Speakers S90: specifications, circuit. Speakers with own hands

Melomaniacs always start arguing about what kind of acoustic system to choose for comfortable listening to music at home. And it's no accident: the whole contingent was divided into two camps. The first ones think that it's worth to pay a tidy sum for buying a cool Hi-Fi (or better Hi-End) system to be happy and forget about headaches about this topic for the rest of your life. But there are also those who are not ready to give the accumulation of their whole lives for expensive acoustics (instead of the car or apartment), so they consider the best option to purchase simpler equipment or to refine old good classics to a good sound.

In this article, we will talk about one of the most popular audio systems still produced in the times of the USSR, which could not leave any of its owners indifferent. Speakers S90, technical characteristics of which are capable of exciting the mind to this day, have become one of the highest achievements of the Soviet firm "Radio Engineering".

Column models

The very first thing that should be mentioned is the present and full name of the model of the speakers - 35АС-012. An important factor is the fact that this acoustics was produced in several variations. The most popular of them are S90 and S90B. Also there were models S90i, S90D and S90f, but they did not get much distribution and now they almost never occur.

The model with the postfix "B" differed from the usual "nineties" with a wider range of reproducible frequencies. Also significant difference was the introduction of the indicator of electric overload of the speakers. The recommended power value of a high-quality amplifier for these speakers is in the range of 20 to 90 watts. It is also worth noting that "Radio Engineering" S90, S90B (and other modifications) were the first models of acoustic systems that met the international requirements for equipment category Hi-Fi.

Design

The enclosure in which the S90 columns are enclosed is, in fact, an indissoluble rectangular box made of chipboards. Facing is veneered veneer of valuable wood. The walls of the columns in thickness reach 16 mm, the front panel is made of 22 mm thick plywood. Internal joints of the walls of the case are connected by special elements, which increase the rigidity and strength of the structure, but do not interfere with high-quality sound.

If you look at the device from the front, the speakers are arranged in the following order (from top to bottom): tweeter, tweeter and woofer. Also on the front panel of the S90 column you can see the frequency response curve (amplitude-frequency characteristic) and the bass reflex orifice. While the AFC is located at the top or bottom (depending on the model of acoustics), the bass reflex is always at the bottom. This is done for reasons of correct design for better sound and giving the speakers good bass.

Speakers S90: Specifications

If you take as an example the usual S90, then they have dynamic heads of direct radiation. More precisely, the high-frequency head 10ГД-35, the mid-frequency head 15ГД-11А and the low-frequency head 30ГД-2 (in later models - 75ГДН-1-4).

The acoustic system is equipped with two stage playback level controls for adjusting the midrange and high frequencies in the ranges from 500 to 5000 Hz and from 5 to 20 kHz. Each controller moves in three fixed positions. In the "0" position, there is no obstacle for the signal from the separation filter, and it is fed directly to the corresponding head. When using the "-3 dB" and "-6 dB" positions, the signal is weakened by 1.4 and 2 times, respectively, with respect to the "0" position. By switching the selected knob, you can make changes to the tone color of the sound.

The power rating of the S90 speakers is 90 watts, while the nominal power is 35 watts. The nominal electrical resistance in this speaker system is at 4 Ohm, and the range of frequencies available for playback ranges from 31.5 Hz to 20 kHz. The nominal sound pressure is the same for S90 - 1.2 Pa. I want to note the rather impressive dimensions of one column - 71.0 x 36.0 x 28.5 cm, and the total weight of the entire system reaches 30 kg.

AU circuit and connection to a sound source

In order to understand whether it is worthwhile to work on the completion of any acoustic system, it is necessary to study all the data and aspects of the apparatus. Below is the electrical diagram of the S90 speakers. Everyone can even understand the beginnings of a radio amateur, you just need to have at least a basic knowledge.

Another important point is the correct connection of the speaker system. After all, if something goes wrong, even when connected, you can, unwillingly, disable the hardware. To understand how to connect the S90 speakers , you do not need to be a professional. The main thing is to have a sound source with an amplifier of not less than 20 watts (in this case, most likely, the sound will not be loud enough for large rooms), but not more than 90 watts. In case of exceeding the permissible value of the amplifier power, the user risks to remain without acoustics because of its breakdown. To connect, however, you will need conventional acoustics wires, which must be connected to the terminals on each column and on the amplifier. The main condition of connection is the observance of polarity.

Modification of 35AC-012

As it becomes clear from the description above, the acoustic system itself has good technical characteristics and is capable of "swinging" even small public spaces. But for home use, the most sophisticated music lover will prefer to modify the S90 speakers with his own hands. And all because assembled more than twenty (and even thirty) years ago, the acoustic systems of the firm "Radio Engineering" already in those years did not have a high quality of assembly and materials used.

Debriefing

In the event that acoustics was purchased in the used condition and at the moment is well worn by life, it is worth giving importance to appearance. To do this, you need to disassemble the S90 speakers, first putting them on the "back".

When removing the speakers, it should be taken into account that the RF and MF heads are attached to the housing using the same screws as the decorative grids and the lining. The woofer is attached separately, and you need to be very careful not to damage it when unscrewing it.

Next, pull out the bass reflex, after removing the cover from it. Since the part is plastic, it is necessary to apply the maximum accuracy, so as not to accidentally break off the fasteners.

The HF / MH regulators are much easier to dismantle than it seems. All that needs to be done is to carefully remove the decorative plugs that are in the center of each regulator. After that, using a screwdriver, it is necessary to unscrew the screw that opened the gaze, and remove the regulator handle itself. Plastic lining should be gently lifted from both sides with flat objects and reach, and the remaining four screws under it, unscrew. After that, the attenuator can be pushed inside the S90 column, not forgetting to remove it from the filter.

Bags of cotton wool, which are inside the body, you need to get it. Again, if the previous owner of the columns did not forget to return them to the site in case of parsing.

It is necessary to disassemble the panel with filters from the output from the back side of the speaker, after that it needs to be dismantled by unscrewing the screws. Now you can remove the panel with the terminals attached to it.

Appearance and body

If the grilles and decorative lining of the speakers are "tired", then it is worthwhile to straighten them and paint them, pre-sanding and degreasing. This will give freshness to the minds of the speakers. The case of the S90 column loosens with time, and it can be strengthened at will. This will result in a better sound from the woofer.

You can do this in various ways, including installing spacers and additional corners inside. Also it is necessary to pay attention to the sealing of all joints and seams with the help of usual sanitary sealant. In addition, it is possible to glue the inner walls of the body (except for the front) with foam rubber, which will increase the volume of the latter.

Terminals and filter

Knowledgeable radio amateurs recommend replacing the standard acoustical connection terminals with universal type terminals with gold-plated connectors. The installation site must be greased with a sealant and put the panel with the terminals in place.

Considerable attention should be given to the sound filter. If it was attached to the body with metal screws, then the filter setting will be stalled. There are cases when the filter was assembled on a metal plate. This should be corrected by transferring all the nodes to the panel from plywood. The scheme of the filter itself could be changed at the manufacturer in connection with various parameters of the speakers, so it's worth making sure that everything is assembled according to GOST. If there are bridges in the filter, they must be disposed of and replaced, for example, with an oxygen-free copper cable with a cross section of 4 mm ² . It is worth removing the attenuator from the circuit, as it simply distorts the sound, and replace the wires used to connect the speakers to the filter.

For woofer speakers, a 4 mm ² wire with a cross-sectional area of 4 mm ² , a 2.5 mm ² for mid-range speakers, and an area of 2 mm ² for high-frequency speakers. After such simple actions, the filter must be returned to its place and covered with foam rubber.

Dynamics and other "trifle"

For the speakers, new seals should be cut. You can do it with cheap or simply obsolete computer mouse rugs. This is the simplest option. After that, you should return them to their seats and put decorative lining and nets.

Before installing the regulators in place, they will have to remove all the resistance from them. When installing them in place, it is necessary to use a sealant, as in the installation of a phase-inverter.

Through such simple manipulations, the S90 speakers acquire a new life. The sound quality becomes an order of magnitude higher, despite the low costs. As a result, we can say that if there is no money for expensive speakers in the format 2.0, you can use this option and become a happy owner of the time-tested AS "Radio Engineering" S90. If it so happens that only half of the speakers are available, do not get upset. It is noteworthy that the column S90, a photo of which can be found practically on any site of acoustics lovers of the USSR, can work alone and give a good result.