What does a Bluetooth audio receiver do?

A Bluetooth audio receiver is a device that allows you to add wireless Bluetooth connectivity to audio equipment. It receives audio signals wirelessly over Bluetooth and then outputs them to another audio device via a wired connection. The main purpose of a Bluetooth receiver is to make non-Bluetooth audio devices, such as speakers, headphones, car stereos and home theater systems, Bluetooth compatible.

Bluetooth audio receivers function by receiving digital audio signals that are transmitted wirelessly from Bluetooth-enabled source devices. This allows you to stream audio from smartphones, tablets, computers and other Bluetooth devices to your wired speakers or headphones. The audio is decompressed and converted to analog signals which are then amplified and output through RCA, optical, auxiliary ports or headphone jacks on the receiver.

In essence, a Bluetooth receiver provides a wireless link between your Bluetooth mobile device and your existing wired audio system. It allows you to stream music wirelessly from streaming apps, as well as take calls hands-free using your car or home speakers.

Receiving Audio Signals

Bluetooth audio receivers get audio signals wirelessly from Bluetooth-enabled source devices like smartphones, tablets, and computers. The receiver contains a Bluetooth radio transceiver that uses Bluetooth wireless technology to receive audio data transmitted over the 2.4 GHz radio frequency band from the source device (1).

The source device’s Bluetooth transmitter takes analog or digital audio signals from the device’s audio output and encodes it into a digital audio signal. This is done by an audio codec like SBC or AAC, which compresses the audio data to efficiently transmit it over Bluetooth. The encoded audio is modulated onto a 2.4 GHz carrier signal and transmitted to the receiver via the Bluetooth radio transceiver (2).

The Bluetooth receiver then receives and demodulates this carrier signal to extract the encoded digital audio data. The onboard audio codec decompresses the audio and converts it back into an analog audio signal. This reconstructed analog audio can then be amplified and output through a wired audio connection to speakers or headphones (3).

So in summary, the Bluetooth audio receiver leverages Bluetooth wireless technology to get audio signals by receiving, decoding and converting the digitally transmitted audio data from a Bluetooth-enabled source device back into analog audio signals (2). This allows the receiver to deliver wireless audio connectivity.

(1) https://www.jameco.com/Jameco/Blog/how-does-a-bluetooth-transmitter-work.html

(2) https://theauris.com/blogs/blog/bluetooth-audio-transmitter

(3) https://www.nytimes.com/wirecutter/blog/what-you-need-to-know-about-bluetooth-audio/

Audio Codecs

Bluetooth audio receivers support various audio codecs that are used to encode and transmit audio signals wirelessly. Some common Bluetooth audio codecs include:

AAC (Advanced Audio Coding) – An audio coding standard that is widely supported across many devices. It is the default Bluetooth codec used by Apple devices [1]. AAC aims to achieve better sound quality than MP3 at similar bit rates.

aptX – A codec developed by Qualcomm that is supported on many Android devices. It is designed to improve audio quality over the standard SBC codec by using higher bitrates. aptX aims to provide near CD-quality audio over a Bluetooth connection [2].

aptX HD – An enhanced version of aptX that supports high-definition audio up to 24-bit/48kHz resolution. It provides better than CD-quality wireless audio.

LDAC – A codec developed by Sony that supports high-resolution audio up to 32-bit/96kHz. It uses optimized coding and higher bitrates to transmit near lossless quality over Bluetooth [3].

SBC – The standard Bluetooth audio codec that all devices must support. SBC uses lower bitrates which reduces audio quality compared to other more advanced codecs.

The supported audio codecs determine the maximum audio quality that can be transmitted over Bluetooth to the receiver. More advanced codecs like aptX HD and LDAC allow high-resolution wireless audio playback.

Amplification

Bluetooth audio receivers contain built-in amplifiers to boost the audio signal received over Bluetooth before sending it to the connected speakers or headphones. The amplifier takes the low-power audio signal from the Bluetooth receiver chip and increases its voltage and current to drive loudspeakers that require more power for quality sound reproduction.

How Does a Bluetooth Amplifier Work? – Auris, Inc explains that amplifiers in Bluetooth receivers allow the small signal from a phone or tablet to be amplified up to the level needed for full-range stereo speakers. The amplification makes it possible to get room-filling, high-fidelity sound from portable Bluetooth devices.

Without an amplifier, the audio signal would be too weak on its own to properly drive most speakers or headphones, resulting in low volumes and poor sound quality. The amplifier takes care of this by boosting the signal to the appropriate line level or speaker level output. Higher quality amplifiers with good circuit designs and power supplies will be able to reproduce the audio with greater fidelity, dynamics, and volume.

Audio Outputs

Bluetooth audio receivers offer various audio output options to connect to speakers, headphones, or other audio equipment. Some of the most common output types include:

RCA – The receiver will often have a left and right RCA output to connect to powered speakers, an amplifier, or other RCA input devices. RCA outputs provide an analog stereo signal.
3.5mm Headphone Jack – Allowing you to connect headphones directly to the receiver. Some models may have both a 3.5mm headphone and RCA output.
Optical/TOSLink – An optical digital audio output compatible with devices that have an optical input like soundbars, AV receivers, and more. Optical can transmit surround sound like Dolby Digital.

Coaxial/SPDIF – A coaxial digital audio output that functions similar to optical but uses an RCA style connector.
6.3mm Headphone Jack – Some higher end models may have a 6.3mm output for connecting audiophile headphones.

The audio output options allow the Bluetooth receiver to connect with a wide variety of audio equipment from basic speakers to sophisticated home theater systems. Models with both analog and digital outputs provide the most flexibility.

Bluetooth Versions

Different versions of Bluetooth technology have varying capabilities when it comes to audio quality and range. Here’s a comparison:

Bluetooth 1.0 and 1.1 had monophonic audio quality, which means they could only transmit a single audio channel rather than stereo. The range was also very limited at only 10 meters (32 feet).

Bluetooth 2.0 introduced support for stereo audio and increased range up to 10-30 meters (32-98 feet). This allowed for improved audio quality on headphones and speakers.

Bluetooth 3.0 didn’t improve audio capabilities much but increased data transfer speeds. Range remained 10-30 meters.

Bluetooth 4.0 brought a major boost to range, extending it up to 60 meters (197 feet) through improved antenna technology. This allowed connections to be more stable. The audio bitrate remained similar to older versions, though some codecs like aptX provided higher quality.

Bluetooth 5.0 again dramatically increased range, now up to 800 meters (2,600 feet) through changes to the radio system. It also doubled the bandwidth, paving the way for high-resolution audio support. Tests show little audible difference between Bluetooth 4.2 and 5 for music listening.

So newer Bluetooth versions allow for longer range and improved audio quality, especially with high-bandwidth codecs, even though Bluetooth 5+ headphones don’t necessarily sound much better than Bluetooth 4.2 for normal music playback.

Power

Bluetooth audio receivers get their power from a few different sources. Many devices use a standard USB connection to draw power when plugged into a USB port, power adapter, or external battery pack. This allows them to be powered by computers, wall adapters, portable batteries, and vehicles. Some Bluetooth receivers run on disposable or rechargeable batteries like AA or AAA batteries. This gives them portability for use away from power sources. Higher-end home and car audio Bluetooth receivers may have an AC adapter to plug into an electrical outlet. This provides consistent power without draining batteries. Some devices also allow pass-through charging, so they can charge a connected smartphone or audio device while powered over USB. Choosing a receiver with the right power options is important depending on the intended application and portability needs.

Applications

Bluetooth audio receivers have many common applications in people’s lives. In the home, they allow you to add wireless streaming capabilities to existing speakers or home stereo systems that lack Bluetooth. This eliminates the need to buy new wireless speakers just for streaming music services, podcasts or audio from a smartphone or tablet (Source). A Bluetooth receiver easily connects existing wired speakers to modern devices.

In the car, a Bluetooth receiver can be used to add wireless calling and music streaming to older vehicles without built-in Bluetooth. The receiver plugs into the auxiliary input and allows the car stereo to play phone calls and audio from a smartphone wirelessly. This is a low cost way to add hands-free calling and wireless music to an older vehicle (Source).

For portable Bluetooth speakers without a headphone jack, a Bluetooth receiver allows you to connect wired headphones. The receiver plugs into the USB charging port on the speaker and transmits the audio wirelessly to headphones. This allows private listening from a portable speaker.

Bluetooth receivers are also commonly used to add wireless connectivity to wired headphones. A small receiver plugs into the headphone jack and pairs wirelessly with smartphones, tablets and computers for music or calls. The user gains the freedom of wireless listening while still using their preferred wired headphones.

Brands

Some of the top brands for Bluetooth audio receivers include iFi Audio, Audioengine, Avantree, TaoTronics, 1Mii, and others. Popular models from these brands include:

iFi Audio Zen Blue – An audiophile-grade Bluetooth receiver known for its high-end DAC and support for hi-res audio codecs.
Audioengine B1 – A premium Bluetooth receiver with analog, optical and HDMI ARC connectivity options.

Avantree Oasis Plus – A budget-friendly receiver with low latency aptX LL codec support.
TaoTronics TT-BA08 – An affordable receiver with dual connectivity allowing two Bluetooth connections.

These major brands offer Bluetooth receivers across a range of price points and with different feature sets. iFi Audio and Audioengine products cater more to audiophiles, while brands like Avantree and TaoTronics offer budget-friendly options.

Conclusion

A Bluetooth audio receiver is a useful device that provides wireless connectivity to audio sources. Some key benefits of using a Bluetooth receiver include:

Enables any audio system to receive wireless audio signals from Bluetooth-enabled devices like smartphones, tablets, and laptops.
Allows easy streaming of music, podcasts, audio books and more to home and car stereos without cables.

Offers ability to add Bluetooth functionality to older audio equipment.
Provides options for amplifying audio and connecting to various outputs like RCA, optical, and headphone jacks.
Supports newer Bluetooth versions for higher quality audio and extended range.

Compact and portable design that’s easy to set up and use.

In summary, a Bluetooth receiver is a simple and convenient way to make audio systems wireless compatible. It brings key connectivity and flexibility benefits for music listening and other audio applications.