Sourcing Bluetooth Speakers From China: Drivers, Cabinet Thump and the Battery Paperwork Everybody Forgets

Every few months a buyer messages me with the same story: the samples sounded great, the reviews complained about distortion at high volume, and the battery paperwork turned out to be a photocopy the factory made of somebody else's report. Bluetooth speakers are one of the most competitive categories in China, and that competition pushes factories toward corners that only show up after the container lands.

Decide the acoustic tier before you talk price

The single question that fixes your whole cost structure is how loud and how clean you need it. A 5W single-driver box and a 2.1 system with a passive radiator are not the same product at different prices; they are different products.

What drives the sound:

Driver size and magnet. A 40mm full-range driver with a decent neodymium magnet sounds nothing like a 40mm driver with a cheap ferrite magnet of the same size. Ask for the driver spec sheet, not just the diameter.
The cabinet. Plastic housings are cheap and resonant. A sealed or ported MDF cabinet gives you the low end people describe as "full". If the marketing spec promises bass from a pocket-sized plastic box, be suspicious.
The passive radiator. This is the flat disc you see on the side of many portable speakers. It is not a gimmick; it is what produces the punch below 100Hz without a bigger driver. Cheap implementations rattle at high volume.

If you want a number, ask for the frequency response curve and a THD figure at rated power. A factory that cannot produce either is selling you a box, not a speaker.

The amplifier chip and the real wattage

Most Chinese speakers use class-D amplifier chips, and the brand of that chip matters. Common options come from TI, ST and a handful of well-known Chinese chip makers, with the cheap no-name clones sitting underneath. Ask which chip and whether it is genuine.

Then there is the wattage claim. The number on the box is often "peak" or "PMPO", which is meaningless. Ask for RMS or rated power per channel. A speaker advertised as 40W that measures 8W RMS will get slaughtered in reviews when buyers turn it up.

The battery is a compliance product, not an accessory

This is the part that kills shipments. Any lithium battery in a Bluetooth speaker must have a UN38.3 test summary report, and it must cover the actual cell and pack you are shipping, not a similar one. Shipping lines will ask for it, and so will customs.

On top of UN38.3 you will usually need:

An MSDS for the battery, with the test summary and a proper classification.
IEC 62133-2 test reports for the cells and the pack if you sell into the EU or markets that enforce it.
Capacity marked accurately in Wh, because the shipper needs the watt-hour figure for the air waybill and the label.
The charger or USB-C input compliant with your market's safety rules, and CE or FCC marks that actually trace to a test report.

Do not accept a report that names a different capacity. Batteries get swapped between models constantly, and a swapped pack invalidates the paperwork the moment someone checks.

Waterproofing claims: read the fine print

IPX7 means it survives 30 minutes at one metre in still water. IP67 adds dust. Neither means the speaker survives a wave, a pool drop onto concrete, or salt water. If your market cares, ask for the actual IP test report and check the depth and duration, because many listings quietly stretch an IPX5 result into "fully waterproof".

Also test the port cover. A flap that is loose after fifty open-close cycles is the number one failure on supposedly waterproof speakers.

What I check before the container ships

I test five pieces from the production line, not the sample room, at full volume for an hour and look for distortion and thermal cutout. I confirm the firmware version, the Bluetooth chipset version, and that pairing and multipoint actually work on both iOS and Android. I check the battery report names the right cell model. And I measure the actual shipping carton against the stacking load, because speakers are heavy for their size and the boxes crush easily if nobody calculated it.

Shenzhen and Dongguan are the deep end of this category, and the good factories there will happily hand you the chip spec, the driver spec and the battery reports. The ones that dodge those questions are telling you something.