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Sony SRS-XB31 Portable Bluetooth Speaker
4.4Overall Score
Name: SRS-XB31
Price (RRP): $179
Manufacturer: Sony

I’ve been dismissive of it before, but the “Extra Bass”function in the Sony SRS-XB31 Bluetooth speaker lifts it above most.

Sony SRS-XB31 Features

It’s small but not tiny. At 231mm wide by 87mm tall by 81mm deep, the Sony SRS-XB31 doesn’t really use very much space. And at 890 grams, it’s not too hard to take with you. So, yes, it is portable.

And should you drop it in the drink, all should be fine. Sony rates the speaker at IP67, which means that it’s totally dust-tight, and can survive a dunking in a metre of water for up to half an hour. It comes with a plastic pseudo weave covering that absorbs some of the impact should you drop it. You can choose red, blue, white or black models. The review unit was red.

Sony SRS-XB31

Inside are two 48mm full range drivers, with a passive radiator between them. A passive radiator is a kind of weighted panel – sometimes it’s just another speaker driver but without any wires. It is designed to convert the energy from the inside of the enclosure into sound. Remember, if the speaker enclosure is sealed, the air inside it is being repeatedly compressed then released as the driver cone vibrates. With a properly chosen passive radiator, the bass portion of this energy can be released into the room. That provides deeper and more powerful bass.

Sony does not mention how powerful the internal amplifier is.

Sony SRS-XB31
A peek at the drivers inside (but the grille can’t really be removed)

It uses Bluetooth as the main means of signal inputs, of course, but it also has a 3.5mm stereo socket for analogue inputs. That socket is in a recess on the back underneath a silicon/rubber panel. With it is a Micro-B USB socket for charging up the unit, and a Type-A USB socket for powering your phone, if necessary.


There are the usual control buttons on the top for switching the unit on and off and for putting it into pairing mode and play/pausing. That last button can be used to skip tracks forwards and backwards if double- and triple-tap.

There are also three control buttons in the recess under the cover. One is for adding another Sony SRS-XB31 speaker so that they can form a stereo pair. Another links the speaker in with several others to form a “Wireless Party Chain”. That is, a bunch of similar speakers can be scattered around, providing the same music across a larger area.

The third button is dual function. A quick press makes a voice tell you the battery level to the nearest ten per cent. Hold it, and you can switch the lights on and off.

Sony SRS-XB31

Lights? What lights? Well, tracing the front grille all the way around, and down the sides to the back, is a strip of (presumably) LED lights. There are also two bright white LED lights under the grille near the left and right edges. I was startled when I first charged up the unit, paired it to my phone and listened to some music, to see this light band pulsate in a wide range of colours to the music, while those white lights flashed under the grille.

They are on by default.

Sony Music Center app

The glitzy default light setting isn’t the only one available. But to change this, as with several other settings of the Sony SRS-XB31 speaker, you must install the Sony Music Center app on your phone. This was formerly known as SongPal. It’s available for both Android and iOS in the usual stores. There are a dozen different light modes to choose from. I kind of liked the default “Rave”, but you can try things like “Calm Cinnabar” if it’s all a bit too frenetic for you.

I wasn’t going to bother too much with the app, but I had noticed some disappointing aspects to the speaker. First, although the packaging makes it clear that the speaker supports the AAC and LDAC codecs, my Google Pixel 2 XL only reported the Bluetooth standard: SBC. Both AAC and LDAC provide higher audio quality than SBC.

Sony SRS-XB31
Things you can control in app

It turns out that, by default, the Sony SRS-XB31 is locked into an SBC-only mode out of the box. To enable AAC and LDAC, you have to switch them on using the Sony Music Center app.

So get the app. Amongst other things, it allows you to change the sound mode (Extra Bass is the default, but Standard and Live Sound are also available) and use a three band equaliser. By default, the speaker switches off after fifteen minutes of doing nothing. You can disable off.