At first the idea arose to buy a powerful mobile Bluetooth speaker, but branded JBL ones cost up to $300, and their power rarely exceeds 40 watts, so it was decided to start assembling my own. The “boombox speaker” was based on a TDA7492P UMZCH module with a power of 2x50 W and a Li-Ion battery with a total voltage of 21 V and a capacity of 3500 mAh (70 W).
Most of the parts were ordered from the well-known AliExpress website, including the speakers. While the batteries are charged with a separate IMax charger, in the future it will be necessary to make a ready-made charger in the case itself.
The speakers are two broadband speakers with a power of 25 W each and two high-frequency speakers with a power of 10 W each, which gives us a total of 70 W, but in peaks they can handle 100 W. The manufacturer of these speakers is the little-known Aiyima, but the quality of their performance and sound quality was a pleasant surprise, which allows us to recommend it for assembling small speakers. Their parameters are as follows:
- Frequency range range: 81 – 5400 Hz
- Sensitivity: 87 dB
- F res. about 115 Hz
A USB module has been added as a Power-Bank. The body is made from 10mm thick MDF and measures 12x12x27cm. It was glued together with wood glue and also reinforced with screws on each side, except for the plate on the back which was glued in place with hot glue in case any repairs or modifications were needed.
Testing a homemade speaker
Tests have shown that these two full-range speakers, unfortunately, are not fully capable of reproducing the entire frequency range, so 10 W tweeters were installed along with them. The HF speakers were connected in series with film capacitors.
As for the bass amplifier on the TDA7492 (the sound is received by the bluetooth 4.1 module), the sound quality is very good and clear. The only problem with this board is that the speakers are slightly noisy when listening to music quietly. There is a solution to this problem on the Internet; only a slight modification of the board is required, but this is not particularly disturbing.
The housing must be very sealed, otherwise the pressure inside the speaker causes air to escape through small holes, which causes unpleasant “farts” from the speaker.
Cost of all assembly costs
- TDA7492P 2x50w 10$
- USB converter 0.8$
- Bluetooth receiver $2
- 5S Lithium-Ion battery $2.5
- MDF 10mm approx. 1$
- Speakers 3″ ShP $36
- Speakers 1.5″ HF 12$
- Battery 18650 packaging Panasonic 3400 mAh 5x4$
- Plus wires, switches, capacitors: $70 total
The TDA7492 chip is, the circuit operates in the range of 8-25 V, so 21 V is not the limit - you can supply 6 cans. According to the specification per m/s at THD 10%, the total is almost 100 watts of power.
Difficulty level: Not easy
What you will need:
- microcircuit TDA2003 or its analogues, K174UN14 - domestic analogue (price approximately 0.3 $)
- capacitors: a) 10 mf 16v - 1 pc. b) 100 mf 16 v - 2 pcs. c)0.1 mf 16v - 1 pc. d) 470 mf 16 v - 1 pc. (you can use capacitors larger than 16v, but as a rule they consume more energy)
- resistors: a)10 om - 1 piece b)1 om - 1 piece c)1kom - 1 piece
- speaker (more on that later)
- soldering iron, solder.
1 step
Chip TDA2003
We make a list of the components we need and go to the nearest radio store, where we will buy all the parts and assemble our MONO amplifier. I suggest choosing a mono amplifier for several reasons:
1) less energy consumption compared to a stereo amplifier.
2) from a portable speaker, in my opinion, such things as sound quality, volume, battery life are required.
Step 2
MONO amplifier circuit on TDA2003
After we have purchased all the components we need, we can proceed directly to assembling the amplifier. (diagram on the left) I have tested this circuit more than once, it has good sound quality, and it is quite simple to manufacture and does not require configuration.
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It is recommended to assemble the amplifier on a printed circuit board, but if you don’t have the skills to make one, you can assemble it on cardboard (just pierce holes, insert parts into them and connect according to the diagram)
Step 3
An example of assembling an amplifier on cardboard
After we have safely completed the assembly, we need to take care of cooling the TDA2003. For this
I recommend using a small heatsink that is bolted to the hole on the chip; you can also use thermal paste for better heat transfer.
Step 4
Now we need to take care of the power supply to our amplifier, here are its power ranges - from 8 to 16 V. (recommended 14.4 c.). I used 3 batteries from mobile phones, which in total produced 11.1 V. which is quite enough to power our amplifier.
You can also use AAA or AA batteries, we need 8 pcs. , which will give a total of 12V.
Step 5
speaker selection. This amplifier is suitable for 2, 4, 8 ohm speakers.
2 ohm 10 watts
4 ohm 5 watt
8 ohm 2.5 W
but from my own experience I will say that I connected a 30 W PIONEER car speaker (4 ohm), and it played very loudly and with high quality
Step 6
Example of a wooden case
We can take the case from a broken computer speaker as the basis for the case for our portable speaker, but for high-quality sound we need to make a wooden case ourselves. It is made from 5-7-layer plywood, in such a case the speaker will have more low frequencies and clear sound at high frequencies.
- When soldering, do not solder the part for more than 3-4 seconds.
- organize your workplace well, there should be nothing superfluous in it
For a computer user, a laptop is undoubtedly a convenient, compact and quite functional device. But, unfortunately, this device is not without flaws.
Surely many users of laptops and netbooks have encountered the problem of quiet sound playback through the built-in speakers of these devices.
If at home you can connect an external stereo system, then outside the home walls this may be impossible and you have to limit yourself to headphones. In this case, there is no talk of collective viewing of any film or series.
How to fix the situation?
Portable computer speakers powered by a USB port will help correct this situation. Now there is a huge selection of these devices on store shelves, but their quality can vary significantly.
The price of portable computer speakers powered by a USB port is quite low and affordable to a wide segment of the population. Despite this, the purchase of this device may be unsuccessful, since the quality of sound reproduction by such a system will leave much to be desired. Oddly enough, among the cheap devices of this class there are devices of very good quality, both in design and in sound reproduction quality.
Let’s perform an “opening” of a portable speaker system powered by a USB port and examine the electronic components of this device. From the point of view of a radio amateur, it is interesting to know from what electronic components such devices are assembled. The knowledge gained can be useful when independently constructing portable audio speakers powered by USB or repairing them.
We will disassemble portable multimedia USB speakers of the brand Sven 315. Despite their cheapness, this model of portable speakers showed good playback quality and sound power sufficient to cover a small room.
Disassembling computer USB speakers
Portable speakers are easy to disassemble. To open the case, you must carefully remove the front decorative panel.
In order to remove the amplifier circuit board, you need to unscrew the fixing nut, which is hidden under the plastic volume control knob. After this, the electronic board can be freely removed from the housing.
Electronic filling
The composition of the electronic filling of the device turned out to be quite simple. An integrated circuit of a stereo amplifier based on a microcircuit is mounted on a small printed circuit board LM4863D. With a supply voltage of 5 volts, this microcircuit can produce 2.2 W of output power per channel with a speaker voice coil resistance of 4 ohms. Based on the description (datasheet) THD + noise ( THD+N) at maximum output power is 1%.
Amplifier board and speaker
Based on these data, we can conclude that based on the LM4863D chip, you can assemble a pretty good stereo amplifier with a low-voltage supply (5V) and an output power of 2 W per channel. Many who are not yet familiar with modern microcircuits believe that the TDA2822 will be suitable instead of the LM4863D. It's a delusion! The TDA2822 is very power hungry (compared to the LM4863) and produces severe signal distortion at maximum power. Also, the optimal power supply for the TDA2822 is about 12 volts, which is not good for portable equipment. The TDA2822 can be recommended as a readily available replacement if the LM4863 is not available. This can happen, for example, during repairs.
It is worth noting that the LM4863 chip was developed specifically for compact systems, so the chip requires a minimum of external elements (the so-called harness). The microcircuit is available in different packages, from the usual DIP to compact SOIC.
If you want to independently assemble an amplifier based on the LM4863 chip, you may encounter a problem. Finding this microcircuit on radio markets is not so easy (as it was at the time of writing this article). But it was not difficult to find such a microcircuit on online trading platforms. For example, in the AliExpress.com online store, the LM4863 chip can be easily found in all kinds of packages and in any quantity. The price of 1 microcircuit is less than $1, if you buy 10 pieces at once.
I told you how to buy radio components on Aliexpress.
In addition to the amplifier chip itself, the printed circuit board contains a connector for connecting a passive audio speaker (without a built-in amplifier), a dual variable resistor for adjusting the input audio signal, and an electrolytic capacitor. On the side of the printed conductors of the circuit board, SMD wiring elements are installed, which are necessary for the operation of the integrated amplifier. The microcircuit is powered from a USB connector, which connects to any free port of a laptop or desktop computer.
A typical connection diagram for the LM4863 microcircuit is taken from the description (datasheet) for this microcircuit and is shown in the figure.
Typical circuit diagram for connecting the LM4863 chip (taken from the description)
Based on the typical connection diagram for the LM4863 chip, it can be seen that it can also work with regular headphones ( Headphone), whose resistance is 32 Ohms. The chip provides a circuit for detecting the connection of headphones and pin 16 (HP-IN) is allocated to implement this function.
For those who understand electronics and datasheets in English do not scare them, LM4863 microcircuits can easily be found on the Internet at alldatasheet.com.
Amplifier circuit for portable USB speakers
The circuit diagram of the amplifier is made manually from the printed circuit board of Sven-315 USB computer speakers. The diagram shows one capacitor C2 instead of two (C7, C9) that are actually present on the printed circuit board (see below). This was done because on the printed circuit board the capacitors are connected in parallel (C7 and C9), and in the summarized diagram, capacitor C2 indicates the total capacity of these two capacitors.
Schematic diagram of an amplifier based on LM4863D (manually assembled)
As you can see, the typical circuit from the description differs from the one drawn manually from the printed circuit board of a computer speaker amplifier. The diagram does not include elements that are installed if a headphone jack is added to the diagram. Otherwise, the circuit corresponds to the standard one given in the description for the LM4863 chip.
Placing elements on a printed circuit board
If you plan to use portable speakers without a laptop, for example, together with an MP3 player, then a 5-volt power adapter is quite suitable for powering the speakers. The main thing is that the power adapter can provide sufficient load current (as a rough guide: the standard load current for USB ports is no more than 500 mA). According to the description for the LM4863 chip, the maximum quiescent current (when no sound signal is supplied to the chip) is 20 mA. Naturally, during playback the current consumption will be higher.
The photo shows an option for powering portable speakers SVEN-315 from a 5-volt adapter, which is used to charge an iPod. The maximum load current of the adapter is 1A, which is more than enough for the normal operation of portable speakers.
As it turned out, high-quality sound reproduction of SVEN-315 portable speakers lies in the rational design of the housing. As you know, the quality of sound acoustic systems is influenced not only by the loudspeakers used in them, but also by the housing. To verify this, just pull the speaker out of the case and turn on playback. The quality and sound power of playback will be much worse. This remark was not made by chance, since a comparison was made of the sound reproduction quality of portable speakers SVEN-315 and similar, but more expensive USB speakers SVEN PS-30.
Despite the fact that SVEN PS-30 sound speakers are mounted on the basis of an integrated USB audio chip CM6120-S, which includes a 16-bit DAC and class D audio amplifiers, the quality of their sound reproduction is subjectively (by ear) much worse due to poor performance of the speaker system housing.
The body of the SVEN-315 portable speakers is made of ABS plastic. Perhaps it is the design of the housing that allows you to “squeeze” all their modest capabilities out of small-sized speakers.
When you want to enhance the sound of your device, be it a phone or tablet. Turn the volume all the way up and the app drains the battery. But sometimes the volume is not enough. At home, if there is an outlet, speakers are used. Outside the home, a portable speaker can help solve the power problem, but their prices are quite high. I decided to remake cheap speakers. The cost of modification is low, and the result will satisfy many.
Will need
Accessories and tools:- - small-sized computer speakers;
- - wires;
- - soldering iron, drill.
Making speakers for a smartphone
The computer speakers Defender SPK-165 were taken as a basis. I bought them on a local forum for 100 rubles. The sound was, to put it mildly, terrible. We had a pair of 1 watt speakers available and installed them and they worked until this alteration.Having disassembled we see the simplest configuration. Transformer and amplifier board with volume control and power off button. There will be a separate discussion about the button later.
Unsolder the mains transformer and power wire. We put them aside, they will no longer be useful to us.
Initially, I calculated power from two Lithium-ion batteries of the 18650 format. But due to the fact that the speakers in the speakers were changed to one-watt (they were half a watt and very quiet), I had to use Lithium-polymer flat batteries. I have them used, but the total capacity is more than enough.
Our batteries will be charged using a charge controller from China. The controller is equipped with deep discharge protection. The board is marked V-/B+; the battery is connected to them. OUT+/OUT-, the load is connected to them.
The charge controller is mounted in the sole. We cut out a window for the connector and file the board, the main thing is not to damage the tracks. The board is glued with double-sided tape; for reliability, you can also secure it with hot glue.
Since the speakers supplied mains power directly to the transformer, and from it to the diode bridge, we will redo this part. We solder all the diodes, 4 of them.
Power from the battery, or more precisely from the charge controller board, is soldered to the plus and minus of the diode bridge. Also, the power plus will be switched by the speaker switch.
First we solder our circuit with a canopy on the wires and check for functionality.
Flat batteries are secured with a simple brace made of copper wire with an insulating tube attached to it.
To control the charging process of the batteries, we make a hole in the sole opposite the LED indication of the charge controller and fill it with hot-melt adhesive. Cut off excess glue. We twist the speakers and connect the charger. Charges from any charger from a smartphone, tablet and micro USB output. The display is clearly visible.
That's how, and with almost no effort, we modified computer speakers with mains power to become portable speakers. Later I will add more batteries to increase the battery capacity.
This review is dedicated to the miniature 40mm speakers that I used in a homemade speaker. I’ll say right away that the speakers met my expectations as tweeters and, together with the low-frequency sound, they gave quite acceptable sound for a fairly compact speaker.
It all started with a miniature subwoofer that came with the ASUS N55S laptop
I used it quite rarely, but despite this, the 2.5" connector on the laptop to which this speaker was connected began to make poor connections and finally simply fell inside the laptop. I didn’t see any particular need for repairs, since the laptop was used mainly for work and didn’t really need good bass.
But the idea of using this speaker as a portable miniature speaker has been in my head for a long time. Unfortunately, it was problematic to fit anything other than this speaker into that housing, so I decided to change the speaker housing.
At first I wanted to build a speaker using a pair of half-watt speakers from old computers. 
Their diameter was too large, and the sound was simply disgusting. Repulsively creaking, and a little more volume - even more rattling. The woofer did not improve the sound quality. Something different was needed. And then on the Internet I found the speakers from the review.
I bought them on EBAY, although it was possible on ALI and TAO:
Stated characteristics
- Diameter - 40mm
- Height - 20mm
- Magnet diameter - 22mm
- Rated power - 3W
- Resistance - 4 Ohm
- Frequency range - 170KHz
- Harmonic distortion factor - 1%
Components used
- Speakers 3 W 4 Ohm 40 mm from the link above $1.9 x 2 = $3.8
- If I were to buy the case (left over from another project), I would take it without a transparent cover, size 115x90x55
- - $0.99 for 2 pieces
- ~ $0.5
- Woofer 5 W 4 Ohm
- Battery from a faulty phone at 2200 mAh
The size is smaller than that of speakers from computer cases.
Therefore, a 120x80x55 mm instrument case with a transparent cover, which was lying around idle, came up, which is absolutely unnecessary in this product.
Dimensions correspond to declared
Weight 25g (maybe someone from TAO will order) 
Resistance is also quite normal 
All speakers included 
Miniature amplifier boards based on PAM8403 
Lithium battery charging boards with a current of 600mA on TP4056 (current can be adjusted up to 1A) 
Initial testing of the speakers led to a slight rattling at maximum volume, so I installed a volume divider and a high-pass filter on a 0.1 mKF capacitor at the input
The final diagram looked like this 
Cut holes in the case for the speakers, button and MiniUSB connector 
Glue in the speakers, install the board, solder the battery 
Connect to the phone. 
You can close the case 
Well, what can I say about the sound? The quality was pleasantly surprising. For such a small rattler, the sound is very loud and high quality. The sound can be slightly adjusted using the equalizer on your phone/tablet/computer. There is bass, normal highs.
Consumption is 150mA at maximum volume, that is approximately 0.5 W. With a battery capacity of 2200 mAh, it will last for 12-20 hours, depending on the volume. It is also possible from the network through any power supply with a USB connector or a computer.
The speaker suited us quite well. 
The Chinese would boldly write HiFi on it))) 
Just a little work left to do with the appearance. I cover the speakers with window nets. 
And I cover it with carbon-look film that I have lying around somewhere in the closet. And here is the finished product, the fruit of several evenings.
In the future, we will improve this speaker with a volume control, a battery charge indicator and replace the line input with a bluetooth module (or FM/MP3/USB)
Read about all my crafts in