1. Product Overview
The COOLMUSIC AC20 is a versatile 20-watt acoustic guitar amplifier designed for various musical applications, including live performances, studio recording, and practice. It features two independent channels, a 3-band equalizer, and built-in Reverb and Chorus effects. Connectivity options include Bluetooth, USB, and auxiliary inputs, providing flexibility for different audio sources.
The amplifier is equipped with an 8-inch woofer and a 2-inch tweeter to deliver clear and natural sound reproduction for both acoustic instruments and vocals.
Image 1.1: Front view of the COOLMUSIC AC20 Acoustic Guitar Amplifier.
Image 1.2: Internal speaker configuration with an 8-inch woofer and a 2-inch tweeter.
2. Setup
2.1 Unpacking and Initial Inspection
Carefully remove the amplifier and all accessories from the packaging. Inspect the unit for any signs of damage. The package typically includes the AC20 amplifier, a power adapter, a microphone, and an audio cable.
Image 2.1: The AC20 amplifier shown with an included microphone and audio cable. Note that microphone types may vary.
2.2 Power Connection
- Ensure the amplifier's power switch is in the OFF position.
- Connect the provided power adapter to the DC IN port on the rear panel of the amplifier.
- Plug the power adapter into a suitable electrical outlet.
- Turn the power switch to the ON position. The power indicator light should illuminate red.
Important: Use only the original power adapter supplied with the amplifier. Using a non-original adapter may cause damage to the unit.
Image 2.2: Rear panel illustrating the power switch, DC IN port, and safety warnings.
2.3 Instrument and Microphone Connections
The AC20 amplifier features two input channels:
- Line 1 (Microphone/Instrument): This channel typically features an XLR/TRS combo input for microphones or instruments. It includes Gain and Reverb controls.
- Line 2 (Instrument): This channel typically features a 1/4-inch input for instruments. It includes Gain, 3-Band EQ (Bass, Mid, High), Chorus, and Reverb controls.
Connect your acoustic guitar, microphone, or other instruments to the appropriate input jacks on the front panel.
2.4 Bluetooth Connection
To connect a Bluetooth device:
- Ensure the amplifier is powered on.
- Press the MODE button on the amplifier's control panel until the Bluetooth indicator is active.
- On your Bluetooth-enabled device (e.g., smartphone, tablet), search for available Bluetooth devices and select "AC20" (or similar name).
- Once paired, you can play audio from your device through the amplifier.
Image 2.3: Visual representation of connecting a mobile device via Bluetooth to the amplifier.
3. Operating Instructions
3.1 Control Panel Overview
The front panel of the AC20 amplifier provides access to all essential controls for sound shaping and connectivity.
Image 3.1: Detailed view of the amplifier's front control panel.
Image 3.2: Diagram showing the layout of input, gain, effects, and EQ controls for both channels.
3.2 Channel Controls
- Input: Connect your instrument or microphone.
- Gain: Adjusts the input sensitivity for each channel. Set this to achieve a strong signal without distortion.
- Bass, Mid, High (3-Band EQ): Available on Line 2, these controls allow you to shape the tonal characteristics of your instrument. Adjust to enhance or cut specific frequency ranges.
- Chorus: Adds a swirling, shimmering effect to the sound, creating a thicker, richer tone. Adjust the knob to control the intensity.
- Reverb: Simulates the natural echo of a room, adding depth and space to your sound. Adjust the knob to control the amount of reverb.
3.3 Master Volume and Media Controls
- Volume: The master volume control adjusts the overall output level of the amplifier.
- Mode: Switches between different input modes (e.g., Bluetooth, USB, auxiliary).
- BT & USB Controls: Play/Pause, Previous Track, Next Track buttons for controlling media playback from Bluetooth or USB sources.
3.4 Headphone Output
The amplifier includes a Phones output jack on the rear panel for private practice. Connect standard headphones to this jack. The main speaker output will be muted when headphones are connected.
Image 3.3: Headphones connected to the amplifier's output for silent practice.
3.5 DI Output
The D.I. out port on the rear panel allows you to send the amplifier's signal directly to a mixing console or another audio interface. This is useful for recording or connecting to a larger PA system.
4. Maintenance
- Cleaning: Use a soft, dry cloth to clean the exterior of the amplifier. Avoid using abrasive cleaners or solvents.
- Storage: Store the amplifier in a cool, dry place away from direct sunlight and extreme temperatures.
- Ventilation: Ensure proper ventilation around the amplifier to prevent overheating. Do not block any vents.
- Power Adapter: Always use the original power adapter. Disconnect the power adapter from the wall outlet when the amplifier is not in use for extended periods.
5. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No power | Power adapter not connected; Power switch off; Faulty outlet | Ensure power adapter is securely connected and plugged into a working outlet. Turn the power switch ON. |
| No sound output | Volume too low; Instrument/mic not connected; Headphone connected; Faulty cable | Increase Master Volume and channel Gain. Check all cable connections. Disconnect headphones. Test with a different cable. |
| Distorted sound | Gain set too high; Master Volume too high; Faulty instrument/mic | Reduce channel Gain and/or Master Volume. Test with a different instrument or microphone. |
| Bluetooth not connecting | Amplifier not in Bluetooth mode; Device too far; Interference | Press MODE button to select Bluetooth. Ensure device is within range. Restart both amplifier and Bluetooth device. |
6. Specifications
- Model: AC20
- Output Wattage: 20 Watts
- Speaker Configuration: 8-inch Woofer, 2-inch Tweeter
- Channels: 2
- Effects: Reverb, Chorus
- Equalizer: 3-Band EQ (Bass, Mid, High) on Line 2
- Connectivity: Bluetooth, USB, Phone In (Auxiliary), DI Out, Headphone Out
- Compatible Devices: Guitar, Microphone, Keyboard, etc.
- Power Source: Corded Electric (18V DC, 2500mA)
- Item Weight: 16 pounds (approx. 7.26 kg)
- Product Dimensions: 13 x 14 x 15 inches (approx. 33 x 35.6 x 38.1 cm)
- Material: Plastic enclosure