AudioFiles: Beating the Bluetooth Blues

Bluetooth is hard to escape these days—but there are ways to make it sound better

Cambridge Audio’s Alva TT turntable features aptX-HD Bluetooth audio.
Cambridge Audio’s Alva TT turntable features aptX-HD Bluetooth audio.

With headphone jacks disappearing from all Apple phones and many Android phones, listening to audio on the go often demands that you use wireless Bluetooth headphones. Although it’s possible to use wired headphones if you attach a headphone amp dongle, headphone makers tell me almost no one bothers—and that’s why they’re switching their headphones to Bluetooth as fast as they can. Bluetooth is more convenient because it’s wireless, but it also reduces sound quality. This prospect bothers serious listeners. But thanks to the technological advances being implemented on new products, going Bluetooth doesn’t necessarily mean sacrificing quality.

Playing the Standards

The standard Bluetooth audio format is called SBC, for Sub-Band Codec. It’s similar to the MP3 technology often used to reduce the size of digital audio files. Like MP3, SBC discards some of the data in an audio recording, but the data it discards represents subtle details that are difficult or impossible to hear, especially through most headphones and wireless speakers.

Still—as I found when I put together a Bluetooth blind test on my website, brentbutterworth.com—while the loss in sound quality with SBC is fairly benign, it’s almost always audible. For the last few years, the aptX codec has been offered as a sonic upgrade over SBC, but my blind tests show no significant sonic advantage of aptX over SBC.

HiFiMan’s Ananda-BT uses Bluetooth technology.
HiFiMan’s Ananda-BT

Fortunately, Qualcomm, the company that makes aptX Bluetooth chips, now offers aptX-HD, a higher-quality version of aptX that doesn’t throw away as much data. Standard aptX carries 352 kilobits of data per second, while aptX-HD carries 576 kilobits per second, or 63 percent more data. Compare these numbers to the standard CD data rate of 1,411 kbps. You can hear the difference in my blind test, which includes aptX-HD as well as standard aptX and SBC.

To my ears, it’s a significant difference, which is why I’m happy to see aptX-HD now being included in many new headphones, including the Bowers & Wilkins PX, NAD Viso HP70, PSB M4U 8, and Sony WH-1000XM3 noise-canceling headphones, and the Beyerdynamic Amiron Home Wireless and HiFiMan Ananda-BT open-back audiophile headphones.

No Scrapple from Apple

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A complication arises because these headphones can deliver the benefits of aptX-HD only when used with an audio source that also includes aptX-HD—and unfortunately, aptX-HD is available in no Apple products. However, it is available in many Android phones and tablets. It’s also available in some portable music players, such as the Astell&Kern Kann and the FiiO M6, and even in a turntable, the Cambridge Audio Alva TT.

Sony has its own higher-quality Bluetooth technology: LDAC. LDAC carries up to 990 kbps, giving it a serious technical advantage over aptX-HD. However, LDAC has one huge disadvantage: It’s available mostly in Sony products, such as the WH-1000XM3 and WH-H900N headphones. Sony does make LDAC available free to any Android phone maker, though, so you’ll find it not only in Sony’s phones but also in other Android models, such as Samsung’s Galaxy phones.

PSB’s M4U 8 headphones use Bluetooth technology.
PSB’s M4U 8 headphones.

Bluetooth causes an additional problem: latency, or delay, of the audio signal. With SBC, the delay is typically around 200 milliseconds (one fifth of a second), but it can be even longer. When you’re playing music, this isn’t a problem, because you won’t notice if “All Blues” starts a fraction of a second later. But if you’re watching jazz videos on YouTube, you’ll definitely notice it if Elvin Jones’ stick hits his snare 1/5 of a second before you hear the sound, or if Cécile McLorin Salvant’s lips are out of sync with her vocals.

AptX typically has about half the latency of SBC, but Qualcomm offers an even better solution: aptX Low Latency, or LL. It typically has just 32 milliseconds of latency, which you won’t notice. AptX LL is only starting to hit the market, but you can get it now in headphones such as the Bang & Olufsen Beoplay H9 and MEE Audio Cinema Matrix ANC. Unfortunately, I know of no phones that currently include aptX LL, but using the Avantree Leaf or Creative BT-W2 USB Bluetooth adapter, you can add aptX LL to any laptop computer, and Bluetooth modules such as the MEE Audio Connect let you transmit aptX LL from TVs and stereo systems.

Don’t hold your breath waiting for Apple to add LDAC or any variant of aptX—the tech giant is notoriously reluctant to rely on other companies’ technology. But because all versions of aptX, especially, are relatively easy to include in a Bluetooth product, expect to see aptX-HD and aptX Low Latency appearing in many more smartphones and headphones in the coming year. LDAC and aptX-HD are noticeable sonic upgrades for negligible added cost, so if you’re considering a new set of headphones, it’d be a good idea to put either one or both of these Bluetooth audio formats on your “must have” features list.

Brent Butterworth

Brent Butterworth has been a professional audio journalist since 1989, and has evaluated and measured thousands of audio products. He is currently a writer at Wirecutter and editor of the SoundStage Solo headphone site; served as an editor at such magazines as Sound & Vision and Home Theater; and worked as marketing director for Dolby Laboratories. He also plays double bass with several jazz groups in Los Angeles.