Cayin C9 Portable Headphone Amplifier

Introduction

Thank you for choosing the Cayin C9 portable headphone amplifier. Please read this manual carefully before use to quickly master its basic operations.

Before Use

1. To protect your hearing, set the volume to the minimum before use. Adjust the volume to a comfortable level during listening.
2. The Cayin C9 is a high-fidelity headphone amplifier. It is recommended to use it with high-fidelity earphones or headphones to enjoy higher quality music.

Package Contents

• C9 Portable Headphone Amplifier: 1 unit
• C9 Battery Module (pre-installed): 1 unit
• Rear Panel Glass Protector: 1 piece
• Single-ended Portable Interconnect CS-35C35 (3.5 to 3.5): 1 cable
• Balanced Portable Interconnect CS-44C44 (4.4 to 4.4 with GND): 1 cable
• USB Type-C Charging Cable: 1 cable
• Backup Screws for Battery Module: 4 screws
• T6 Screwdriver: 1 piece
• User Manual: 1 copy

Note: Please check if all items are present upon opening the package for the first time.

Product Highlights

• Equipped with 3.5mm single-ended and 4.4mm balanced input/output terminals. The system automatically adapts based on the connection.
• Supports Line (Line In) and Pre (Pre-amp) input modes.
• Built-in four-channel vacuum tube and solid-state timbre circuits for user selection.
• Selectable high/low gain settings to match headphone characteristics or user preference.
• Supports Class A/AB amplifier operation modes for tonal differences.
• Features a high-quality four-channel discrete component headphone amplifier circuit.
• Volume control utilizes an ALPS potentiometer combined with a precision electronic volume IC for consistent feel and four-channel volume synchronization.
• Uses a pluggable high-performance power module supporting fast and standard charging (charger not included).

Basic Operation and Features

Controls and Features

1. Mode (Line/Pre) Input Mode Switch:
• Line: Line input mode (fixed voltage input).
• Pre: Pre-amp input mode (variable voltage input).
2. Gain (H/L) Switch:
• H: High gain, recommended for high-impedance, low-sensitivity headphones.
• L: Low gain, recommended for low-impedance, high-sensitivity headphones.
3. Volume Control Knob: Rotate clockwise to increase volume; rotate counter-clockwise to decrease volume.
4. Timbre (Tone) Switch:
• [Tube Symbol]: Vacuum tube timbre. The device preheats the vacuum tube for 5 seconds upon selection, indicated by a flashing indicator light.
• [Solid State Symbol]: Solid-state timbre.
5. A/AB Class Amplifier Operation Mode Switch:
• A: Class A operation mode.
• AB: Class AB operation mode.
6. 3.5mm Single-ended Headphone Output: For connecting 3.5mm single-ended stereo headphones.
7. 4.4mm Balanced Headphone Output: For connecting 4.4mm balanced stereo headphones.
8. Power Switch: Press to turn on the device (indicator lights up). Press again to turn off (indicator turns off).
9. Power Indicator Light:
• Solid light: Normal operation.
• Slow flashing: Initialization or vacuum tube preheating.
• Rapid flashing: Machine malfunction.
10. 4.4mm Balanced Audio Input: For connecting LINE or PRE-amp audio sources with a 4.4mm balanced plug.
11. 3.5mm Single-ended Audio Input: For connecting LINE or PRE-amp audio sources with a 3.5mm single-ended plug.
12. PRE-amp Input Activator: A two-step process to switch from LINE to PRE-amp input mode.
13. Pre Input Indicator:
• Indicator on: PRE-amp input mode.
• Indicator off: LINE input mode.
14. Type-C USB Port: Supports PD and QC3.0 fast charging protocols. Use a quality charger for optimal charging.
15. Battery Charging and Level Indicator:
• 'H' light on: Battery is at high level.
• 'L' light on or all lights off: Battery is at low level.
• Flashing lights: Charging in progress.
• All four lights solid: Battery fully charged.

Setup and Conversion

The following illustrates system setup and cable connection between the Cayin C9 and a source device (e.g., N6ii Digital Audio Player with 02 Audio Motherboard).

Connection Diagram

[Diagram showing Cayin C9 connected to N6ii (A02) and headphones via 3.5mm single-ended and 4.4mm balanced connections.]

Connection Scenarios

1. Single-ended Connection: N6ii (A02) to C9 (3.5mm input), C9 (3.5mm output) to 3.5mm headphones. The entire system operates in single-ended mode.
2. Single-ended to Balanced Conversion: If using 4.4mm headphones connected to the C9's 4.4mm balanced output, the C9 seamlessly converts the single-ended input to balanced output.
3. Fully Balanced Connection: Connect N6ii (A02) to C9 via 4.4mm balanced cable (CS-44C44). The C9 operates in fully balanced mode.
4. Balanced to Single-ended Conversion: If using 3.5mm headphones with the fully balanced connection described above, the C9 seamlessly converts the balanced signal to single-ended output.

Basic Operation

1. Connect your audio source to the C9's input.
2. Connect your headphones to the C9's output.
3. Rotate the volume knob counter-clockwise to the minimum level.
4. Press the Power Button; the indicator will flash.
5. Wait approximately 5 seconds for the initialization process to complete.
6. Play music and adjust the volume on the C9 to a comfortable listening level. Enjoy your music!

Notice

• Ensure input and output devices are securely connected to the correct sockets.
• DO NOT use mono headphones, as this can cause a short circuit.
• Listen at a moderate volume to protect your hearing. If you experience tinnitus, lower the volume or stop using the device.

Using PRE-amp Input Mode

In PRE-amp input mode, the C9 functions as a power amplifier with volume control disabled (0dB attenuation), operating at full power. Due to its high power output, a secure two-step procedure is required to prevent accidental activation.

Switching to PRE-amp Input Mode:

1. Turn down the C9's volume and set the Mode switch to 'PRE'.
2. Connect your PRE-amp audio source to one of the input connectors. It is recommended to lower the source volume at this point.
3. Connect your headphones to one of the output connectors.
4. Press and hold the Pre-amp Input Activator for 3 seconds. A click sound and a solid white LED indicate the switch to PRE-amp mode.
5. The C9 is now in PRE-amp input mode. Adjust volume using the source device's volume control (C9's volume control is disabled).
6. If input/output devices are disconnected or the C9 is restarted, it will automatically revert to LINE input mode. The PRE-amp input mode needs to be reactivated.
7. When changing music sources or headphones, repeat step 4 to reactivate PRE-amp input mode.

Warning: PRE-amp input mode is designed for sources with variable voltage output (PRE-amp output). DO NOT connect Line Out from devices without PRE-amp output to the C9 in PRE-amp input mode.

Charging and Battery Care

• The C9 uses 4 rechargeable, user-replaceable 18650 Lithium batteries.
• Charge batteries via the USB Type-C connector. The C9 supports standard USB chargers, PD, and QC3.0 fast charging.
• Use the supplied USB Type-C cable for charging.
• Charging and battery indicators flash during charging, showing the current level. All 4 indicators light up when fully charged.
• It is recommended to turn off the C9 before charging. QC3.0 fast charging takes approximately 3 hours.
• Charging time may increase if battery voltages/capacities differ significantly.
• The detachable battery module can also function as a standalone 18650 battery charger. Consider purchasing an extra module and batteries for heavy use.
• Lithium batteries have a limited number of charge cycles. Proper care extends battery life. They have no memory effect and can be charged at any level. Shallow charging is recommended to maintain battery health.
• Infrequent full discharges may lead to inaccurate battery level readings. Perform a full discharge followed by a full charge to recalibrate.
• Optimal charging temperature is between -10°C and 30°C.

Warnings:

• The battery module and C9 audio circuit do not share a common ground. Charging the C9 via USB from a connected audio source device may trigger short-circuit protection or damage the devices. Use a separate USB charger for the C9.
• If the C9 battery module enters protection mode, charge it for about 10 seconds to reset and resume normal operation.

Removing and Installing the Battery Module

[Diagram illustrating battery module removal and installation]

1. To Remove: Unscrew the two screws on the rear with the T6 screwdriver and pull out the battery module.
2. To Install: Align the module with the rear opening of the C9, push it in, and tighten the screws.

Replacing 18650 Batteries

If batteries need replacement, remove the battery module as shown in the diagram. Carefully remove old batteries and install new ones, ensuring correct polarity (+/-). Reversing polarity can damage the battery, module, and amplifier.

Notice: After replacement or removal, the battery module enters protective mode. Charging for about 10 seconds will reset it.

Warnings:

• Use only the recommended 18650 batteries for the C9. Do not share batteries with other devices or use them outside the battery module.
• Install batteries according to the polarity markings on the module.
• Do not short-circuit the battery.
• Do not disassemble, puncture, crush, or expose batteries to fire.
• If a battery swells, discontinue use immediately and replace it.
• Do not expose batteries to high temperatures.
• Do not immerse the C9 in water.

Safety Precautions

• Do not use the C9 while driving or in other inappropriate situations.
• Listening at high volumes for extended periods can damage hearing. Adjust volume to an appropriate level. If you experience tinnitus, lower the volume or stop use.
• Moisture inside the device can impair functionality. Avoid use until internal moisture has cleared. Moisture can result from:
• Exposure to steam or humidifiers.
• Placement near heating devices.
• High-temperature environments.
• Moving from cold to warm, humid environments.
• Do not connect the device to a USB charger for extended periods; charge regularly.
• Clean the chassis with a soft, dry cloth. Do not use volatile or corrosive cleaning agents.
• Keep the device away from liquids. Do not place cups or other liquid containers on or around the device.
• Avoid tampering or dropping the device. Do not sit on or place heavy objects on the device.
• Only authorized service technicians should perform disassembly, service, or maintenance.
• The device may become warm during operation. Ensure adequate ventilation.
• Battery life may be temporarily reduced in low-temperature environments.
• Dispose of used electronics and batteries according to local environmental regulations.

The product is suitable for use at altitudes up to 2,000 meters and in non-tropical climates.

Troubleshooting

Product Specifications

Notes:
1. Unless otherwise stated, all parameters are measured at 32Ω loading.
2. All parameters are measured when the batteries are fully charged.

Battery and Duration

Notes:
1. Test condition: Standard line level audio signal input, volume at 10 o'clock position, low gain, connected to 32Ω headphones.
2. Charging time may be extended if the four lithium batteries have different voltages (capacities).

Disclaimer

The manufacturer, distributor, importer, and reseller are not responsible for any damage caused by improper use or operation of this product, including accidental or human damage.

This user manual is based on specifications at the time of printing. Cayin reserves the right to make changes to product specifications, features, or technologies without prior notice.

The manufacturer, importer, and reseller shall not be liable for any data loss or damage to associated equipment resulting from the use of this product.

Service, warranty, and after-sales support may be refused for products that have been repaired or modified by unauthorized personnel or obtained through unauthorized channels.