Starting Out With aptX HD: How Far Has Bluetooth Audio Come?

Part 1, Noam Gets A New Phone

In this series, I’ll dip a toe or two into the weird world of Bluetooth Audio sound quality. I’ll start with some background and acquiring a phone/source, and in upcoming segments, delve more into it while reviewing audio gear from iFi, Hifiman, NAD, Bluesound, and maybe a few others that come along over time. Mainly I’ll be focusing on the sound quality attainable using the aptX codec (especially aptX HD).

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Bluetooth Today: A Slew Of Codecs
Lately, if you look at Bluetooth audio appliances, the number of acronyms and logos could almost rival the video world. Codecs with names like SBC, AAC, LDAC, aptX, and a number of sub-variations, are all popular today and in wide use. Some devices, e.g. certain Android phones, offer the option to support several of these (my phone included). Both the LDAC and aptX HD codecs can handle higher audio bitrates, at least to an extent (Bluetooth itself has limited bandwidth). And both codecs are well regarded. While LDAC uses less compression, aptX HD is the one I’m really interested in at the moment. If I’m able to compare the two head to head, I will.

 

Bluetooth? Why?

In the past, Bluetooth’s bandwidth was limited to about the equivalent of listening to a 128kbps MP3 music file. Three years ago I tried a cheap Bluetooth audio adaptor for my wife to connect to, and it sucked. But things are changing, and I see a couple of reasons now to write about this topic.

Just before we dive in though – a quick, loose definition of two important terms:

WiFi: When you use your handheld device to control music that’s streaming from your WiFi router, we’ll call it “WiFi

Bluetooth: When you use your handheld device to play or stream music to a stereo receiver or headphone, we’ll call that “Bluetooth“.

Although these technologies both accomplish wireless data sending and receiving, their purpose and capability are different. Simply put, Bluetooth can be done with or without using WiFi – i.e. if you’re playing files stored on your phone, or using cellular network data to stream from services like Tidal or YouTube, then no WiFi connection is needed. Same way you don’t need WiFi to make a phone call, or play a downloaded podcast. Bluetooth is also the portable option – if you have the aforementioned music files and/or enough cellular data, then you can use it outside, in the car, at the cottage, and so on. It’s “wireless without the WiFi”, if you will. I hope no one’s confused yet. WiFi, on the other hand, tends to be available only at home or at a hotspot – unless you happen to live in a “smart city”.

 

Starting with the Source – A Phone

For various reasons, I decided that my next phone should support aptX HD. This latest, greatest Qualcomm codec is now supported by some well-known audio companies. aptX HD, along with LDAC, are the most appealing Bluetooth audio options – for us audio-oriented Android folks. The main reason I wanted aptX is that I’m now also a dealer who carries NAD, Bluesound, and other compatible gear, and I wanted to be able to connect my phone via Bluetooth, to demonstrate the capability of that option – even if I’m not using it myself as a daily/main source of personal music listening.

NAD D3020 & Huawei Mate 20 Pro

Given my needs and budget, I soon settled on the Huawei Mate 20 Pro – this phone seemed to offer everything I was looking for (mainly good audio and camera functions), and I could afford it. So far it’s been working out well for me. The Mate 20 Pro is from late 2018, so it was a free upgrade for me on Virgin Mobile (MSRP was $1300 when it came out!). Being about a year behind the latest gadgets is a good way to go if you’re on a tight budget. Now, before anyone rushes out to order a Huawei phone, please do some research – the company is entangled in many legal issues with US and European authorities. Their very latest phones will likely not be supported by the latest Android OS and Google Play ecosystem, which is a big deal. Caveat Emptor. They do make some nice phones though.

 

 

Wah Way

Bitrate Blues: with some connected devices and aptX toggled on, Android doesn’t let me change the bitrate (same for sample rate)

What can this Huawei phone do in the Bluetooth Audio realm? Well, quite a bit – but I learned quickly that the dumbed-down user interface/settings force the audiophile to be persistent. If you’re impatient or timid, it mostly just defaults to Sony’s LDAC codec. Not bad at all, but not what I bought this phone for. As configured (running initially on Android 9.0 and now on 10), I had to break into the “Developer Mode” settings and do some trial and error in order to change the audio settings and enable aptX. This is kind of a pain in the ass, and to be honest that alone may be enough to deter quite a few people. It’s not horribly difficult, but it’s not all smooth sailing or convenient either.

Remember, this is a consumer communication device, it’s not in any way designed for audiophiles. That said, my Huawei does have a 32-bit/384kHz DAC. It seems they’re dangling high-res in the audiophile’s face, but assuming that it doesn’t matter to most folks, so let’s not clutter the common settings with all that. Fair enough, these are advanced options. Geeks and brave souls, proceed forward.

iFi Zen Blue, Finale/Pentode6 amp, Huawei phone

 

I’ll be the first to admit, I’m a bit of an Average Joe with smart devices, and even digital audio formats. There’s a fair bit I don’t know about this stuff. At times I may be approaching things the hard way – but I deliberately wanted to come at this from the perspective of a “dabbler”. Interested, yes, but I’m not investing my life into this topic. For example, all my tests so far were done in close range – I just assume Bluetooth is going to be troublesome at more than a 10-15ft distance.

In any case, initially I did struggle somewhat to get settings to cooperate – I’ll try to say a little more on that in the individual gear reviews to follow. Most of all, it’s important to remember that unless you connect an aptX HD-capable device to your aptX HD-enabled phone, the connection will be with a lower spec codec, and you won’t have access to the superior/HD processing. Suffice to say that there isn’t a whole lot of easily-parsed info on this topic – by that I mean, yes there’s lots of info for geeks and developers, but I found useful pages directed toward the audiophile to be scarce. This page is a decent primer on the codecs themselves.

Clear Blue Streams

OK Bluetooth. I’ve been listening to Tidal and Spotify streams with aptX enabled, and I’m impressed. Sound quality is good, and the data is as glitch-free as a small town dweller with mid-level internet could expect. I haven’t done back to back comparisons with WiFi, but that will come as I spend more time with Bluesound’s terrific Powernode 2i – it does both. In particular, I’m impressed by the Ananda-BT from Hifiman, which is really a “dedicated” Bluetooth device, and said to be the world’s best Bluetooth headphone. More in-depth reviews/evaluations will follow – at this point my comments aren’t an endorsement of a particular product (vs its competitors), but a validation that the underlying tech delivers good SQ.  It does. With all the devices I’ve been playing with, the differences in streaming quality between Spotify and Tidal are clear. The differences between mastering versions are also noticeable. aptX may not reveal everything, but within my current testing envelope, it reveals more than it obscures.

Poweramp – The App
And this isn’t just about streaming, either. I downloaded a trial of the popular Poweramp app, and transferred some of my high-res FLAC music files to my phone. Within the context of this experiment, the result was excellent sound quality, and a very impressive array of configurable options. But keep in mind: the bandwidths here, for example 4856kbps on Kind Of Blue, these are in some cases more than twice what even WiFi can deal with, much less Bluetooth/aptX. To really hear these files in their full glory, you’d want to use a wired connection capable of high bandwidth.

What aptX does is encode the signal going out, and the receiving aptX device decodes it coming in. This allows a smooth flow of (compressed) data, but with encoding that’s sophisticated enough to “rebuild” the file on the receiving end with most of the audio fidelity intact. That’s the plan, anyway. If you’re starting with, say, a 1300Kbps Tidal stream, the reduction to aptX levels (around 650Kbps) isn’t super drastic. If you start with a 24/192 FLAC file, the compression does seem, in theory, pretty severe. But my initial impressions of how well aptX handles big files is very favourable. Context is important: if you have a $50k digital system and $50k worth of ripped/downloaded music, you won’t be using a wireless smartphone to feed your amp. Let’s not get carried away.

24/192 Miles;  24/96 Blues;  Poweramp file info

 

Where to next?

With my new phone driving the iFi Zen Blue DAC, music sounds good through my system. Actually, it sounds very good. When I pair my phone to the Bluesound Powernode 2i, or the Hifiman Ananda-BT planar magnetic headphones – well, now this is beginning to approach high-end audio, or a damn close cousin. Something I never would’ve thought possible with a Bluetooth connection. Enough to make me want to ditch the big system? No. But honestly – if this had been around 25 years ago, with a world of music in my pocket….it’s doubtful whether I’d ever have gotten back into big system audio. This is like mid-fi done well. Really well.

What does all this mean? Based on what I’m hearing, it means that better audio quality is becoming available to more consumers than ever before – and it’s not just “for them”. Both audiophiles and those on the periphery can use a modern smartphone as a source of high quality audio, biases aside. Portable/personal audio, cottage audio, your office system – can all be excellent, and without breaking the bank or undertaking big, delicate setups. For Android device users, I think aptX HD has established itself as one of the quality codecs – how many audio-oriented companies will ultimately support it isn’t clear, but some of the ones who do will be getting ink in my reviews this year.

In the next segment, I’ll take a closer look at the C$189 iFi Zen Blue, maybe the best value DAC I’ve seen since the Aq Dragonfly first appeared some eight years ago.

With kind thanks to Lily at Motet Distribution for the iFi and Hifiman loaners.

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2 Comments on Starting Out With aptX HD: How Far Has Bluetooth Audio Come?

  1. Terry Mcdonald // 2020/04/08 at 4:16 am // Reply

    Nice overview , I just reviewed the iFi blue zen , and yes i used aptX i was really impressed fir it being bluetooth actually i was shocked! Was it better than a connection no but its not far behind either ! Thanks and this is TeeJay The Stereo-Bargin File utube handle 😆

  2. Well Said. Thanks

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