1. Introduction
The Questyle CMA18 Portable is a high-resolution portable DAC and headphone amplifier designed to deliver exceptional audio performance for smartphones, PCs, and laptops. It integrates advanced audio technologies to provide a desktop-grade listening experience in a compact form factor. This manual provides detailed instructions for the proper use, setup, and maintenance of your CMA18 Portable.
2. What's in the Box
Please verify that all items are present in the package:
- Questyle CMA18 Portable Headphone Amplifier
- USB-C to USB-C Cable
- USB-C to Lightning Cable
- USB-C to USB-A Adapter
- User Manual (this document)
3. Product Overview
The CMA18 Portable features a robust design with sandblasted aviation-grade aluminum surfaces, silver high-gloss buttons, and custom Corning glass panels. Its internal amber-colored LEDs illuminate the circuitry, highlighting the device's sophisticated engineering.
Figure 3.1: Front and back view of the Questyle CMA18 Portable, showcasing its transparent glass panel revealing internal components.
Equipped with the latest XMOS XU316 platform and AK4493 DAC chip, the CMA18 Portable supports high-resolution audio up to PCM768/DSD512. It incorporates four sets of self-developed current-mode PCT patented SiP chips (CC630/CA630) for optimal thrust and low power consumption.
Figure 3.2: The CMA18 Portable connected to a smartphone, demonstrating its use as an external audio device.
The device offers both 3.5mm and 4.4mm headphone outputs and features high/low gain mode switching to accommodate various headphones and in-ear monitors (IEMs).
Figure 3.3: The CMA18 Portable connected to in-ear monitors, highlighting its compatibility with different audio devices.
Product Features:
- Portable Size, Desktop Performance: Designed for high-fidelity audio on the go.
- Advanced DAC Chip: XMOS XU316 USB chip and AK4493 DAC support PCM768/DSD512.
- Current-Mode Amplification: Four sets of patented SiP chips (CC630/CA630) for powerful and efficient audio output.
- High-Resolution Wireless: Supports aptX HD and LDAC Bluetooth codecs for optimal wireless sound quality.
- Analog Input Recording: Features 3.5mm (AUX IN) and 4.4mm (BAL IN) inputs for external audio equipment, capable of lossless analog-to-digital conversion.
Video 3.1: An overview of the Questyle CMA18 Portable Headphone DAC Amplifier, showcasing its design, features, and connectivity options.
4. Setup
4.1 Initial Charging
Before first use, fully charge the CMA18 Portable. Connect the device to a 5V/2A USB power adapter (not included) using the provided USB-C cable. The charging indicator LEDs will show the battery status.
4.2 Connecting to Devices
- For Smartphones/Tablets: Use the appropriate USB-C to USB-C or USB-C to Lightning cable to connect your device to the CMA18 Portable's USB DAC IN port. Ensure your smartphone supports USB audio output.
- For PCs/Laptops: Connect the CMA18 Portable to your computer's USB port using the provided USB-C to USB-A cable or USB-C to USB-C cable. Install any necessary drivers if prompted by your operating system (typically plug-and-play for most modern OS).
- For Analog Sources: Use a 3.5mm or 4.4mm audio cable to connect your analog audio source (e.g., turntable, pre-amp) to the corresponding AUX IN or BAL IN port on the CMA18 Portable.
5. Operating Instructions
5.1 Power On/Off
Press and hold the Power button on the side of the device for approximately 3 seconds to power on or power off the CMA18 Portable.
5.2 Input Selection
Press the Function button to cycle through the available input modes: USB, Optical (OPT IN), Bluetooth (BLUETOOTH), 3.5mm Analog Input (AUX IN), and 4.4mm Balanced Analog Input (BAL IN). The corresponding indicator LED will light up.
5.3 Gain Settings
The CMA18 Portable features a gain switch (HIGH/STD) to optimize output for different headphones. Use the 'HIGH' setting for high-impedance or less sensitive headphones, and 'STD' (Standard) for sensitive IEMs or low-impedance headphones. Adjust based on your headphone's requirements and desired volume level.
5.4 Volume Control
Use the '+' and '-' buttons on the side of the device to adjust the output volume. Adjust the volume gradually to prevent sudden loud sounds.
5.5 Bluetooth Pairing
- Switch the input mode to Bluetooth.
- The Bluetooth indicator LED will blink, indicating pairing mode.
- On your source device (smartphone, tablet), search for Bluetooth devices and select "Questyle CMA18 Portable" to pair.
- Once paired, the Bluetooth indicator LED will remain solid.
5.6 Analog Input Recording Function
The CMA18 Portable can function as an external, lossless, high-performance Analog-to-Digital Converter (ADC) for its 3.5mm (AUX IN) and 4.4mm (BAL IN) inputs. Connect your analog source to the desired input. When connected to a computer via USB, the CMA18 Portable will appear as an audio input device, allowing you to record the analog signal. You can simultaneously monitor the input via the 3.5mm or 4.4mm headphone outputs.
6. Maintenance
6.1 Cleaning
Wipe the device with a soft, dry, lint-free cloth. Do not use abrasive cleaners, solvents, or chemical sprays. Avoid getting moisture into any openings.
6.2 Battery Care
To prolong battery life, avoid fully discharging the battery frequently. If storing the device for an extended period, charge it to approximately 50% before storage. Recharge every few months to prevent deep discharge.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound output | Incorrect input selected; Volume too low; Headphones not connected properly; Source device issue. | Verify input mode; Increase volume; Ensure headphones are fully plugged in; Check audio settings on source device. |
| Bluetooth pairing fails | Device not in pairing mode; Source device too far; Interference. | Ensure CMA18 is in Bluetooth pairing mode (blinking LED); Move source device closer; Restart both devices. |
| Sound distortion or noise | Gain setting too high for sensitive headphones; Poor cable connection; Source audio quality. | Switch to 'STD' gain mode; Check and re-seat all cables; Use high-quality audio files. |
| Device not recognized by PC/Laptop | Incorrect USB cable; Driver issue; USB port issue. | Ensure data-capable USB cable is used; Try a different USB port; Check device manager for driver status. |
| Battery drains quickly | High volume usage; Old battery; Background processes. | Reduce volume; Ensure device is powered off when not in use; Contact support if battery life significantly degrades. |
8. Specifications
| Feature | Detail |
|---|---|
| Model Name | CMA18 Portable |
| Headphones Jack | 3.5mm & 4.4mm |
| Connectivity Technology | Wireless, Wired (Bluetooth, USB, Optical, Analog) |
| Wireless Communication Technology | Bluetooth 5.0 (aptX HD, LDAC) |
| Frequency Range (PCM) | Up to 768 kHz |
| Max Output Power (BAL) | 1000mW@32Ω |
| THD+N | <0.0003%@20mW, 300Ω |
| SNR | >120dB |
| Battery Life | >10 Hours |
| Charging Time | 3.5 Hours |
| Product Dimensions | 4.33 x 2.75 x 0.59 inches |
| Item Weight | 1.23 pounds |
| Material | Aluminum |
| Manufacturer | Questyle |
9. Warranty and Support
The Questyle CMA18 Portable comes with a standard manufacturer's warranty. For detailed warranty information, technical support, or service inquiries, please refer to the warranty card included with your product or visit the official Questyle website. Keep your proof of purchase for warranty claims.
