1. Introduction
Thank you for choosing the Monster Open Ear AC520 Wireless Headphones. This manual provides essential information for setting up, operating, and maintaining your new headphones. Please read it thoroughly to ensure optimal performance and longevity of your device.
2. What's in the Box
- Monster Open Ear AC520 Headphones ×1
- Charging Case ×1
- Portable Lanyard ×1
- Type-C Charging Cable ×1
- User Manual ×1

Image: The complete package contents of the Monster Open Ear AC520, showing the headphones, charging case, portable lanyard, Type-C charging cable, and the user manual.
3. Product Overview
The Monster Open Ear AC520 headphones feature an innovative open-ear design for comfort and situational awareness, coupled with advanced audio technology for a rich listening experience.

Image: A top-down view of the Monster Open Ear AC520 headphones and their charging case, highlighting the sleek design.
Key Features:
- Pure Monster Sound: Advanced HiFi sound technology with dynamic audio.
- Open-Ear Comfort: Non-intrusive design for extended wear, even with glasses.
- 24H Long Playtime: Up to 8 hours on a single charge, 24 hours with the charging case.
- IPX6 Water Resistance: Protection against sweat and light rain.
- Advanced Bluetooth 6.0: Fast, stable connection with low latency.
- ENC Clear Call: Environmental Noise Cancellation for clear conversations.
- Unique Handbag Design: Stylish charging case with a removable lanyard.
4. Setup
4.1 Charging the Headphones and Case
Before first use, fully charge the headphones and the charging case.
- Place the headphones into the charging case.
- Connect the Type-C charging cable to the charging port on the case and to a USB power source.
- The indicator lights on the case will show the charging status.
A full charge takes approximately 1 hour for the headphones and case. The headphones provide up to 8 hours of listening time on a single charge, and the charging case extends total playtime to 24 hours.

Image: An illustration detailing the battery life and charging times: 1 hour for charging, 7 hours for a single charge, and 24 hours total with the charging case.
4.2 Pairing with a Bluetooth Device
The Monster Open Ear AC520 headphones utilize Bluetooth 6.0 for a stable and efficient connection.
- Open the charging case. The headphones will automatically enter pairing mode.
- On your device (smartphone, tablet, computer), enable Bluetooth.
- Search for "Monster Open Ear AC520" in the list of available Bluetooth devices.
- Select the headphones to connect. Once connected, a voice prompt will confirm successful pairing.
The headphones will automatically reconnect to the last paired device when taken out of the case, if Bluetooth is enabled on the device.

Image: A visual representation of the earbud's internal structure, emphasizing the benefits of upgraded Bluetooth 6.0 technology, including improved connection stability, reduced power consumption, lower audio latency, and an extended transmission range.
4.3 How to Wear
The open-ear design ensures a comfortable and secure fit without entering the ear canal.
- Take out the earbuds from the case.
- Place the earhooks behind your ears.
- Lightly twist the earbuds until they feel comfortable and secure on your outer ear.

Image: A step-by-step guide on correctly wearing the headphones, showing how to position the earhooks and adjust for a secure fit.
5. Operating the Headphones
5.1 Touch Controls
The Monster Open Ear AC520 headphones feature intuitive touch controls on each earbud.
| Action | Control | Function |
|---|---|---|
| Click ×2 (L/R) | Music Playback | Play/Pause |
| Hold ×2s (L/R) | Voice Assistant | Activate Voice Assistant |
| Click ×3 (L) | Music Playback | Previous Song |
| Click ×3 (R) | Music Playback | Next Song |
| Click ×2 (L/R) | Call Management | Answer Call |
| Hold ×2s (L/R) | Call Management | Hang Up Call |
| Click ×1 (L) | Volume Control | Volume Down |
| Click ×1 (R) | Volume Control | Volume Up |

Image: A visual guide to the touch controls on the headphones, illustrating actions for music playback, call management, voice assistant activation, and volume adjustment.
5.2 Call Functions
The headphones are equipped with Environmental Noise Cancellation (ENC) for clear calls.
- Answering/Ending Calls: Use the touch controls as described above.
- Clear Communication: The ENC algorithm minimizes background noise, ensuring your voice is heard clearly during calls.

Image: A graphic demonstrating the effectiveness of the AI noise reduction algorithm, showing a 'Before' state with audio distractions and an 'After' state with clear call quality.
5.3 Audio Experience
Experience Pure Monster Sound with dynamic audio and HiFi quality.
- Dynamic Audio: The 14.5mm speaker and acoustic cavity structure deliver rich, detailed sound.
- Situational Awareness: The open-ear design allows you to enjoy your audio while remaining aware of your surroundings, enhancing safety outdoors and facilitating interaction in office environments.

Image: A cutaway diagram illustrating the 14.5mm speaker and acoustic cavity structure responsible for the dynamic audio performance, labeled as 'Pure Monster Sound'.
6. Maintenance
6.1 Cleaning
- Wipe the headphones and charging case with a soft, dry, lint-free cloth.
- Avoid using abrasive materials or harsh chemicals.
6.2 Water Resistance
The Monster Open Ear AC520 headphones are rated IPX6 water resistant.
- This means they are protected against powerful water jets, making them suitable for workouts and light rain.
- Do not submerge the headphones in water.
- Ensure the charging port is dry before charging.

Image: The headphones are shown with water splashing around them, visually representing their IPX6 waterproof rating, which protects against sweat and light rain.
7. Troubleshooting
If you encounter issues with your Monster Open Ear AC520 headphones, please refer to the following common solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Headphones do not power on. | Low battery. | Charge the headphones and charging case fully. |
| Cannot pair with device. | Bluetooth not enabled, headphones not in pairing mode, or device too far. | Ensure Bluetooth is on, open the case to enter pairing mode, and keep devices within 10 meters. Try forgetting the device and re-pairing. |
| No sound. | Volume too low, not connected, or media paused. | Increase volume on both headphones and device. Check Bluetooth connection. Ensure media is playing. |
| Intermittent connection. | Interference, distance, or low battery. | Move closer to the device, avoid strong electromagnetic interference, and ensure headphones are charged. |
| Microphone not working. | Microphone muted or not selected as input device. | Check device settings to ensure the headphones' microphone is selected as the input. Unmute if necessary. |
8. Specifications
| Feature | Specification |
|---|---|
| Model Name | Monster Open Ear AC520 Headphones |
| Connectivity Technology | Wireless (Bluetooth) |
| Bluetooth Version | 6.0 |
| Bluetooth Range | 10 Meters |
| Battery Life (Headphones) | Up to 8 Hours (single charge) |
| Total Playtime (with Case) | Up to 24 Hours |
| Charging Time | Approximately 1 Hour |
| Water Resistance Level | IPX6 |
| Ear Placement | Open Ear |
| Control Type | Touch Control |
| Audio Driver Type | Dynamic Driver |
| Item Weight | 7 ounces (0.2 Kilograms) |
| Manufacturer | Monster |
9. Warranty and Support
For warranty information and customer support, please refer to the warranty card included in your product packaging or visit the official Monster website. You can also contact Monster customer service for assistance with product registration, troubleshooting, or service requests.







