aptX vs. aptX HD: What's the difference?

Whenever you read anything about Bluetooth, you'll come across plenty of letters and numbers and other cryptic specs. One of the latest on these is aptX HD, which takes a previously cryptic specification and adds HD on the end. We all know HD means "High Definition", but what about the aptX part? And what makes aptX (which is also a high-definition specification) different from aptX HD?

Don't worry if you aren't quite sure of the answer because you're not alone. And we're about to go through the details so we can figure it out together.

What is aptX?

aptX is a Bluetooth audio codec that can transmit 16-bit/44.1kHz audio with a compression ratio of 4:1 at 352kpbs.

That's not very helpful, but it's what you would find if you dug up the specifications for aptX. What it means is that a device — your phone, your computer, your A/V receiver or just about anything else that can send Bluetooth audio — transmits audio with "CD-like" quality. It sounds better as long as the source of the audio is CD quality or higher.

The original aptX codec promised CD-like quality, and it mostly delivered on it.

Notice the claim of "CD-like" quality versus CD quality. It's stated this way because of compression. aptX, like every other Bluetooth audio codec, uses compression on the audio before sending, and the receiving device — your headphones or any other speaker — decompresses it while it's playing. Compressing the data and sending it is necessary because Bluetooth can't stream stereo audio fast enough to send raw data that would still sound good. The aptX codec also was designed to reduce latency, which is the amount of time that passes between sending the audio and hearing it.

If you're listening to music, latency doesn't matter. There could be a fairly big delay between your phone and your headphones and you wouldn't notice it. But if you were watching a video you most certainly would! We've all seen streams get a little funky and the words just don't sync with the actor's lips!

Latency is bad news when you're watching Netflix.

There's even an aptX LL (Low Latency) codec for cases where latency is super important. The aptX LL codec cuts latency down to 32 milliseconds which is fast enough that our brains can't detect it. You'll find aptX LL in things like gaming headsets where latency is more important than quality, though aptX LL can transmit 16-bit/44.1kHz, too.

When it's all said and done, aptX makes audio sound better than most other Bluetooth audio codecs. Since we all want our audio to sound good, aptX is a feature of almost every device that can send or receive audio over Bluetooth.

What is aptX HD?

AptX HD is a Bluetooth audio codec that can transmit 24-bit/48kHz audio with a "gentle" compression ratio of 4:1 at 576kpbs.

Again with the numbers, but this time we can make more use of them. For starters, higher quality audio can be sent using aptX HD without increasing the latency or pausing the data stream. 24-bit 48kHz files are true HD files that people with expensive wired headphones appreciate, where you hear very little background noise and can hear each individual thing making sounds clearly. Phones like the LG V series can send higher quality audio through the 3.5mm headphone jack, but these numbers have almost reached the point of diminishing return once you get to 24-bit 48kHz.

aptX HD ups the ante and can transmit a true hi-res audio stream.

The difference between a 24-bit 48kHz audio stream over a wired connection and one over Bluetooth is the compression. aptX HD has a better compression algorithm than standard aptX (note the "gentle" 4:1 compression) but any compression introduces fuzz and hiss. You've heard this at play even if you didn't know it — rock guitarists use compression taken to the extreme in order to make their guitar sound more "chunky" and "fuzzy" and it works. The compression used in the aptX HD codec was specially developed to not make things sound chunky and fuzzy, but it still injects some noise.

A bigger bandwidth pipe means less compression is required, and that means better sound quality.

The final difference is the most important. Apt X transmits audio at 352kpbs and aptX HD transmits at 576kbps. The kbps stands for kilobits per second, and this is the same way we measure our internet connection speed. One Mbps (megabit per second) is equal to 1,000 kilobits per second. We all know that more bits per second with your internet connection is better, and that's true with Bluetooth audio as well. The higher bandwidth means more data can be streamed which means it doesn't need as much compression, or as we see with aptX HD, a looser compression algorithm can be used.

Note that this measurement is in bits (lower-case b) and not bytes (upper-case B as in kBps) and is talking about the data transmission rate and not the file sizes that can be sent.

After we cut through all the numbers and tech talk, aptX HD can send higher quality audio than standard aptX, without introducing any extra latency. That means it sounds even better and approaches the quality you can get over a wire.

Where to find aptX HD

aptX HD isn't something that any equipment can deliver. It's something Qualcomm developed (as was the original aptX and all variants of it) and you need their hardware as well as their software. Their current high-end solution, the CSR8675 Bluetooth Audio SoC delivers aptX HD, Bluetooth 5, active noise cancellation over Bluetooth and Qualcomm TrueWireless stereo on a single chip. Like all hardware that supports aptX HD, it's 100% backward compatible with standard aptX, too.

LG first brought aptX HD to the smartphone world with the G5 and continues the trend with current models.

The first phone with aptX HD to be sold was the LG G5. LG has spearheaded the aptX HD movement and you'll also find the codec present in the LG V20, the LG G6, and the LG V30. Sony delivers aptX HD in the Xperia XZ1 and XZ1 compact, OnePlus has the feature in the OnePlus 3, 3T and 5, and a handful of lesser-known (in the smartphone space at least) companies like Sharp and Luna also make aptX HD capable Android phones.

On the listening end, you'll find aptX HD headphones from Sony (opens in new tab), Audio Technica (opens in new tab), and LG (opens in new tab) as well as other lesser-known brands. The list of aptX HD products will likely keep growing as the codec delivers better sounding audio without any extra work needed from the companies who use it.

As far as the sound versus wired audio, that's something each of us will have to evaluate on our own.

Jerry Hildenbrand
Senior Editor — Google Ecosystem

Jerry is an amateur woodworker and struggling shade tree mechanic. There's nothing he can't take apart, but many things he can't reassemble. You'll find him writing and speaking his loud opinion on Android Central and occasionally on Twitter.

  • Jerry, have you tried any of these aptXHD headphones? How do they sound to you?
  • The difference is night and day. I had a v20 and the tone platinum headphones from LG. Listening to something with aptx HD is louder, and clearer. Switching to non aptx HD is like listening through mud... I switched to the v20 because I had a note 7. Once the s8+ came out I switched back to Samsung. And the only 4 things I miss from the v20 is the more powerful DACs, the better positioned finger print sensor, the wide angle camera, and the ability to use aptx HD. My tone platinums sound so muddled and dull with my s8+ compared to the amazing sound that came from the v20... I miss it every single day. You would think that Samsung would jump on the aptx HD since it is considered the #1 Android phone... And you'd think Qualcomm would be fighting nail and tooth to get it into their phones!
  • Samsung would rather brand their own version of aptX that only works with their headphones. They have the market share to pull it off and make some extra cash.
  • Nope. Started looking for a pair that supports aptX, aptX HD, and LDAC. Just don't want to spend $350 on the Sony 1000XM2. That's a lot of cash for something I'll probably never use after I've tested them.
  • Thanks! I don't think I'd use them either but was just curious.
  • Jerry I have the original MX series and they sound really good. The best sounding Bluetooth headphones I've found. (Go to Best buy and try).
  • Didn't know the updated version did APTX-HD. Nice
  • I like the part where the author gets confused between compression (as in loudness) and compression (as in size reduction) for like a paragraph. There is no compression (as in loudness) going on here.
  • What are you talking about? There's nothing of that in this article lol
  • He means where I talk about audio compression guitar effects and he talks about a compressor in-line switch or onboard switch/microchip in an amp. I mean signal modulation, compression, then stretched to fill the original time. Not a stomp switch or dial on an amp. But it's all good, I probably explained it poorly :)
  • Yeah. When guitarists think compression we think of an effect that reduces the dynamic range of the signal by amplifying quiet signals and reducing loud signals. To get the "chunky" sound you use distortion which amplifies the signal to the point where the signal peaks get cutoff/flattened, causing the distinctive distortion 'fuzz'.
  • I set my phone to aptX HD for two very important, highly technical reasons: 1. The name sounded more impressive, because "HD"! 2. I'm probably never going to use it anyway, because the 3.5mm port is still a thing on my phone.
  • I have a 3.5mm headphone jack and use high impedance headphones on my V20. I just want to know from Jerry how aptX HD sound compares, as I'm an audio enthusiast.
  • aptX 4K or GTFO
  • Or just use a wired connection and not worry about any of these problems that didn't exist until the OEMs decided we didn't need a headphone jack anymore...
  • OR ... Just use a wired USB-C headset and buy a phone with Wireless Charging. But I am glad that the Note 8 still feels relevant to use headphone jacks. People can whine it's old tech, but it works, and works well for what it does. I hated that I couldn't charge and jack at the same time with the PH-1. Not sure I could tolerate it. Don't like having to keep a dongle around for a simple adaptation that already works.
  • I don't think anybody actually whined about the headphone jack being old tech....but more so whined about "courage" for not using it lol
  • I was hoping that Jerry also compares AptX(HD) to LDAC and his thoughts about it, but sadly, LDAC isn't even mentioned in the article.
  • saving a comparison of aptX HD to LDAC after I've tried them both long enough to give some opinion on top of the tech breakdown.
  • Not that I disagree, that's only available on Sony headphones at this point, so there are less options than headphones with AptX HD
  • It's in Android Oreo for free. Give it some time and the market will catch up. How many headphones do APTX-HD?
  • LDAC codec is free on Android Oreo?!?! No way!! If so....can't wait to try out with my MDR-1ABT's!! :D
  • Can anyone point me to where I'd find AptX HD in the settings on a OnePlus 3? Thx.
  • Settings > Advanced > Bluetooth Audio Codec
  • Thanks, I don't have the Bluetooth Codec option in my advanced settings. Would I need to be on a beta release or unlocked the boot loader to see it?
  • LG for the freaking win. I knew audio sounded better than anything else I've used before my V20 but I could never figure out why. I think this explains what my ears were hearing.
  • Over Bluetooth?
  • He is most likely referring to DAC which isn't used over BT. I love my V20 as much as he does though, lol!
  • Interesting, thank you.
  • For some reason I could never get the HD part to work with LG's Platinum Bluetooth headsets. It was always greed out, but when I plugged in my wired ear buds, it works like a charm. Hopefully that will be resolved, because I heard that the LG5 had this ability with wireless Bluetooth..
  • What's the best in ear headphones that support this technology?
  • I had the LG Platinum headset but was less than impressed. They were ok... Lacking in bass and weren't very comfortable
  • Just give me a ******* headphone jack.
  • .
  • Are aptx HD earbuds good enough to listen to audio from my TV without appreciable lag? Or do I need aptx LL?