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Suitable trash amplifier


Hello. Each house is probably either lying somewhere in the pantry, on the mezzanine, or just what we need for the next homemade. Namely: a DVD player and some boombox / tape recorder. And of these, we will make a fully functional amplifier.


To do this, you will need:

Dvd player
Amplifier from an old boombox or tape recorder or any other ULF (homemade for example)
6-pin on / off switch (I have a toggle switch)
Mains switch 220 v (Most DVDs already have one)
Acoustic connection pad
Soldering iron with accessories
Mounting wire
Drill
Dremel or similar shredding tool
Multimeter
And other screwdrivers, wire cutters, strippers, scalpels ...

So let's get started.

Since everyone has different devices, it makes no sense to bring a specific circuit and layout, so I outlined a block diagram that makes it easy to understand what and where.


I’ll explain a little: Two PSUs are needed if you are assembling a powerful amplifier, in this case the DVD PSU will not bear the load, but if the power as in my case does not exceed 15 W, then the DVD feeder can handle it, it’s very easy to take voltage from it: more often all on the output block all voltages are signed:

Just solder to the necessary +12 and GND and that's it. Well, or call with a multimeter.
However, if the sound is distorted when the volume is increased, it is better to power the amplifier unit separately.

Further: the option with internal speakers is highlighted in red on the diagram, if the case size allows and there is a desire, then the native speakers from the boombox are placed inside, and in order to output sound to external speakers, you need to install an additional switch S3. If this is not necessary, then the highlighted in red can be ignored. Here, by the way, is the option with built-in speakers in the case from the VCR, but I did not like it, the sound is like from an iron.

We continue. Now we disassemble and carefully remove the insides from our experimental subjects and lay them on the table


We throw out the unnecessary DVD-drive, an amplifier will fall into its place.

Getting to the assembly. To begin with, let's figure out how all this will be located in the case and drill-cut the necessary holes, then on the knee we solder according to the scheme everything in a heap, as in the photo above, we again figure it out:

A few nuances: since I have a non-native case, I had to resort to such a barbaric method to get control on the front panel: I hid the panel with buttons and an indicator from the working DVD inside the case, and using the cable of wires I soldered the extension cords to the existing buttons, so - the indicator popped out and stuck it where it should be on the extension cable. To do this, removed all unnecessary radio elements and foil, left only the buttons and the LED




Well, if you assemble in your own building, then you will not need such perversions. Just leave everything in regular places. Next, ennoble the hull. Since there is a gap left from the discarded drive, this is not comme il faut. The aluminum top cover from the laptop caught my eye. What you need! I remove the decorative cover with a slit from the body and from these two components I make a muzzle that looks pretty to me:


Further: since the dvd-yuk was karaoke, there was a hole from the microphone input, where the mains switch remarkably stood. Nearby in a regular place is a USB input. I drilled a new hole under the volume control.

I didn’t change anything on the left side, just cut off a piece of the old cladding and left it there

Further: there are somehow too many holes in the back

We’ll cover them with the same aluminum plate, as well as cut out the holes for the toggle switch, the headphone output and the speaker connection block:


We drill the necessary holes for mounting the boards inside the case. We remember that the case is metal, and so in order not to short-circuit it, we raise the boards on the dielectric legs-washers, you can make homemade cut from anything, for example, felt-tip pens.

We fasten everything in place and once again go over the joints for proper assembly and if anything fell off during installation. If necessary, paint and assemble finally.

And we see that dialog polochniki with a torn amplifier and holes instead of it, by no means fit into the general layout. Well, well, we still have a lot of laptop covers.



That will be better! Well, that's all, good luck to everyone!
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12 comments
The idea is worthwhile, but each may have his own performance. For example, I used the filling from the home theater, so there even the PSU is not pulsed, but on a good torus.
1. "Soviet" Watts - power at normalized (depending on the class of equipment) non-linear distortions.
2. "Chinese" - short-term (units of milliseconds) non-destructive power.
Yes, no one made any complaints, it was normally done. First, I reported how in a thin case and with a not very powerful source you can increase the power if you wish, and only then the rest of the conversations went to a more theoretical side, not related to your product.
Author
In general, this homemade product was not positioned as a “Hi-End class supercar”, but how to make something useful out of junk. Regarding nutrition, the description also says that if the normul pulls, if not, feed separately. In any case, like, say, computer speakers sounds pretty good to yourself. And for a half-quarter disco and crippling neighbors there are other solutions, but that's another story)
Loudspeaker sensitivity - sound pressure of a loudspeaker measured at a rated power of 1 W, at a distance of 1 m (in dB). Sound pressure was previously reported (typical values ​​0.2 ... 0.3 Pa), now sensitivity (typical values ​​85 ... 95 dB),
Yes Yes. I fully agree with the definition of "sensitivity". The correct definition is "Sound Pressure".The speaker power is a parameter that shows how much power this speaker can dissipate for a long time without the risk of destruction, and at the same time, the THD does not exceed the specified value. And sound waving is the mean square value of the sound pressures developed by the head in the nominal operating frequency band on the acoustic axis at a distance of 1 meter from its acoustic center.
All speakers have diffusers made of different materials, different suspension systems, etc. Therefore, it sometimes seems to us that the 10-watt speaker “screams” as much as 100 W smile
At the same time, one should not forget that the speaker is in the bass reflex box. And sound waves from the back wall of the diffuser are reflected from the back wall of the box and, changing phase, go out through the hole forward. And add up to the waves from the speaker. As a result, sound pressure increases. For the listener, this looks like an increase in volume.
Quote: Valery
I’m completely confused about the “different watts.”

There are 2 points.
1. “Soviet” or Euro-American watts are “honest”, and Chinese, especially Chinese, are far from always, they like to indicate several times baboutlower power, sometimes cheating only slightly: they give not rated, but peak power, and sometimes it’s not clear what they write, most importantly, to get more.))
2. The volume depends not only on the power of the amplifier, but also on the sensitivity (return) of the speaker. For example, the Soviet speaker 4GD-8E, intended for installation in cars, had the maximum sensitivity for that time, and the low-frequency speakers designed for installation in a closed box, the sensitivity is much lower. Or, for example, 0.5GD-30 - also with great recoil, stood in the Parus-301 cassette, so if you put it on the window, you could hear for about a hundred meters on the street. And just half a watt.
I also love loudly in the car ... But without fanaticism !!! I have a “radio” 4 to 50. Speakers - in the front doors are “noisy” “Prolodges” - broadband, in the front struts are “high-frequency”, in the rear doors are low-frequency, and separately high-frequency ... (Middle ones in front “arrive”) And that's it , No subwoofers in the trunk !!! I like the sound to be "transparent" .... And when the bass "kick in the ass" - it's more show off ...

But something tells me that the "50 watts" in the car is not even the "10 watts" in that old amp ... If I ran it to the fullest in a small cabin .... Probably it would go deaf ...
And there are fans to listen to everything! As it happens in a car, Mouzon yells so that there is no time to follow the road ...
This one works for me on S30 and for the whole I never turn it on.
https://enm.imdmyself.com/9316-prostoy-usilitel-v-korpuse-modema.html
A maximum of 30 percent volume and YouTube for the whole, this is more than enough.
Sorry ... I’m completely confused with the "different watts" ... Explain if you can ...
For example, I have a Soviet amp in the basement ... The capacities there are only 2 to 10 ... It’s connected to the Soviet speakers S30 "Radio Engineering" too ...
..And these unfortunate 10 watts are capable of screaming so loudly (and quite cleanly) in a small room that you don’t need to do it anymore!)))) ... Yes, and you don’t need so much - I never turn on the full one ...
And here you are saying that 2x7 watts is "about nothing" ...
Am I misunderstanding something? .. Or, just everyone except me needs to be very loud ...
On the back of this DVD, power consumption is indicated as: less than or equal to 20W. Therefore, no good amplifier will work if you use a native power supply. Maximum 2x7 watts. This is when using a class T amplifier. And if you use an amplifier from a boombox or tape recorder (class AB or B), then only 2x5 watts.
To get a decent sound, you need a switching power supply and appropriate amplifiers.
Homemade is suitable for acquiring skills in combining finished blocks into a single design.
To use the "native" PSU of a DVD player and get decent power output without the use of large radiators, it is advisable to use a T-class amplifier. It fits perfectly into a thin case, and its efficiency is more than 80% with distortions acceptable for ordinary everyday listening.

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