The Electro-Voice Sx300 is a 300-watt, 12-inch two-way, high-efficiency, constant-directivity compact speaker system with Ring-Mode Decoupling (RMDTM). Through the extensive use of computer-aided design and modeling, Electro-Voice engineers have developed a state-of-the-art professional loudspeaker system. The high-frequency section of the Sx300 utilizes a molded-in, 65° x 65° constant-directivity horn. This unique pattern contributes to high intelligibility. Vocals sound natural yet “cut through” in reverberant, noisy rooms. In addition, the coverage pattern is unusually uniform over its range of operation. Sound quality off axis is very well maintained, even at 45° off axis (a 90° total coverage angle), well beyond the rated coverage angle. The horn’s unique, VaripathTM throat geometry helps direct driver output to the corners of the room, points of coverage not described in the usual specifications of horizontal and vertical coverage angles, and parts of the audience that typically do not receive the trongest coverage.
the Sx300 is the cabinet. Constructed of highimpact polypropylene structural foam, it provides a stiff and extremely durable enclosure. Molded into the cabinet are an integral carrying handle and a stand socket for mounting on 1 3/8-inch stands such as the Electro-Voice 100BK. Rubber feet that are attached to the bottom of the cabinet and mating sockets that are molded into the top provide a means of stacking systems. The trapezoidal-shaped cabinet, in combination with the uniform, 65° x 65° directivity characteristics, make the Sx300 ideal for use alone or in arrays.
In situations requiring additional bass output, the Sx300 can be used in combination with the Electro-Voice Xp200A system controller. The Xp200A includes a low-frequency enhancement circuit that is tailored to match the low-frequency characteristics of the Sx300. Up to 12 dB of additional bass output can be obtained from the system when used with the Xp200A system controller. The amount of low-frequency enhancement can be adjusted to suit the user’s personal preference.
For the most demanding situations, two bassmodule models are available to complement the Sx300: the Electro-Voice Sb121 nonpowered bass module and the Electro-Voice Sb121a powered bass module. Both bass modules were designed to be used with the Sx300 and are constructed in similar structural foam enclosures. The Sb121a includes a 300-watt power amplifier that is built into the speaker cabinet. The Xp200A system controller provides a subwoofer output that is a crossed-over sum of the left and right channels.
The Sx300’s high-frequency horn is driven by the DH2010A one-inch-throat, widebandwidth, titanium-diaphragm driver. The DH2010A uses a unique, convex-drive Time PathTM phasing plug structure (U.S. Patent #4,525,604) for smooth and extended high-frequency performance. The voice coil is coupled to the diaphragm with EV’s exclusive Resonant DriveTM technology. This increases and smooths the highfrequency response and reduces the amount of internal equalization required for flat frequency response. Driver output extends to 25,000 Hz. A self-resetting high-frequency protection circuit, EV’s PROTM circuit, is included with the Sx300 to prevent against accidental overdrive and improve system reliability. If the input power to the high-frequency driver exceeds the nominal rating, the protection circuit is activated and reduces the power delivered to the driver by 6 dB. The system will remain in this mode of operation until the input power is reduced to a safe level.
The bass section of the Sx300 is designed using Thiele-Small parameters for efficient performance to below 80 Hz. The woofer is a DL12Sx 12-inch Pro-Line unit featuring beryllium copper lead wires, a low-mass, edge-wound voice coil and high-temperature materials. The system combines professional-quality components, arranged in a time-coherent vertical array, with an unusually durable Thiele-Small-aligned vented enclosure. The result is clear and articulate, high-quality sound.
Ring-Mode Decoupling (RMDTM)
The Sx300 controls both acoustical and mechanical ring modes to provide dramatically increased intelligibility, using techniques learned from the development of the Electro-Voice X-Array concert speakers. There is much less coloration of the sound from resonating sources, leaving only the intended sound to be heard by the audience.
The combination of a 12-inch woofer, widebandwidth high-frequency driver and an equalized crossover results in the wide and smooth overall response shown in Figure 1. This response was measured at 10 feet, using a 4-volt input in an anechoic chamber, and was measured using a swept sine-wave input. No external equalization was used. Figure 1 has been averaged and corrected for 1 watt at 1 meter.
Constant-Directivity Speaker System
The crossover frequency and speaker component geometries have been selected so that the directional characteristics of the woofer and constant-directivity horn match at the crossover frequency to create a special system type-the constant-directivity system. Response within the 65° rated coverage angle is uniform, which means dependable audience coverage without “hot spots” or dead zones at certain frequencies. The 65° dispersion characteristic also helps avoid early reflections from nearby floor or side-wall surfaces which could degrade performance. The controlled directivity of the high- and lowfrequency transducers also eliminates response irregularities caused by diffraction off nearby enclosure edges. And, in combination with an essentially flat on-axis frequency response, produces a total acoustic power output that is uniform with frequency.
To our knowledge, Electro-Voice was the first U.S. manufacturer to develop and publish a power test closely related to real-life conditions. First, we use a random-noise input signal because it contains many frequencies simultaneously, just like real voice or instrument program. Second, our signal contains more energy at extremely high and low frequencies than typical actual program, adding an extra measure of reliability. Third, the test signal includes not only the overall “long-term average” or “continuous” level-which our ears interpret as loudness-but also short-duration peaks which are many times higher than the average, just like actual program. The long-term average level stresses the speaker thermally (heat). The instantaneous peaks test mechanical eliability (cone and diaphragm excursion). Note that the sine-wave test signals sometimes used have a much less demanding peak value relative to their average level. In actual use, long-term average levels exist from several seconds on up, but we apply the long-term average for several hours, adding another extra measure of reliability.