As a neurologist, I have to treat patients with tension-type headache. Quite often it occurs in people working at a computer screen for a long time. At the same time, despite the wholesale replacement of monitors with an electron ray tube for liquid crystal monitors, this pathology is becoming more and more.

The reason is that most office workers have no idea what can be adjusted on an LCD monitor other than brightness and contrast. Users believe that the liquid crystal panel itself cannot pose a health hazard, since there is no strong electromagnetic field, soft X-ray radiation, and screen flickering inherent in cathode ray tube monitors.

Unfortunately, an incorrectly installed and configured LCD monitor can cause a lot of headaches to its owner. This article has attempted to explain, in a concise manner, the basic principles of properly setting up LCD monitors for text processing and home entertainment.

For professional graphics work, some of my setup tips will be detrimental, since the focus of the article is on reducing fatigue when working for a long time on the LCD monitor.

A bit of theory

The image on a liquid crystal panel is formed by passing light from backlight lamps (or LEDs) through a matrix that forms the color of individual dots on the screen. To transfer data from a computer to a monitor, either an analog VGA interface or a digital DVI interface is used.

The digital interface allows you to transfer data without interference, so that the input of the monitor unit that controls the display of the picture on the screen receives data from the video card without distortion.

For the analog interface, things are not so simple. Since the VGA signal must be converted twice - from digital to analog at the output of the video card and from analog to digital at the input of the monitor, careful tuning of the analog signal converter is required to correctly display the image on the screen.

Setting up an analog monitor

To correctly display the picture on the screen of the liquid crystal monitor with an analog interface, it is necessary to adjust the parameters of the picture position on the screen, the clock frequency and the phase.

Usually, the position of the picture on the screen and the clock frequency are adequately adjusted in the automatic adjustment mode.
It is quite simple to check the quality of the picture position setting: run the Nokia Monitor Test program (http://www.noo.com.by/download/mon_test_ru.zip) and select the Geometry menu item - there should be a dotted line along the edge of the image, if you cannot see it on any side of the screen, you will have to adjust the position of the image manually - the monitor settings menu items “H.Position” (horizontal position) and “V.Position” (vertical position).

To check the synchronization frequency, you will need to select the Moiré menu item from the Nokia Monitor Test - if the value is incorrect, vertical stripes will appear on the screen. If the picture has such a distortion, you will have to manually adjust the “Clock” parameter in the monitor menu.

One of the most common causes problems with the display of the analog signal is not quite accurate adjustment of the phase of the conversion of the analog signal to digital. If the phase is not adjusted accurately, the image will flicker on the screen, horizontal waves may appear on the Moiré test image in Nokia Monitor Test. To get rid of this defect, you need to change the screen refresh rate setting in the video card driver properties to the one recommended by the monitor manufacturer (usually 60 or 75 Hz). After that, you can adjust the "Phase" phase in the monitor menu.

Sometimes, even with manual adjustment, the image on the monitor screen still flickers - most likely, there is some kind of pickup on the analog interface cable - to level this factor, it is necessary to connect the computer and peripheral devices only to sockets with a working ground. Also, move the interface cable away from the monitor and computer power cables.

Installing a surge protector also does not hurt - even for a monitor with a digital interface, voltage fluctuations in the power supply network can lead to image flickering on the monitor due to backlight brightness fluctuations.

Adjusting brightness and contrast

Important for reducing eye fatigue is correct installation monitor backlight brightness. Since the human eye is best adapted to perceive reflected light, too bright screen backlighting can lead to visual fatigue and headaches.

It is advisable to set the brightness value to a comfortable minimum, most LCD monitors are characterized by too high backlight brightness values ​​​​for factory settings. It should be noted that the eye quickly enough adapts to the lower brightness of the monitor screen, which serves as the basis for an even greater decrease in brightness.

To test the correctness of the settings, there are test pictures for contrast and brightness (in the attached files). With the correct settings for contrast and brightness, numbers over 250 (for contrast) and numbers less than 5 (for brightness) should be distinguishable.

Other important settings

Due to the increase in the diagonal of the screen, the distance between the screen and the user's eye tends to increase, and standard values font sizes are too small for comfortable work.

For more comfortable work in the dialog for setting screen properties, it is possible to change the scaling for displaying fonts on the screen (the standard scale is 96 dpi), for comfortable work, for a distance from the eye to the screen of 80 cm, a scale of 120 dpi or more is usually needed.

Some users, instead of scaling the image, change the resolution of the image displayed on the monitor. In this case, the monitor electronics "stretches" the picture to full screen and creates the appearance of scaling.

However, with this method, distortions are great, which leads to great eye fatigue when working with "non-native" resolutions. Therefore, setting in the screen properties the resolution corresponding to the physical resolution of the monitor is required (including for gaming applications).

The choice of color temperature for the white point on the screen is important for the rapid adaptation of vision when looking at the surrounding objects and back to the screen. When surrounded by warm colors and artificial lighting with incandescent lamps, it is desirable to set a warmer color temperature.

Conclusion

I hope this article will help the reader to set up their LCD monitor so that the eyes and brain are less tired from working at the computer. Naturally, a properly configured monitor does not eliminate the need for work breaks and gymnastics.

For those who want to get more useful information about the device and the principles of operation of LCD monitors, there is a very informative page:

I have worn glasses all my life. Astigmatism as a complication after an illness in childhood with +42°C. Survived.
But on the computer he worked without glasses. I always intuitively set up the monitor and computer so that my eyes do not get tired.
The other day I noticed that my eyes began to get very tired again. Especially when working for a long time, but this was not the case before. But they gave me an LCD monitor and, given that I have to work a lot with photos, I set it up using Adobe software gamma. This required raising the brightness to expand the dynamic range of the monitor (working out dense colors). And only then I remembered why everything was fine before. And everything was fine with vision before because I set my computer monitor to the minimum (optimal) brightness.

There are many theories, advice, SanPiN 2.2.2 / 2.4.1340-03, protective screens and special programs, all of which are dedicated to protecting the eyesight of people working on a PC. But back when I was running DOS and the monitors were green and had a refresh rate like regular TVs but this problem already existed. And even then I found a way out for myself. Since then, I have been working on a PC without glasses (I walk and drive with glasses). More than once I watched how before my eyes people who did not follow my advice for several months were forced to switch to glasses.

So what should be done?

Well-known rules for organizing a workplace:

• the monitor stands at arm's length from the user (50-70 cm is allowed),
• external light should not create glare on the monitor screen,
• the monitor should be at a height when the top edge is at eye level or the center of the screen is at eye level,
• choose for yourself the frequency of breaks and their duration (recommended 1-2 times in 2 hours for 10-15 minutes),
• when working more than 5 hours, take a break of about 1 hour,
• take a break, do some relaxing eye exercises or take a walk down the hallway or room,
• do not put the monitor in front of the window,
• do not place the monitor so that the light from the window falls on it,
• use special programs to train and relax your eyes.

Individuality of vision

Our eyes are very individual. As a person themselves, they tend to evade work, and therefore, as soon as the opportunity arises, they begin to demand more comfortable conditions for themselves. And this primarily applies to the illumination of the working field. They want comfortable lighting for themselves, but we, without thinking about the consequences, add light. Although excessively bright light is even more harmful to the eyes than its lack.

If you feel eye fatigue - this is the first signal of improper organization of light in the workplace. And the most important aspect of the organization of the workplace is optimal lighting.

But, as mentioned above, our bodies and eyes are very individual. This means that each person needs individual working conditions for the illumination of the workplace, and hence the PC screen. And don't be alarmed if you feel that your eyes felt a loss of comfort when changing the lighting in the room, they are right because, as will be said below, the comfortable illumination or brightness of all objects in the workplace is related.

Monitor Brightness

The main requirement is to set the brightness of the monitor screen to a comfortable level (I reduce it if possible). With such brightness, the screen should not be too pale and require eye strain when reading text. But it shouldn't be too bright either. Both in the first and in the second case, the eyes get tired and even faster. Moreover, as I never tire of repeating, this setting is strictly individual and a monitor with the optimal setting for one user may not be optimal for another.

Screen refresh rate

On cathode ray tube (CRT) monitors, the maximum screen refresh rate is desirable.

This is due to the fact that the phosphor of the dots that form the image on the screen glows for a limited time, and the image unfolds in half-frames at a frequency equal to half the sweep frequency you specified. And this frequency is on the verge of the reaction of the eye to changes in brightness, which is about 22 Hz.

(The critical frequency is about 20 Hz, but it is also individual. As the hearing of one person distinguishes sound with a maximum frequency of 18 kHz, and the other only 13 kHz (sometimes less), so the vision of different people has a different reaction to a change in light (screen refresh rate ) in Russian television standard frequency sweeps at 50 Hz and fields follow at 25 Hz.)
By increasing the frame rate (screen refresh rate in the monitor settings), we move away from this critical point and have a screen refresh rate with a frequency that guarantees no flicker. The main thing is that the monitor and video card support this maximum frequency.

For progressive (frame) scan monitors, the screen refresh rate should not be a multiple of 50 Hz (the flickering frequency of lighting fixtures) and the maximum for dynamic (fast motion games) applications.

With progressive scanning, the entire frame is constructed by sequential inclusion of screen pixels (by line and by frame) from the first to the last. And the screen bypass frequency is equal to the frame rate. It is more than 2 times higher than the refresh rate of CRT monitors. Therefore, the problem of flicker, it seems, should not exist. A high refresh rate is needed to increase the monitor's response to fast movement in the game, fast graphics (viewing fast-changing processes). If the refresh rate of the LCD monitor is low, such scenes become blurred (lose clarity). In office applications, graphic editors, a frequency of 60 Hz is enough.

Modern LCD monitors have high speed switching, so they are subject to recommendations similar to CRT monitors. (Maximum Refresh Rate)

Experiment with the screen refresh rate (look at the screen when different frequencies updates). You will notice that the frequency above which the text on the screen will begin to distort (smudge, appear fringing or blur). Reduce the frequency to the highest definition of the image and work. Your eyes will be less tired.

Workplace lighting

All of the above applies to the lighting of the workplace. The illumination of the table with the keyboard and documents should be approximately the same throughout the work and not too high. To do this, in rooms where they work with a PC, both general lighting of the room and local lighting should be combined. General lighting should be dim comfortable, with its lack, it is used as additional - local lighting.

Now what do the regulatory documents say about ambient light.

SanPiN 2.2.2/2.4.1340-03

Clause 7.3.
Hygienic requirements for personal electronic computers and organization of work says:

"Illumination on the surface of the table in the area where the working document is placed should be 300 - 500 lux. It is allowed to install local lighting fixtures to illuminate documents. Local lighting should not create glare on the screen surface and increase the screen illumination by more than 300 lux."

SA. As you noticed, SanPiN limits the maximum illumination values. Practice shows that it is impossible to strive for them, taking into account the individual properties of your body, the illumination must be optimized. Moreover, it is necessary to strive for minimum levels illumination. At these levels, eye strain is reduced. You may not be able to change the general illumination of the room (the light only turns off), but in any case, local lighting (table lamp) must be provided with a regulator and an incandescent lamp. (Other types of lamps do not allow you to smoothly adjust their brightness over a wide range)

Clause 7.4.
The line should be limited glitter from light sources, while the brightness of luminous surfaces (windows, lamps, ceiling, etc.) in the field of view should be no more than 200 cd / sq. m.

SA. T Auger limits apply only to the maximum, and increased brightness leads to rapid eye fatigue.

Clause 7.7.
It is necessary to limit the uneven distribution of brightness in the field of view of the user of the VDT and PC, while the ratio of brightness between the working surfaces (table, monitor screen) should not exceed 3: 1 - 5: 1, and between the working surfaces (table, monitor screen) and wall surfaces and equipment - 10:1.

SA . If SanPiN 2.2.2 / 2.4.1340-03 set the maximum values, then the really normal levels should differ by no more than 30-50%. We must try not to approach the values ​​​​of SanPiN, since even here clause 7.7. contradict clause 7.3. after all, 500/300 lux is not 3/1, much less 5/1. If we take for the normal brightness of the working surface 100 cd / sq. m, then according to clause 7.7. the brightness of working surfaces can be up to 500 cd/sq. m, and the surfaces of walls and equipment up to 1000 cd / sq.m. and the maximum is twice as much, and this is with a limit of 200 cd / sq. m according to clause 7.4.

From paragraph 7.7. follows the relationship between brightness monitor - table - surface walls , equipment, furniture and other items in the working room, and even if the actual values ​​\u200b\u200bare indicated, then SNIP and practice confirm that their brightness (from work surfaces to surrounding equipment) should not differ much.

Clause 7.14.
Ripple factor ( refers to the pulsation of the brightness of the lighting - SA ) should not exceed 5%, which should be ensured by the use of gas discharge lamps in general and local lighting fixtures with high-frequency ballasts (HF ballasts) for any type of fixtures.

SA . This requires special measurements and verification of which fixtures are installed. In addition, fluorescent lamps, like any devices with a volumetric discharge, are subject to external influences of magnetic and electric fields, which modulate their discharge current and, accordingly, the brightness of the light.

This is all the more important since energy savings encourage the use of fluorescent (economical) lamps, which is why most office luminaires are fluorescent. The vast majority of them operate in a pulsed mode (even with electronic ballasts). As a result, there may be light pulsations with frequencies of 50 Hz, with the operating frequency of the electronic ballast, frequencies of external electromagnetic interference (when their period is less than the afterglow time of the phosphor of a fluorescent lamp).

These pulsations of light are superimposed on each other, on the pulsations of your monitor.

I hope you know the principle of operation of the stroboscope and you will understand the consequences for your vision of these pulsations.

Lamps using incandescent lamps do not have pulsations (their level is many times less) due to the inertia of heated coils, especially lamps with halogen lamps.

Therefore, I can join the advice of Konstantin Furst:

"2. Lamps daylight it's better to smash everything at once SA - this is a joke, there is mercury in the lamp, do not break it!) by installing an ordinary incandescent lamp on the ceiling. You should not place the only light source in the form, say, table lamp behind the monitor. If this cannot be avoided, then at least direct the light of the lamp towards the ceiling - this will give a softer lighting. Do not agree to work with a computer in complete darkness for any price. The ancient forces of evil will instantly move into it and do with you what is usually done with the heroes of the second plan in horror films. "

SA. I can add that I do not recommend using fluorescent lamps, regardless of the switching scheme or the types of ballasts used. They have a harder light, and sometimes there are lamps with poor quality phosphor coating, so you can sunbathe under them, since they serve as a source of ultraviolet (UV). A sign of this is the smell of ozone, but for this the level of UV must be many times higher than the permissible one. I came across a couple of times with such lamps. Measurement of the level of UV radiation in such premises (with installed fluorescent lamps) is mandatory, but usually not carried out anywhere.

The physics of burning a discharge in a fluorescent lamp (a gas-discharge fluorescent lamp) says that the discharge current flows through it in pulses only when a certain potential difference is applied to the discharge gap. The ignition rate of the heated gas mixture is high. Such discharge current pulses can flow even in a fluorescent lamp with a high-frequency ballast at the moments when the supply voltage passes through zero (a sinusoidal current flows in the network).

The only way to reduce light ripples fluorescent lamps- the use of phosphors with a large afterglow (more than 0.04 sec). Those who used the old pulse oscilloscopes know that there are phosphors with an afterglow of up to several seconds, only such phosphors, if my memory serves me, are all colored.

A message flashed, probably sponsored by contact lens manufacturers:

"26.04.09, EuroNews - Spanish ophthalmologists have conducted a study on the effect of fluorescent lamp light on vision.

Their conclusion.

The light of fluorescent lamps is harmful to the eyes due to its rigidity, the presence of UV components in the spectrum. It was also said about the presence of pulsations (brightness modulation) in fluorescent lamps.

LCD monitor

... and Nokia Monitor Test

My practice shows that liquid crystal monitors overload the eyes (according to my feelings, even more than cathode-ray). In my subjective opinion, because of too much brightness and not always sufficient clarity of the fonts. This overloads the eyes by increasing the load on them.

To reduce the load, it is necessary to work with texts at reduced brightness ( I had a 21% brightness level on my FLATRON L1918S monitor, and now the LG E2240S is about 13%) or choose 10% gray page background in editors.

There is a Nokia program Monitor Test - NTest designed to adjust LCD monitors.

It allows you to adjust the monitor and its parameters such as "Frequency", "Phase", "Clearness". All these parameters are adjusted on small vertical lines (test 4th from left, thin vertical lines) or on thin text. When setting up, you will choose the most convenient test for you. But checking on thin vertical lines must be done anyway. You may need to adjust the phase or frequency.

This setting allows you to get maximum quality fonts.

...and ClearType

To improve the readability of fonts, Microsoft ClearType screen font smoothing is available on Windows XP and later operating systems. It is designed to improve the readability of fonts when using LCD monitors. This is similar to reducing eye fatigue when reading. text documents. In Windows Vista it is enabled by default, while in XP it must be enabled.

To enable ClearType anti-aliasing on XP, you need to:

• click right click mouse on desktop,
• in context menu select "Properties",
• in the "Properties - Display" dialog box that opens, open the "Appearance" tab,
• click on the "Effects" button,
• check "Apply the following screen font smoothing method",
• select "ClearType" from the dropdown list.
• then press "OK", ..... to save the selected settings.

Eye exercises

Exercises for relaxation according to William G. Bates "Improving vision without glasses using the Bates method", Moscow, 1990. Chapter 24

Rest for the eyes

The simplest way to rest the eyes is to close them for a more or less long period of time and mentally imagine something pleasant. This method serves as a means of first aid, and it must be resorted to in the first place. Only very few people do not benefit from it.

palming

An even greater degree of relaxation can be achieved if a person closes his eyes and covers them with the palms of his hands to completely block out the light. Close both eyes and cover them with the palms of your hands, while your fingers are crossed on your forehead. The simple exclusion of exposure to light is often enough to achieve a significant degree of relaxation, although sometimes tension can increase. Generally, successful palming involves knowing other ways to relax. Simply covering the closed eyes with the palms of the hands is useless if at the same time the state of mental calm is not achieved. When you succeed in perfect palming, you will see a field of view so black that it is impossible to remember, imagine or see anything blacker. When you achieve this, your vision will become normal.

turns

See for yourself that turns not only improve your vision, but also reduce or completely eliminate pain, discomfort and fatigue.

Stand with your feet about a foot (about 30 cm) apart, facing one of the walls of the room. Lifting the left heel slightly off the floor, simultaneously turn the shoulders, head and to the right until the line of the shoulders becomes perpendicular to the wall to which they were facing. Now, as you lower your left heel to the floor and lift your right heel off the floor, twist your body to the left. Alternate between looking at the right wall and then at the left, paying attention to the fact that the head and eyes move with the shoulders. When the turns are made easily, continuously, effortlessly, and without paying any attention to the moving objects, one will soon notice that the tension of the muscles and nerves is reduced. (Remember, however, that the shorter you can make these turns over time, the greater your progress will be.)

Stationary objects move at different speeds. Those that are almost directly in front of you will appear to be moving at the speed of an express and should be heavily lubricated. It is very important not to make any attempt to see clearly objects that seem to a person at the time of the turns to be swiftly passing by him.

SA. The exercises are given in the original source as curative, but they are simple and can be used to relax the eyes.

This is no longer William G. Bates!

Exercise for the muscles of the lens

For this exercise, you need to use a window from which you can see a lot of eye-catching objects on different distances. On the glass at eye level, apply a small dot with clear outlines. Standing in front of it, look out the window, there should be several contrasting objects on the same line with the dot, at different distances (the farthest one is more than 500 m).

Standing at a distance of 50 cm in front of your point, focus your gaze first on this point, then on an object located at a distance of several meters, then at a distance of 10-15 m and so on up to the farthest object or horizon line. When focusing on an object, it will be clear, all others are fuzzy.

Repeat the exercise several times for each eye separately.

Eye muscle exercises

Eye movements are performed with a motionless head in one position.

1. Vertical. Eye movement up (you want to see the ceiling above your head), down (the floor under your feet),
2. Horizontal. Without tension, move your eyes to the right to the left.
3. Circular. First clockwise, then against.

The last two exercises are no longer William G. Bates! and improve blood supply to the eyes.

The easiest exercise

sent by the reader Olga.

You have listed good exercises, there is one more, quite simple and effective.

Within one and a half to two minutes, you need to quickly - quickly blink, and then close your eyes several times. From blinking, blood flow to the eye increases, and by closing your eyes, the muscles of the eyes are toned.

Vision improves noticeably and immediately!

This exercise also helps to wash the cornea of ​​​​the eye with tear fluid, which improves its condition. And, no less important, there is a sparkle in the eyes.

Eye training and relaxation programs

Safe Eyes

The problem of visual fatigue and diseases associated with it in computer personnel has been officially confirmed by the World Health Organization (Geneva, 1989). In this regard, in the early 90s, the Russian company "Sensor" (now I have not found it) developed a program that relieves visual fatigue.

The methodology is based on the discovery of the English neurophysiologist F. Campbell. The scientist found an increase in visual functions when showing certain geometric images. There are specialized devices that use the so-called Campbell effect for therapeutic purposes in a clinical setting. The developed software tool "Safe Eyes" includes the display of certain dynamic graphic images built on the basis of the Campbell effect.

The duration of the procedure is 8-10 minutes. Systematic use software tool during breaks and (or) at the end of work, it allows to increase the efficiency of personnel and to prevent eye diseases that occur during permanent job on the computer.

The program is free and works on all operating systems starting from Windows 95.

Despite this statement, once on the developer's website it was said that it was commercial. I could not find the owner of the program to ask him for permission to post the program on the site. The site of the program developer, the SENSOR company, disappeared from the Internet. It would be nice to develop new program, which will work under modern operating systems. I suspect that their means of this program will be of higher quality.

It must be admitted that the program "Safe Eyes (the program starts and works normally under Windows Xp)" certainly deserves attention. According to our data, this is the first Russian development of this kind, designed for the mass user.

Now there is an assembly of the program on the Internet Safe Eyes for Windows 7, which contains a DOS emulator - QEMU. According to some reports, this assembly was made by SUPERNOVA DIGITAL RESCUE. Before you start, read the read.me file, I especially recommend paying attention to the procedure for closing the QEMU emulator!

When I enter some institutions, I still see so-called "protective screens" on the screens of monitors.
Outdated!
But for those who still use I'll leave it.

Screen protectors don't help protect your eyesight, they only dampen the brightness of monitors, but at the same time they increase the brightness of glare. You can lower the brightness of the monitor yourself. The brightness of glare from protective screens is high due to their polished surface. Monitor screens are now all matte! The only effect from the use of screens is a faster failure of the cathode ray tubes of monitors (by about a third).

P.S.

I may seem old-fashioned to some, but modern tendencies in lighting sources (Economical, LED lamps) requires close attention. Their use without an attestation certificate (with a specific indication of the level of pulsations) is unacceptable. Moreover, a constant examination and measurement of the characteristics of the luminous flux and its pulsation is necessary.

LED bulbs create a narrowly directed light flux, which enhances the non-uniformity of illumination of large surfaces, which is unacceptable during the intense work of vision.

At the workplaces of PC operators LED lights should have light diffusers that create uniform illumination on the working surface (in my opinion, the non-uniformity should not exceed 5%). Although this condition, purely technically, is almost impossible to fulfill for these light sources.

You can send your opinion on whether this article helped by mail, and briefly through

Literature:

• SanPiN 2.2.2/2.4.1340-03 Hygienic requirements for personal electronic computers and organization of work. http://www.skonline.ru/doc/37965.html
• Tips for organizing a workplace from Konstantin Furst. http://www.vision-ua.com/patient/sovet/CVS/Anti-EyeStrain.php
• Safe Eyes eye training program (to my great regret, the links given here earlier are broken, I can recommend searching for the file of this program by file name - se.exe or by query "Safe Eyes download" - you will find it quickly).
  • Safe program Eyes for Windows XP can be downloaded.
  • program safe eyes for Windows 7 you can download . Before work, read the read.me file, especially I recommend paying attention to the procedure for closing the QEMU emulator!
• American Academy of Ophthalmology recommendations for PC users http://medicinform.net/comp/comp_vis2.htm
• Relaxation exercises according to William G. Bates "Improving vision without glasses using the Bates method", Moscow, 1990. >>

Purchase large subwoofer does not guarantee that you will get great bass from your audio system. This guide tells you everything you need to know to get the best acoustic performance.

Subwoofer Setup: Placement and Positioning
Although the low-frequency sound emitted by a subwoofer is non-directional, you should not install the sub in any place that you think is most convenient in the room, as there is a possibility of partial loss of the sound quality that you paid for.

Subwoofers with small drivers (8 inches or less) are best placed about a meter in front of the front left or right speaker. With too much offset, it's much harder to maintain the illusion that the bass is coming from the speakers rather than straight from the subwoofer. This remark is doubly true for small home theaters with a subwoofer in the kit, place it as close as possible to the front speakers. Oh, and when looking for the right spot for a sub, don't forget to turn up the volume just enough to clearly hear what's coming down from there.

Some tips for locating a subwoofer may also be helpful. When playing a CD with large quantity deep bass, by moving the subwoofer, track all acceptable listening locations. You will be amazed at how much the sound changes depending on the location of the subwoofer. In some cases the bass will be muddy, sometimes louder and sometimes quieter. The goal of the experiment is to get the optimal balance between deep bass, top the low frequency range reproduced by the subwoofer and the mid frequencies of other speakers. In some rooms, this condition is difficult to achieve. In my experience, there are "problem" rooms where the bass is always booming or unclear.

In such cases, try the following method. Move your couch or chair to another location, or try listening to the subwoofer in another room. Then turn on music or a movie with a lot of bass and also move the subwoofer to find the best listening position. As you move around, you will notice that the volume and definition of the bass changes from place to place.

If all else fails, try placing the sub as close to the sofa or chair as possible. Such an arrangement can be very successful.

Large speakers are usually easier to match with a subwoofer. It is more difficult if small and / or if the speaker system has a small subwoofer. In this case, more careful adjustment may be required to achieve the desired effect.

Subwoofer Setup: Connecting and Fine-Tuning
Pictured back panel subwoofer HSU Research is considered fairly typical. Although for those new to acoustics, the multitude of connectors can be intimidating. But in most cases, just one cable connected to the "SUB IN" input provides effective sound. On other subwoofers, this input may be labeled "LFE", "Direct", or "Bypass".

To connect to the Sub / LFE input, you will need a long connecting cable, which can be purchased from stores consumer electronics. How long should the cable be? Measure the distance between the A/V receiver and the subwoofer and be sure to allow for additional distance if needed to allow the cable to go around a doorway or other obstruction. If, after opening the package, the cable is shorter than necessary, you will not be able to return it back to the seller.

Then turn the knob frequency response(crossover) to the maximum value. We will rely only on the frequency division system built into the A / V receiver sound signal. It should send the mids and highs for playback by the channel speakers, while the subwoofer should receive only the low frequencies (bass).

In the receiver's menu, you'll find crossover controls that determine how much of a frequency the speaker's speakers will produce. Some receivers have an extended subwoofer tuning range from a low frequency of 40 hertz to a high frequency of 200 Hz. For specific recommendations, see the manual for your subwoofer or speaker. AT otherwise You can use the following guidelines to adjust the crossover. For small speakers with 2" or 3" woofers, try values ​​from 150Hz to 200Hz, for mid-sized speakers (4" or 5") the low frequency drops to 80 or 100Hz, and for larger tower or bookshelf speakers try 60 or 80 Hz.

If you happen to own large floorstanding speakers with an 8" or larger woofer, you can label them in the menu as "Large" speakers with no crossover at all. But the center, front and rear speakers will probably still sound better in the "Small" speaker mode using the crossover settings mentioned in the previous paragraph.

Another subwoofer volume control is labeled "Phase". It is necessary because the speakers and subwoofer speakers sound best when they are "in phase", that is, the speaker cones move back and forth in sync. To check if the phase setting is correct, listen to music with a lot of bass for about a minute, then ask a friend sitting near the subwoofer to change the position of the phase control. It is necessary to slowly move the regulator knob to the 180 degree position, then back and forward again. The "correct" setting is the one at which you will hear more bass. You may have to listen to a few recordings before you notice the difference, and in doing so, it may be worth turning up the volume a little. If you don't notice any difference between the "0" and "180" positions of the phase control, leave it in the "0" position.

Nearby on the panel is a subwoofer volume control. An exact match between subwoofer, center, front and rear speaker levels is important, but bass volume is more subjective. Some people like to hear the subwoofer running all the time, while others prefer to turn it on only at moments of bass boosting special effects while listening to music and watching movies. A sound level meter (such as the Radio Shack model 33-4050) can be a great help in setting speaker levels, but it is almost useless in determining the correct subwoofer volume. In this case, the "by ear" method works best.

The bass content of the sound is usually fairly consistent when listening to DVDs, but CDs have more bass variation. After listening to a few discs, set the desired volume (directly on the subwoofer or on the receiver, whichever is easier). With DVD discs you can set the volume to the optimum level after 10 minutes or less, but CDs can sometimes take you almost an entire day.

A/V receivers' automatic audio tuning systems can do a good job with regular speakers, but most are less adept at subwoofer tuning. In fact, most receivers have subwoofer auto-tuning, to put it mildly, unimpressive. Try changing the crossover settings, check the phase and volume settings. If you don't like the changes, run automatic setup to return to the original values.

As a preamble to this section we decided to present a set of basic recommendations from THX regarding the installation and setup of subwoofers in rectangular rooms. It consists, in fact, in this: there are several options for installing subwoofers, depending on how many of them you have. Smaller rooms always have problems with standing waves ruining the bass. The following five measures will help bring their negative impact under control:

• Choose a room of such dimensions that its modal frequencies do not intersect;
• Locate viewpoints away from modal peaks and troughs;
• Position the subwoofers so that they help better control the amplitude of the standing waves;
• Use low-frequency absorbers to remove excess bass energy;
• Apply an equalizer or electronic equalization (last resort, when everything else has already been optimized as much as possible).

In general, if you have four subwoofers, THX recommends that you start by placing them in all four corners. If there are two, put them in the middle of the front and rear walls. If there is only one subwoofer, place it in one of the front corners. Next, listen to the difference from place to place and move the subwoofers along the walls until you get the smoothest sound coverage of the viewing area. The ability to move the subwoofer around the room often outweighs all the advantages of the option, tightly built into the wall. Follow the given placement guidelines, take the necessary acoustic measurements, and always trust your ears.

Based on this, it becomes clear how much time and attention should be paid to the location of the subwoofers, the acoustic design of the room, and how much to the final fine-tuning or, as it is often called, calibration. And yet, we will get the maximum result by going all the way. So what is this last step? Let's go in order. First, let's look at setting up a single subwoofer.

Setting up a single subwoofer

We take into account the following initial data (we recommend considering them as starting points at the stage of finding a place for a subwoofer):

• if the subwoofer has a high-pass filter (LPF) control, it is set to the maximum value (usually 120 Hz);
• The Phase switch on the subwoofer is set to "0" or "Normal", the phase control (if any) is set to the extreme position indicating "0";
• The subwoofer volume control is set to 1/3 of the maximum value;

Velodyne subwoofer built-in amplifier controls

• On the AV receiver, all speakers are set to “Small”, the subwoofer is on, and the crossover frequency for all speakers is set to 80 Hz;
• The sound mode “Stereo” or similar is selected on the receiver so that your subwoofer is guaranteed to receive and reproduce the low-frequency component of the sound track (to be sure, you can touch the speaker with your hand - its vibrations should be felt).

Pioneer AV Receiver GUI Example of Setup Screens

Phase setting

The first step is to correctly set the phase of the subwoofer, because. this greatly affects all subsequent manipulations. The system is considered to be phase-matched if the woofers of the main speakers and the subwoofer move back and forth in sync. If their speakers move out of sync, the low-frequency waves overlap and they cancel each other out. As a result, you will hear less bass and the system will be considered out of phase.

Unfortunately, in conjunction with the subwoofer and main speakers, another problem may arise. If the speakers play the same bass notes as the subwoofer, at some point there will be humps at certain frequencies. Dips may appear at other frequencies. The solution would be to instruct playback low frequencies subwoofer only by setting the main speakers to "Small" in the receiver's menu. This will help produce a more even bass throughout the room.

To get the best bass, you need to find the correct position of the phase switch, which will maximize the SPL at the listening position. This can be achieved by applying a test signal to the receiver at the crossover frequency (80 Hz in our case) and a sound level meter (SLP meter). You need to turn on the test signal, measure the SPL at the listening point, flip the phase switch, measure the SPL again, then compare the obtained numbers and draw an unambiguous conclusion. The phase switch, respectively, must be left in the position where the sound pressure level is maximum. If you don't have a sound level meter, you'll have to trust your ears. In this case, play music (not a movie) with a repetitive bass line (drum or bass guitar). Flick the phase switch and settle on where the bass is more "full" and "faster". If you don't hear a difference, leave the switch in the "0" or "Normal" position.

Example of a signal phase switch on a subwoofer amplifier

Fortunately, most subwoofers have a phase switch, and advanced models even have a rotary control that allows you to smoothly change its value from 0 to 180 degrees. And if you are too lazy to get up from the couch, then there is one little trick for this case: changing the value of the distance to the subwoofer (aka signal delay) in the AV receiver menu has the same effect as smooth rotation of the phase control on the subwoofer itself. Choose what is closer to your soul, and act!

An example of a smooth phase control of a signal on a subwoofer amplifier

Adjusting the volume level and frequency of the crossover section

After the phase is set, you can proceed to adjust the subwoofer volume level. To do this, it is enough to use the test signal built into any AV receiver or processor, which, as a rule, is reproduced at a level of 75 dB (pink noise). Ideally, a specialized test signal generator should be used, or at least a disk with their recordings. Do not even try to adjust the level by ear - as a rule, nothing good will come of it. To correctly set the level, we need a sound level meter or SPL-meter. We turn on the test signal, look at the sound level meter and adjust the subwoofer level so that the device shows the coveted 75 dB. You can go further and adjust the level even more precisely. To do this, use 4 sinusoids from the range 1/3 octave below 50 Hz and 4 sinusoids from the range 1/3 octave above 50 Hz as test signals (for example, 42, 45, 46, 48 and 54, 58, 62, 64 Hz). It is necessary to measure the SPL at each of the frequencies, calculate their arithmetic average and adjust the level of the subwoofer. And so on until the average value becomes equal to 75 dB.

Examples of portable sound level meters (SPL Meter)

Don't forget to check all the other channels of our system, which should also give out the same 75 dB. This completes the subwoofer volume setting. Let's move on to setting up the crossover.

crossover- this is an analog or digital block that is responsible for what frequency range of a particular channel will eventually go to a particular loudspeaker or speaker. A full-range signal (20-20000 Hz) enters the crossover input, and at the outputs it is already divided into two or more channels, each of which already has a range of the original signal limited from above or / and from below by a certain frequency. On the frequency response graph, in theory, it looks like this:

The work of the crossover on the frequency response graph

It is the crossover that allows you to "redirect" the bass from all 5 or 7 of your satellites to the subwoofer for its more correct reproduction in viewing areas.

All crossover settings must be made on the AV receiver/processor, not on the subwoofer itself. If your front speakers are large and capable of decent bass reproduction, feel free to set their crossover frequency to 80 Hz. If they are small (shelf, wall or built-in), set the crossover frequency to 100-120 Hz. The US Recording Academy recommends setting the crossover frequency between 80 and 100 Hz for best results.

Example of the crossover setting screen in the AV receiver menu

A more precise adjustment of the crossover will allow only the presence of measuring equipment that allows you to see the frequency response curve. Such equipment is commonly referred to as a spectrum analyzer or Real Time Analyzer (RTA for short). The goal of all our manipulations remains the same - to obtain the most linear frequency response graph. In terms of choosing the correct crossover frequency, this goal is achieved by repeatedly and successively measuring the frequency response, each time changing the crossover frequency by the minimum possible number of units (usually 5-10 Hz). "Probing" in this way the range from the lower boundary frequency of the speaker to 100-120 Hz, we select and stop at the option where the frequency response graph is the most linear.

Portable Dual Channel Spectrum Analyzer (RTA) Phonic PAA6

In most cases, when you have large floorstanders that can play quite low, they will be easier to match with a subwoofer than the small bookshelf speakers that most have. However, not necessarily the best result can be obtained by setting the crossover frequency to the minimum value in order to neutralize the special signature of the subwoofer at frequencies that the speakers are already capable of reproducing. If the crossover frequency is set to the minimum value, the subwoofer will not be able to stimulate the dynamics of the main speakers in their vicinity. resonant frequency, allowing them to be the dominant oscillator. If the cutoff frequency is set slightly higher, the sound waves from the subwoofer and the main speakers can reinforce each other, resulting in a bass that is smoother and more pleasant to the ear. Keep this in mind.

Applying the equalizer and electronic equalization

As you may have noticed, equalization and electronic equalization are the last steps you can take to get your subwoofer to play at 100%. This state of affairs is not accidental, despite all the attractiveness, immediately turn on the automatic setting and forget about everything else, like a bad dream. All the subwoofer tuning measures described in this article are strictly in descending order of the degree of their influence on the final result as a whole. Changing this order is highly discouraged, because it can easily lead to unsatisfactory results, which can be corrected only by repeating all the activities anew and in order. So save your time and get it right from the start.

So, returning to equalizers and electronic correction, it should be noted that most installations occur without their use by installers. On the one hand, it is often possible to achieve good result, acting correctly at the previous stages, and on the other hand, the necessary equipment or functionality in the receiver / processor is far from always available. A lot depends on advancement and cost. specific model. Inexpensive receivers will not be able to please you with the presence of an advanced version of the auto-calibration system, which also works in the range below 1 kHz, and the equalizer for the LFE channel will most likely be limited to 4 fixed bands (for example, 25, 50, 85 and 120 Hz). Such a set of tools is by no means satisfactory for solving our problem. Top Models AV receivers and processors always have on board a full-range electronic room correction or auto-calibration system (Audyssey, ARC, YPAO, etc.) and a parametric equalizer with an acceptable resolution. If there is no confidence in the processor's instrumentation, you have the right to use a dedicated equalizer on the subwoofer channel. The most important characteristic equalizer in case of its use in conjunction with a subwoofer - this is its resolution. The higher the resolution, the more accurate frequency response correction it will allow you to make. Ideally, it should be at least 1/12 octave per band. And it's a completely different matter when it comes to a parametric digital equalizer. In this case, you are free to make adjustments at almost any frequency.

Two-channel LA Audio graphic equalizer

Basic Equalization Rule in relation to the subwoofer frequency range - cut the humps but don't touch the dips. Any dip in the frequency response graph in the low-frequency range tells us that either the listener or the subwoofer is located near the zero nodal point of the standing wave. Trying to correct this frequency with an equalizer will only add distortion, but will not affect the audibility of the desired note in any way. Remember this.

A modern alternative to a graphic or parametric equalizer is a variety of systems for electronic correction of room acoustics (or automatic sound calibration). These solutions are present in most modern AV receivers and processors. These allow you to make basic adjustments to the sound of your surround sound system almost automatically. All you need to do is place the included measurement microphone in the designated location and follow the instructions. The system itself will reproduce the test signals and measure them at several points in the room, after which it will issue recommendations for setting the following parameters:

• Small or Big for each pair of speakers (Front, Center, Surr, etc.);
• Crossover frequency for each pair of speakers;
• The distance to each of the speakers, including the subwoofer.

Tuning microphone from the receiver with the Audyssey auto-calibration system

Along with this, the auto-calibration system will calculate and be ready to apply a special frequency filter, the imposition of which on the current frequency response of each channel will (in theory) make it as linear as possible. Unlike a parametric EQ, auto-calibration systems like the Audyssey MultiEQ operate with hundreds of so-called. points on the frequency response curve, inverting dips and humps with jeweler precision exactly where it is needed. To repeat this with the most advanced parametric equalizer (we are talking about the full frequency range) will not work. With regard to the low-frequency range, one can still argue, but using an automatic system will definitely save time and most likely result in a flatter frequency response.

How the Audyssey System Works Compared to Conventional EQ

If you decide to use such a system, do not forget to return the speaker settings to their places later (Small instead of Big, crossover frequency values ​​\u200b\u200band speaker distance) - here auto-calibration can easily “give a rooster”. You can’t trust her 100%, especially when we have already made all the necessary measurements and settings ourselves.

Features of setting up a system of several subwoofers.

Now let's pay attention to setting up a bass section consisting of several subwoofers. There are some peculiarities here. Let's move on to them.

1. Use identical subwoofers

If you want to avoid losing a large number time spent on manipulations when setting up a link of 2 or more subwoofers, use the same devices. Only twin subwoofers can have the most similar characteristics of all components and the resulting sound, which is essential to obtain a predictable effect of even bass coverage of the entire listening area.

We are talking about the practices of the most optimal arrangement of multiple subwoofers in a room, discussed in detail in the section of our article.

3. Make sure all subwoofers are playing the same "tune"

Believe me, it will be extremely problematic to set up an array of subwoofers that reproduce a different signal. Once again, make sure that the LPF on each subwoofer is turned off or turned up to its maximum value so as not to interfere with the bass management system of the AV receiver / processor. The phase settings must also be identical. As a general rule, the phase switch or control should be left in the “Normal” or “0” position. If the receiver / processor has only one output from the preamp to the subwoofer, it's time to use Y-splitters. If the receiver has several subwoofer outputs enabled and enabled, make sure that the bass management for each of them is set up correctly and gives the same signal to all outputs (“Both” or “LFE+Main”). In short, you need to make sure that each subwoofer is receiving a mono signal from all of the speakers labeled "Small" plus the LFE channel signal. Some receivers/processors (in particular, some models from Denon) support a stereo subwoofer configuration, the use of which for our purposes will only introduce a destructive component. Make sure it is not enabled (Mono is selected).

4. Equalize the volume of all subwoofers

It is very important to set the same sound volume on all available subwoofers. If this is neglected, you risk ending up with poor integration, and even overload during loud moments if some subwoofers are tuned louder than others. This will result in distortion at lower volume levels relative to what your system is actually capable of. The correct way to level-match all subwoofers is to use the receiver/processor's built-in pink noise generator and measure it with a sound level meter in C-weighted mode. Measure the level of each subwoofer individually, physically turning off all others during the measurement. Measurements must be taken at the same distance from each of the subwoofers. And if you are very tight with time, you can measure the level in the near field of the subwoofer by placing the sound level meter or measuring microphone on the floor at a distance of 10 cm from the wall of the device where the emitter is located.

Example of measuring microphone placement in the near field

If the subwoofer is a bass reflex subwoofer, the microphone should be placed halfway between the center of the speaker and the bass reflex port (already on a tripod). This technique becomes very problematic if the subwoofer has multiple speakers, which is why we recommend that you measure at a point equidistant from all devices, and this point will not necessarily be in the listening area. Once you have aligned the volume of all subwoofers relative to each other, it's time to move on to leveling the volume of the subwoofer in relation to the front speakers or center channel.

Measure the level for the front LR and C channels and the subwoofer array at at least two locations (primary and secondary listening positions, such as the first and second rows). Write down the results in a table so that you can more accurately make the necessary adjustments. It's a really good idea to measure at least two points and calibrate the levels so that the difference is no more than 1-2 dB so you get the most correct SPL coverage over the entire listening area. Even THX recommends taking your time when taking measurements. Take some time to experiment with RTA and SPL meters, and be generous. THX recommends that each measurement be taken for at least 20 seconds. Some professional calibrators allow up to a full minute for each measurement. This will provide you with a guaranteed correct result. Why? Because pink noise is not always uniform at low frequencies. Noise is, by definition, random. The longer the instrument takes to measure noise and calculate the average, the less likely it is to get SPL measurement errors due to the natural inhomogeneity of pink noise. Spend as much time as you need to make good weighted measurements - it's worth it in the end.

5. Measure the original frequency response

Before moving on to automatic calibration or active equalization, it is necessary to understand what we will start from initially. It is critical to get maximum integration of the front speakers with your subwoofers. An alternative point of view - the most important is the correct integration of the center channel and subwoofers. If you will mostly watch movies and listen to multi-channel music, perhaps this is exactly what you should do. However, as practice shows, a person is much more susceptible to incorrect playback of music by a front stereo pair than to accurately determine whether there is a perfect match between the center channel and subwoofers during instant action scenes of a movie. If you prefer to listen to 2-channel music programs, please calibrate the subwoofers relative to the front LR channels. If you watch movies more often than listen to music, feel free to calibrate the subwoofers with respect to the center channel speakers.

Connect your RTA's output to a free pair of stereo line-in receiver/processor inputs, place the device or its measurement microphone at the main listening position at head level of a seated person, and let the fun begin! Set up the instrument to measure from 10 to 200 Hz and at 60 dB spread so we can see exactly what's going on at low frequencies in your system. Remember to make sure you have a measurement resolution of at least 1/12 dB/oct. A lower resolution will not allow you to clearly see the real state of affairs.

The process of measuring the frequency response in full swing

Once you have your original frequency response plot, freeze it and then try playing around with the following settings to see if you get any measurable improvements (smoother plot, less hums and dips):

• Main speaker size: Large / Small (Large should only be considered if it gives a real improvement in the frequency response and your speakers are able to play all the necessary low frequencies at the reference volume level (105 dB at the listening point) and without overload and distortion) ;
• Crossover frequency of the main speakers;
• Distance to subwoofer (delay);
• subwoofer phase.

It is not recommended to deviate in the crossover frequency value more than 20 Hz from the often optimal and recommended THX 80 Hz. It has also been noticed that some receivers/processors tend to cut the LFE channel if cutoff frequencies are set below 80 Hz. If, however, the crossover frequency is set much higher than 80 Hz, there may be a problem of localization of subwoofers, especially if some of them are located close to the listening area. If you have small satellites, 100 Hz is likely to be the optimal crossover frequency. The stereo effect at frequencies below 150 Hz is extremely weak, and depending on the sensitivity, distortion, and natural roll-off frequency of the main speakers, setting the crossover to 100 Hz can create the most full sound. The key to success in this business is experimentation. If your satellites are so small that they require a crossover frequency set too high, you should consider replacing these speakers or placing the subwoofers as far away from the listening area as possible in order to eliminate the problem of their localization.

Again, in most cases it is recommended to leave all satellites in the Small mode. This will achieve best integration between them and your subwoofers, as well as more dynamic range from mainstream speakers who no longer have to carry the heavy burden of bass reproduction. In addition, this will entail a reduction in the amount of distortion in the speakers themselves and the amplifiers that serve them.

Subwoofer distance is an extremely important setting in maximizing the integration of subwoofers with each other and with the main speakers. If each subwoofer is connected to a dedicated pre-out, measure and set the correct distance for each. If all subwoofers are ideally installed in a rectangular room, a single delay (distance) value will do for them. Moreover, it is recommended to maximize the effect of leveling standing waves.

However, if your setup isn't ideal, you'll probably need to play around with the delay settings for each subwoofer individually. In such cases, try to calculate the average distance from the listening area to a group of subwoofers sitting on the same line output. For example, if you have one subwoofer at 3 meters and the other at 2.5 meters, the average would be 2.75. It is worth starting with this delay value in the receiver / processor. Most likely, it will be adjusted upward due to the presence of a natural delay in the subwoofer digital amplifier path. We can get the ideal delay value by measuring the SPL (LCR + subwoofer) at the crossover frequency: change the delay, measure it - and so on until the SPL is maximum.

MiniDSP UMIK-1 and Dayton Audio OmniMic measurement microphones for use with PC-based RTAs

When you've finally achieved the best measurable result for your main listening position, repeat the entire process for the next most important seat in the room. Try to find a combination of settings that allows you to get best sound for both points. You can go on and on, but as practice shows, if you did your best in the first two cases (for example, in the center of the first and second rows), other places will also benefit from this. Again, the more correctly you were able to position the subwoofers during installation, the less body movements and advanced settings you will have to do to achieve a stable and even frequency response graph for all viewing positions.

6. Use an equalizer or automatic calibration system

Now that we have an acceptable result of integrating all of our subwoofers with the main speakers, it's time to put the finishing touches on the picture and drive the frequency response into even narrower limits. The recommendations below are based on using the Audyssey MultEQ Pro auto-calibration system with an external measurement microphone and software, but for the most part they will be valid for most other similar systems, because they all work on similar principles.

• Install the measuring microphone at the level of the listener's head at the listening position, using a microphone stand and pointing the microphone straight up;
• Avoid microphone installations where direct sound from the speakers is blocked by obstructions. In particular, tilt the backs of the theater seats so that they do not interfere with the direct sound from the rear speakers;
• Measurements must be taken at points located around and near the main listening area;
• Avoid the most extreme side places. It is important to measure in a specific area between the most frequently used listening positions;
• Double the number of measurements at the two most important listening locations. This will allow Audyssey to give more weight to these measurements in the final picture;
• Adjust the settings for bass management, delays, and crossover section frequency after calibration is complete.

The last point is quite important, because. autocalibration quite often makes mistakes in setting the AC type (Large instead of the recommended Small) and in choosing the optimal crossover frequency (lowering it). In this case, the delays are determined, as a rule, quite accurately.

Audyssey System Calibration Video Tutorial

Any automatic calibration system must be checked by subsequent measurement of the resulting frequency response and comparing it with the original graph. It got better - great! It got worse - we return to the starting point, check the correctness of our body movements when using the auto-calibration system, and do it again. And so on until it gets better.

7. Listen and make adjustments

No even the best and most accurate measurements in the world can guarantee a great sound in the end. Now is the time to sit down and listen with your own ears to the fruits of your labour. Put on the music you know with intense bass lines. Listen to it in two-channel + subwoofers at all the main places in your listening area and try to understand how it sounds. Then listen to the music in multi-channel mode (originally multi-channel recordings and 2-channel recordings through the ProLogic decoder). In most cases, the bass will seem more pronounced when moving from 2 channel to 5.1/7.1 matrix. Make sure you get satisfying bass in all modes throughout your listening area. Feel free to turn the subwoofer level up or down a couple dB if you like. Experiment and tweak the bass management settings (both speaker size and crossover frequency) to make sure your optimal settings, based on measurements, sound similar - optimal.

You can relax a bit and listen to your favorite records

When you have achieved linearity in the low-frequency range, there is often a desire to add a couple of dB of volume to the subwoofer. It is much more comfortable to listen to a sound with raised bass when you have a flat frequency response than when it has pronounced modal humps that make the bass boomy and unnatural. So don't be afraid to set your subwoofers a couple of dB higher than your main speakers once you've achieved overall linearity. In some cases, you may even need to turn up/down the level of one particular subwoofer. Most often this applies to the subwoofer located closest to the listening area.

If you are not happy with the sound with the auto-calibration system turned on, turn it off or try to calibrate again and see / listen if you managed to get it this time top scores. Simply put, don't dwell on calibration results if they don't sound good to you. Fine tuning is usually still necessary to get the best sound, but there is no denying that there is a strong correlation between great sound and great measurement results.

Results and conclusions

One of the main properties of a serious system is its ability to cover the main viewing area with a smooth and pleasant bass for the ear. The best way to achieve this effect is: to minimize the impact on the sound of standing waves by choosing the size of the room and its acoustic design; use multiple subwoofers; correctly arrange and adjust acoustic systems, subwoofers and spectator seats; apply active equalization. Never underestimate any of these basic components of success when rushing to use the automatic sound calibration system. Otherwise, you run the risk of simply spinning in place, like a "dog behind its tail", and spend a lot of time on speculation and unnecessary experiments in an attempt to achieve an acceptable result.

As soon as you listen to a properly calibrated bass with a smooth, pleasant bass throughout the entire audience area, there will be no turning back - after all, it is the low-frequency component of the soundtrack that makes you believe in the reality of what is happening on the screen!

The correct integration of subwoofers into the system is either worth the time and effort spent on it. With the right tools, necessary knowledge and patience, you can achieve such an amazing effect from your theater that it will easily compete with the best public cinema in the city. And don't forget about the absence of neighbors munching on popcorn and talking loudly on the phone!

Tired of the public cinema? Contact !

It is important to remain methodical and consistent throughout the process of setting up and calibrating your . Investment in good tool like TrueRTA from True Audio, LMS from LinearX Systems or even an FFT analyzer will save you time and allow you to achieve much more accurate results than you would rely on your ears, test signals and an SPL meter. Forget about folk remedies and let science unleash your full potential!