At its basic core, Bluetooth employs UHF radio waves in the ISM bands to connect between source and receivers. When first designed and brought to market in the ‘90s, it was primarily for transmission over very short distances of up to 10m. The technology is shared by nearly 40,000 partners and governed by a central body that licences and certifies applications and formats (codecs).
Few of us give a second of a thought to the strangely named and omnipresent Bluetooth technology which has been in our pockets, bags, homes and cars since what seems like forever. In recent years the technology has seen an exponential widening of use and applications. In addition to connecting mobile devices, it has also been adopted by the pro-audio fraternity and is commonly used as a wireless connection for guitars and earpieces on stage during live events, as well as being increasingly present in boardrooms up and down the land which are festooned with Bluetooth in-ceiling microphones, etc.
Faster, higher capacities and range
For most of us the blue molar is synonymous with access to audio emanating from speakers in cars and at home as well as the connection of choice with IEMs and headphones. Most consumers will never quibble with the quality of sound transmitted from source to transducer. We hear, we’re happy, it’s as good as it needs to be for most consumers.
However, audiophiles and hi-fi fanatics may be interested in a revolution of sorts that has been quietly brewing and is enabling high sound quality with this humble tech. Equally significant is that it costs next to nothing and in many cases is available from the mobile phones we all use.
In recent years, companies with names like Qualcomm and Sony and more obscure names such as Savitech, have been advancing the capabilities of Bluetooth technology in a drastic and positive fashion. They quietly developed Bluetooth formats that are rivalling the much more complex and costly high-end wi-fi network streaming platforms and offer high quality, low cost musical performance and the ability to turn an analogue audio system into a high resolution streaming system in seconds.
Today’s Bluetooth world is governed by formats. Major formats are divided along the lines of the tech giants’ interests. The battle royal is staged in the main between the armies of Google and Qualcomm against Apple and Microsoft.
SBC: The granddaddy of Bluetooth formats is shared by all and compatible with all, be they Microsoft, Apple or Google.
AAC: Adopted by Apple as the be all for its Bluetooth audio applications and conversable with all other Bluetooth formats.
aptX: A Qualcomm designed format that is widely available on Android based devices and is embedded on just about every Snapdragon chip ever made. It has also been adopted by Microsoft as its format of choice.
aptX HD: Qualcomm solution for instant connection between hi-res ish audio and amps or active speakers. Android.
aptX Adaptive: As per the aptX HD but with even lower latency rates. Android.
LDAC: A Sony designed format that enables far greater capabilities than those of the Qualcomm formats. Android.
LHDC: Savitech developed format(s) with slightly higher sampling rates than those of the Sony LDAC format. Android.
There are some versions of LHDC and aptX that are not listed as they are identical in nature or available in a very small number of devices. Android.
So far, so clear so, much less compressed, but coaxing the best performance requires a little bit of tweaking. To allow transmission of 24/96 out of your Android device from stored or streamed music, you will need to unlock hidden settings in the form of Developer Option menus. Chrome OS and Android OS, are not similar and a Chromebook will not be able to offer the same capability. Apple smartphones use AAC format and as such are not able to transmit 24/96 content via Bluetooth.
While most recent Android phones are capable of utilising the various aptX formats, few will be able to overcome the self-imposed 48kHz/24-bit maximum resolution and sampling rates of the aptX HD and aptX Adaptive design. The 24-bit transmission at all sample rates and speeds is still subject to a form of mild compression. If a decent media player is used it will be capable of playing high resolution 48/88.2/96kHz/24-bit content, I used the JetAudio app. And those who assume that all streaming platforms offer high resolution music files should consider the fact that Spotify for instance is limited to 320kbps (so-called high grade MP3).
The above example is for Jet Audio on a Xiaomi Redmi 10pro smartphone, the process will vary with other player apps. When all the settings are correctly applied, the result can be astonishing. And when taking in to account that great sound can be had with a Bluetooth DAC costing well below £100, the happiness per kHz is increased yet again in an exponential fashion. The cause of hi-res Bluetooth DACs has been championed by the likes of iFi, FiiO, Audioengine, One For All and a host of brands that are not part of the audiophile world.
Fortunately most of the interaction required between smartphones and headphones or BT HD receivers will be negotiated automatically. But not all Android audio player apps can play 24/96. Some of those that do are listed below:
Poweramp 24-bit no specific sampling rate (kHz) is specified.
Onkyo HF specifies up to 24/192
Jet Audio 24/96 will be upsampled to 32/96
The sound quality available with carefully set up Bluetooth is a subject best left to the listener’s bias, ears, room acoustics and other factors that cannot be measured in any empirical fashion. But as mentioned, the sound per pound factor is astonishingly high. Consumers do not need to consider the expense of a wireless streamer, where the typical cost of a respectable specimen will start at £500-£600 and rise from there. In comparison, an LDAC, LHDS, aptX HD equipped Bluetooth DAC with a sturdy RCA L+R output and an optical digital output to boot, will set you back between £60-£160.
Components used in this evaluation:
Home audio system
CD: Resolution audio Opus 21
Amp: Krell 300i
DAC: Cambridge Audio DACmagic
Speakers: Apogee Stage ribbons
15” prototype active subwoofer with 200W A/B type power amp
Various single ended and balanced interconnects
Harmonic Technology speaker cables
The 1Mii Lava Audio DSP200pro Bluetooth DAC used on the occasion is equipped with a Sabre ESS converter chip that’s found in many high quality DACs. It favours Sony’s LDAC but has been tested playing every type of 24-bit content owing to a very lowly priced smartphone with every imaginable BT codec included in it.
The Lava audio DAC is housed in a minuscule box just 3.5cm thick and weighing about 120grams. It has a surprisingly high-quality RCA L+R output as well as a digital optical output.
Source 1: Dell i5 laptop- aptX (44.1kHz/16-bit), OS-Windows 10
Media player-Microsoft two media players. Source 2: Xiaomi Redmi 10pro smartphone (aptX/aptX HD/aptX adaptive/aptX adaptive+TWS/LDAC/LHDS) OS-Android 13
Media player: JetAudio app with high resolution audio mode offering upsampling of all content to 32-bit.
The immediate impression with the Lava Audio DSP200pro Bluetooth DAC was very favourable. It is transparent but the bass is a touch lazy. However once placed on an isolation gadget it has produced excellent, fast, rich bass. The soundstage is remarkably wide and tall and the image is portrayed correctly with depth and strong definition of instruments and voices, all projected behind the plane of the speakers. The experience exceeded all expectations, especially when considering the fact that this Bluetooth DAC cost me only £80 (current price on Amazon £99).
Those who have looked askance whenever the words ‘Bluetooth’ and ‘high resolution’ were uttered in their midst, may wish to reconsider, when properly set up Bluetooth can deliver streamed audio that sounds great at a very reasonable cost.