How to Set Up Your Sonos Sub (Gen 3)

Beginner 10-15 minutes

What You'll Need

  • Sonos Sub (Gen 3)
  • An existing Sonos speaker to pair with (Arc, Beam, Ray, Five, Era 300, etc.)
  • Sonos app (iOS or Android)
  • Wi-Fi network

Step-by-Step Setup

  1. Choose a position for the Sub. It can stand upright or lay flat on its side. Bass is omnidirectional, so placement flexibility is wide, but the spot you choose does matter for how it sounds in your room.
  2. Plug in the Sub and give it a moment to boot up. The LED on the front will light up.
  3. Open the Sonos app on your phone.
  4. Add the Sub to an existing speaker:
    • Navigate to System and select the room that has a compatible Sonos speaker
    • Tap room settings and look for "Add Sub"
    • The app will discover the Sub and pair it with that room's speaker
  5. Adjust Sub settings to taste:
    • Sub Level: Raise or lower the bass output relative to the main speaker. Start at 0 and adjust from there.
    • Phase: Try both 0 and 180 degrees and pick whichever sounds fuller from your listening position.

Placement Tips

Bass is less directional than mid and high frequencies, so the Sub does not need to be right next to your main speaker. That said, placement still affects how the bass fills the room. Start by placing it near the wall but not directly in a corner. Corners tend to exaggerate the bass and make it boomy and undefined.

If you have the Sub standing upright, try different walls and distances. Moving it even a couple of feet can change how the bass interacts with your room. Laying it flat under a couch or behind furniture works well too since the sound is not directional. Just make sure there is enough ventilation around it.

The force-cancelling driver design means the Sub produces almost no vibration on the surface it sits on, so you do not need to worry about rattling shelves or floors.

Tuning the Sub to Your Room

After placing the Sub, run Trueplay again for the room if you have an iOS device. Trueplay re-calibrates the entire system including the Sub. This step makes a significant difference in how clean and tight the bass sounds.

The Phase setting (0 or 180 degrees) compensates for how sound waves from the Sub interact with your main speaker. Sit in your normal listening spot, switch between 0 and 180, and pick whichever sounds smoother and more integrated. There is no right or wrong answer here; it depends entirely on your room layout.

Troubleshooting

  • Sub not found in the app: Make sure the LED is visible on the front. If it is not lit, unplug the Sub and plug it back in. The app should find it within 30 seconds. Keep your phone near the Sub during discovery.
  • Bass sounds boomy or muddy: Pull the Sub away from corners and walls. Lower the Sub Level in the Sonos app a notch or two. Also try the Phase toggle to see if 180 degrees cleans things up.
  • Bass sounds hollow or thin: Try flipping the Phase setting. If it is at 0, switch to 180 (or vice versa). Also try moving the Sub closer to your main speaker.
  • Sub disconnects from the system: This usually indicates a Wi-Fi issue. Make sure the Sub has a decent signal. If your Sonos system uses a wired speaker as a network backbone, ensure that connection is solid.
  • Factory reset: Unplug the Sub. Press and hold the Connect button while plugging the power back in. Hold until the LED flashes amber and white, then release.

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