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Simple Alarm Clock provides flexible alarm tone options, allowing you to use system default sounds, custom ringtones from your device, or even silent alarms for visual-only notifications.

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Alarm tone types

The app supports four types of alarm tones:

System default

Uses the device’s default alarm sound set in system settings

Default

Uses the default ringtone configured in the app settings

Custom sound

Any audio file or ringtone from your device

Silent

No sound - visual and vibration only (if vibration is enabled)

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Setting alarm tones

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Global default ringtone

Preference key: default_ringtone
Default value: System default This setting controls the default alarm tone for new alarms:
  1. Open Settings
  2. Find “Default alarm tone” or “Default ringtone”
  3. Select your preferred sound
  4. All new alarms will use this tone unless you override it
The global default ringtone is stored as an Alarmtone.SystemDefault when first initialized, which automatically uses your device’s default alarm sound.

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Per-alarm ringtone

Each alarm can have its own unique ringtone:
1

Open alarm details

Tap on an alarm to open its details screen
2

Find ringtone option

Look for the alarm tone or ringtone selector
3

Choose sound

Select from:
  • System default
  • Default (app default)
  • Any custom ringtone from your device
  • Silent mode

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Alarm tone storage

Alarm tones are stored as URI strings internally:
The app uses a sealed class hierarchy for alarm tones (source: Alarmtone.kt):
sealed class Alarmtone {
  object Silent : Alarmtone()
  object Default : Alarmtone()
  object SystemDefault : Alarmtone()
  data class Sound(val uriString: String) : Alarmtone()
}
  • Silent: No sound will play
  • Default: Uses the app’s default ringtone setting
  • SystemDefault: Uses Android’s system default alarm sound
  • Sound: Custom ringtone with a specific URI

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Alarm tone behavior

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Fade-in effect

All alarm tones (except silent) fade in gradually:
  • Default fade-in time: 30 seconds (preference key: fade_in_time_sec)
  • The volume starts at 0% and gradually increases to full volume
  • Fade-in applies to both regular alarms and pre-alarms
  • You can set fade-in to 1 second to effectively disable it
Pre-alarms play at half the configured pre-alarm volume, then that volume is faded in over the fade-in duration.

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Volume control

Alarm volume is separate from media volume:
  • Uses the system’s alarm volume stream
  • Can be adjusted independently from notification and media volumes
  • Pre-alarm has its own volume setting (default: 5 out of 10)
  • Regular alarms use the system alarm volume
The actual volume played is calculated as:For regular alarms:
  • System alarm volume × fade-in percentage
For pre-alarms:
  • (Pre-alarm volume setting / 10) × 0.5 × fade-in percentage
Source: KlaxonPlugin.kt:117-122

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Ringtone manager integration

The app integrates with Android’s RingtoneManager:
1

URI conversion

Internal alarm tone objects are converted to URI strings that RingtoneManager can understand
2

Ringtone loading

The RingtoneManager loads the audio file using the URI
3

Playback

Audio plays through the alarm audio stream with the appropriate volume

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Default alarm alert URI

The system default alarm sound is accessed via: 
Settings.System.DEFAULT_ALARM_ALERT_URI
This ensures compatibility across different Android devices and versions.

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Silent alarms

Silent alarms can be useful for:

Vibration only

Wake up with vibration but no sound

Visual notifications

Get notified without disturbing others

Testing

Test alarm functionality without sound

Reminders

Use alarms as silent reminders with notifications
Even with a silent alarm, the alarm notification will still appear, and vibration will work if enabled.

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Troubleshooting

If your alarm isn’t making sound:
  1. Check that the alarm tone is not set to “Silent”
  2. Verify your device’s alarm volume is not at 0
  3. Ensure Do Not Disturb allows alarms
  4. Check that the alarm tone file/URI is still valid
  5. Try selecting a different ringtone
If a custom ringtone is no longer available:
  • The audio file may have been deleted or moved
  • The app will show an error or may not play sound
  • Select a new ringtone from the alarm details
  • Consider using system default tones for reliability

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Migration and compatibility

The app includes migration logic for users upgrading from older versions:
  • Empty strings are converted to “Default”
  • null values are converted to “Silent”
  • System default URIs are normalized to “Default”
  • Custom URIs are preserved as Sound types
Source: Alarmtone.kt:54-61

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