Engadget: Bluetooth speaker wattage is not a direct loudness score

The guide explained that speaker power is commonly listed in two ways. Peak power is the maximum electrical power an amplifier can handle for short bursts, while RMS, or root mean square, reflects sustained power over longer periods. A speaker may be rated at 40W peak but handle only 20W RMS, Engadget reported. Manufacturers often publish the higher peak figure and omit RMS, and retailers do not always distinguish between the two, the article said.

Engadget cited the JBL Go 4 as an example. JBL’s official specification sheet rates the speaker at 4.2W RMS, but Target does not list a power rating for the product, according to the report. Some manufacturers do not publish RMS figures at all, leaving buyers to rely on independent reviews that include real-world testing, Engadget said.

Even comparing accurate RMS figures does not settle the question. Engadget reported that drivers and their sensitivity play a more important role than wattage alone, and an efficient 10-watt speaker may outperform a 20-watt model. The article recommended treating power ratings as a starting point rather than a definitive comparison.

The guide also said power and loudness are not linearly related. Doubling power increases sound output by about 3 dB, while listeners perceive a sound as roughly twice as loud only after an increase of about 10 dB, Engadget reported. Moving from 10W to 20W or from 20W to 40W therefore produces about 3 dB each time, and a tenfold power increase is needed to double perceived loudness, according to the article. The difference between a 25W speaker and a 35W speaker is smaller than the numbers suggest, Engadget said.

Engadget noted that speakers in the same power range can have very different sound profiles and volume levels. The article said spec sheets, power ratings and size alone make it difficult to judge performance. Size can be especially misleading for Bluetooth speakers, because a large battery can make a unit look more powerful than it is, according to the guide.

For shoppers, Engadget described broad power bands. The smallest Bluetooth speakers generally carry 3W to 10W RMS ratings, enough for listening a few feet away but not for overcoming background noise or filling medium-to-large rooms, the article said. Many small speakers distort at maximum volume, so users rarely push them to their limits, Engadget reported.

Speakers with up to 40W RMS are still relatively portable but often include two drivers instead of one, which can produce clearer sound without requiring full volume to fill a small space, according to the guide. In the 40W to 100W range, Engadget said, several models are marketed for outdoor use, including the Soundcore Boom 3i, which is rated at 50W RMS and marketed as loud enough to overcome environmental sounds. At the high end, the article pointed to JBL Boombox and PartyBox series speakers with high RMS ratings.