How to Setup Any EdgeTX Radio to Play Custom Audio Files and Adjust Volume with a Knob

EdgeTX radios can play custom audio files from the SD card, allowing you to add music, startup sounds, voice announcements, or sound effects triggered by switches. You can also assign a rotary knob or slider to control the radio’s volume conveniently. The procedure is mostly the same on radios running EdgeTX, including the RadioMaster TX16S, Pocket, Boxer, TX15, GX12, Zorro, and Jumper T-Pro.

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Demonstration:

Step 1: Prepare the Audio File

EdgeTX radios do not normally play MP3 or AAC files directly, you need to convert the audio to an uncompressed WAV file before copying it to the radio.

For speech and short sound effects, consider normalising the audio before exporting so it is loud enough without clipping.

Using Audacity

To convert MP3 to WAV file format, you can download a free tool called Audacity.

How to convert in Audacity:

1. Open the audio file in Audacity
2. Go to “Tracks” in the menu, and select “Stereo Track to Mono” (Radios typically only has 1 speaker and can only play mono tracks)
3. Set “Project Rate (Hz)” to 32000 (located at bottom left of the screen). This is very important, if this is not set correctly, your music will not play
4. Go to “File”, and select “Export Audio” and save it as WAV file.
5. Select signed 16-bit PCM as the encoding if the option is available.
6. When naming the audio file, make sure the name is as short as possible and avoid symbols, otherwise the file might not be picked up by the radio – e.g. “song1”, “song2” etc

Using other tools

If you wish to use other tools, simply follow this format settings:

• File type: WAV
• Codec: PCM
• Sample rate: 32kHz
• Bit depth: 16-bit
• Channels: Mono

EdgeTX also supports lower sample rates and 8-bit audio, but 32kHz, 16-bit mono PCM is a reliable starting point.

On some radios and SD card structures, filenames may need to be short, so I recommend using simple names such as music1.wav, intro.wav, or alert.wav.

Step 2: Copy the File to the EdgeTX SD Card

1. Connect the radio to your computer by USB and select USB Storage.
2. Open the following folder: \SOUNDS\en\
3. The en folder is used when the radio’s voice language is set to English. For another language, use the folder matching the selected voice language.
4. Copy your WAV file directly into this folder.
5. EdgeTX makes audio files in the active language folder available to functions such as Play Track and Background Music.
6. Safely eject the storage, reinstall the SD card if necessary, and restart the radio.

Step 3: Test the Sound File

Before assigning the file to a switch, check that the radio can play it.

On your radio:

1. Open Radio Settings (press the SYS key).
2. Go to the Storage page.
3. Open SOUNDS folder
4. Open the folder matching your language.
5. Scroll down to the WAV file you just added there.
6. Select Play.

If the file does not appear or will not play, check:

• It is a WAV file rather than an MP3 renamed as WAV.
• It uses PCM encoding.
• It is mono rather than stereo.
• It is inside the correct language folder.
• The filename is short and uses simple letters or numbers.
• The radio is using the same voice language as the folder.

Setup a Switch To Play the Audio File

You can setup a switch so that when it’s activated, an audio file is played. For example, when you flip the arm switch, the radio would announce “Send It!”.

1. Go to Special Functions.
2. Add a new function.
3. Switch: Choose the physical switch that will trigger the sound.
4. Function: Play Track
5. File/Value: Select your WAV file.
6. Repeat: Select 1x or - (dash = play once when switch changes)
7. Enabled: Make sure the function is active.

For example:

• Switch: Your arm switch (e.g. SD↓ for armed)
• Function: Play Track
• Value: Choose “armed.wav” (or whatever sound file you want to use)
• Repeat: –

Apart from Play Track, you can also use BgMusic function, which is for playing a full music track and keep looping until you deactivate it. There is also another useful function BgMusic II. It’s basically a pause button to the background music. When it’s triggered it pauses your music, and when unpaused it starts again where it stopped.

You can assign a rotary knob or slider to the EdgeTX Volume function, so you can conveniently adjust volume any time.

Most people don’t really use the sliders and knobs on their radio, so they are perfect for volume and screen brightness controls. On a radio like the TX16S and TX15, suitable controls include S1, S2, LS and RS.

Configure the Volume Function

1. Open Radio Settings.
2. Go to Global Functions.
3. Add a new function.
4. Set the switch condition to ON.
5. Select Volume as the function.
6. Select the knob (S1 or S2) or slider (LS or RS) as the source.
7. Enable the function.

For example:

• Switch: ON
• Function: Volume
• Source: S1

On a monochrome screen it looks like this:

Final Thoughts

Setting up custom audio in EdgeTX is straightforward once the file format and folder structure are correct. Use Play Track for one-time sounds, BgMusic for looping music, and BgMusic II when you want a pause control. For the best everyday setup, assign the Volume Global Function to a spare rotary knob. This gives you immediate control over the radio’s audio without opening any menus, while keeping model-specific music and sound effects assigned through Special Functions.