【 Weak current College 】 public broadcasting system with a professional sound system of differential-Power By 【 China power house network 】

Preface with civil (family) sound compared to public broadcasting (PUBLICADDRESS) is a professional audio. But we usually speak of professional audio (PROFESSIONALAUDIO) is especially stage (performances) class audio. While the public broadcasting and such sound is different. Public broadcasting is limited (but can be quite large) for public service broadcasting. In General, the public broadcasting signals through housed in broadcasting service area in the broadcast line, often a one-way (download) cable. Public broadcasting is typically set at the authorities, armed forces, businesses, schools, communities, building, supermarket and a variety of venues, for publishing news and information, publication and rest within the signal, provides the background music and paging (Paging-such as broadcast search) and been forced into disastrous accident emergency broadcast, etc. Public broadcasting is also useful for wireless transmission, but it's not mainstream. 1. the most simple of the public broadcasting system and features a public broadcasting system at least configure the following link: broadcast radio, speakers, amplifiers, microphones. The simplest system shown in Figure 1.
Public broadcasting system with a professional sound system differences 100W below low power radio power amplifier usually bring their own front panel level, without having to configure the preamplifier, commonly known as the merge type broadcasting machine. Power is large (for example, hundreds of Watts or more) of broadcasting amplifier are usually required with broadcasting preamplifier. But neither the merge type broadcast machine of preamplifiers or separate broadcasting preamplifier, its input should have priority. Usually at least one microphone is the priority, the microphone signals can automatically suppress other input signal (the so-called "silent tone with the automatic" feature), so that page as well as an emergency, could be forced into the emergency broadcast. This General HiFi (or professional) preamplifier and mixer are somewhat different. The system of terms: microphone, line, amplifier, speakers, etc. are generally electroacoustic workers or familiar to lovers of electro-acoustic sound. But the broadcasting channels, broadcast radio, amplifier and speakers and an ordinary speaker cables, power amplifier, speakers are slightly different. The key is usually quite broadcasting channels (more than a few hundred meters and km), and the General professional audio speaker cables are rarely more than a hundred meters. To reduce the transmission loss that the broadcasting signal principle is "high-voltage/low current" mode transfers. Therefore not be broadcasting channels generally expensive speakers line simply ordinary twisted pair; if configured in outdoor lightning protection equipment, should be added. Due to the high-voltage transmission system, so the radio power amplifier shall deliver high voltage signal. Usually radio power amplifier with output transformers are built to improve (or standard) its output voltage, known as the "pressure type" power amplifier. Pressure-power amplifier output terminal marking 70V/100V/200V 120V/etc, nominal output voltage (NormalOutputVoltage) specifications, rather than the professional power amplifier that marks the rated load impedance values (ohm-Ώ). The latter will therefore be referred to as "fixed resistance-" amplifier. Radio speakers are broadcasting system of the Terminal, since broadcasting channels provide "high-voltage/low current" signal, so accordingly, in broadcasting the speakers should be high, and they have built-in, "for the impedance converter line transformer", its input terminals also marked 70V/100V/200V, 120V/nominal voltage specification (and rated power value), not its impedance value. IP broadcasting speakers do not have to calculate their impedance, simply apply voltage specifications with broadcasting channels nominal transmission voltage line can put their hook up, but attached (parallel) during the same line of radio speakers total power cannot be greater than the drivers that line broadcasting amplifier's rated output power. Otherwise broadcasting amplifier will overload. Radio speakers the minimum amount is not restricted to broadcasting amplifier will not light or no-load and cause performance degradation, will not be damaged. Figure 1 shows the simple system can only publish voice broadcast, such as notifications, paging, speech, etc. If you want to broadcast a soundtrack, broadcast news, publishing, sound recording, you must install CD, decks, Tuner (radio), etc. Radio power amplifier usually have more of a priority ranking of input interface, you can easily connect with these devices. By the way, some people think that down pyramid amplifier output voltage ever should be equal to the nominal voltage, they use a voltmeter (or level meter) monitor running at constant pressure amplifier, I always found that the output voltage, so that power amplifier is faulty. In fact, this is a misunderstanding. "Pressure type" radio power amplifier "nominal output voltage" refers to the corresponding to the rated output voltage at the output, instead of always having the output voltage. In fact, because of the sound signal is a strong or weak signal is not fixed, so audio power amplifier on the working time of the actual output voltage is constantly changing. Without overload conditions, only the peak signal will reach the nominal value and the average output is always less than the nominal value. This is a level meter monitoring "always undervoltage" reasons. The so-called "pressure type" refers to the output voltage does not load the severity of the change (without overload conditions) — that is, the output voltage source characteristics, rather than the output voltage will be like electricity supply voltage fixed, in a measure. The vast majority of modern audio power amplifiers use a big loop voltage-feedback technology, therefore, even the so-called "fixed resistance-" amplifier, in fact, the vast majority are also "pressure", but in the output-side marked not rated output voltage value, and this corresponds to the load impedance value. In addition, the public broadcasting system in principle is not a stereo system. Stereo system is capable to a certain extent, to reproduce the original sound source position of electro-acoustic system. We all know that, in order to create an orientation property of the sound image, stereo system requires at least two channels, i.e. at least two the configured according to certain rules speakers two road is related but not identical. While the public broadcasting system in principle only one channel. Although the public address system may have many speakers, but they only play the same sound; multiple speakersIn order to create sound and image, but rather to create the broadcasting service area as possible, even heavy bursts into field. Of course, if you must be in the public broadcasting system to broadcast in stereo programs, it is not impossible, but only in a limited area of broadcasting, and to spend the extra investment. 2. public broadcasting equipment with professional sound equipment for Exchange can use professional audio equipment to establish a public address system or the opposite? the answer is Yes, but not necessarily appropriate. If you use the amplifier to replace radio power amplifier, you will need to upgrade (or standard) its output voltage. Approach: · select an appropriately rated output power amplifier or amplifier combination (bridging or threaded), to acquire and broadcast speaker compatible pressure output (usually 100V). · in the amplifier's output with the appropriate output transformer. Professional amplifier output voltage with its rated output power (Po) and rated load resistance (Rz) have the following relationships: U = (Po · Rz) 1/2 Accordingly, 2500 W/4 Ω professional power amplifiers have 100V output voltage that can be used directly. But the total power of the radio speakers cannot exceed 2500W (just consider the load carrying capacity of the amplifier, do not take into account the requirements of the relevant statutes); on the other hand, regardless of the total power of the radio speakers and how small, you cannot use small power amplifier, otherwise can not guarantee that the transmission of the broadcast line voltage. With two 650 W/4 Ω professional power amplifier bridge or you can get close to 100V output voltage. Obviously, when radio speaker's total power far less than 2500W, this approach is very effective. If you want to use the loudspeaker with the radio is in power amplifier, you should press the up-calculated its output voltage, and then with the appropriate output transformer. However, as a professional power amplifier with output transformers can easily cause damage to the power amplifier, you need to take appropriate measures (from here). Professional speakers can also be used as a broadcast sound box, but with the "Transformers" line. As mentioned earlier, the "from" line transformer impedance transformation, so that the "fixed resistance" professional speaker in the "pressure" of broadcasting transmission lines drawn with their rated power equivalent. No "line transformer", converting several professional speaker series-parallel up appropriately, or you can use, but have to go through tedious calculations; but also in the running, as long as one of the only speaker damage to the system it is possible to Subversion (all no sound or burning of other speakers or burnt power amplifier). Use a mixer to act as a broadcast preamplifier is barely possible. But a mixer often no signal priority, not easy to achieve broadcasting prerequisites "forcibly insert" function. In turn, broadcast radio, amplifier and speaker system can also be used for professional audio systems. But because they have built-in output transformer or line transformer, its frequency response far as grade professional power amplifier. Broadcasting preamplifier for professional sound systems are managed, because it has no grouping, equalization, effects, and other functions, and its priority sorting capabilities for professional audio system, mostly redundant. Therefore, Exchange public broadcasting system and professional audio systems equipment is possible, but not necessarily appropriate. Usually will certainly lead to deterioration in the price-performance.