Quality & Testing

Every speaker, microphone and module we ship passes the same chain of checks — incoming materials, in-process inspection on the line, and 100% end-of-line acoustic test. Below is what we test, with what equipment, and at which stage.

Three Lines of Inspection

01

Incoming Quality Control

Frames, cones, magnets, voice coils, PCBs, cables and packaging materials are checked against the drawing and AQL plan before they enter the warehouse — dimensions, appearance, materials and key electrical parameters.

02

In-Process Inspection

IPQC patrols every production stage: coil winding, assembly, glue curing and soldering. First-article checks open each batch, and spot checks continue at fixed intervals so problems are caught on the line, not at packing.

03

Final & End-of-Line Test

Before packing, every unit passes 100% end-of-line testing — impedance scan, polarity and sweep listening — plus a final visual check. Batch records link each unit to its shift, line and material lots.

In-House Testing Lab

Our lab in Jiashan runs the measurements that decide whether a speaker sounds right and lasts. Acoustic data is captured with a B&K (Brüel & Kjær) microphone chain and an MLSSA system — the same class of equipment our customers’ acoustics teams use — so your curves and ours match one-to-one.

What We Test, and Where

Each test has a defined condition, sample size and pass criterion written into the control plan. Items we do not measure in-house — for example full EMC testing — are handled by accredited third-party laboratories, and we share the reports with you.

CategoryTest itemsEquipment / methodStage
AcousticFrequency response, impedance, sensitivity, THD, Rub & Buzz, polarity B&K microphone chain + MLSSA system; impedance testers Sample validation; 100% at end of line
Electrical / powerRated and maximum power handling, life endurance, temperature rise Power test rig, endurance rigs Design validation and first samples
EnvironmentalHigh / low temperature, humidity, thermal cycling, vibration, drop, water exposure CTHM climate chamber, YWX environmental chamber Per project plan and key batches
Mechanical / assemblyDimensions, sealing and air-leak check, torque, appearance Calipers, custom gauges and assembly fixtures IQC, in-process and OQC
ComplianceRoHS and REACH substance screening XRF RoHS tester; accredited third-party laboratories for certificates Incoming materials and per batch

Three Stages, Three Different Questions

Prototype Testing

The first question: does the design work at all?

Design Validation

The second question: does it survive real use?

End-of-Line Testing

The third question: is this exact unit good to ship?

How Quality Is Managed

Control Plan

Every product ships with a control plan that maps each check, its sample size and its pass criterion.

Batch Traceability

Material lots, shift and line data are recorded per batch, so any field issue can be traced to its root.

Change Control

Material, tooling or process changes are notified to you before they ship — no silent substitutions.

8D & Corrective Action

Nonconformances go through a structured 8D process with root-cause analysis and verified preventive actions.

From the ZEHSM Blog

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