HT5009 Plus - Troubleshooting: How to Fix Audio Quality Issues? – Avantree Support

If the audio sounds distorted, too loud, too sharp, muffled, crackly, or unnatural, open the sections below and try each check in order.

The HT5009 Plus uses Voice Clear by default and adds a +6 dB Volume Boost with Optical input. These features make dialogue easier to hear, but may make some audio sound louder or sharper.

Start here: First try Balanced Mode. If you use Optical, also set OPT Volume to Normal.

1. Change the EQ to Balanced Mode

Play audio through the headphones.
Find the EQ button on the left earcup.
Press the EQ button once. You should hear “Balanced Mode.” Tap it only once.
Listen again and check whether the sound is clearer and more natural.

Recommended: Use Balanced Mode if the sound is sharp, strong, distorted, or unnatural.

Good to know: The selected EQ mode stays saved after power off and power on.

2. Set OPT Volume to Normal

Use this check if you use an Optical (OPT) cable and the sound is too loud or distorted.

Find the OPT Volume switch on the side of the transmitter.
Slide it to Normal.
Play the TV audio again and listen for improvement.

The boosted setting can make some TV audio sound too loud or distorted.

After a reset: The EQ returns to Voice Clear. Select Balanced Mode again if needed.

3. Set the TV Audio Format to PCM

Use this check if you connect the transmitter with an Optical cable.

Open the TV's Settings.
Go to Sound or Audio.
Find Digital Audio Output Format or a similar setting.
Choose PCM or Stereo. Turn Dolby off if that option is shown.
Restart the TV, transmitter, and headphones. Then test again.

PCM is a standard digital audio format. If you cannot find this setting, check your TV manual or the TV manufacturer's support page.

4. Check the Cable and Audio Connection

Unplug the audio cable from the TV and transmitter.
Plug it back in firmly at both ends.
For Optical, connect the TV's Optical OUT / Digital OUT to the transmitter's Optical IN.
If possible, test another compatible cable.
Restart the TV and transmitter. Then test the sound again.

5. Sound Cutting Out, Crackling, or Unstable?

Nearby wireless devices can interfere with Bluetooth audio.

Move the headphones closer to the transmitter.
Temporarily turn off Bluetooth on nearby phones, TVs, computers, speakers, and other devices.
Move the transmitter away from Wi-Fi routers and other wireless equipment.
Restart the headphones and transmitter. Then test again.

Why Does This Help?

Voice Clear EQ changes the sound profile, while Volume Boost raises the Optical volume. These features can be helpful, but some listeners may prefer the more natural sound of Balanced Mode with OPT Volume set to Normal.

Good to Know

Your selected EQ mode stays saved after a normal power off and power on.
If the headphones are reset, the EQ returns to the default Voice Clear mode.
If the sound changes after a reset, select Balanced Mode again.

Something Doesn't Look Right?

No Sound?

Check the TV output, cable connection, and audio format.

Fix No Sound

Need to Find a Button?

See the headphone and transmitter controls and indicator meanings.

View Guide

Pairing Problem?

Pair and lock the headphones to the transmitter again.

Pair & Lock

Need the Full Setup Guide?

Follow the complete HT5009 Plus setup instructions.

View Guide

Still Not Fixed?

Contact Avantree Support and tell us:

How the transmitter is connected to your TV.
What the sound problem is.
Whether the headphones sound normal when connected directly to a phone or computer.

Contact Avantree Support