Acoustics for background sounding

In the fifteenth issue of the Sound show, we talk about indoor acoustics, various myths related to this topic [ More on the podcast ] [ Listen to this issue ].


Dmitry Kabanov: We already discussed various aspects of the voice acting of rooms and did it in the winter, when we discussed moisture-proof speakers that are resistant to snow. Now it is almost autumn, it has begun to rain, and it is worth returning to this topic.

Timofei Shikolenkov: Good topic. But first, let's talk about a related topic that is with us every day - let's talk about equipment, sound in public places . Coming to a bar, sometimes you see a tape recorder on the counter, almost a cassette center, playing a radio. There are cases: you come to a recently opened institution in which they made a beautiful repair and at the same time bought some strange equipment and put it on a rack. This strangeness always surprised me.

The second thing, which is surprising, however, is less common: in some rooms where ceiling speakers are usually used - in large spaces they practically do not take up space and make uniform voice acting - instead of special built-in speakers, car speakers are installed.

Dmitry: We realized that you don’t need to put a tape recorder on a shelf, bought some center 5.1, 2.1 and decided to distribute it all in the corners on the ceiling.

Timofei: I even saw situations when [in public buildings] they put a car radio with a transformer and lead wires to the car speakers located on the ceiling. People do not understand that car speakers are designed for the volume that the car body can accommodate.

It is important to understand that for each speaker system, the acoustic design is very important, that is, in which box, case it is located.

Dmitry: Imagine a cafe the size of an average sedan. It would be great to sit.

Timothy: It is unlikely. People are trying to reinvent the wheel. Probably, they are guided by the fact that professional equipment, and the word "professional" always scares everyone, expensive. Professional speaker systems, which are designed for voice acting, background music, are cheap.

There are such speaker options: a small speaker, ceiling or wall, costs about a thousand rubles. She needs an amplifier. In such cases, hybrid devices, mixer amplifiers are usually used. This is one box that can be placed in a rack or other convenient place.



Professional active acoustics Eurosound ES-5A

Professional equipment designed to work 24/7 - around the clock for a long time. Household audio equipment is not designed for such use, it cannot and should not work like that. She has a certain, finite service life and operating conditions.
In this case, an amplifier is needed in any case. Maybe automobile equipment seems most familiar to people, and [therefore] they put it on.

The situation is similar when a [home] printer designed for a small print volume is bought at the office and printed on it from morning to evening. During the warranty period, the printer breaks, and employees do not understand what happened. It's good that during the warranty period, and not a day later. The device is not intended for use in this mode.

Returning to the topic of audio: the economic aspect is incomprehensible, it is not justified. The same car radio costs money, it still needs to be adapted to work outside the car.

Dmitry: It will be more expensive, and it needs to be fixed, but this is not provided for by the design.

Timothy:For money it will turn out the same. The issues of reliability, stability, volume are also important. I have long wanted to talk about volume. Everyone loves to measure volume in watts, although it is a unit of measure for power. And people think that the larger the number is written on a speaker or amplifier, the louder.

Of course, these values ​​are combined to some extent, but the volume is not measured in watts. The volume is measured in decibels - this is the sound pressure. This is the primary value in which the volume is measured.

In professional equipment, the sound pressure characteristics are always indicated in the description of the characteristics of the speaker systems. It is very important. To understand what numbers can be indicated there: ten decibels is a soft whisper, rustling leaves, fifty decibels is the sound pressure that we create in a calm conversation.

In headphones or speakers, the sound pressure is different. Seventy-seventy-five decibels - this is a scream, ninety decibels - a subway car passes us by. One hundred twenty decibels - a pain threshold, more than a person can not stand.

If we want to voice the room in which people sit and work, it should be quiet music. If this is a warning system ... in English there is a phrase “public address”, you can try translating it into Russian as “broadcast”, “radio broadcast”, “warning system”. It's just that there is no such phrase in Russian.



APart SPH20 wall-mounted loudspeaker

Dmitry: It looks like the system it used to be at [western] universities when some kind of announcement is turned on or a local local radio station is broadcast. Something like that.

Timothy:This is the same as apartment radio points, that is, sockets into which the loudspeaker is connected. Returning to power: more than 85 decibels in the room where people who need to be notified are sitting should not be, and the music should be even quieter. In professional acoustics, sound pressure is usually indicated at a distance of 1 meter with a power of 1 Watt.

We turn to power. If we take small ceiling or wall speakers in which the maximum sound pressure is 92 decibels, that is, more than we need, then it turns out that at 1 Watt we already get what we need.

Dmitry: It turns out that you do not need to buy amplifiers for 100 watts and spend a lot of money on it.

Timothy:A second question arises: why is such equipment recommended? It is very simple to calculate power. If an amplifier, for example, 100 W, is indicated on the amplifier, this means that we can connect one hundred speakers with a power of 1 W each. Marketing equipment is rarely used in professional equipment. “They attributed an extra zero, and immediately everyone ran to buy, so loud, so powerful,” - there isn’t such a thing.

If it is written on Public address systems that the speaker power is 2 or 3 W, 5 or 20 W, then that is the way it is. The column is designed for such power that will be supplied from the amplifier. The volume depends on the room and the distance - we have already talked about this.

Another advantage of such systems: these systems allow the use of fairly long cables, you can transmit sound over long distances - several hundred meters. It turns out something in between: on the one hand, professional use, on the other hand - not quite everyday.



Built-in acoustics Apart CMSQ108

Dmitry: Given that the cable is laid on the walls, and the room can be large, the sound of fifty square meters will require tens of meters of cable.

Timothy: Of course, and it is very convenient. Why? Traditional Hi-Fi systems require each speaker to extend its own separate cable, this is a given. In the case of Public address systems, this is not required. You can connect a large number of speakers in parallel, as many as you need.

It is interesting that on such speakers there is a power switch, that is, conditionally, a volume control for each speaker. In the bar, restaurant, where the ticket office is located, it is necessary that the sound is quieter, while the speakers can be the same.

Dmitry: You can physically limit the [power supplied] to these speakers ...

Timofei: Yes, to these speakers without any adjustments in the amplifier. But the amplifier has a general volume control and, accordingly, in some areas we can make it quieter, in some - louder. In this case, the power will change, which will need to be calculated based on the capabilities of the amplifier.

It would be nice to make a small margin of power so that the amplifier does not work to the limit. If we buy a 35-Watt, 50-Watt amplifier, then these are real and sufficient numbers, we have already discussed this.

Dmitry: Let's talk about prices.

Timothy: The mixer amplifier is a hybrid device that immediately with a volume control and amplifier, with a capacity of about 35-50 watts, costs around ten thousand rubles. There are more “sophisticated” devices and completely hybrid devices sold with the source. As a rule, the source is either a computer that is nearby, or some kind of player. The main task is to find an object where to turn on the sound source.



Mixer amplifier APart MA35

Dmitry:We can physically limit the power on certain speakers, and if we have some old systems from what we already used, for example, an old music center, can we partially use these speakers, in addition to what we buy?

Timothy: No way. Because the main difference between these systems is that they increase the amplitude by about five times during transmission. That is, the amplifier has a step-up transformer, and no Hi-Fi and not Hi-Fi are designed for this, that is, ordinary household speaker systems.

The speakers have a step-down transformer, and the speaker does not work in extreme mode. If you connect ordinary speakers that are not designed for this, for some time they will work to the limit and quickly fail. There is no need to use such options. One column for such a professional system can cost about a thousand rubles. A good one costs two thousand rubles, a very good one costs three to four thousand.

They can be of different capacities, but if this is a background sound, then, as a rule, these are ceiling or wall systems. It all depends on how to place them indoors. A variant of the street system is possible, and all this is connected to one amplifier.

Dmitry: If we take a small cafe - is it 50-70 thousand rubles for all the equipment?

Timothy:Not. Twenty, a maximum of thirty thousand rubles, and that if we want to build something super-quality. If you just make a background sound, then you can limit yourself to twenty thousand, including waterproof speakers on the veranda. It is strange that people are trying to solve the problem in complex ways, despite the fact that there is a solution that is quite inexpensive, and most importantly, easy to install.

An inexpensive cable is taken, laid along the wall, a gap is made in the right place, a column is connected, which is placed in this place. You can add speakers anywhere if you have a supply of cable. No need to pull one hundred cables to one hundred speakers. All this is very simple, convenient and durable.

Dmitry: Does it make sense to think about wireless solutions?

Timothy:Not. Wireless solutions exist, but they are domestic. This means that they are not designed for long-term work.

Dmitry: We figured out the case of a small cafe. If we have a middle one and closer to a large cafe, then we can observe the division into two, three segments, where, including some kind of mini-scene for micro-performances can be used.

Timothy: Yes, it often happens, because all these systems and mixer amplifiers are usually multi-channel. Of course, there are single-channel ones and there are many of them designed for several zones.

In this case, you can adjust the volume and connect a microphone. Naturally, they all come with microphone inputs: with one, two, three, four, different sources. Different sources can be sent to different zones. All this, again, is done once and further controlled in one place by one simple device.

Dmitry: If necessary, you can bring to the farthest corner and zone the sound that comes from the microphone from the one who performs, or vice versa, remove this sound and send music to it that does not prevent people from enjoying what they are doing.

Timothy:The main thing is that these planned zones from the very beginning should be connected to the amplifier at different outputs, that is, the outputs of different zones. If we initially made only one zone, then we should not hope that the speakers themselves will understand what sound they play.

When we talk about performance, about live sound, such systems are not good. As a rule, if we are talking about restaurants and bars, then other equipment is used for stage equipment - mixers, stage large professional acoustic systems. In institutions that have both a daytime sound and a stage in the evening, possibly a disco, live performance, two systems are used.

Firstly, this is a Public address, that is, a subsonic during the day, and in the evening - powerful professional acoustics, you can connect musical instruments to the bark. Such a hybrid.

Dmitry: If you compare with a small cafe, how much more will this solution be?

Timothy: Depends on how many speakers there are, how different sources are needed, for example, simple amplifiers can be divided into zones. Take a microphone: there is background music that plays everywhere, and there is an automatic function to mute the music when some kind of notification starts, as soon as you start talking into the microphone. This is usually all.

If you need to do something more, you can put two mixer amplifiers and make two separate systems. There are multi-zone, more serious mixer amplifiers or separately amplifiers and mixers. The scope for creativity is unlimited. It all depends on the task. The main message I wanted to make for our listeners was that it is very simple.

My friend, opening a cafe, turned to me for help in the field of sound. In the evening we did everything. It took more time to drill holes in the walls to mount the wall speakers. The cable was laid very quickly, where you need connected speakers.

Dmitry: The main conclusion: “professional” does not mean that it is expensive, it means it is necessary for work, and it is not so difficult not to assemble a rocket.

Timothy: As for the professional - in this area “professionally” means “inexpensively”. And you need to understand that the equipment is very different, and if the column is similar to the column, then this does not mean that it is suitable for any task. The tasks are different, and there are many.

And if we know what equipment is suitable for which tasks, then we easily solve them without spending a lot of money, investing in the future, because it will work for a long time, without requiring maintenance. This is reliability, quality, and a reasonable waste of money, which everyone is looking for.

Dmitry: There are still questions that are often asked by those who want to do this?

Timothy: You can talk about street things to talk about.

Dmitry: What to do in autumn and winter?

Timothy: It happens that people buy waterproof speakers, but they are very different. There is a standard that describes how much moisture can get on speakers.

There was a case when a client came with the desire to install the speakers in the pool in the water. It was not possible to find out from him why this is because nothing will be heard. Unfortunately, they could not help him.

In general, there are various classes and you need to understand that if it hangs on the street under a roof, and it is a humid environment, there will be no direct water flow, this is one system, if it is completely open space - another system, if a sauna with 100% humidity - third system.



Waterproof speaker Visaton FRS 10 WP / 8

Dmitry: There is a class of protection against moisture, which you need to pay attention to.

Timothy: You need to look in the description for what application this acoustics is used.

Dmitriy:If you recall the systems that look like floor stones and more. How much does it cost to apply on the street?

Timothy: There are such very interesting and beautiful landscape solutions. One must carefully read for what application they are, external or internal. If the column looks like a beautiful pebble, then this does not mean that it can be put on the track. We need to see what class of protection against moisture.

If it is assumed that the column will be placed in a lowland, then the equipment must be of the appropriate class, or it is necessary to reorient and put the column in another place. Fundamentally, nothing will change, plus or minus half a meter is not very important, and the system will be more durable.

Dmitriy:Are there any moments of impact resistance? Random contacts with furniture? Can people hurt something?

Timothy: No, as a rule, everything is built into the ceiling or hung on walls or in corners. Impact resistance is difficult to apply here. The speakers are made of plastic with various elements, you cannot beat them with your fists, of course.