How can I transfer audio over WiFi

Here's how it works: Stream sound from your cell phone to audio devices

Stream sound from smartphone to audio devices
Image: Almost all hi-fi systems, amplifiers, but also many kitchen radios, boomboxes and other devices have audio inputs (AUX). HiFi systems are mostly cinch inputs, while smaller devices often have a 3.5 millimeter jack socket. In order to connect the sound from the smartphone in a wired manner, the user needs a cable connection from the headset output of the smartphone to the desired playback device. Corresponding cables are sometimes already included with the smartphones as accessories, otherwise they are available from specialist retailers.

Wired connection: Cinch, jack & Co.

Stream sound from smartphone to audio devices
Image: The user only has to select the AUX function on the audio device (sometimes the designation is different, for example "External" or "MP3") and the user can use an Internet radio station, a music streaming service or his own Play music files from the smartphone. All other audio inputs (such as CD players, tuners, tape decks, MP3 players, etc.) can also be used with hi-fi amplifiers. The exception is the phono / turntable input, as it is designed for a different voltage (2 mV instead of 200 mV at 1 kHz).

Smartphones can also be connected to numerous other output devices for sound transmission, for example home theater receivers, soundbars, active speaker systems or even televisions. An audio input is required in each case.

It is also possible to forward music files stored on the smartphones to audio output devices via USB, if these have a corresponding USB connection. In this case, the user connects the mobile phone to the USB input of the audio device via the charging cable output. With a USB connection, however, smartphones must be switched to mass storage mode (with Android via: Settings - Wireless and Networks - USB connection: Mass storage), the music files are then controlled from the audio output device, e.g. the hi-fi system.

Wireless connections: Bluetooth and WLAN

Wireless connections for audio transmission are popular. This is convenient for the user, who can, for example, conveniently control music files or Internet radio stations from the couch using their smartphone, for example using Bluetooth technology. If the audio output device, such as the hi-fi system, the AV receiver or the soundbar, has a Bluetooth function, the user can stream the sound from the mobile phone wirelessly. After activating Bluetooth on the smartphone, the name of the audio device appears on the display and the user can establish a connection. The sound can then be heard on the hi-fi system, for example. In most cases, the user has to switch on the Bluetooth function here as well, some devices also automatically switch to this mode.

Bluetooth speakers are becoming more and more fashionable. These are now available in all price ranges - from the small mobile box for 15 euros to the high-end wireless speaker for over 1000 euros. Such wireless boxes can completely replace kitchen and bathroom radios as well as hi-fi systems. The control center is always the smartphone, here the user selects an Internet radio station, a music album or a music streaming program and transmits the sound wirelessly to the loudspeakers. We have presented some inexpensive models in this overview.

It is also practical to network different music sources and speakers across multiple rooms. In technical jargon one speaks of multiroom systems. Instead of Bluetooth, the signals are mostly distributed in the home network via WLAN. To do this, the user has to load an app, connect the smartphone and boxes to the router and can then control the individual speakers in the various rooms from the smartphone. It is possible that all speakers play the same thing, but they can also play different music sources, for example an internet radio station in the living room and a music album in the kitchen. We have already explained the principle in more detail in this guide.

Older audio output devices and those without an audio input can also be used wirelessly to play music from the smartphone. The sound can be transmitted to a free radio frequency via a mini FM transmitter. Such small VHF transmitters are available in stores from around 10 euros. The transmitter is simply connected to the headset output of the smartphone. The sound can be received with any conventional FM radio within a radius of up to 10 meters.

Apple and Google developed and launched their own streaming technologies. Apple's Airplay allows music and videos to be played back to compatible receivers - these can be speakers or home theater systems. Google Cast, on the other hand, is a protocol that smartphone apps can use to view and control media content on a television. To do this, the user must have a Chromecast HDMI stick. The Chromecast Audio is used for pure audio purposes. We have already tested this.