Why inspect Loudspeaker before purchasing?
This is to mitigate safety risks, verify that core audio quality parameters meet standards, confirm the actual functionality and compatibility, and prevent latent faults caused by shipping damage-thereby ensuring that the investment yields a reliable product that meets expectations.
Loudspeaker Inspection Standards
Part 1: Inspection of External Appearance and Structure
1. Unit Casing: Plastic or metal housing free from deformation, sink marks, burrs, stains, paint loss, or color inconsistency; seams are uniform (≤0.8mm); no abnormal noise or sound of loose internal parts when the housing is pressed.
2. Speaker Grille: Metal or fabric mesh is smooth and free from holes, pulled threads, or unraveling; does not collapse when pressed.
3. Buttons and Knobs: Power, volume, track navigation, and mode buttons operate smoothly with good tactile feedback-no sticking, sinking, or looseness; screen-printed characters are clear and durable (no paint loss).
4. Ports and Interfaces: AUX, USB, TF card, and DC charging ports are centered and properly aligned; insertion and removal resistance is appropriate; no tilting or blocked openings.
5. Indicator Lights: LED cutouts are neatly finished; no light leakage or misalignment.
6. Logo and Labels: Brand name, model, specifications, and certification marks are clearly printed; labels are applied flatly without peeling or curling at the edges.
Part 2: Power-on Functional Test of the Complete Unit
Power Supply & Lithium Battery System (Focus: Bluetooth Speakers)
1. Power On/Off: Logic functions correctly; indicator light transitions (red/green) match the design; low-battery alerts (pop-up notifications or light indicators) trigger as expected.
2. Charging Test: Normal charging upon connection; charging indicator lights up; indicator changes color automatically when fully charged; includes overcharge, over-discharge, and short-circuit protection (to prevent battery swelling or fire).
3. Battery Life Verification: Continuous playback at 50% standard volume; actual battery life must be ≥80% of the rated capacity to pass.
4. External Power Supply Models: Stable power delivery via adapter; no unexpected power loss or restarts.
Wireless Connectivity
1. Bluetooth Pairing: Quick discovery, pairing, and connection with mobile phones/computers; automatic reconnection to the last paired device after disconnection.
2. Connection Stability: 30 minutes of playback within a 10-meter range in an open area with no stuttering, disconnections, or static; compatible with both Android and iOS systems.
3. Additional Features:
• NFC One-Touch Pairing: Rapid pairing triggered by tapping the phone against the device (mandatory test for NFC-enabled models).
• Wi-Fi Connectivity & DLNA Casting (Smart Speakers): Smooth network playback without stuttering.
Comprehensive Audio Playback Testing
1. Audio Source Coverage: Sound output functions correctly across all channels: Bluetooth, AUX wired input, USB flash drive, and TF card playback.
2. Volume Control: Smooth adjustment from 0 to maximum volume; no sudden jumps or popping sounds; no severe distortion at maximum volume.
3. Channel Balance: Consistent volume between left and right channels; no imbalance (e.g., one side louder than the other).
4. Noise Performance: No background electrical hiss or AC hum during standby; no static, feedback (whistling), distortion, or crackling during playback of vocals, pop, classical, or heavy bass tracks.
5. Sound Effect Modes: Preset modes (e.g., Bass, Pop, Classical) switch and function correctly.
Additional Features
1. Microphone (for Calls): Answering/ending calls works correctly; clear voice pickup; no echo or background noise (standard feature for portable speakers).
2. FM Radio: Stable station scanning; minimal static; proper stereo separation.
3. Remote control function: All buttons on the remote control respond sensitively within a range of 5 meters.
Part 3: Electroacoustic Acoustics Professional Parameter Standards
1. Total Harmonic Distortion (THD): ≤2% at rated power (higher values indicate poorer sound quality)
2. Signal-to-Noise Ratio (SNR): ≥55dB; ≥70dB for high-end speakers (higher values indicate lower background noise)
3. Frequency Response: 80Hz–18kHz for standard portable speakers; subwoofers can extend down to below 50Hz
4. Channel Crosstalk Attenuation: ≥30dB (ensuring no interference between left and right channels)
5. Maximum Sound Pressure Level (SPL): Meets the product's rated power specifications; no audible distortion or "tearing" sound with highly dynamic audio sources
Part 4: Electrical Safety Testing
1. Insulation Resistance: ≥2 MΩ between live parts and the enclosure; prevents electric leakage.
2. Dielectric Withstand Test: Withstands 1500V high voltage for 60 seconds without insulation breakdown or arcing.
3. Grounding Protection: Reliable grounding continuity for the metal enclosure; prevents electric shock.
4. Unit Temperature Rise: No abnormal overheating of the enclosure or plastic odor after 2 hours of continuous full-load operation.
5. Cable Safety: Power and charging cables meet gauge specifications; insulation is free from damage or tearing.
Part 5: Environmental Reliability and Durability Testing
1. Free Drop Test (Mandatory for export products)
Height: 1.2m; one drop on each of the 6 sides (front, back, left, right, top, and bottom)
Pass criteria: No casing cracks; internal speaker/circuit board remains securely attached; all functions operate normally after the drop
2. Environmental Temperature and Humidity Cycling
• High temperature: +45°C for 48 hours; Low temperature: -10°C for 24 hours
• Damp heat environment: 40°C and 93% RH for 48 hours
After returning to room temperature: Powers on normally; no moisture-induced short circuits; no degradation in sound quality
3. Vibration Test
Simulates turbulence during truck or sea transport: Continuous vibration of the unit in both horizontal and vertical directions for 2 hours; no loose internal components or abnormal noises
4. Waterproof Test (IPX4/IPX7 Outdoor Speakers)
IPX4: No water ingress when sprayed from any direction; IPX7: No water ingress after immersion in 1 meter of water for 30 minutes; unit powers on normally
5. Salt Spray Test (For coastal export orders)
Neutral salt spray for 24 hours; no rust or corrosion on metal parts
Part 6: EMC (Electromagnetic Compatibility) & Environmental Compliance Testing
1. Electromagnetic Interference: Does not interfere with nearby electronic devices (such as mobile phones or TVs) during operation; free from RF interference noise.
2. Electrostatic Immunity: Withstands static discharge from plugging/unplugging cables or touching the unit housing without freezing or rebooting.
3. RoHS Compliance: Heavy metal content (lead, mercury, cadmium) in plastics, circuit boards, and solder meets regulatory limits; free from pungent or harmful odors.
Part 7: Inspection of Packaging, Accessories, and Documentation
1. Outer carton and color box: Printed graphics, model number, and specifications match the actual product; no crushing, damage, or moisture exposure; shipping marks and destination labels are correct.
2. Internal cushioning: Foam or paper inserts hold the product securely in place, preventing movement or impact damage during transport.
3. Complete accessories: Charging cable, AUX audio cable, remote control, and power adapter are all included; specifications match the order requirements.
4. Paper documentation: Multilingual user manual, warranty card, certificate of conformity, and certification documents (CE/FCC/RoHS) are all included.
