Many of our readers are familiar with the term "convergence", which implies the interaction between different digital devices. Indeed, who modern world Do you need devices that cannot communicate with each other? But there is also the other side of the coin: more devices provide our digital leisure, the more wires we have to endure in the apartment. To everyone electronic device power supply is required, there is no escape from this. In addition, wires are also required for the interaction of devices with each other. So, let's say a DVD player has to be connected to a TV with a cable, music Center- to the speakers, the computer - to the monitor, and so on. Usually in an apartment you can count a dozen different cables, or even more. Even in order to listen to music not on a computer, you have to lay wires! But it is not all that bad. A lot of devices have already appeared on the market that allow you to enjoy music anywhere in the apartment without annoying wires.
Music without wires
Traditional cassettes and audio CDs are slowly giving way to MP3s and other audio formats. Indeed, today any player "understands" different formats of compressed audio, which previously could only be played on a computer. And the computer itself is gradually becoming a repository of music, sending racks with discs to a well-deserved rest. The computer has become truly the center of the "digital universe". But a problem arises: how to listen to music from a computer on household appliances? It is unlikely that you will enjoy, for example, burning music on a CD in order to then play it on a music center. Yes, and laying a web of wires is also not the best way out.
Today, solutions have appeared on the market that allow you to transfer music wirelessly. As a rule, they consist of a transmitter that connects to a computer via USB, and a receiver that is already connected to the music center. Sometimes the receiver contains an amplifier and allows you to directly connect speakers, for example, 2.1. Music is read from the computer and transferred to the receiver without any extra wires. There are also mobile solutions, combining speakers and a receiver in one case. The choice is quite extensive, you can buy a similar system, focusing on the criteria of quality, portability and size. If technology allows, then you can listen to music even in the courtyard of the house.
Most often, wireless communication uses a frequency of 2.4 GHz and supports a range of up to 30 meters. Many companies rely on proprietary communication technologies that require no configuration and work immediately when you take the receiver and transmitter out of the box and turn them on.
Some equipment relies on standard technologies such as Bluetooth. With the advent of version 1.2, the range of Bluetooth communication has increased to 30 meters (up to 100 meters with line of sight). There will be no connection problems here either, since the transmitter and receiver are usually sold as a set. A Bluetooth connection is created automatically after the receiver and transmitter are turned on.
Another option - WiFi network. In this case, you will most likely buy only the receiver. For such a connection to work, it is necessary to existing network WiFi. As a rule, such products provide the widest range of features and functions.
Finally, it is possible to transfer music over the usual electrical network that is already installed in your home. Installation is also simple and should not be difficult. Just plug the receiver and transmitter into an outlet.
Products Apple It's always nice to test. This manufacturer is always trying to offer products that are innovative in one way or another.
The Airport Express is a cross between a computer accessory and consumer electronics. In addition to transmitting audio over a WiFi network, the device works as a wireless access point and even allows you to connect a printer. The base of the Airport Express is very compact. If you want to use the base as an access point, for example, to connect your computers via wireless network to the Internet, it is enough to connect the base to an ADSL or cable modem via an RJ-45 socket.
Since there is no display on the base, configuration will have to be done through the Assisting Airport Express utility. On a computer that needs to be equipped with a WiFi card, the AirTunes app must be installed. It can interact with iTunes so you don't have to reorganize your music library. From the base, you can give an audio signal in both digital and analog form. The sound quality is just great. There are no delays or pauses. The range of the Airport complies with WiFi specifications, that is, it is just enough for an apartment.
There are no control buttons on the Airport Express. Therefore, to change the music, you will have to turn to the computer. Airport Express is an interesting universal solution that will allow you to create WiFi networks and enjoy music anywhere in your apartment. More detailed information available on the Apple website at the link below. At the time of publication, the base Apple Airport The Express retailed for about $160.
Devolo specializes in network devices using for communication electrical wiring. The company uses reliable CPL transmission technology certified by EDF. The Audio dLan solution is very easy to install, as it is enough to plug the receiver and transmitter into an electrical outlet. Then connect the transmitter to the PC via USB interface or LAN network, and the receiver - to the headphones or music center. The sound quality is excellent. We did not experience any pauses or delays. And the range is one of the best in our testing. Theoretically, CPL allows you to cover an apartment of up to 200 m². The receiver and transmitter work fine, even if you turn them on through an extension cord.
The connection is made automatically. Software very easy to use. It is enough to install a special plugin for Windows media player or winamp. Then, when the player starts playing music, it will be automatically transferred to the receiver. Unfortunately, all operations with music (track change, pause, etc.) will have to be performed on the computer.
Interestingly, the Audio dLan receiver also allows you to transmit an audio signal to a computer. You can connect a microphone or any other source to the audio input of the receiver, which becomes a transmitter, and then record the sound on the computer. This feature is very interesting, for example, for recording vinyl discs from a Hi-Fi system.
The transmission quality is excellent. We did not feel any restrictions if we stayed within the same electrical network. But the price of such a solution is quite high, and it is very difficult to find Devolo equipment in Russia.
A very compact Wireless Music System (WMS) for PC consists of two parts. The tiny transmitter resembles an ordinary USB key fob. A receiver, also very small, is connected to the music center. A retractable antenna is built into the receiver and transmitter. To transmit sound, the receiver has outputs "mini-jack" and "tulips". Therefore, without unnecessary adapters, you can connect the receiver to a music center or headphones. The receiver also has a power socket.
On the top panel The receiver contains control keys (stop, play, pause, etc.), volume control and mute.
The connection between the receiver and the transmitter is very simple. It is enough to press the "Connect" keys on both modules, after which the connection will be established. As soon as you connect the USB transmitter to your computer, it will start working as an audio output. That is, all music played on the PC will be transmitted to the receiver. Best to use Windows Media player. Then you can control playback using the keys on the receiver.
Logitech has also included a remote control in the box. The transmission system is compatible with WiFi networks and is able to cover the entire apartment and even the house, if the communication conditions are normal. The transmission quality is excellent, there are no pauses or delays. If you want to stream music to multiple devices at the same time, you can purchase Logitech receivers. The Logitech Wireless Music System retails for $130 at press time.
The SLA5500 is part of Philips' Connected Planet line. All products in the line use a WiFi wireless network and allow you to stream audio and / or video.
The SLA5500 solution is designed for music transmission. Stylish gray body goes well with other household appliances. You can connect headphones, multimedia speakers or a music center to the case.
The SLA5500 requires a PC and a WiFI wireless network or, better, a wired network to operate. Receiver setup is done on screen using the supplied remote control.
For a PC, you need to install Philips Media Manager, which allows you to create a music library with playlists. It should be noted that the SLA5500 also supports Internet radio stations, and you can listen to them even without a computer. Finally, WMA 10 online music playback is supported.
Thanks to WiFi after initial setup the connection works reliably. The sound quality is good. And the range of action also pleasantly pleased us. The remote control allows you to conveniently control all the functions of the SLA5500.
Saitek's product range is quite extensive. In addition to game controllers, this manufacturer also produces audio equipment. Externally, the A-250 resembles a compact cassette player. Appearance really classy.
Saitek A-250 can be used as external speakers paired with a player via a 3.5 mm mini-jack input. But we are more interested in wireless capabilities. To use them, you need to connect a USB Bluetooth transmitter to your PC. No driver is required because the USB stick is recognized by Windows as external sound card. After connecting, you can immediately apply sound to it.
The A-250 receiver has a small LCD screen that displays, among other things, the quality of the Bluetooth connection and the volume. A separate power key is responsible for turning on the receiver, two keys allow you to adjust the volume, and the remaining three keys are responsible for playback and skipping the track forward and backward. To listen to music, you must use Windows Media Player, in which it is enough to create a playlist.
For such a compact design, the sound quality is excellent. Of course, everything here depends on your preferences, but the A-250 room will be able to pump. For power, you can connect both a power supply and install four AA elements inside (they last for six hours). Not a bad solution for mobile music enjoyment. At the time of publication, the Saitek A-250 was sold at retail for 4,800 rubles.
The Terratec Noxon system is equipped with a wide blue LCD screen that displays the titles of music stored on the PC. The package includes a remote control. From the connectors there is a power socket, USB, network and audio outputs.
Communication with a PC is carried out via a wired or wireless WiFi network of the 802.11g standard. USB port allows you to connect a flash key fob or player for direct music playback.
You can connect headphones, multimedia speakers or a music center to the receiver (the kit includes an adapter from "mini-jack" to "tulips"). There is also a digital output that allows you to connect a receiver to the receiver. The setup is relatively easy once you know your WiFi settings. The sound quality is very good, and the range too (it complies with the WiFi standard).
On the PC side, it is enough to install Windows Media Connect and give it to general access music files. Then you can directly play music from PC by selecting the desired song on the LCD. It is possible to listen to Internet radio stations. It should be emphasized that the Noxon system can work with DRM. Therefore, you can listen to online music in WMA 10 format.
How I really wanted to do everything on WI-FI ...
Of course, one could start this article with a lyrical digression about the "smart" houses of the future (or apartments), in which miniature (or not so) are everywhere. sound speakers, delighting the owners with music. It will probably happen in the near future, when every device in our house will be equipped with a penny WI-FI adapter. But for some reason, at present, such technical solutions related to wireless sound distribution over WI-FI can cost some unreasonable money. Here, for example, are multi-room systems from SONOS, where there is only one! wireless WI-FI column, will cost the buyer more than twenty thousand rubles.
In general, a good article of 2016 about WI-FI distribution audio is called “Wireless audio systems: crooked, expensive, very interesting”, where the last two words of the title reflect the author’s hope that in the future at least something will finally change for the better.
So, until the Chinese overwhelm us with cheap audio speakers with their famous ESP8266 chip (which allows you to establish a full-fledged data exchange via WI-FI with the target device and which enthusiasts shove anywhere up to light bulbs and coffee makers, etc.), we can only turn to already proven time technical solutions.
1. Wires. (which, as it were, is already discordant with the title of our article)
2. Bluetooth.
3.FM radio.
Specifically, in my case, I wanted to listen to musical compositions launched on the computer throughout the apartment, so much so that the sound came from wherever it was possible and impossible. For this purpose, 12 active speakers were originally placed in a whimsical order on window sills, cabinets and bookshelves under the ceiling. There was also a TV responsible for the whole wall. I also wanted to use its sound reproducing system in parallel, since I already had a wireless HDMI transmitter installed (you turn on the movie on your computer, and you watch it with sound on TV and no brake dongles or media players with forever outdated video formats).
So part 1. Or maybe make everything simple? ..
Initially, I laid a lot of things with wires. In principle, along the windows and at a distance of up to 10 meters, everything turned out quite civilized and imperceptible, and as it turned out, the output of the computer's sound card perfectly pulls even a dozen active speakers connected in parallel (it has been pulling for two years, by the way).
But with the rest of the walls and doorways, and even in other rooms, everything was no longer so cloudless. Obviously it was required to transmit sound through the air. Yes, and I also wanted to turn on the TV in common network(in vain, perhaps, is the Japanese quality disappearing there?). Then I decided to use Bluetooth technology ...
But as they say, everything has long been stolen invented before us. Back in 2006, the notorious LOGITECH company released the so-called Logitech Wireless Music System for PC with a reasonable price of $75. you received in bluetooth hands a transmitter connected to your computer, and already it distributed sound to the same bluetooth receivers in the amount of up to four, which was quite suitable for my requests.
The only major drawback of this device was that it had been discontinued for about five years, if not more. In principle, you can still buy this device on eBay, if you have a desire. But here in Russia you won’t find it during the day with fire. I found only one set in Moscow. But there was only one receiver when I needed, well, at least two. The search for similar devices from other manufacturers also did not bring success, the only thing I constantly came across was either just ordinary Bluetooth speakers, or another device from the already mentioned company, the so-called Bluetooth Audio Receiver (which, fortunately, has not yet been removed from sale ).
In general, this is the same Bluetooth receiver that you can connect active speakers to, but without the possibility of networking until you have a transmitter. And we don't have it. Or is there? Maybe it's still possible to somehow distribute sound to several such devices directly from our computer, which will be a Bluetooth transmitter?
I tried to try. In the presence were: a Bluetooth speaker, Bluetooth headphones and the aforementioned Bluetooth Audio Receiver (it can also be called the Logitech BT Adapter Stereo), with ordinary active speakers connected to it.
The very connection to the list of playback devices on the computer (hereinafter, by default, we will talk about Windows family) was trivial (standard for all bluetooth devices) and does not deserve separate consideration.
It turns out in the end, something similar to the following picture.
Now you can try to listen to all the audio devices we have connected. As it is easy to find out in the end, we can only listen to one device, namely the one on which the green tick(which means default device). The rest of the audio devices are silent like fish until they get the desired tick. On the one hand, this is understandable, but on the other hand, it is a little surprising if we conduct a simple experiment.
Let, for now, the default sound output is Real High Definition Audio. This is the usual line output of a computer sound card. By attaching ordinary wired headphones to it, we will directly verify this. They reproduce in this moment sound. But if we click right click click on the wireless headphones that are still silent (in my case, this is MDR-ZX330BT Hands-Free), and select the “Advanced” property, and in it “Check”, then we will hear how the headphone speakers alternately blink. That is, they are normally connected, they can broadcast sound (test), but here is the music, like the wired ones that are working now, shish with oil.
That is, theoretically, Windows can push sound to all devices at the same time (taking into account, of course, the performance of the computer), but does not want to do this. You can only choose one thing (actually two).
The only possible trick to listen to two audio devices at the same time in Windows is to use the stock stereo mixer.
One of the devices should be the computer's audio line-out (the one to which you connect wired headphones and speakers). I have it labeled as Real High Definition Audio. It should be in the "Default Device" state. Now let's select the second audio device.
Go from the "Playback" tab to "Record", "Stereo Mixer", "Properties", "Listen". In the drop-down list, select the audio device we need
I chose the Logitech BT Adapter Stereo I have. Now you can play music on these two audio devices at the same time. And they really will be played at the same time.
However, this scheme has two drawbacks. The first - the limitation of two devices can still be experienced. The second drawback, which crosses out the entire scheme, is that the sound sounds out of sync. Music on the bluetooth channel (as well as on the television HDMI), LACKS behind the music played through the line audio output. The difference is about 0.2-0.3 seconds, but because of this, listening to 99% of the soundtracks is simply impossible, because in the end you hear a sound mess. In rare cases (there are sounds of nature or all sorts of bells), such a desynchronization is even funny in its own way, a sort of effect of depth and presence is created. But just music, especially songs, is simply unbearable to listen to.
The problem here is probably the buffering of digital data for wireless transmission, due to which the signal delay occurs. But it ends up ruining everything. If it were possible to somehow adjust the signal delay for the linear audio output, then the desynchronization situation could be corrected by manually setting the duration of this delay, for example. But unfortunately regular Windows tools they don't seem to have such a possibility.
It would seem that then you can not use the standard audio output, but take, for example, one Bluetooth device by default, and pass the second through the aforementioned Windows stereo mixer. Then the delays in buffering will be the same, there will be no desynchronization, and we will still get two simultaneously playing devices. But again, unfortunately, we will not succeed, since this scheme with a stereo mixer only works if one of its participants is a linear audio output.
It comes out just like in the book "Three in a boat, not counting the dog" with one of its characters:
“Then Harris began to tell us stories about how he crossed the English Channel in such a storm that the passengers had to be tied to their bunks, and only two people on board - himself and the captain of the ship - resisted seasickness. Sometimes the ones who resisted seasickness were himself and the second mate, but invariably it was himself and someone else. If it wasn't himself plus someone else, then it was him alone.
As they say, nothing to add and nothing to take away. Linear audio output is Harris. And still, after that I was not disappointed. After that I tried my luck with an FM broadcast...
Part two. FM transmitter. Help ultrashort waves.
After reading the relevant article on Habré, a plan to build a radio network immediately arose in my imagination, where in the center there is a small FM transmitter connected to the audio output of the computer, and around it, throughout the apartment, respectively, there are five FM receivers, from the output of which already ordinary active speakers. It turned out to be easy to implement the idea.
A car FM transmitter was bought for 500 rubles, with a line input; in the documentation, it passes as an AUX input (by the way, not all transmitters have it! USB inputs, everyone has memory card reading, but the simplest line input half of these devices no longer exist!).
True, I had to modify it a little, since twelve-volt power outside the car is rare. Therefore, I connected a cord to the USB transmitter, from which I took five-volt power wires and soldered them to the input of the 3.3-volt voltage regulator already inside the transmitter itself (there on printed circuit board everything is marked, it is difficult to make a mistake). I connected the audio output of the computer to the AUX input of the transmitter, and when turned on, it began to stably broadcast radio waves at the default frequency (its value can then be adjusted with the buttons if desired).
Accordingly, for the receiving part, such an FM receiver was purchased:
A pleasant feature of this device was the presence of a female connector for headphones, where the male connector from active speakers perfectly went. If you tune the receiver to the desired frequency, and it is also very conveniently tuned with buttons, and not like the old fashioned way with a vernier or wheel, then you will hear exactly what your FM transmitter transmits - THIS beautiful warm radio sound. You immediately remember your childhood when, among the crackling and whistling, you catch banned songs from the BBC. It's not some cold clean computer sound!
In short, no matter how I changed the frequencies on the transmitter and, accordingly, on the receiver, I did not manage to achieve a normal clear sound. Actually, when the music itself is playing, the interference is not yet very audible, but as soon as there is a pause, you will hear all possible radio turbulences within a radius of ten kilometers. I'm not talking about the case when you are NOT listening to music, but just let's say you are sitting at a computer; but even then you also hear a continuous crackle and police talks - the receiver is working, something is catching.
Therefore, plans for transmitting sound over FM channels also had to be abandoned.
Part 3. Everything is a program...
At first, I was looking for mixer programs. Somehow hope didn't leave me programmatically organize a signal delay at the audio output of the computer in order to listen to at least two audio devices simultaneously without desynchronization. And digital mixers are supposed to do that sort of thing. But as it turned out, basically these programs are able to mix audio tracks from different sources into one final one, but to breed from one to different devices playback, they are somehow not very good, that is, this is definitely not their main function. And even if this function exists, it is buried somewhere deep in the bowels of the settings, from where it still needs to be dug out. In addition, you need to manage to somehow integrate these mixers into the audio stream of the same browser, from which, for example, you listen to music.
But going through all these mixers and audio editors, I came across an interesting Virtual Audio Cable, with the help of which I finally solved all my problems.
Quote:
The program creates several audio devices in the system, called "virtual cables", each of which contains an input and output device for sound. Any application can send its audio stream to the "output" part of the cable, while any other application can receive audio from the "input" part of this virtual cable. The transmission takes place entirely in digital form, due to this the sound quality is not reduced.
The program seems to be initially paid, but it will not be difficult for you to find its free version either. And once you've made your choice, all you have to do is run it and apply it to our connected audio devices. In my case, these were: a SHARP TV connected to a computer via a wireless HDMI channel.
Two pieces of Bluetooth Audio Receiver with active speakers attached to them. There are four speakers on one adapter, eight on the second.
Bluetooth headphones «SONY MDR-ZX330BT
Bluetooth speaker BoomBot 2
Now we will try to make all these devices function in parallel and without noticeable delays. To begin with, we check in the list of equipment that all these devices are already connected and ready to work (this is important, connecting on the fly is fraught with glitches). Looking ahead, I’ll say that the only thing we won’t use is the computer’s linear audio output, because, like that hero from a book, he always pulls the blanket over himself (yes, Harris was also different in this). To completely neutralize it, we stick the cheapest wired headphones into it, such as these:
We put Real High Definition Audio (line output) in the list of devices as the default device, set playback from it in the “Stereo Mixer” (see above), throw the headphones behind the system unit and forget about it now forever.
Now let's install the Virtual Audio Cable program. In the folder of the program itself and the x64 subfolder (for those who have 64-bit Windows) there are two files we need to execute: vcctlpan.exe and audiorepeater.exe (which we will simply call “audio repeater” in the future).
Let's run the first one first:
In it, we actually set the number of virtual cables - one, and the signal sources "Line". We close the program, we no longer need it. We now launch the browser, and in it some Youtube composition. If everything is in order, then we will hear a barely audible sound from somewhere behind system block. This earned wired headphones.
But from the second file "audiorepeater.exe" we make a shortcut directly to the desktop, we will need it regularly.
Now we open it for the first time and change two lines in it: from the “Wave in” drop-down menu, select “Stereo Mixer”, since we routed the audio channel through it, and from the “Wave out” drop-down menu, select the TV and click “Start” . The TV should sound. As before, the sound from it will lag behind wired headphones, but we won't care anymore, we just won't hear them.
In general, as it turned out, the “Wave” in line can not be changed, but the original “Reassignment of sound devices” can be left. It seems like the program itself understands where the desired input is by default. Therefore, we do not even touch this line in the future. We save energy.
Now we start a new instance of the audio repeater. In it, select the first Bluetooth Audio Receiver (it is slightly different from the second in the name) and click "Start". Speakers connected to this receiver begin to vote.
We do the same with the second Bluetooth receiver. Now the speakers connected to it are singing.
Now we are taken for the BoomBot 2 wireless speaker.
And the final touch - wireless headphones MDR-ZX330BT. Are they playing?
Please note that due to approximately the same buffering delays, no desynchronization of the sound is felt (by the way, it can now be adjusted by changing the value in the "Total buffer" field). Sound quality? To be honest, I'm not an audiophile, I'm fine with it. Although, of course, professionals in this field will scold me for both bluetooth transmission and speakers. As for the communication range, within the same room, the signal passes steadily at a distance of ten meters (I didn’t measure it anymore, the apartment was over) and successfully overcomes one interior partition.
Of course, I would like to use a linear audio output, since it is available. But again there is a problem of desynchronization. It would seem that the signal to it can also be passed through an audio repeater and set a delay, but alas, it will still be played in parallel with the audio output itself. That is, for some reason it is always present both in the virtual cable and in the present. Maybe someone will be able to defeat him, but I did not succeed.
Now about some subtleties. Not all wireless devices are enabled by default, such as the TV or headphones. Therefore, when you turn on the computer, Windows assigns some “live” device at that moment as the default device. That is why we use the same wired headphones as such, so that we are guaranteed to always have the same default playback device (and since they always turn on simultaneously with the computer, the system finds them first). Accordingly, in a stereo mixer, the signal is also reproduced through them, but even if there are sound overlays, we don’t care anymore (we can’t hear them). But if they weren’t there, then Windows, at startup, would assign some currently enabled device as the default device. remote device, and even duplicated it through a stereo mixer. You can, of course, check the list of devices at startup every time, but it seemed convenient to me to put a “stub” in the form of wired headphones and forget about these nuances. By the way, the stereo mixer itself cannot be turned off, nothing works without it.
And now about the fly in the ointment in our barrel of honey:
1. The number of devices connected via the Bluetooth program cannot be brought to the theoretical limit (71 pieces, like?). In reality, a maximum of three such devices work at the same time absolutely stably for me. Well, plus a TV via an HDMI channel to them (it seems that he absolutely does not care about the number of neighbors; it always works correctly). Already four bluetooth speakers begin to stutter sooner or later, and the "VirtualCable" buffers overflow. There is a version that it could be bluetooth adapter and the sound card of the computer itself no longer has time to distribute their audio streams.
2. Not all Bluetooth devices are compatible with each other. When I tried to connect an additional "Defender" wireless speaker, it suddenly started to conflict with the BoomBot.
In general, they tried to sing at the same time, but they only succeeded in taking turns. And they did not conflict with other devices. Only with each other. This issue also needs to be studied.
In the end, after all, I got what I wanted, even in such a limited quantitative version. You can listen to the birds singing in the forest and in the living room and in the bedroom, or watch the flames play in the fireplace (on TV, of course) and firewood crackle, and outside the window the winter wind howls or the rain pours or the waves splash. Youtube is full of these hours of videos. You can share the screen on the computer, let the children watch cartoons on TV additional screen and sound, and to work and listen to music on the computer itself through wireless headphones (or watch a teleconference on it), while the wife reads a book in the bedroom and listens to birds singing in the forest through wireless speakers. Well, and so on.
I will be glad if my article is useful to someone.
Tags: Add tags
This article is printed specifically for beginner radio amateurs, in which we will tell you how to transmit a musical signal without wires! In the previous article, we talked about a device that can wirelessly charge, for example, a mobile phone, or power LED lights without connecting them to a power source. This article describes in detail the circuit for transmitting sound over a laser beam.
First, about the design. The sound signal is from a mobile phone or a PC, that is, we need a low-power sound source with a power of less than a watt. The signal is then fed to the primary winding of the transformer. The same signal comes out of the secondary winding, and<умощняется>using a battery, then the signal is fed to the laser diode.
The laser beam is directed to a photodetector, which, in turn, is connected to the input of a low-frequency power amplifier. Thus, the music is transmitted wirelessly for several meters. I must say that the device performs a fairly high-quality sound transmission and there are no distortions in the transformed music, though low frequencies are not very powerful.
So, let's get down to business. The laser is an ordinary toy laser, which can be purchased at the store for $ 1. The transformer is ferrite ring from the power supply, it contains two windings. Primary winding- 15 turns of wire with a diameter of 0.8 mm, secondary - 10 turns of wire with the same diameter as the primary. You can generally abandon such a transformer and use any network, with a secondary winding of 6 or 12 volts.
A transformer is needed with a power of no more than 20 watts (more is possible, but it makes no sense). The circuit uses a standard lithium-ion battery from a mobile phone, it can be replaced with a stabilized power supply with a voltage of 3.5-4 volts and a current of no more than an ampere. The laser is connected through a 5 ohm 0.5 watt limiting resistor. This laser can be replaced with an ordinary one, but then the music transmission range will be no more than 40 cm.
You can supplement the LED with DVD laser optics and achieve a longer transmission, while you need to concentrate the light into one beam. We will have a solar module as a photodetector.
Its parameters are the maximum voltage up to 14 volts, with a maximum current of 100 mA. Why did you use the solar module? It just has a large area, and so you can use any kind of photodetectors, of any size. The device for wireless sound transmission is ready.
It works very well, and most importantly - it has the simplest design! It turned out to be a great gadget for a PC, you can turn on music on your computer, go to another room and listen, and the sound goes without wires! Thank you for your attention - AKA.
Discuss the article WIRELESS SOUND TRANSMISSION
Wireless technologies Audio transmissions are becoming increasingly popular in the Hi-Fi market and are being actively adopted by audio companies.Save and read later - 
Wireless audio transmission technologies are becoming more and more popular in the Hi-Fi market, and they are being actively adopted by companies specializing in the production of audio equipment.
Conventionally, all currently existing methods of signal transmission between audio devices can be divided into three classes. The first are technologies developed and patented by the Hi-Fi companies themselves. They imply the presence in the playback device (for example, an active acoustic system) signal receiver, as well as an external transmitter (supplied in the kit, or purchased separately), which must be connected to the signal source. Examples of such systems include Dynaudio and Audio Pro acoustics, as well as Arcam docking stations.
Another class of Hi-Fi equipment involves the use of Wi-Fi transmission, for which the playback equipment must be connected to an existing wireless network (with the assignment of an IP address). After that, it will be possible to stream the sound broadcast from any device (PC or portable gadget) operating in the same "grid". As one of the varieties of this kind of connection, AirPlay can be mentioned, which provides a direct connection between the receiver and the transmitter, provided that the iTunes software player is used to listen to music.
third kind wireless communication in audio, which will be the subject of our closer examination, is Bluetooth. Introduced to the market more than 10 years ago, initially this technology provided not very high sound quality, and was used to create wireless headsets for mobile phones. However, Bluetooth 2.0, which has more high speed data transmission, and better communication quality, had a very serious potential for improving the quality of the transmitted sound. And the latest Bluetooth 4.0 format, while maintaining all the advantages of the "second" version, is even more economical, which is necessary to extend the operating time of portable devices.
Encoding sound
There is a so-called Bluetooth Profile, which describes the functionality of this wireless connection. In particular, the A2DP (Advanced Audio Distribution Profile) profile determines how well the audio will be transmitted (mono or stereo) when using Bluetooth.
In turn, A2DP supports several codecs that encrypt the original digital audio signal for transmission over Bluetooth. All Bluetooth-enabled devices support the so-called basic codecs (SBC), but may also support additional codecs such as Apt-X, AAC, MP3, etc. They provide best quality sound than SBC, and Apt-X is by far the most advanced audio codec.
The basic SBC codec uses a limited frequency range of the transmitted signal with a sharp drop in the frequency response above 14 kHz, so it is not suitable for high-quality music listening. getting worse.
The Apt-X codec uses ADPCM audio processing technology, which is a lossless data compression with support for 16 and 24-bit processing, and a dynamic range width of up to 120 dB. In fact, the differences between it and MP3/AAC codecs are the same as between audio files compressed in MP3/WMA and FLAC/WAV. At the same time, the Apt-X codec can transmit audio encoded in MP3 and AAC without additional processing without compromising its quality.
Processing received sound signal starts with less than 1.9ms latency, while MP3 and AAC latency is over 100ms. The base SBC codec also has low latency, but it achieves it through the use of buffer memory, which imposes certain restrictions on the structure of the transmitted data packets, and ultimately leads to a deterioration in sound quality. Apt-X does not require data buffering. In addition, the Apt-X codec has auto-synchronization between the receiver (encoder) and transmitter (encoder), which allows, in case of loss of communication, to restore it within less than 3 ms.
The Apt-X codec can be used to transmit audio in Hi-Fi technology, although it requires more computing power from the audio processor (32 MIPS for Apt-X versus 12 MIPS for SBC). Therefore, if you are interested in high-quality wireless audio transmission in your home system via Bluetooth, make sure that both the transmitter (for example, a smartphone) and the receiver built into your active speakers or audio system support this technology.
However, as always in such communication systems, the principle backward compatibility. That is, if a transmitting device that supports, for example, the Apt-X codec tries to communicate with a receiver that does not support it, then it will switch to the basic SBC codec, of course, with a deterioration in sound quality.
The main parameters of the A2DP Apt-X codec:
- Compression ratio: 4:1
- Audio Format: 16bit, 44.1kHz (corresponds to CD-Audio)
- Bitrate: up to 352 kb/s (SBC - 320 kb/s)
- Frequency range: 10 Hz - 22 kHz (SBC - 20 Hz - 17 kHz)
- Transmission delay: less than 1.89 ms at 48 kHz
- Dynamic Range: 16bit, over 92dB
- Noise and distortion: - 68.8 dB.
Prepared based on the materials of the portal "www.hifinews.ru", April 2013www.hifinews.ru