An Introduction to Car Audio System Design, Stereo Imaging and Staging

Here I will explain the basics of the subject and briefly discuss how these principles are applied to the car audio world. This is not supposed to be a complete guide to the sound because we do not want to send you to sleep if you want to know more about the sound and the principles of hi-fi sound reproduction there any good books on the subject.
So what sounds
Sound is caused by the movement of air. If a large wooden panel beside the air vibrate driven away. If the vibration is slow, the air just moves out of the way but as the level increases a little vibration to the tens and tens of thousands of requests per second the air can not move out of the way fast enough and therefore compress the panel pushed it away. Air natural elasticity comes into play. Airborne particles of the panel encouraged the subsequent particles push against the next and so create a pressure wave. As the panel back to the starting position the air becomes less dense because it fills a void in the front panel.
You may be one step ahead of me now but this is why we find a small tweeter and woofer is huge. All sizes can produce sound speakers and tweeters reason why small and large woofer has much to do with the size of the waves they tried to reproduce the pressure and weight and characteristics of the panel move - which in the case of the speaker cone is usually a dome or sometimes flat diaphragm. To reproduce the high frequency cone or dome needs to move very quickly. The smaller and lighter it gets easier for the amplifier to control it. We will come to this later. First we need to understand a little more about the sound itself.
Pressure waves
Notes of the musical scale represent only noise at a certain frequency. Middle A on a piano is such Hz wave ft in length. In the case of the church pipe organ or an electronic synthesizer may be possible to play a four-octave A under A. This medium has a major or fundamental frequency is very low additional frequency or harmonics are added naturally that gives each instrument its tonal character of the individual. Hz wavelengths around the foot end of the scale A literal play three octaves above middle A has a frequency of about Hz and a wavelength of only inches.
Size of musical instruments and loudspeakers tend to show that the wave length is designed to produce. The soundboard is a piano and the organ pipes of the church is able to produce large wavelength means lower frequency. Similarly-inch diameter subwoofer is designed to provide a low bass. If we ignore for a moment the mechanical limitations there is nothing stopping either inch mid-woofer from a very low frequency reproduction. It can move in cycles per second required but its size means that only can replace a number of air during each cycle. This can result in very low frequency but only at a very low level of output. This brings us back to the analogy of the hand and a plate dinner in a bathtub full of water. Inch subwoofer surface area is like a dinner plate able to move enough air in one cycle to generate a pressure wave capable of rattling the windows in the house across the street
Imaging and Phase ... creating the illusion of reality
If we listen to and record the sound of a single flute in our living room for example, and then replay with a single full-range speakers are positioned in exactly the same place as the flute player there is a good chance if the recording equipment and hi-fi system is good enough quality that it will sound more or less identical. Characteristics reverberation room will be the same and since we only use one speaker rather than trying to artificially create flautist position in space using instruments stereo techniques have seemed to be in exactly the right place.
Stereo aim to create the exact position of the instruments by using only one pair of loudspeakers and achieve this primarily by increasing the levels of specific instruments in one channel relative to the other channels. Just different levels - the wavelength of both left and right channels will be the same in every other way. They are said to be in phase. This means that if you could somehow freeze the sound and see the wavelengths coming from two speakers will both wavelengths at the same point in their cycle.
If we sit in front of the car near the left-hand speaker then we will hear the voice of the speaker was a little earlier than the sound from the speakers on the right and from the speakers behind us. It is also possible that the frequency of extremely short wavelengths where the sound we hear with our ears left and right may be slightly out of phase. It's time and phase distortions confuse the brain and can destroy the stereo effect. When this happens you will hear the sound mostly comes from the speaker closest to you instead of the imaginary stage windscreen - stereo tricks failed to work.
our earlier analogy with water can also help us to understand what is meant by voice in phase and out of phase. Imagine that you start the gentle waves from one end of the tub. If you use both hands to launch two waves at exactly the same time the peak of the wave will occur at exactly the same point and in the phase of the wave can be said. Now start the gentle waves from the end of the tub. What happens when two waves meet Both clashes wave and effectively cancel each other out. Now imagine the speakers in the front and rear of each vehicle produce sound pressure waves. this mixture and make some very complex changes to the sound. As the air pressure waves can meet strong push in the same direction in which we have been traveling so may lead to additional peaks in the frequency response or a pressure wave may push for another trip in the opposite direction. In the latter case if the two waves are identical in terms of frequency and pressure, and exactly half of the wavelength phase they will cancel themselves out completely leaving silence.
Usually two sound patterns are so complex that they will only partially cancel but relatively long wavelengths of pure tone and high pressure are more likely to feel cancel. The lower frequencies are produced and reproduced over loudspeakers no more likely frequency range phase cancellation will occur. If the speaker cables and - terminals reversed on one speaker speaker placed a half-wavelength degrees out of phase. In theory they should be self-canceling but in practice the bass region suffers most and cancellation of the remaining votes to be confused with the central image a little or none.
Speaker placement ... for those without a McLaren F
By installing a lot of speakers in the vehicle we created a very complex mix of pressure waves that can cause problems with the overall sound. This does not mean that it is a bad thing to install a large number of speakers. We may want to divide the frequency range into small portions - sub-bass bass bass midrange mid-upper midrange and high frequency ultra-high frequencies - so the distance each had a pair of speakers dedicated to it. Due to the limitations of the speaker is probably a good idea if we look for absolute sonic fidelity. Space is limited only in the vehicle so that we tend to put less speakers typically include sub-bass midrange and mid-bass frequencies above. It can provide a good reproduction of the tone quality of the various instruments and voices but still there is a problem of time alignment and phase off-axis performance to consider.
larger bass speakers can often be installed in the door without too much effect on the image if you are sure that the crossover point is set so that they do not overlap the output frequency range midrange speakers too much. Subwoofer or subwoofers usually have to be installed at the rear of the vehicle because of their size. Be careful when choosing the slope and setting the crossover point on the channel's eating these speakers. With dB per octave low-pass filter filters that only pass certain frequencies below the crossover point is set to output in Hz Hz dB would only lower and therefore tend to be driven hard subwoofer pressure waves created in the mid-frequency region may be strong enough to interact with speakers at the front of the vehicle. It is generally wise to choose dB or dB slope for the subwoofer.
Installing a full-range speaker on the rear shelf or at the back door is often confusing picture on the front of the car stereo since the same sound coming from more than one source and this is not fair. If you need to install the speakers are here to provide an atmosphere or double rear front of the stage because you often carry passengers in the back seat to adjust front / rear fader control on the CD player so that the front speakers are much louder than the rear speakers when listening from the driver's seat.
You may still find that the stereo imaging on the front of the car confused. If this is the case worth experimenting with flipping / - connections to all full-range speaker on the back to put their degrees out of phase with those in front. It may sound crazy but sometimes it works well. Always make sure that you reverse the connections on both speakers in a pair.
Shake Rattle and ... why the material resonates
Musical instrument that produces sound electronically naturally not do well something that causes it to resonate - like guitar strings and piano or leather and the metal surface of the drum kit, etc. - or by moving air as in the case of wind and brass instruments. Each ingredient has a specific resonance frequency - this is the frequency at which the material will vibrate or resonate most free - and this together with the size of the resonating objects and many other factors contribute to the sound that would result if the object was quite pleased.
Unfortunately the bass cabinets brick-built car has not really caught on and more practical alternative should be developed to make the cage wood and metal parts of the car is less resonant. Good quality MDF particle boards are very solid and provide a good starting point and can be treated if necessary with sound deadening sheet or spray treatment. In the case of sheets of sound deadening material bonds to the panel off an acoustic easier as excited as the inside of the vehicle panel metal door panel in the trunk or boot. This sheet helps to absorb panel resonance for its own resonance frequency is so low that the resonance occurs at lower frequencies and become less visible. In the case of spray treatment NoiseKiller developed by the Swedish company Audioform resonance absorbed by the material is not only the frequency shift. Instead converted into small amounts of heat. This appliance manufacturers say that the material did not produce sound themselves - in other words resonant panels are completely eliminated.