LOMEHO AM-AX3 4-Channel Mini Portable Audio Mixer

1. Introduction

The LOMEHO AM-AX3 is a compact and versatile 4-channel audio mixer designed for various audio applications, including live sound, home recording, and DJ setups. It features Bluetooth connectivity, USB playback and recording capabilities, 99 built-in DSP effects, and individual +48V phantom power for condenser microphones. Its portable design makes it ideal for on-the-go use.

Figure 1: Front view of the LOMEHO AM-AX3 Audio Mixer with controls labeled.

2. Safety Information

• Ensure the power supply matches the specified voltage (DC 12V 2A).
• Do not expose the unit to rain or moisture to reduce the risk of fire or electric shock.
• Do not open the casing; refer all servicing to qualified personnel.
• Avoid placing the unit near heat sources or in direct sunlight.
• Always disconnect the power adapter before cleaning or when not in use for extended periods.
• Do not use +48V phantom power with dynamic microphones, as this may cause damage.

3. Package Contents

Please check that all items are present in the package:

• Audio Mixer (1 pc)
• Power Adapter (1 pc)
• Instruction Manual (1 pc)

Figure 2: Included items in the LOMEHO AM-AX3 package.

4. Product Overview

The LOMEHO AM-AX3 features a user-friendly layout with clearly marked controls for each channel and master output. Key components include:

• Microphone/Line Inputs (CH1/2): XLR/TRS combo jacks for microphones or line-level instruments.
• Phantom Power Switches: Individual +48V phantom power for CH1 and CH2.
• Line Inputs (CH3/4): TRS jacks for stereo line-level signals.
• Main Output (L/R): TRS outputs for connecting to amplifiers or powered speakers.
• Rec Out (L/R): RCA outputs for recording.
• Phones Output: 6.3mm TRS jack for headphones.
• USB Port: For U-disk playback/recording and PC connection.
• Digital Audio Player Section: Controls for USB/Bluetooth playback, including mode, volume, and record.
• DSP Effects Engine: Controls for selecting and adjusting 99 built-in effects.
• Gain Knobs: Adjust input sensitivity for each channel.
• EQ Knobs (HI/LOW): Tone control for high and low frequencies.
• EFFX Knobs: Adjust the amount of effect sent to each channel.
• Level Knobs/Faders: Control the output level of individual channels and the main mix.

Figure 3: Detailed view of the mixer's control panel.

5. Setup

5.1 Power Connection

Connect the provided DC 12V 2A power adapter to the mixer's 'DC12V IN' port and then to a suitable power outlet. The mixer uses an EU plug type.

Figure 4: Power adapter for the LOMEHO AM-AX3 mixer.

5.2 Connecting Microphones

The mixer supports both dynamic and +48V condenser microphones via the XLR/TRS combo jacks on CH1 and CH2.

5.2.1 Dynamic Microphones

• Use an XLR cable to connect your dynamic microphone to the mixer's XLR input. Using a 6.3mm (TRS) plug may result in lower volume.
• Important: Ensure the +48V phantom power switch for the connected channel is OFF. Activating phantom power with a dynamic microphone can cause damage.

Figure 5: Dynamic microphone connection guidelines.

5.2.2 +48V Condenser Microphones

• Connect your +48V condenser microphone using an XLR cable to the mixer's XLR input.
• Activate the +48V phantom power switch for the corresponding channel. The red LED next to the switch will illuminate.
• If your condenser microphone does not support +48V, it cannot be used with this mixer's phantom power feature.

Figure 6: +48V Condenser microphone connection guidelines.

5.3 Connecting Line-Level Devices

• Mono Channels (CH1/2): Use TRS cables for line-level instruments or devices.
• Stereo Channels (CH3/4): Use TRS cables for stereo line-level signals. CH3 is typically for the left channel, and CH4 for the right.

5.4 Connecting to Speakers/Amplifiers

Connect the 'MAIN OUT' L/R (TRS jacks) to your power amplifier or powered speakers.

5.5 Connecting Headphones

Plug your headphones into the 'PHONES' 6.3mm TRS jack.

5.6 Connecting to a PC for Playback/Recording

Use a USB cable (not included) to connect the mixer's USB port to your computer.

Figure 7: Mixer connected to a computer for USB audio.

5.7 Connecting a U-disk

Insert a FAT32 formatted U-disk into the mixer's USB port for playback or recording.

Figure 8: U-disk connected to the mixer's USB port.

6. Operating Instructions

6.1 Basic Audio Mixing

• Gain Knob: Adjusts the input sensitivity of each channel. Turn clockwise to increase gain. If the 'PEAK' light illuminates, reduce the gain to prevent distortion.
• EQ Knobs (HI/LOW): Use these to shape the tone of each channel. 'HI' affects treble frequencies, 'LOW' affects bass frequencies.
• Level Knobs: Control the individual volume of each channel in the main mix.
• Main Fader: Controls the overall output volume of the mixer.

Figure 9: Gain knob and Peak indicator.

6.2 Channel Configuration (CH1/2 and CH3/4)

• CH1/2 (Mono): Signals from CH1 or CH2 will be output equally to both the Left and Right main outputs.
• CH3/4 (Stereo): If a signal is input to CH3, it will only be output to the Left main output. If a signal is input to CH4, it will only be output to the Right main output.

Figure 10: Channel input labels.

6.3 Stereo Pan Button (CH1/2)

The 'STEREO PAN' button for channels 1/L and 2/R affects how their signals are routed to the main output.

• Button Bounced Up (Mono): Sound input to channels 1/L or 2/R will be heard from both the right and left speakers. Use this setting when using 1/L or 2/R individually.
• Button Pressed Down (Stereo): Sound input to Channel 1/L will be heard only from the left speaker, and sound input to Channel 2/R will be heard only from the right speaker.

Figure 11: Stereo Pan button.

6.4 Bluetooth Function

The mixer can receive Bluetooth audio signals from devices like smartphones. It cannot send Bluetooth signals to speakers.

• Pair your Bluetooth device with the mixer.
• After successful pairing, press down the 'ST3-4/USB MP3' button to route the Bluetooth signal to the main output.

Figure 12: Bluetooth connection to the mixer.

Figure 13: The mixer cannot send Bluetooth signals to a speaker.

6.5 99 DSP Effects

The mixer includes 99 digital signal processing (DSP) effects to enhance your audio.

• Parameter Knob: Rotate to select an effect (01-99).
• Program Knob: Adjusts specific parameters of the selected effect.
• Level Knob (EFFX): Controls the overall output level of the effects.

Figure 14: DSP effects list and controls.

6.6 USB Playback and Recording (U-disk)

The mixer supports U-disk for playing audio files and recording the main mix.

• U-disk Format: Must be FAT32 (NTFS is not supported).
• Playback Formats: MP3, WMA, WAV, FLAC.
• Recording Format: MP3.
• To record, ensure there is at least one song already on the U-disk.
• Press down the 'ST3-4/USB MP3' button to route the U-disk signal to the main output.

6.7 PC Playback and Recording

Connect the mixer to your PC via USB for audio input and output.

• PC Playback: In your computer's sound settings, select the mixer as the playback device (speaker). The computer's audio will then be routed to the mixer. Press down the 'ST3-4/USB MP3' button to hear the PC audio through the main output.
• PC Recording: In your recording software, select the mixer as the input device (microphone). The mixer's main mix will be sent to the computer for recording. Note that PC recording is MONO only.

6.8 Headphone Volume Control

Adjust the 'LEVEL PHONES' knob to control the volume of your headphones. The 'MAIN OUT' fader does not affect headphone volume.

Figure 15: Headphone level control.

6.9 ST3-4/USB MP3 Button

This button determines the source for channels 3/4 and the digital audio player section.

• Button Bounced Up: Activates the line input signals for channels 3/4.
• Button Pressed Down: Activates signals from the U-disk, Bluetooth, or PC connected via USB.

Figure 16: ST3-4/USB MP3 button.

7. Specifications

Figure 17: Mixer dimensions.

8. Troubleshooting

• Low Microphone Volume:
  - Ensure you are using an XLR cable for dynamic microphones. 6.3mm plugs may result in lower volume.
  - Check the Gain knob for the respective channel and increase it if necessary, but avoid the 'PEAK' light.
• Microphone Not Working:
  - For +48V condenser microphones, ensure the +48V phantom power switch is ON.
  - For dynamic microphones, ensure the +48V phantom power switch is OFF.
  - Verify the microphone is properly connected to the XLR input.
• U-disk Not Playing/Recording:
  - Ensure the U-disk is formatted to FAT32. NTFS format is not supported.
  - Check that the audio files are in a supported format (MP3, WMA, WAV, FLAC).
  - For recording, ensure there is at least one song already on the U-disk.
  - Make sure the 'ST3-4/USB MP3' button is pressed down.
• No Sound from Bluetooth:
  - Confirm your device is successfully paired with the mixer.
  - Remember the mixer only receives Bluetooth signals, it cannot send them to a Bluetooth speaker.
  - Ensure the 'ST3-4/USB MP3' button is pressed down.
• No Sound from PC (Playback):
  - Verify that the mixer is selected as the playback device (speaker) in your computer's sound settings.
  - Ensure the 'ST3-4/USB MP3' button is pressed down.
• PC Recording Issues:
  - Confirm the mixer is selected as the input device (microphone) in your recording software.
  - Note that PC recording is limited to MONO audio.
• Headphone Volume Not Changing:
  - Adjust the 'LEVEL PHONES' knob. The 'MAIN OUT' fader does not control headphone volume.
• Excessive Noise or Distortion:
  - Reduce the 'Gain' knob for the input channels. If the 'PEAK' light is on, the signal is too hot.
• Lavalier Microphones with 3.5mm Jack:
  - The mixer cannot supply working power to devices like lavalier microphones that require power through their 3.5mm jack, even with plug adapters. These devices may not function correctly.

Figure 18: Incompatible lavalier microphone type.

9. User Tips

• For optimal sound quality and to avoid issues, always use high-quality XLR cables for microphone connections.
• Before connecting any microphone, double-check its power requirements and adjust the +48V phantom power accordingly.
• When using a U-disk, ensure it is formatted to FAT32 to guarantee compatibility.
• Experiment with the 99 DSP effects to find the best sound for your specific application.
• If you experience any unexpected behavior, try restarting the mixer and checking all cable connections.

10. Maintenance

• Cleaning: Use a soft, dry cloth to clean the exterior of the mixer. Do not use liquid cleaners or solvents, as they may damage the finish or internal components.
• Storage: When not in use, store the mixer in a cool, dry place away from direct sunlight and extreme temperatures.
• Cable Care: Regularly inspect all cables for damage. Replace any frayed or damaged cables to ensure safe and reliable operation.

11. Warranty and Support

For warranty information and technical support, please refer to the seller's policies or contact the point of purchase. Keep your proof of purchase for any warranty claims.