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Crestron Surround Sound, User Manual

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Crestron 

Surround Sound

  

Primer 

 

Low Pass 

A low-pass filter passes on a majority of the low frequencies and 
blocks or attenuates the higher frequencies. Sometimes it is called a 
high-frequency discriminator or high-frequency attenuator. A low-pass 
filter passes all frequencies below the specified frequency, while 
attenuating all frequencies above this specified frequency. 

Low Pass Filter 

 

 

Primer – DOC. 6122 

 

Surround Sound  

•

  27 

 

Summary of Contents for Surround Sound

Page 1: ...Crestron Surround Sound Primer...

Page 2: ...Pro Logic II Dolby Digital Dolby Digital 5 1 and the double D symbol are trademarks of Dolby Laboratories Manufactured under license from Digital Theater Systems Inc DTS DTS Digital Surround Sound DTS...

Page 3: ...round Sound 9 Early Surround 9 Quadraphonic 9 Dolby 10 Dolby Pro Logic 11 Dolby Pro Logic II 12 Dolby Digital 12 Dolby Digital Surround EX 12 DTS 13 DTS ES 13 DTS Neo 6 14 Pulse Code Modulation 14 Spe...

Page 4: ...t We Hear in a Room 22 Speakers Placed in Cabinets 22 Stereo Imaging 23 About Surround Sound 23 Subwoofer Placement 24 Equalizers 25 Graphic Equalizer 25 Parametric Audio Filters 25 Parametric GUI 35...

Page 5: ...e Frequency Frequency is the number of distinct positive or negative sound wave elements that repeat in one second Frequency is measured in Hertz Hz A 20 Hz frequency contains 20 positive and negative...

Page 6: ...aham Bell the B is capitalized for Bell and is used in both audio and video applications Decibel is a logarithmic scale measuring the intensity pressure level of sound Decibels are ratios not fixed qu...

Page 7: ...harmonic distortion level in the recorded signal Decibel dB meters measure instantaneous audio power A dB meter responds very rapidly and considers the audio power at each instant Its zero is set to...

Page 8: ...ree dimensions and assumes that the vibrating particles of air are held semi rigidly In the real world air molecules are in constant random motion in all three dimensions Air pressure constantly chang...

Page 9: ...ditory perception It includes the physical characteristics of sound waves the physiological structure of the ear the electrical signal from the ear to the brain and the subjective interpretation of th...

Page 10: ...slightly delays the sound each ear receiving a slight difference when the sound is not equally distant from the two ears Although the time delay differences are very slight the brain extracts precise...

Page 11: ...rves affect the way sound is heard A sound is coming from behind or above bounces off the pinna in a different way than from in front or below When the indirect reflected sounds from the pinna combine...

Page 12: ...the sound is reflected and scattered against room boundaries and objects within the room Reverberation is essentially an echo that increases by bouncing off of hard surfaces Reverberations are dampen...

Page 13: ...ain the illusion of the phantom sound from between the speakers Surround recordings add additional audio channels so that sound comes from multiple directions In effect widening the sweet spot and enh...

Page 14: ...els into two signals Also described as 4 2 4 matrixing these signals compatible with two speaker stereo playback can be decoded into multiple channels Basic Dolby Surround decoding yields front left f...

Page 15: ...different in left total and right total are applied to the front left and right speakers 6 Signals that are identical and in phase are applied to the center channel 7 Signals that are identical but o...

Page 16: ...997 takes advantage of DSP It uses a digital processing method which exploits the limits of human hearing Playback of Dolby Digital is similar to that of Dolby Surround but the technologies are very d...

Page 17: ...llowing for a wide range of bit resolutions and sampling rates Its operation ranges from low bit rate lossy perceptual coding meaning that it reduces data based on psychoacoustics principles to high q...

Page 18: ...in air pressure This signal is measured or sampled at a rate of at least twice the maximum frequency contained in the audio signal the Nyquist rate typically 44 1 kHz for Compact Discs or 48 kHz for...

Page 19: ...ave similar response characteristics to the other speakers in a surround sound system to present a uniform sound environment This is also referred to as timbre matching NOTE When referring to loudspea...

Page 20: ...which it was designed NOTE Bass management sends the bass content of small speakers to the front speakers if they are large and there is no subwoofer Speaker Set up Suggestions The following are sugge...

Page 21: ...e and amplify the original sound creating the booming bass sound Standing waves can be reduced or eliminated by careful placement of subwoofers rearranging furniture and equalization adjustment Phase...

Page 22: ...peakers if possible The left and right front speakers are positioned at an angle of 45 to 60 degrees to the center most listener An angle nearer to 45 degrees is preferred if the system is used primar...

Page 23: ...tional center rear information is split between the left and right rear surround channels Rear channel speakers should be placed at an angle of 60 to 90 degrees to the prime listening spot Ideal 7 1 S...

Page 24: ...a flatter frequency response more closely matching the original signal by compensating for the room acoustics and speaker deficiencies The following diagram illustrates the use of equalization on an a...

Page 25: ...o be reproduced either movie audio or other kinds of audio and the types of speakers used The first thing to recognize when constructing a home theater system is that the room itself can be more impor...

Page 26: ...the sound level but decreasing clarity This situation can be resolved by adding some absorption material You can use a variety of materials such as acoustical foam and acoustic fiberglass Even a drap...

Page 27: ...reflections will help greatly If a little more spaciousness is desired allow for reflections and you can even add diffusers to help create the desired sound Doing either of these is fine as long as t...

Page 28: ...t that particular position Meanwhile people that may be sitting in off center may have loud and muddy bass because at this position the room mode is doubling the amplitude of the frequency that is cau...

Page 29: ...ustic space Graphic equalizers use a set of predetermined frequency bands to adjust the amplitude of the waveform at specific frequencies The center frequencies that are used and bandwidth affected by...

Page 30: ...e the desired flatness High Pass A high pass filter passes on a majority of the high frequencies to the next circuit and blocks or attenuates the lower frequencies Sometimes it is called a low frequen...

Page 31: ...cks or attenuates the higher frequencies Sometimes it is called a high frequency discriminator or high frequency attenuator A low pass filter passes all frequencies below the specified frequency while...

Page 32: ...ample to increase the bass frequencies to a subwoofer you can set the bass shelf filter to uniformly increase the amplitude of all bass frequencies The bass shelf filter can also be used to uniformly...

Page 33: ...Crestron Surround Sound Primer Bass Shelf Filter Increasing Overall Bass Response Primer DOC 6122 Surround Sound 29...

Page 34: ...ncies Because bass frequencies have longer wavelengths small speakers may sound distorted when trying to reproduce these frequencies The treble shelf filter can increase the proportion of treble to ba...

Page 35: ...Crestron Surround Sound Primer Treble Shelf Filter Decrease Overall Treble Response Primer DOC 6122 Surround Sound 31...

Page 36: ...increasing the amplitude of the 4 kHz signals If this increase in amplitude closely matches the loss of the room then the frequency response is flattened creating a more realistic sound In the followi...

Page 37: ...ample of the use of a notch filter is with an audio program that has been contaminated by 60 Hz powerline hum A notch filter with a center frequency of 60 Hz can remove the hum while having little eff...

Page 38: ...Primer Crestron Surround Sound Notch Filter 34 Surround Sound Primer DOC 6122...

Page 39: ...g on either side of the center node allow for a bandwidth adjustment also called an octave range or Q In the following example of a parametric filter with center frequency of 4 kHz a range of frequenc...

Page 40: ...Paper 6 Information courtesy of Smyth S M F Smith W P et al DTS Coherent Acoustics Delivering High Quality Multichannel Sound To The Consumer 100th AES Convention Preprint 4293 May 1996 7 Information...

Page 41: ...ome manufacturers have developed products using several FFT processes C Codec coder decoder H A pair of processing elements that code a signal prior to storage or transmission and then correspondingly...

Page 42: ...of one sound is raised by the presence of another In both digital video and digital audio a technique that allows a system to delete superfluous inaudible or invisible artifacts from a data stream by...

Page 43: ...eet spot may be large enough to accommodate multiple listeners T Toslink A type of fiber optic cable connection that uses light beams to transmit digital information from digital audio components Most...

Page 44: ...MPEG 37 Notch 34 Nyquist Sampling Theorem 37 Octave 37 Parametric Audio Filters 25 Parametric Equalizer 37 PCM 37 Perception 3 Perceptual Coding 37 Phantom Image 38 Phase 17 Pink Noise 38 Pinna 38 Pi...

Page 45: ...Crestron Surround Sound Primer This page intentionally left blank Primer DOC 6122 Surround Sound 41...

Page 46: ...Crestron Electronics Inc Operations Guide DOC 6122 15 Volvo Drive Rockleigh NJ 07647 11 03 Tel 888 CRESTRON Fax 201 767 7576 Specifications subject to www crestron com change without notice...

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