Refinement of Chinese acoustics (SVEN SPS-678)
Hi,% username%. Today I will tell you how to upgrade your computer acoustics a little. Immediately I would like to say that this guide is not intended to make B & W out of your acoustics, but to improve the sound only reasonably with minimal time and money.
So, we have the following columns:
What is the problem of such devices ?? And the fact that the Chinese are saving absolutely everything that we can be convinced of by looking at the amplifier circuit diagram found on the network:
')
Columns have all almost identical scheme, so that you,%% username, should not be difficult to figure out.
Here you can download in full size.
Having opened, you should see something like this:
What we need:
Let's start with the power supply. Transformer 2 * 13V 1.2A. But how so,% username% !! ?? After all, it is written on the box that the speakers should give out 18 W of power each, and with such a transformer you get only P = U * I = 15.6 W for 2 channels !!! But here everything is actually a bit more complicated. Such a calculation will be correct for a sinusoidal signal, but the real music signal is much more complicated, it reaches its maximums quite rarely. If we take the average level of the signal, then compared to the sine, it is several times smaller. Comprehensive information can be found in this article.
So using the program you can make sure that our transformer almost fits the requirements.
Next we have a diode bridge D1-D4 of the diodes 1N4007 . 1-amp diodes, replace with Schottky diodes, since the direct voltage drop on them is less than on silicon diodes. I set 1N5819 . Any diodes will do, if only the current and reverse voltage match the circuit parameters.
On average, the voltage drop across silicon diodes is 0.5-0.6V; in my specimens, the voltage drop was only 150 mV.
And do not forget to very grease the flux of the soldering point with grease, then the solder will gather into beautiful shiny balls around the leads. If you smear a little, it will be bad to stick to the contacts and spread in all directions.
Here, the masters from the Middle Kingdom also decided to save money and put only 3300 uF in the shoulder. Not enough, it is necessary to increase, but without fanaticism !!! The more capacity you put, the more current goes through the diodes at the time of charging the capacitors and they can not stand it.
I put an additional 4700 uF in the shoulder, leaving my relatives.
With the power supply all.
At the entrance are electrolytes (C9, C10) - disarray, as it works on alternating current without bias, which is not good at all. The datasheet on the chip is a capacitor with a capacity of 1 microfarad, though also an electrolyte.
We go to the store and buy our domestic film K73-17 with a capacity of 1 microfarad and set it up. Since it is much more electrolyte, it is better to put a heat shrink on your feet so that nothing closes. Seal:
If you can call it the electrolytic capacitor 4.7 microfarads.
There are two options:
We have a capacitor on Twitter, which cuts the lower frequencies (filter of the first order), and the whole range goes to the subwoofer. It would be possible to make a crossover, but the quality / labor ratio would not work out in favor of quality. Therefore, we choose the first option. And again we put the film capacitor K73-17 4.7 microfarad:
We do not forget to perform a similar operation in the second column.
It also does not shine with elaborate design, so if you wish, you can turn it off by connecting the wires from the input directly to the volume control (R9, R10). But I decided to leave it for now.
It's all very subjective. But my view has become noticeably denser.
But there are objective parameters:
So, with minimal financial investments and time costs, you can slightly improve the sound of your speaker system.
So, we have the following columns:
What is the problem of such devices ?? And the fact that the Chinese are saving absolutely everything that we can be convinced of by looking at the amplifier circuit diagram found on the network:
')
Columns have all almost identical scheme, so that you,%% username, should not be difficult to figure out.
Here you can download in full size.
Having opened, you should see something like this:
What we need:
- soldering iron
- solder
- flux
- heat-shrink tubing
- details to taste :)
Power Supply
Let's start with the power supply. Transformer 2 * 13V 1.2A. But how so,% username% !! ?? After all, it is written on the box that the speakers should give out 18 W of power each, and with such a transformer you get only P = U * I = 15.6 W for 2 channels !!! But here everything is actually a bit more complicated. Such a calculation will be correct for a sinusoidal signal, but the real music signal is much more complicated, it reaches its maximums quite rarely. If we take the average level of the signal, then compared to the sine, it is several times smaller. Comprehensive information can be found in this article.
So using the program you can make sure that our transformer almost fits the requirements.
Rectifier.
Next we have a diode bridge D1-D4 of the diodes 1N4007 . 1-amp diodes, replace with Schottky diodes, since the direct voltage drop on them is less than on silicon diodes. I set 1N5819 . Any diodes will do, if only the current and reverse voltage match the circuit parameters.
On average, the voltage drop across silicon diodes is 0.5-0.6V; in my specimens, the voltage drop was only 150 mV.
And do not forget to very grease the flux of the soldering point with grease, then the solder will gather into beautiful shiny balls around the leads. If you smear a little, it will be bad to stick to the contacts and spread in all directions.
Filter capacitors
Here, the masters from the Middle Kingdom also decided to save money and put only 3300 uF in the shoulder. Not enough, it is necessary to increase, but without fanaticism !!! The more capacity you put, the more current goes through the diodes at the time of charging the capacitors and they can not stand it.
I put an additional 4700 uF in the shoulder, leaving my relatives.
With the power supply all.
Amplifier.
At the entrance are electrolytes (C9, C10) - disarray, as it works on alternating current without bias, which is not good at all. The datasheet on the chip is a capacitor with a capacity of 1 microfarad, though also an electrolyte.
We go to the store and buy our domestic film K73-17 with a capacity of 1 microfarad and set it up. Since it is much more electrolyte, it is better to put a heat shrink on your feet so that nothing closes. Seal:
Crossover
If you can call it the electrolytic capacitor 4.7 microfarads.
There are two options:
- just put the film
- think of a new crossover
We have a capacitor on Twitter, which cuts the lower frequencies (filter of the first order), and the whole range goes to the subwoofer. It would be possible to make a crossover, but the quality / labor ratio would not work out in favor of quality. Therefore, we choose the first option. And again we put the film capacitor K73-17 4.7 microfarad:
We do not forget to perform a similar operation in the second column.
Timbre
It also does not shine with elaborate design, so if you wish, you can turn it off by connecting the wires from the input directly to the volume control (R9, R10). But I decided to leave it for now.
Sound
It's all very subjective. But my view has become noticeably denser.
But there are objective parameters:
- an increase in the capacitances in the BP filter gives less drawdowns and at high volume there will be no feeling that the sound is falling.
- The use of Schottky diodes slightly increases the supply voltage, allowing the chip to overclock to more power (22V datasheet voltage)
- film capacitors introduce several times less distortion than electrolytic
In custody:
So, with minimal financial investments and time costs, you can slightly improve the sound of your speaker system.
Source: https://habr.com/ru/post/121819/
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