This document describes the UGREEN Bluetooth Audio Receiver/Transmitter, model CM667 (P/N: 35223), a versatile device designed to add Bluetooth audio capabilities to a wide range of electronics. It functions as both a transmitter (TX) and a receiver (RX), allowing users to stream audio wirelessly in various scenarios.
Function Description
The UGREEN CM667 serves two primary functions:
- Transmitter Mode (TX): In this mode, the device allows you to wirelessly stream audio from non-Bluetooth sources to Bluetooth earphones or speakers. This is particularly useful for devices like TVs, PCs, Nintendo Switch consoles, or in-flight entertainment systems that lack native Bluetooth audio output.
- Receiver Mode (RX): As a receiver, the CM667 enables you to stream audio wirelessly from Bluetooth-enabled devices (such as phones, tablets, or computers) to non-Bluetooth stereo systems. This includes amplifiers, car stereos, or any speaker system with a 3.5mm audio input.
Important Technical Specifications
The CM667 boasts a robust set of specifications:
- Bluetooth Version: 5.2, ensuring stable and efficient wireless connectivity.
- Frequency Band: Operates within the standard 2400MHz-2483.5MHz range.
- Max. RF Output Power: 4 dBm (conducted).
- Transmission Distance: Up to 10m/33ft (without obstructions), providing ample range for most home or office setups.
- Bluetooth Profile: Supports A2DP, AVRCP, HSP, and HFP profiles, ensuring compatibility with a wide array of Bluetooth audio devices.
- Codecs:
- RX (Receiver Mode): Supports SBC/AAC codecs for high-quality audio reception.
- TX (Transmitter Mode): Supports SBC codec for reliable audio transmission.
- Frequency Response: A broad range of 20Hz-20kHz, capturing the full spectrum of human hearing.
- Output Level (Receiving): ≤630mV rms RL=100KΩ.
- Input Level (Transmitting): ≤0.75Vrms.
- SNR (Signal-to-Noise Ratio): ≥92dB A-wt., indicating a clean audio signal with minimal background noise.
- THD+N (Total Harmonic Distortion + Noise): ≤0.1%, signifying very low audio distortion.
- Mic Sensitivity: -40±3dB (0dB=1V/Pa), allowing for clear voice pickup when used with a microphone.
- Audio Port: Standard 3.5mm audio jack for universal compatibility.
- Charging Port: USB-C, offering modern and convenient charging.
- Battery Type: Polymer Lithium-Ion Battery.
- Battery Capacity: 300mAh 3.7V (1.11Wh).
- Limited Charging Voltage: 5.25V.
- Charging Time: Approximately 2 hours for a full charge.
- Operating Time:
- TX (Transmitter Mode): Approximately 27 hours on a full charge.
- RX (Receiver Mode): Approximately 22 hours on a full charge.
Usage Features
The CM667 is designed for intuitive operation with several key features:
- Slide Switch: A physical slide switch allows for easy toggling between Transmitter (TX) and Receiver (RX) modes.
- Multi-Function Button (MFB):
- Single-click: Reconnect, Play/Pause Music, Answer/End A Call.
- Double-click: Force Pairing.
- Press and Hold for 3s: Power On/Power Off, Reject A Call.
- Press and Hold for 10s: Clear Paired Devices List.
- Volume Control: Dedicated buttons for Volume Up (16-level adjustable) and Volume Down (including Mute). These buttons also serve as Previous Track and Next Track controls when pressed and held for 1s.
- Indicator Lights & Voice Prompts: The device uses a combination of solid and flashing blue, red, green, and white indicator lights, along with voice prompts (in RX mode), to communicate its status, including power on/off, pairing, connection status, low battery, and charging status.
- Automatic Reconnection: After initial pairing, the device will automatically reconnect to the last paired device upon subsequent use.
- Multi-Device Pairing: The CM667 can save up to 5 paired devices in its memory. When connecting a 6th device, the oldest device in the memory list is automatically cleared.
- Dual Device Connection (TX Mode): The transmitter mode supports connecting to two Bluetooth earphones or speakers simultaneously.
- Dual Device Connection (RX Mode): The receiver mode supports connecting to two Bluetooth-enabled phones or iPads, though it only supports music playback from one device at a time.
- Auto Power Off: The device will automatically power off if disconnected for 5 minutes. It also has an auto-power-off feature when the battery is low.
- Automatic Power On: The product will automatically turn on when connected to a power supply.
- Charging Operation: The device remains operational during charging and cannot be shut down while charging.
Maintenance Features
The CM667 incorporates features for ease of maintenance and safety:
- Clear Paired Devices List: Users can clear all pairing information by pressing and holding the MFB for 10s after powering off, indicated by alternating red/green/blue lights.
- Resetting: The device can be reset by pressing and holding the MFB after powering on, then connecting it to a power supply via the USB-C cable. The product will automatically restart.
- Battery Status Indicators:
- Low battery: Flashing red once every 10s.
- Start charging: Solid red for 3s.
- Fully charged: Solid green for 3s.
- Temperature Protection: The device has built-in protection mechanisms that automatically power it off under extreme temperature conditions:
- During charging: If the battery temperature is less than 0°C/32°F or greater than 45°C/113°F.
- When not charging: If the battery temperature is less than -10°C/14°F or greater than 60°C/140°F.
- Safety Warnings: The manual emphasizes critical safety warnings regarding the built-in polymer lithium-ion battery, advising against dismantling, crushing, squeezing, or exposing it to fire. It also warns against using the device if the battery is submerged or swollen, exposing it to excessive temperatures, and keeping it out of reach of children. Immediate medical attention is advised if the battery is accidentally swallowed or placed inside any part of the body.
The UGREEN Bluetooth Audio Receiver/Transmitter CM667 is a comprehensive solution for integrating wireless audio into both legacy and modern electronic setups, offering a blend of performance, ease of use, and safety features.
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