Weak current College】 【public broadcasting system speaker selection and configuration.

<br> <br> 1, public broadcasting system speaker selection: in principle, should be considered as environmental selection of different varieties and specifications of the radio speakers. For example, in a ceiling, ceiling-mounted indoor, use embedded, not the .back cover of the ceiling speakers. If CH-705 series. The speakers structure simple, relatively cheap and easy construction. The main disadvantage is that there is no back cover, susceptible to insects and rodents bite. <br> <br> The only .frame ceiling without ceiling Interior (such as the us market), expressing the hoisting-and-tube-type box (ST-708S) or back cover of the ceiling speakers (such as XT-701N ~ 705 series). Since the ceiling is .equivalent to an infinite baffle, self-love a ceiling under the conditions of use without the back cover of the speakers also does not cause sound short circuit. And when the situation without ceiling, if you still use no speakers back cover of smallpox, the .effect is very poor. Then, in principle, the use of lifting and speakers. However, if such investment is large, you can also use the back cover of the ceiling speakers. Have the back cover of the back cover of ceiling speakers not only .general mechanical protection and, to a certain extent, to prevent the role of sound circuit. <br> <br> In ceiling-mounted indoor (such as the underground car park), to choose wall-mounted speakers or indoor sound columns. The .former as BG-105, BG-106, BG-108 series, the latter as SN-302 ~ 304 series. <br> <br> Outdoors, use outdoor sound columns or horn. The former as SY-510 ~ 540, SY .-611 ~ 616 series: the latter as HS-30Q ~ 150Q series. This type of code string and Horn is not only waterproof function and the volume is large, spacious outdoor environment, no reverberation effect, select the volume for a large variety is .necessary. <br> <br> In the garden, lawn, use grass speakers. If S-601 ~ S-1001, KT-620, 28A, DT-21A ~. This type of speaker waterproof, beautiful, and the volume and .audio quality are very high. <br> <br> The decoration is fastidious, ceiling high wide Hall, use elegant, tonal harmony of hoisting-and-speakers, such as the series, set fire to ST-708S demanding situations, use set .of speakers. For example ST-708S series. These speakers are sealed type, its outlet port matching with flame retardant casing. <br> <br> 2, radio speaker configuration <br> <br> Public broadcasting system speaker, in principle, .to the principle of uniform, dispersed in broadcasting service area, the degree of its dispersion should guarantee the service area of signal to noise ratio is not less than 15DB. Typically, advanced Office noise floor of the corridor is about 48 ~ 52DB, supermarket of .the noise floor, approximately 58 ~ 63DB downtown section of background noise is approximately 70 ~ 75DB. Considering that in the event of an accident, the site may be confusing, so the need for emergency broadcasting, even if the broadcast service area is the Office ., and do not put the background noise estimation too low. Made sure of this, as a general consideration, in addition to the bustling lively places, it may be more or less the background noise as 65 ~ 70DB (except for special circumstances). .According to this projection, radio coverage of the sound pressure level to more than 80 ~ 85DB. <br> <br> In view of the radio speakers are usually distributed configuration, the broadcast coverage of the sound pressure level can be approximated as a single .radio speakers. According to the theory of electro-acoustics, speaker covering area of the sound pressure level of sensitivity SPL with speakers-LM, fed to speakers power P, listening points and speaker distance R, the following relationship: <br> <br .> SPL = LM +10 LgP-20Lgrdb (1) <br> <br> Ceiling speaker sensitivity level in 88 ~ 93DB: rated power: 3 ~ 10W. To 90DB/8W, BM in the speakers sound pressure level at approximately 81DB. < .br> <br> The above calculation does not consider early reflections group contributions. Indoors, the early reflections and the adjacent speakers contribution will enable the sound pressure level increase of about 2 ~ 3DB. <br> The approximate calculation based on the above, .the ceiling is not higher than 3 m venue, ceiling speakers generally can mutual distance 5 ~ 8M uniform configuration. If you only consider background music regardless of the emergency broadcast, you can increase the distance to 8 ~ 12M. In addition, applicable to the .Chinese mainland's fire radio design installation specification (hereinafter referred to as "specifications:) there are some mandatory:" corridors, halls, restaurants and public places, speaker configuration number, should be able to guarantee that any part of this layer to the last speaker .walking distance not exceeding 15M. The intersection in the aisle, the corner should set speakers. Aisle at the end of the last speaker distance from wall is not greater than 8M ". <br> <br> There was virtually no outdoor places early reflections .group, a single radio speakers effective coverage can only take the floor above calculations. Due to the lower bound of the corresponding distance is short, so in principle should be used by multiple speakers consisting of allweather. Fed to speakers groups (for example allweather) .signal power each doubled (provided that the group could accept), sound pressure level can enhance 3DB. Please note that the "double" meaning. From 1 to 2 is double and critical increase by 2 is doubled. In addition, the distance each doubles ., sound pressure level decreases 6DB. According to the above-mentioned rules is not difficult to project the outdoor sound column configuration. For example, to CS-540 outdoor sound columns, for example, its rated power 40W, is a single ceiling speakers of .more than 4 times. Therefore, the effective distance covered is greater than a single ceiling speakers 2 x. In fact, this distance can also be larger. Because the sound column of sensitivity than individual ceiling speakers to high (about 3 ~ 6DB), .while each additional point DB, distance can be doubled. That is the 540 allweather can be up to the distance covered, but the code above 20M column comparison of radiation angle in its narrow, just in front of about 60 ~ 90 ° (horizontal) .or so effective. The specific calculation available-(1). <br> <br> Public broadcasting system power amplifier selection radio power amplifier is different from the HI-FI amplifier, its main feature is a 70V and 100V voltage output terminal, this .is because the broadcastingLines are usually fairly long, high-voltage transmission line loss can be reduced. Radio power amplifier of the most important parameter is the rated output power, should use the rated output power, subject to the total power of the radio speakers. .<br> <br> The broadcasting system, as long as broadcast speaker power less than or equal to the amplifier's rated power and voltage parameters are the same, you can feel free to adapt, but considering the line loss, aging and other factors, .should be appropriate to leave power. According to the "standard" requirements, PA equipment capacity (corresponding to the rated output power) should normally be calculated according to the following type: <br> <br> P = K1.K2.P0 Sigma .(2) P - amplifier device output total power (W) P0 - each tap (equivalent to partition) at maximum power when broadcasting P0 = KI-PIPI - the I partition speakers rated capacity KI - the I partition at the .same time need to factor in the service broadcast room programs, take 0.2 ~ 0.4 background music system, take 0.5 ~ 0.6 business of broadcasting, 0.7 ~ 0.8 fire broadcasting, 1.0K1--line attenuation compensation coefficient: 1.26 ~ 1.58K2--aging .coefficient: 1.2 ~ 1.4 accordingly, if that is the background music system, broadcasting amplifier's rated output power shall be broadcast speaker total power of 1.3 times. <br> <br> However, all of the public broadcasting system in principle should be can ' .t casualty emergency broadcast. Therefore, the system shall be provided with emergency radio power amplifier. According to the "standard" requirements, emergency broadcasting amplifier's rated output power shall be broadcast speaker largest three partitions in the speakers volume totals 1.5 times broadcasting partition a public .broadcasting system is often divided into several zones, from the management (or pre-programming) decide which area shall publish broadcast, those regions to suspend the broadcasts, the region shall insert the emergency broadcast, etc. <br> <br> In principle ., the partition scheme depends on the customer's needs. Usually refer to the following rules: <br> <br> 1. building usually to floor area, shopping centre, playground, usually to sector partition, stadiums usually stand partition, residential, resort, .usually by property management Division, and so on. <br> <br> 2. Management and public places should be located. <br> <br> 3. important departments or broadcast speaker tone King necessary adjusted by on-site staff of separate .communities. In General, the partitioning is designed for easy management. Anyone who needs to be treated separately in part, should be split or a different area. However, each region, the total power of the radio speakers should not be too large, with .partitions and amplifier's capacity to adapt to SYB series PAS-2013D partition manager, for example, each region's power capacity to 500VA, but 10 districts should not exceed capacity 1000VA, accordingly, if the 10 districts full load operation, the average area should not exceed .100VA (approx. 100W). <br> <br> Community public broadcasting system structure housing community public broadcasting system structure consists of four parts: <br> <br> Radio power amplifier, audio sources in / out, reproducing equipment, intelligent play .. 4 persons for organic seamless integration of a unified public broadcasting system. The structure's design takes fully into account the needs of the community features, and focus on the construction costs of the system. <br> <br> <br>.