Preparation:
Outdoor performances are generally a temporary performance system, which involves more technical content, and requires fast and high-quality completion. This requires a complete and detailed plan to be taken out in advance and can be completed through multi-party collaboration. At present, outdoor performances can be roughly divided into two types: one is a variety of cultural performances of enterprises and institutions, including some non-commercial performances such as sports games, and the other is a commercial performance for profit. As the sound designer, the positioning of the audio equipment should be carried out according to the requirements and objectives of the host responsible for the sponsor or the agent (and of course the lighting, this article focuses on the audio part). For example, how many viewers are there in the show (how large is the venue), what types of programs are included in the show, how many electroacoustic instruments are there, and how many acoustic instruments are there (such as the commonly used wooden guitar, violin, trumpet, trombone, erhu, saxophone...) The most important thing is the price of the funds paid by the organizer or the merchant. These are important basis for positioning the equipment. Because only you can figure out these, you can decide the choice of sound reinforcement equipment and peripheral equipment. For example, in general, small and medium-sized performances of less than 1,000 people need about 2,000-5,000 watts, which has good intelligibility. Thousands of people are already relatively large projects, generally requiring 5000-20,000. The power of the watt can be satisfied. Of course, this is not completely absolute. Because the sensitivity of the speaker is 3dB higher, the power can be reduced by a factor of two. Therefore, the general power tolerance also has a large fluctuation, which is inseparable from your audio design. The reasonable design can reduce the number and grade of amplifiers and speakers.
In addition, since many of the equipment required for the current project are rented by the contracting audio company (or leasing company or manufacturer), there are many matters involved that should be taken seriously: First, the organizer must sign with the rental company. The lease contract includes the amount of the lease, the time limit, the model and quantity of the equipment, the damages clause, the rent deposit, etc., and secondly, the detailed division of labor and the related labor costs. One of the most interesting concerns is the issue of damages. This issue must be clearly marked on the contract with the price of each piece of equipment and the amount of compensation involved in order to avoid contractual disputes in the future. Because the environment for outdoor performances is very complicated and difficult, sometimes such problems are inevitable. The last important thing must be also achieved. That is, before signing the contract, it is necessary to carry out the unpacking and plug-in inspection of each piece of equipment with the engineering and technical personnel of the leasing company and the relevant supervisors. Once the contract was signed, it was found that there was a problem when it was shipped to the site. It was a troublesome thing. In some projects, the organizer and the leasing company often neglect the contract for the contract because they often cooperate. It is not advisable. We should be aware that the contract is an important basis for avoiding disputes, because the actual project burns the speakers, amplifiers or Other broken phenomena occur frequently. This is a problem we have to pay attention to.
Sound system design
In fact, the engineering design has been completed before the contract with the rental company. Here mainly talk about its commonly used design methods. In the outdoor performance, since there is no indoor reflection sound field and reverberation sound field in the room, the calculation of the power capacity should take a larger value relative to the indoor.
As for the placement of the speakers, large and medium-sized performances often use a centralized array hanging design to ensure uniform sound field in the vertical horizontal range. This technology is currently recognized as an ideal and mature industry.
But point out a common phenomenon: no matter what box can form an array! This is actually unscientific. It should be known that the real array system can not only improve the sound pressure level, but also cover the audience area in close range and far distance, and can reduce the sound pressure level by only 3dB! It also guarantees minimal acoustic interference between individual speaker units. It can be done in linear arrays developed by many manufacturers today with their own proprietary technologies. This of course is not something that can be done by any combination of speakers. In addition, many designers use all the same type of speakers in the array, which is not suitable for ultra long distance. Because the mid-high frequency diffusion angle of each unit in the array is certain, such an array system may be good for coping with medium and short distances, but it is somewhat weak for the COSCO shooting distance. Therefore, in dealing with long-range projection, the horn system with a wider spread angle in the vicinity, as the distance has been increased, the angle of the horn should be narrower and narrower. Only in this way can the energy concentrate in the long-distance propagation. In order to ensure that the audience in the distance still has a good listening effect (in the case of non-line arrays). Note: There are many brands of low-frequency loudspeakers that have directionality. Therefore, low-frequency sound reinforcement should also follow this principle as much as high frequency.
If your design does not use this linear array method, such as the main sound reinforcement plus auxiliary sound, the sound-filled speakers should be accurately delayed according to their distance. Generally speaking, if the front-rear distance between the sound box and the main sound box is greater than 16 meters, the delay should be added. It should be emphasized. If there is no delay, the intelligibility and listening of the audience area. The sound effect is harmful. Also note that when there are high-rise buildings around some projects, there is a serious echo in the entire sound reinforcement field, which should also attract attention. Now computer-aided design (CAD) technology is quite mature and popular (such as related software CADP2, EASE), and the application of engineering design and debugging is easy. The array system mentioned above and the auxiliary delay calculation can take them. To predict and simulate.
Equipment installation
Once the sound reinforcement method is established, the equipment can be installed. The first is the construction of the stage (performance area), followed by the lifting of the speakers and the laying of the lines. These basic work must be done carefully, even if a snagging shock absorbing gasket is in place. Be aware that safety always takes the first place at all times. Especially for the hoisting of the speaker array system, no matter how strong the wire rope is, the insurance key must be hung. At the same time, the application of hoisting parts for parallel imports and defective products should be absolutely avoided. There must be no temperament in the installation process. In addition, the hanging angle of the speaker must be carried out in accordance with the requirements of the construction drawings, otherwise it will not be able to achieve the expected results, or even destroy the entire sound field, causing trouble for later debugging.
Before connecting the equipment, it should be determined that all the connectors are intact, open circuit, short circuited, it is best to use the meter to measure, so as not to appear in the connection of the equipment, it can be more troublesome to check. The most common problem is between the amplifier and the speaker. Because the speaker cable tends to be long, and often people step on it, the cable diameter of the speaker cable should be as high as possible with a large cross-sectional area, and there must be no connection in the middle. Phenomenon, the added knot is often the culprit of the accident. As for the plug, I recommend using the Neutrik specification as much as possible. Its safety and stability are very good. It is not recommended to use a 6.5-inch large two-pin plug. This plug is particularly prone to de-soldering and virtual connection. In addition, it is important that the hot and cold ends of the connectors in different regions are not the same. Before all the devices are turned on, familiarize them with the instructions to understand the cold, hot, and ground termination methods of their connectors. The main performance and features of the equipment, especially the output power of the power amplifier under different impedances and different connection modes, is the direct basis for mating the speakers.
Since the flow is exposed and the interconnection order of the various devices, the author believes that the connection position of the compressor should be placed last (except for the electronic crossover). This is mainly because of safety considerations, because there are many people in the field environment, and because of the busyness, sometimes accidentally hitting a switch or knob of the peripheral equipment during the performance may cause an accident. In view of this, the author also strongly recommends that all cabinets should be close to the sound engineer, so that the sound engineer can observe the operating status of each device in time, such as level indication, overload alarm, heat and abnormal smell, etc. The equipment is burnt out after being in an abnormal working state for a long time.
system debugging
After the device is connected and confirmed, follow the order of the sound source - mixer - peripheral - power amplifier. If there is a power sequencer, the boot sequence should be set according to the above principles.
Before the official audition, you should adjust the gain of each channel of the mixer to the appropriate level, that is, when the PFL overload lamp is just lit, then attenuate 6db. Here to emphasize the point: because peripheral devices such as compressors, equalizers, exciters, and electronic crossovers have input and output level adjustment knobs, care must be taken to handle them because of the rise of some devices. The range is very large. If the adjustment is not good, the overall dynamic range of the sound will be narrowed, the signal-to-noise ratio will decrease, the sound quality will deteriorate, and the power amplifier and speaker will be burned out. The general experience is: bypass each peripheral device, observe the level of the level when it is connected and bypassed, too large and too small are not desirable; in addition, listen to its sound without significant distortion and phase distortion, if any The symptoms were adjusted one by one. As for how to operate peripheral devices, there are too many articles in this article, and this article will not be repeated.
For safety reasons, the gain knob of the amplifier should not be opened too much. At this time, put a song that you are very familiar with, and then listen to each speaker separately. If the playback is normal, turn the knob of the amplifier to the maximum (because The power matching between the pre-amplifier and the speaker has been designed, and it can be opened with confidence.) After everything is debugged, the main output (Master) fader of the mixer is pushed to the Odb position and remains unchanged. Also don't move, except for special needs of the show). Let's adjust the maximum sound pressure level of the system. Since the power of the amplifier and the speaker has been designed before, the maximum sound pressure level can be quickly calculated according to the sensitivity and power of the speaker (you can also directly search for the manual), and finally calculate the sound pressure of the synthesized sound of the speaker. We can find the position when the fader is pushed to the maximum sound pressure level. The quick and easy method is: one person holding a sound pressure meter standing in the sound field at any distance of 4 meters, 8 meters, 16 meters from the speaker array (depending on the size of the array), if the previous array calculates the total maximum synthesized sound The pressure level is 136db / m, and the sound pressure meter is placed at a distance of 16 meters from the array, then the sound pressure meter should be able to get 112db (some linear arrays should be calculated according to the distance doubled sound pressure level by 3dB, depending on the specific Depending on the situation) At this time, slowly push the music up to about 112db, and note the number of decibels at the position of the sub-fader at this time and the total level indication (or VU meter) of the mixer. The level of the output cannot exceed this value.
The last thing that should be tested is the frequency characteristics of the sound field. Although it is outdoor, the quality of the sound field depends mainly on the frequency characteristics of the speaker and the influence of the audience. Now many speakers have their own dedicated controller to compensate for the lack of frequency response of the speaker, but the frequency characteristic test of the sound field is still Necessary, because only by testing and audition, can we test the sound system's effect. The most common method used today is to connect a high-precision dedicated test microphone to the notebook computer, and cooperate with the relevant test software to achieve this method. This method is convenient and accurate, and the cost performance is also high. Commonly used software is PAS, SIA Smarrtlive and so on.
Instrument effect adjustment:
Here mainly refers to the electric guitar in the current electro-acoustic band, electric bass effects. Because these effects are indispensable in the electroacoustic team. So this article wants to focus on the considerations related to them.
1Because most of these effects are independently operated by musicians in live performances, they have already been adjusted in advance according to their own feelings and musical style. So this work must be done in consultation with them.
2 Distortion, heavy metal is the most used effect in live performances (especially rock shows), musicians often like to increase the high frequency of these two sound effects, generally 12db-----16db thinks that it has good Penetration and irritation. Although the author agrees with this feeling, it must be pointed out that the amount of promotion is not easy to exceed 9db. In fact, most of the current effects, no matter what style of music, at this time, the distortion of the grain is already very strong, and then it is very big. Difficult to blend with other instruments.
3 The use of reverberation and delay effects will destroy the sound field level and clarity of the performance. This is the most overlooked problem for musicians. When debugging their own effects music, they are often debugged by one person and a single instrument. This will cause a good sound when listening to a single voice, but the scene is When the whole band is together, it is often not the reverberation or the delay effect is too heavy, the tone is too thin, or it is too thick and too turbid. Therefore, the tuning color must be carried out during the rehearsal of the whole band, and it is best to perform in the upcoming band. The scene is carried out, and the volume is about the same as the normal performance, because the small volume is not good. These points are very important. In particular, tell the musicians to understand these points. Sometimes they often encounter blind opening in live performances, but they are still unclear and even noisy. If such a vicious circle continues, In the end, it’s not just the speakers that burned.
4 In the tens of hundreds of sounds of the effect, the volume of each different style of sound must be balanced. For example, in the lyric accompaniment of Adagio, the guitar is decomposed with the tone and the melody distortion tone of the upcoming solo. The volume of the two tones must be well balanced. Otherwise, the accompaniment volume is good when the accompaniment is broken. However, when performing solo, the distortion sound may suddenly become very large (or very small). At this time, the sound engineer can hardly and accurately control this sudden tone conversion, and when you find it, you can adjust it. Maybe the music atmosphere is out of touch. Obviously, it is a necessary pre-work to balance the volume of each tone (including the tone) in advance. This also guarantees the compactness and smoothness of the performance, and also greatly reduces the pressure on the field of the sound engineer.
Field control
In the live performance, the author wants to focus on the coordination between the sound engineer and the band.
Each musician should have a margin of ±3 - 5db for each performance. That is, it is important to allow each musician to increase or attenuate their voices by 3db (maximum of 6db). Otherwise, the above situation will occur, resulting in an unbalanced speaker effect. Many musicians like to control the volume of their own voices. They often say, "Open my voice and let me control my size." From the perspective of overall sound balance control, this is obviously unreasonable, and if so, the sound engineer cannot control the balance of the entire sound field. They often want their voices to stand out from others. You just adjusted the volume of the guitar accompaniment to the right position. As a result, the guitarist feels small and he raises the volume himself! The keyboard player and the bass player will not show weakness! (Don't forget, they all have a volume control). This cycle can be imagined - the singer only yells! Remember one thing: the maximum volume reference for the entire show should be based on the sound gain of the sound field! To be more informal, it is based on the volume of the singer's microphone (including the microphone of an acoustic instrument). Other instruments have a large range of rise and fall, but the microphone does not. Therefore, it is not too great to leave a dynamic balance for each musician in the performance. It is worth noting that since the position of the musician's performance is generally on the stage (behind the main speaker), the sound he hears cannot be the effect of the main sound field, so it is not accurate.
So how do you satisfy the feeling of the musician? The musician is the main body of the show, and a good feeling is indispensable. This also puts higher demands on the return of the performance. Specific method: assign each player a callback box, and in each of the callback boxes, adjust his voice to be slightly larger than the others (this can be signaled by the auxiliary transmission of the mixer) So that the musicians will have a good sense of the scene, which is more conducive to their full play. As for the drummer, it is a bit special. Because there are at least four microphones for the jazz drum (one for each of the snare drums and the drums, and two for the gongs and drums), if the drummers are to be heard at this time, it is easy to whistle, so it is best. The way to wear the headphones to the drummer is not only beneficial to the drummer, but also does not interfere with the sound field.
In addition, as a sound engineer, not only must the live performance be guaranteed, but also the safety of the equipment you use. It is often said that there is a phenomenon that the speaker is burned, which not only brings economic losses to the organizer, but also brings great trouble to the live performance. Serious or even interrupted the performance, the consequences can be imagined.
Be aware that the safety of the device is completely in your hands! Of course, a pair of sensitive ears and a mind that keeps a clear mind is also essential. For example, some systems have not designed enough sound power, and at this time, there are leaders who put pressure on you and force you to open up. At this time, you have to be rational! (I said before, how big the speaker can be, you have to count). If at the expense of expensive equipment for the show, this is obviously a wrong concept.
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