, SRT, and RTSP), as well as from the dedicated analog audio input ports. The USB (UVC/UAC) ports on the rear panel will accept a USB microphone (UAC).
Dedicated analog audio input ports are:
- Two XLR/TRS combo jacks.
- XLR mic-level input (balanced), supports 48 V phantom power.
- TRS ¼" professional line-level input, +4.0 dBu up to 12.3 V RMS (+24 dBu) (balanced/unbalanced).
- One 3.5 mm stereo mic level input for electret microphones (unbalanced).
- One stereo pair RCA consumer line-level input (-10 dBV).
The XLR and TRS combo jacks are configured as a left/right stereo pair by default. The 3.5 mm audio ports and the RCA audio ports are linked. You can configure the device to use both or just one of the audio sources using the Admin panel.
This table offers some guidelines for adjusting the gain of the audio input ports for common types of audio devices. You should add the suggested gain to the audio input to get an average signal to register at a nominal level in the VU meter (i.e. where the green bars change to yellow). The actual amount of gain needed depends on the strength of the original audio signal.
Table — Audio gain guidelines for different audio devices
| Audio source | Input port | Gain |
|---|---|---|
| Dynamic microphone | XLR | Add +50 to +60 dB gain to the audio input port. |
| Electret microphone | XLR | Add +18 to +40 dB gain to the audio input port. |
| 3.5 mm | Add +6 to +12 dB gain to the audio input port. | |
| Wireless microphone receiver | XLR | Add +18 to +40 dB gain to the audio input port. |
| 3.5 mm | Add +6 to +12 dB gain to the audio input port. | |
| Condenser microphone with phantom power | XLR | Add +40 to +60 dB gain to the audio input port. |
| Mobile phone or other consumer line level device | TRS | Add +6 to +12 dB gain to the audio input port. |
| RCA¹ | Nominal | |
| Professional mixer | TRS | Nominal |
| RCA¹ | Not recommended. | |
| USB microphone | USB | Nominal |
¹ To avoid unwanted signal noise on the RCA ports, we recommend adding no more than 12dB of gain to the RCA port or when XLR B/RCA is used.
Connecting devices that are not designed for phantom power when phantom power is enabled for the two XLR ports can seriously damage those devices. Always check the phantom power LED before connecting devices to the XLR ports.
To choose a different audio device for the channel:
- Using a web browser on the admin computer, go to the IP address of the device and log in.
- From the Channels menu, select your channel (e.g., HDMI-A or HDMI-B) and click Layouts. The custom channel layout editor page opens.
- Check the audio source that you want to use for the layout and click Save.
- (Optional) Adjust the gain for an audio input source: select the input port from the Inputs menu and adjust the amount of gain on the configuration page for the audio input port. Click Save when you're done.
Device differences
- Pearl-2 and Pearl Nano have materially different analog audio hardware (input port counts and types) and are documented separately in their own guides.