User manual ELECTRO-VOICE DX34A

[. . . ] 5 EV HAS ALL THE PERFECTLY POSITIONED PRODUCTS!. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 EV Business Audio Product Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 EVID Surface Mount Speaker Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] When you use several suppliers, you encounter differing lead times, minimum order quantity requirements, freight policies and payment terms that complicate your ability to respond quickly and consistently to demands from your customers. These are "hidden" overhead costs that affect your ability to generate a profit. Speaker Selection Distributed loudspeaker systems for paging and background music are among the most important "bread and butter jobs in sound contracting. In most cities, new restaurants, hotels, health clubs and clinics are continually sprouting up. Each one has needs that can be met by a distributed system, and each represents a potential client for the enterprising contractor. The overwhelming majority of paging and background systems are relatively small, however. With the margin on many installations running in the $400 to $600 range, there's not much room for error or misunderstanding, since the cost of a single callback can eat up most of the profits. To succeed with distributed sound systems, the professional contractor needs to be able to count on his jobs going in smoothly and efficiently. In this article, we'll explore some of the "nuts and bolts" issues that affect profitability in the distributed sound system market, and offer suggestions for improving your chances of success in the business. Ceiling vs. Surface Mount Systems Several factors will determine the choice of surface mount or flush mount (ceiling) speakers for a given job. The most common criteria are: · · · · Audio coverage requirements Audio performance needs Building structure design Esthetic requirements of the environment Evaluating the choices among these primary criteria will often determine the format which is required for a listening area. It is important to note here that any installation may employ both types of products for different areas or to meet certain performance needs. This is called the listeningplane coverage specification of the speaker. The listening-plane spec represents the reality of the speaker's coverage for the listeners. Laws of physics dictate that the listening-plane coverage is always more narrow than the polar coverage pattern. Let's take a speaker that has a 140° polar coverage (i. e. , its 6dB down points) as an example. It would be a mistake to assume that this speaker can cover 140° over the listening plane. In fact, the level at the edges of a 140° pattern is actually more than 15 dB down compared to on-axis -- not 6 dB down. It's interesting to note that the same proportions hold true for any ceiling height: No matter how high the ceiling is, the off-axis distance is even farther away by the same proportion. So for the loudspeaker in this example, whether the ceiling height is 8 feet or 20 feet, the listener who is at the edge of the 140° pattern, who you might think is at the 6dB down point is really 15 dB down. The actual listening-plane coverage depends on the polar plot of each speaker. On average, the coverage of the listening plane from a speaker with a 140° polar coverage is usually between 90° and 110° . ElectroVoice/Dynacord BGM Guide Page 18 Converting Coverage Specs to A Layout How do you convert polar coverage to listening-plane coverage as you design sound systems?One is to use the EV ceiling speaker layout program that does the conversion for you. [. . . ] It is important to note that amplifier bridging should only be done when the amplifier is specifically designed for this purpose. The manufacturer's instructions should be followed when using this technique. You must take the amplifier's bridged, 8-ohm power rating as the reference maximum power figure for loading calculations. Remember that the minimum load impedance for a bridged power amplifier is twice that of each individual channel. [. . . ]