WHITEPAPER Advantages of Christie Vive Audio planar ribbon and line array technologies for cinema sound
WHITEPAPER Christie Vive Audio comprises a range of cinema sound solutions based on advanced ribbon driver technology and unique line array loudspeaker system configurations. These solutions elevate sound quality to a level that was previously unachievable. Vive Audio technology finally provides tools and solutions that match the latest advancements in video projection with high dynamic range and high-resolution audio. With Christie Vive Audio, exhibitors can now choose a cinema sound solution that gives their audiences the complete cinematic experience. Advantages of planar ribbon driver technology Christie Vive Audio uses planar ribbon drivers as the foundation for its loudspeaker design. This superior driver technology offers fundamental advantages over typical compression or dome drivers. Driving force directly acts on the diaphragm, bypassing the voice coil former and glue joint Driving force is evenly distributed over radiating surface, preventing severe break up modes Purely resistive impedance uniform load without reactive inductive component Flat radiating surface coherent wave front with uniform phase Details of traditional dome and compression drivers Radiating area Phase plug slot Compression chamber Bobbin Voice coil Adhesive joint Driving force Throat Central part of a compression driver Details of a planar ribbon driver Metal plate Driving force Magnets Diaphragm Conductors Radiating area 1
Impulse response and cumulative spectral decay (CSD) High-performance compression driver Delayed resonance results in severe coloration, ringing noises, low resolution and harsh, fatiguing audio. Impulse Response volts 3.0 2.5 2.0 1.5 1.0 db 0.00 0.5 6.0 0.42 0.0-0.5-1.0-1.5-2.0 auto 4.0 5.0 6.0 0.0-6.0-12.5-18.0 300.0 1000.0 10000.0 0.85 1.27 1.7 2.12 msec Time msec -18.65db, 1511Hz (82), 2.128 msec (41) Planar ribbon driver Clean and fast impulse decay results in high-resolution audio. Impulse Response volts 3.0 2.5 2.0 1.5 1.0 db 0.00 0.5 0.0 0.42 0.0-0.5-1.0-1.5-2.0 auto 4.0 5.0 6.0-6.0-12.0-18.0-24.0 300.0 1000.0 10000.0 0.85 1.27 1.7 2.12 msec Time msec -27.37db, 1400Hz (76), 1.219 msec (24)
Input impedance 100.00 30.0 Ohms < Magnitude > Impedance Measurement < Phase > High-performance compression driver 10.0 3.0 Planar ribbon driver 1.0 100 Frequency Hz 40k Let s now compare ribbon drivers and compression drivers in an electric domain. The largely irregular impedance of a compression driver reflects a variety of parasitic mechano-acoustic resonances clearly seen in impulse response and CSD. In an electric domain, the presence of a voice coil in a magnetic system operating at high frequencies leads to large inductive component (sharply rising impedance with frequency). Non-linear interaction of the voice coil within a magnetic system generates intermodulation distortion of output signal (voice coil displacement) by input signal current. A planar ribbon driver has resistive impedance without inductive component (no voice coil winding) and is therefore free of modulation of its output by input signal. As a result, intermodulation distortion in a planar ribbon driver is exceptionally low. Key criteria for high quality audio reproduction from a loudspeaker 1. High dynamic capability. A loudspeaker (driver) should be capable of reproducing low level signals, high level peaks and almost instantaneous swings between them without delay. 2. Clean impulse response decay, free of delayed resonance. It should have clean decay that does not impose noise that masks fine details of original signal. 3. Low non-linear distortion. 4. Balanced frequency response. 3
Non-linear distortion 110.00 dbspl 90.0 70.0 Compression driver sub-harmonics Compression driver distortion noise 50.0 30.0 10.0 500 1k 2k 5k 10k Hz 20k CH A dbspl 48KHz 16384 2.93Hz Rectangular Unsmoothed The best comparative metric of loudspeaker non-linearity that has a strong correlation with subjective perception is a multi-tone distortion test. Above is a comparison of multi-tone spectra of a Vive Audio 6" planar ribbon driver (purple) and a 1.5" exit compression driver from a leading manufacturer loaded on a typical 40x90 horn (green). Both drivers have been tested at the same distance at a total SPL of 108dB. The test signal was comprised of a set of sine wave tones that coincide with third octave center points (2kHz, 2.5kHz, 3.15kHz etc.). All harmonic products that lie between test tones represent distortion. The picture does not need much interpretation. It is clear that the ribbon driver has a 10 to 20dB lower distortion spectrum. Compression drivers are so non-linear that they produce significant intermodulation distortion and sub-harmonics that even spread below the test signal range (observe a fence of sub-harmonics from 630Hz to 2kHz from the compression driver and total absence of those from the planar ribbon driver). Summary The great French composer Claude Debussy once said, Music is the space between the notes. What happens between the notes? A performer communicates much information and emotion between the notes when loud impulse signals decay into the space. It is very important to reproduce this low level information fully and faithfully. This is where a lot of things happen that engage listeners, connecting them with the performers and their music. Connect with a consultant If you have additional questions, or if you need some help in selecting the right solution, please contact us. We can connect you with a network of experts who will be happy to help you work through the decision process. Contact us 4
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