Relay Interactive User Guide | Avantree
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INTERACTIVE USER GUIDE · RELAY / TC218

Hear airplane audio in your own Bluetooth headphones.

Relay sends sound from a 3.5 mm audio output to AirPods or Bluetooth headphones. It is a transmitter—not a device you select on your phone.

Avantree Relay Bluetooth airplane transmitterTwo headphones3.5 mm audio

First, know what connects to what

Relay sits between the screen and your headphones.

Audio source3.5 mm AUDIO OUT
→
RelayBluetooth transmitter
→
HeadphonesAirPods / Bluetooth

Important: Do not look for "Relay" in your phone Bluetooth menu. Relay connects directly to your headphones.

QUICK SETUP

Four steps. One clear result.

Keep Relay and your headphones within 3 ft / 1 m while pairing.

STEP 1

Put headphones in pairing mode.

Turning them on is not enough.

  1. Turn off Bluetooth on nearby devices.Phones, tablets, and computers.
  2. Do not use a phone menu or app.Relay pairs directly with your headphones.
  3. Choose your headphones below.Continue after you see or hear its pairing signal.

Choose your headphones

Put AirPods in pairing mode

  1. AirPods 1–3 and AirPods Pro 1–2: keep them in the case, open the lid, then hold the button on the back for about 5 seconds.
  2. AirPods 4 and AirPods Pro 3: keep them in the case. Open the lid, then double-tap the front of the case.
  3. Ready when the case light flashes white.
✓

Success: the pairing signal shown above appears.

USE RELAY

Travel, reconnect, or share.

01

Before your flight

  1. Charge Relay and test it before travel with a laptop, airplane-style seat screen, or other 3.5 mm headphone output.
  2. Pair your headphones before boarding.
  3. Turn Relay off using the side switch after testing.
02

Reconnect

  1. Turn off phone Bluetooth.
  2. Turn on your headphones, then Relay.
  3. If needed, press MFB once to reconnect the last device.
03

Add a second headphone

1. Pair headphone 2

  1. Keep headphone 1 connected. Relay light ① must be solid blue.
  2. Hold Relay MFB for 2 seconds until light ② flashes red + blue.
  3. Put headphone 2 in pairing mode. Keep headphone 1 connected.
  4. Wait up to 30 seconds. Lights ① and ② should both stay solid blue.

2. Make both reconnect together

  1. After both lights are solid blue, turn Relay off.
  2. Turn both headphones off. Put earbuds back in their cases.
  3. Turn Relay on.
  4. Turn both headphones on. Remove earbuds from their cases.
  5. Wait 10–15 seconds.
  6. Continue when lights ① and ② both stay solid blue.

ON THE PLANE

Choose the correct audio jack.

Relay needs an analog 3.5 mm headphone output.

Single 3.5 mm

Plug Relay in directly.

Dual 3.5 mm

Use the included airplane adapter.

Mixed-size jacks

Use only the 3.5 mm headphone jack.

QUICK FIXES

What do you see?

Choose the symptom—not a long troubleshooting list.

Red + blue after 30 secondsHeadphones are ON but may not be pairing
  1. Turn off Bluetooth on nearby phones, tablets, and computers.
  2. Do not use a phone Bluetooth menu or headphone app.
  3. Restart pairing mode on the headphones. Confirm their light flashes rapidly or you hear a pairing voice prompt.
  4. Keep the headphones within 3 ft / 1 m of Relay and wait another 30 seconds.
Only blue is flashingRelay is not in pairing mode
  1. Confirm Relay is ON.
  2. Hold the large round MFB for 2 seconds.
  3. Wait for alternating red + blue. If nothing changes, turn Relay off and on, then try once more.
Solid blue, but no soundConnected—check all 3 volume controls
  1. Use a 3.5 mm headphone or AUDIO OUT port.
  2. Fully reinsert the plug and press play. If possible, test the same jack with wired headphones.
  3. Raise all three: source / airplane screen → Relay (+ / −) → headphones.
②Only one headphone worksPair, then reconnect both together
  1. Turn off Bluetooth on nearby phones, tablets, and computers.
  2. Keep headphone 1 connected while you put headphone 2 in pairing mode.
  3. Hold Relay MFB for 2 seconds. Wait until lights ① and ② both stay solid blue.
  4. Turn Relay off, then turn both headphones off or put earbuds in their cases.
  5. Turn Relay on, then turn both headphones on or remove earbuds from their cases.
  6. Wait 10–15 seconds for lights ① and ② to stay solid blue.
See the complete two-headphone steps ↑
↺Clear all saved pairingsFactory reset
  1. Turn Relay on.
  2. Hold + and − together for 6 seconds.
  3. The lights appear pink for 3 seconds, then flash red + blue alternately.

This clears every saved pairing. Avantree does not document a one-device erase command.

◷Audio is delayedSome Bluetooth delay is normal
  • For lower delay, use headphones that support aptX Low Latency or aptX Adaptive.
  • Keep devices close and away from crowded wireless areas.
  • Relay is not recommended for instruments or real-time monitoring.
Will Relay turn itself off?Use the side switch to turn Relay OFF after use. Do not rely on an automatic shutoff.

REFERENCE

Buttons, lights, charging.

Relay controls showing MFB, volume, power, pairing and battery indicators
MFB = large round multi-function button.

Buttons

Power switch
Slide ON / OFF
+ / −
Press to adjust volume
+ and −
Hold 6 sec to clear all pairing history
MFB
Hold 2 sec: pairing mode
MFB
Press once: reconnect last device
MFB
Double-click: check battery

Connection lights

Red + blue
Pairing
Solid blue
Connected
Blue / 1 sec
Reconnecting
Blue / 5 sec
Standby—not connected
Pink / 3 sec
Pairing history cleared
⚡

USB-C CHARGING

About 2 hours to charge.

  • Use a 5 V USB power source rated 500 mA–2 A.
  • Any battery LED flashing: charging.
  • All battery LEDs off: fully charged.
  • Up to 25 hours playtime; actual life varies with use.

FIRMWARE UPDATE

Update Relay when a fix or feature requires it.

Not part of normal setup. Update only when Avantree Support recommends it or a troubleshooting guide directs you here.

  1. 1
    Download Avantree UpdaterChoose Windows 10+ or macOS 10.14+.
  2. 2
    Connect Relay to your computerUse a USB data cable. A charge-only cable cannot transfer the update.
  3. 3
    Run the updateKeep Relay connected until the updater confirms completion, then restart it.
Open Relay firmware update Notify me about updates View the detailed update guide →

During the update: do not unplug Relay, close the updater, or turn off the computer.

PRODUCT DETAILS

What is included—and what Relay supports.

Relay package contents: transmitter, pouch, USB-C cable and dual airplane adapter
Relay, travel pouch, USB-A to USB-C cable, dual 3.5 mm airplane adapter.

Compatibility

✓

Works withAirPods and Bluetooth headphones; airplane screens, laptops and gym machines with 3.5 mm AUDIO OUT.

×

Not designed forPairing to phones/tablets, TVs, hearing aids, musical instruments or real-time monitoring.

!

Signal generatorsOnly use an analog 3.5 mm headphone/audio output. Bluetooth delay makes Relay unsuitable for real-time work.

Specifications

BluetoothVersion 5.3
ProfilesA2DP, AVRCP
CodecsaptX Adaptive / LL / HD, aptX, SBC
RangeUp to 33 ft / 10 m
PlaytimeUp to 25 hours
ChargingAbout 2 hours
Size125 × 24 × 12 mm
Weight15 g

SAFETY

Listen safely. Travel responsibly.

Lower volume before putting on headphones, then increase it gradually. Stop if you experience ringing or discomfort.

Keep the product dry. Do not open it or replace the built-in battery. Keep small parts away from children.

Follow airline and facility instructions for wireless devices. Do not use headphones where full attention is required.

Read full safety and regulatory information ↗

STILL NEED HELP?

Get the right help for Relay.

For the fastest answer, start with a support ticket. Choose Relay / TC218 and the form will ask for the details our product team needs.

RECOMMENDEDSubmit a Relay support ticketAnswer product-specific questions and add photos or screenshots if needed.Start support request →

DON'T WANT TO SUBMIT A TICKET?

Talk to a real support agent.

Email ussupport@avantree.comCall us in the US800 232 2078