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Sony SRS-X33 review: A standout mini Bluetooth speaker

The Sony SRS-X33 makes a strong case for being a less expensive alternative to the Bose SoundLink Mini II.

David Carnoy Executive Editor / Reviews
Executive Editor David Carnoy has been a leading member of CNET's Reviews team since 2000. He covers the gamut of gadgets and is a notable reviewer of mobile accessories and portable audio products, including headphones and speakers. He's also an e-reader and e-publishing expert as well as the author of the novels Knife Music, The Big Exit and Lucidity. All the titles are available as Kindle, iBooks, Nook e-books and audiobooks.
Expertise Mobile accessories and portable audio, including headphones, earbuds and speakers Credentials
  • Maggie Award for Best Regularly Featured Web Column/Consumer
David Carnoy
4 min read

At first glance, it's hard to tell the difference between Sony's SRS-X3 Bluetooth wireless speaker and its successor, the SRS-X33 (reviewed here). In pictures, they feature the same attractively minimalist rectangular design and come in a variety of colors. But place one model next to the other -- or just look at the specs closely -- and you realize the new X33 is considerably smaller, weighing 1.54 pounds (730 grams) instead of 1.75 (795 grams). It also features better battery life -- 12 hours instead of 7, a significant upgrade.


Sony SRS-X33

The Good

The Sony SRS-X33 is an elegantly designed mini Bluetooth wireless speaker that delivers strong sound for its small size. It has a built-in speakerphone capabilities, NFC tap-to-pair technology for smartphones that support it and good 12-hour battery life.

The Bad

It can distort slightly when played at at high volumes; no carrying case included.

The Bottom Line

The Sony SRS-X33 makes a strong case for being a less expensive alternative to the Bose SoundLink Mini II.

Like its predecessor, the X33 carries a list price of $150 (UK £109, AU $230), although it can be had for less online. While lighter than the X3, it still feels sturdy in hand, with two 10-watt drivers (20 watts total power) and dual passive bass radiators. Its design is straightforward and elegant and the speaker itself has a nice, smooth-to-the-touch finish. I'm a fan of the design, though others might find it a tad dull.

In terms of features, it's got everything you need but no real extras like waterproofing, the ability to charge up other USB devices or the ability to wirelessly join two X33s together to make a stereo pair (with UE Boom and Roll speakers, for instance, you can pair multiple speakers).

It offers the standard Bluetooth range of about 30 feet (10m), has a built-in speakerphone for taking cell-phone calls (it works pretty well), and offers NFC tap-to-pair technology for smartphones and tablets that support it. You also get support for Sony's LDAC codec, which, like AptX, is supposed to make Bluetooth audio streaming sound slightly better. However, you'll need a LDAC-compatible device to actually to take advantage of it. Not too many of those devices exist at this point.

The speaker charges via Micro-USB -- a charger is included, though no protective carrying case -- and around back you'll also find a standard minijack audio input for connecting audio devices without Bluetooth.

The Sony SRS-X33 comes in a few different colors and features speakerphone capabilities. Sarah Tew/CNET


Typically in the speaker world, going smaller isn't usually the best recipe for getting better sound. But Sony's engineers appear to have worked some magic on the inside of this speaker because the new X33 sounds better, with a slightly improved bass performance at higher volumes and a bit more balanced sound overall.

As with many of these small Bluetooth speakers, your first reaction to it will be that it plays quite loud for its size, delivers a decent amount of bass, and can fill a small room with sound. However, the fight with a speaker such as this is how much volume you can get out of it before it distorts. And every compact Bluetooth speaker I've ever listened to distorts. It's just a matter of raising the volume and feeding it material it just can't handle.

For the most part, the X33 sounds really good for a speaker in its size and price class, particularly at more moderate sound levels. Where it runs into some trouble is when you hit it with more complicated tracks with lots of instruments or just bass-heavy material.

Enlarge Image
The back of the speaker with the USB charging port and audio input. Sarah Tew/CNET

The internal DSP (digital signal processor) works to limit or clip certain frequencies (compress is another way to describe it) to keep the speaker from distorting too badly, and you can literally hear the bass pulling back at times.

Again, that's par for the course for these types of speakers and I've made similar statements about such competitors as the Bose SoundLink Mini II .

So, how does this Sony speaker compare to the competition?

Well, we did a little shootout in our audio room at CNET in New York and came away with some interesting impressions. As I said, compared to the earlier X3, this model sounds a little smoother with a little better bass. That speaker can play loud for its size, too, but when you put it up against the X33, it has a little more of an edge to it, which is a polite way of saying it sounds a little harsh, with some sibilance in the treble and upper midrange.

Whether you like the more expensive Bose SoundLink Mini II's sound better will depend on your taste and what music you're listening, too. The Bose is designed to make whatever you throw at it sound decent and it's a little bit warmer, slightly more forgiving speaker than the Sony. But the X33 holds its own and some people may prefer its sound.

What you get in the box. Sarah Tew/CNET

I also pitted the X33 against the JBL Charge 2+ , the new water-resistant version of the Charge 2 , and was surprised to find that the JBL actually sounded a touch better, with a little stronger, tighter bass and slightly smoother sound.

Why was I surprised? Well, I'd previously reviewed the Charge 2 and wasn't as impressed as I hoped I'd be (the bass was boomy on the unit I tested). But the new Charge 2+ seemed like a different speaker. A little research revealed that JBL updated the firmware of the Charge 2 after my review and improved the sound. However, no one at JBL bothered to inform me of that.

Finally, we compared the X33 to Sony's step-up SRS-X55. That larger speaker produces a little bigger sound with more bass. However, while you're getting more volume, the X55 doesn't sound better than the X33 -- at least when operating on battery power (plugged in, the X55 does get a bit of a power boost and sounds slightly better). All things considered, including price tags, I'd personally opt for the smaller X33.


The X33 may still distort with certain tracks at higher volumes, but it's a clear improvement over its predecessor, the X3, both in terms of design and sound. While the JBL Charge 2+ is a good option in this price range, this Sony also makes a strong case for being a less expensive alternative to the Bose SoundLink Mini II.


Sony SRS-X33

Score Breakdown

Design 8Features 8Sound 8Value 8