Audio Competition / Sound Quality

[Cablguy184]

I compete Car Audio for USACI and MECA ... Sound Quality ...

Is there any other competitors out there ???

[Cablguy184]

It takes a lot to create a good Truck / car audio system. Here are six basic steps every Truck / car audio enthusiast should take on the path to great sound.

 

Making up your mind

One of the first things you need to do is decide what type of system you want. Do you want one that can reproduce your music so that it sounds like you're at a live concert? Or do you want a system that can simply blast out a bunch of bass? Maybe you want a system that can do both. By starting with a goal in mind, you can save yourself from potentially wasting money on components or wasting time on designs and installations that don't fit your overall objectives.

 

Doing your homework

Do your homework by researching which components fit your car (the size of the speaker and the factory-radio openings) and best accomplish what you want your system to do, what they cost, and where they're available.

 

Information is power, and the more information you have, the more you'll be empowered to make the best decisions on equipment and system design.

 

Using your ears

A car audio system is a very personal thing — for your ears only. Although you may get advice from others on which components to buy, how they should be installed, and how the system should be tuned, you should be the ultimate authority on the subject. After all, you're the one spending the money on a car audio system. It's your car and they are your ears: They'll tell you what kind of sound is best.

 

Using your head

Are you sure you want to install a system that costs twice as much as your car? Do you really want to rip out the back seat to install subwoofers? Is it wise to fill up the trunk of the car with amplifiers so that you can't even carry a bag of groceries?

 

It's easy to get carried away when planning, shopping for, and installing a car audio system. Try to keep a level head when putting together your system, taking into account how you use your car, how long you plan to keep it, how much you've budgeted, and other such considerations. Too many people make poor choices and regret it afterward.

 

Cranking it up

When shopping for car audio equipment, don't be afraid to play music at loud volumes to get a sense of how a speaker or subwoofer performs. Most components are made to play music at loud volume and perform their best when cranked up. Same thing goes for after you get the stuff installed in your car. Don't hesitate to crank it up from time to time.

 

Turning it down

Of course, there's a limit to how much you want to crank it up. A little distortion is inevitable, but a lot can damage components, particularly speakers. When you hear distortion or a problem with a component, turn it down.

 

And when you're driving through a quiet neighborhood, turn it down. You also want to be careful not to crank it so loud that you don't hear sirens from emergency vehicles. And you don't want to play your system so loud that it damages your ears — otherwise you won't be enjoying music for years to come.

[Cablguy184]

Sound Quality Theories and Principles ...

Listening to audiophiles go on about the sound quality of their audio systems — from their woofers to their tweeters — can sound a lot like oenophiles going on and on about the qualities of wine. To understand such talk, start by understanding the four basics of sound quality:

 

 

Clarity

Dynamic range

Frequency response

Tonal balance

 

Clarity

Clarity is the ability of a system to produce the original signal as intended, without distortion. Distortion can be caused by numerous things — from a head unit that's not level-matched with an amplifier to an amplifier that's clipping, or being overdriven and sending a distorted signal to the speakers. And distortion can come from any component in a system.

 

A good test is to listen to cymbals, which can have a brassy and off-putting sound when distorted. High-pitched female vocals are also difficult to reproduce and can reveal distortion rather easily.

 

Achieving clarity and therefore avoiding distortion is all about proper system design and tuning. It's making sure components are of sufficient quality and compatible with one another and that signal levels are well matched between electronics. It also involves using a component as it was intended and not pushing it past its design limits.

 

 

Dynamic range

Dynamic range refers to the ability of a system to reproduce loud and soft passages in music with the same level of detail. When you're at a live concert, a singer may wail and then whisper or a drummer may hit a drum head with brute force and then back off a bit. Each extreme is an important part of the performance.

 

If the performance is recorded and reproduced by an audio system, the loud and soft parts should be delivered with the same detail and accuracy. But often a system tends to suppress soft parts and emphasize loud ones, meaning you lose the subtleties of the performance.

 

A related concept is linearity, which refers to a system's tendency to lose detail when the volume is turned down. A system has great linearity if it can retain the same detail at a low volume that it does when it's cranked up.

 

 

Frequency response

Every sound you hear, from the low rumble of thunder to the high-pitch wail of a siren, is caused by vibrations in the air that occur at certain frequencies. These vibrations are measured in hertz (Hz), which refers to the number of times per second these vibrations occur.

 

Humans can hear frequencies roughly from 20 to 20,000 Hz. A car audio system's frequency response represents how much of the audible frequency spectrum it can reproduce. The frequency response of a car audio system can be measured by an instrument known as a real-time analyzer (RTA), which consists of a microphone attached to a processor with a display that has a graph that shows a system's response.

 

 

Tonal balance

An ideal car audio system uniformly reproduces the entire audible frequency spectrum from 20 to 20,000 Hz. But no system — at least while playing music — is perfect. Music is dynamic; some parts are loud and some are soft, so a system will naturally have dips and peaks in its frequency response.

 

Although a system can have these peaks and dips in frequency response, it needs to have good tonal balance — a relatively equal amount of sonic energy across the frequency range — to sound good. Subsequently, system designers and tuners often measure frequency response to gauge which frequencies may need to be boosted or cut as opposed to trying to achieve a flat frequency response. This can be done with an equalizer, although it's best that the system is designed in such a way that it has good tonal balance to begin with.

[Cablguy184]

Although the four basic sound quality concepts (clarity, dynamic range, frequency response, and tonal balance) are the most fundamental to understand before purchasing a new car audio system, there are a few other sound quality attributes that are also important.

 

 

Timbre

Timbre (pronounced "TAM-bir") refers to a system's ability to recreate the sound of an instrument as it was originally intended to be heard. An acoustic guitar is usually a good test for this because most people have heard one. Does the sound have that warm, slightly resonant quality that the instrument is known for, or does it merely sound like a low-resolution reproduction of that signature sound?

 

 

Tonal accuracy

Tonal accuracy describes how faithful a system is in general to the original recording. It can apply to instruments as well as vocals. The more accurate the system is while playing a good recording, the more you feel as if you are there, listening to a live performance as opposed to a recording.

 

Tonal accuracy can also apply to the ambiance in a recording, which refers to the space in which a recording is made. Most modern recordings are made in a sort of vacuum, with individual instruments recorded separately or, in the case of some rap music, the individual parts are sampled from other recordings. But many older recordings, some modern ones, and almost all live albums capture the environment in which the performance was recorded. In fact, certain recording studios and performance spaces are known and revered for their sound, which give a recording or performance a specific ambiance.

 

Think of timbre and tonal accuracy as the reproduction of how close you get to the actual performance or how the producer intended for it to sound. Whether it's the sound of Miles Davis's trumpet, Jimmy Page's guitar, a Dr. Dre beat, or the ambiance of Carnegie Hall, how well a system can reproduce it the way it went down in a studio or concert hall determines the difference between a good system and a great one.

 

 

Staging and imaging

Staging and imaging are related concepts that go back to the heyday of stereo, and therefore don't always apply to modern music. The basic idea is that when you're listening to a stereo recording, the system should recreate the illusion of the stage on which the performance occurred, and you should be able to pinpoint the sonic image of the individual performers and instruments within the stage.

 

Think about the example of a basic rock band that includes a singer, guitarist, bass player, and drummer. You should be able to close your eyes and picture the singer at the center of the stage, the guitarist to the right, the bass player on the left, and the drummer center and behind the singer. Keep in mind that this is an ideal that sound quality systems should approach if not achieve. With rap and many pop-music recordings, the vocalist will be centered, but the concept of a band playing on a stage doesn't exactly apply.

 

Speaker placement has a dramatic effect on staging and imaging, and hardcore enthusiasts often go to great lengths to position their speakers for the best possible results. This includes rebuilding door panels to better position speakers. Some have even built elaborate mechanisms to mount speakers in or raise them above the dash in order to achieve better staging and imaging.

 

Finally, no discussion of sound quality would be complete without mentioning interior acoustics. A car's interior, its reflective surfaces (such as glass), and its absorptive materials (upholstery) play a dramatic role in a system's response. And every car interior is different; if you install the exact same components in your Toyota Camry that your friend has in his Chrysler 300C, the systems will sound very different.

[Cablguy184]

Well, What about Sound ressure level competitors ???

[Cablguy184]

How to Measure Sound Quality

 

There are many ways to measure sound quality. Many measurements have been created to specifically measure and rate the quality of sound. Here are a few of the most common types of measurements used for sound quality.

 

THD

 

THD stands for Total Harmonic Distortion. It is a measurement taken to view the total amount of distortion from the original audio signal at playback. Most quality components have less than 1% distortion rate, loudspeakers can have 1 to 5% distortion rate and bass subwoofers can produce the most distortion sometimes approaching 10%. However, human ears can't differentiate distortion at very low bass levels.

 

Output Power

 

Output power is the maximum energy per channel, usually shown as Watts. Most speakers or receivers show the amount of watts that they have. There are two measurements peak and RMS. Peak watts is usually what is shown on advertisements, it is usually the maximum amount of energy that a speaker or receiver can give off for a very short period of time. RMS stands for Root Means Square and is a more appropriate way to determine power over a longer period of time.

 

Frequency Response

 

Frequency Response is an important way to determine the quality of sound. Most human ears can hear frequency (sound) that is from about 20 HZ to about 20K HZ. Bass forms the lower parts of the Frequency response spectrum. Most people consider bass frequencies, those frequencies below 310 HZ. Bass frequencies include percussion and explosions from movie DVD's. Midrange frequencies are those frequencies that range from about 310 HZ to about 12K HZ. These frequencies include dialogue and most of the human voice, piano, guitar and other instruments. High frequencies are at the top of the frequency response spectrum. They are usually from 12K to about 20K or higher. They include cymbals, high notes from the human voice, and some string instruments.

 

Signal to Noise Ratio

 

Signal to noise ratio is the ratio of quality sound to noise. This measurement is used to measure many devices including receivers, CD players, DVD players, etc. Usually the higher the decibel (Db), he better the quality of sound. For instance, a signal to noise ratio of 90 or 100 decibels is considered high fidelity. Most electronics are usually 80 decibels or over which is great for many discerning human ears.

 

It is important to note that the above terms are not the only way to measure sound. There are various ways to measure sound, components and media which are either digital or analog. However, knowing about the above terms does give you some insight into the process of measuring sound quality

 

 

[electricchiken7]

WOW!!

[tazerbro]

Hrmmm

[Cablguy184]

WOW!!

 

Hrmmm

 

Thanks guys ...

[Cablguy184]

Thiele-Small Parameters

 

In the early seventies, several technical papers were presented to the AES (Audio Engineering Society) that resulted in the development of what we know today as 'Thiele-Small Parameters'. These papers were authored by A.N.Thiele and Richard H. Small. Thiele was the senior engineer of design and development for the Australian Broadcasting Commission and was responsible at the time for the Federal Engineering Laboratory, as well as for analyzing the design of equipment and systems for sound and vision broadcasting. Small was, at the time, a Commonwealth Post-graduate Research Student in the School of Electrical Engineering at the University of Sydney.

 

Thiele and Small devoted considerable effort to show how the following parameters define the relationship between a speaker and a particular enclosure. However, they can be invaluable in making choices because they tell you far more about the transducer's real performance than the basic benchmarks of size, maximum power rating or average sensitivity.

 

Fs This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'. With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension (surround and spider) are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well.

 

Re This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the 'DCR'. This measurement will almost always be less than the driver's nominal impedance. Consumers sometimes get concerned the Re is less than the published impedance and fear that amplifiers will be overloaded. Due to the fact that the inductance of a speaker rises with a rise in frequency, it is unlikely that the amplifier will often see the DC resistance as its load.

 

 

Le This is the voice coil inductance measured in millihenries (mH). The industry standard is to measure inductance at 1,000 Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at Fs.

 

 

Q Parameters Qms, Qes, and Qts are measurements related to the control of a transducer's suspension when it reaches the resonant frequency (Fs). The suspension must prevent any lateral motion that might allow the voice coil and pole to touch (this would destroy the loudspeaker). The suspension must also act like a shock absorber. Qms is a measurement of the control coming from the speaker's mechanical suspension system (the surround and spider). View these components like springs. Qes is a measurement of the control coming from the speaker's electrical suspension system (the voice coil and magnet). Opposing forces from the mechanical and electrical suspensions act to absorb shock. Qts is called the 'Total Q' of the driver and is derived from an equation where Qes is multiplied by Qms and the result is divided by the sum of the same.

 

As a general guideline, Qts of 0.4 or below indicates a transducer well suited to a vented enclosure. Qts between 0.4 and 0.7 indicates suitability for a sealed enclosure. Qts of 0.7 or above indicates suitability for free-air or infinite baffle applications. However, there are exceptions! The Eminence Kilomax 18 has a Qts of 0.56. This suggests a sealed enclosure, but in reality it works extremely well in a ported enclosure. Please consider all the parameters when selecting loudspeakers. If you are in any doubt, contact your Eminence representative for technical assistance.

 

Vas/Cms Vas represents the volume of air that when compressed to one cubic meter exerts the same force as the compliance (Cms) of the suspension in a particular speaker. Vas is one of the trickiest parameters to measure because air pressure changes relative to humidity and temperature — a precisely controlled lab environment is essential. Cms is measured in meters per Newton. Cms is the force exerted by the mechanical suspension of the speaker. It is simply a measurement of its stiffness. Considering stiffness (Cms), in conjunction with the Q parameters gives rise to the kind of subjective decisions made by car manufacturers when tuning cars between comfort to carry the president and precision to go racing. Think of the peaks and valleys of audio signals like a road surface then consider that the ideal speaker suspension is like car suspension that can traverse the rockiest terrain with race-car precision and sensitivity at the speed of a fighter plane. It’s quite a challenge because focusing on any one discipline tends to have a detrimental effect on the others.

 

Vd This parameter is the Peak Diaphragm Displacement Volume — in other words the volume of air the cone will move. It is calculated by multipying Xmax (Voice Coil Overhang of the driver) by Sd (Surface area of the cone). Vd is noted in cc. The highest Vd figure is desirable for a sub-bass transducer.

 

 

BL Expressed in Tesla meters, this is a measurement of the motor strength of a speaker. Think of this as how good a weightlifter the transducer is. A measured mass is applied to the cone forcing it back while the current required for the motor to force the mass back is measured. The formula is mass in grams divided by the current in amperes. A high BL figure indicates a very strong transducer that moves the cone with authority!

 

 

Mms This parameter is the combination of the weight of the cone assembly plus the ‘driver radiation mass load’. The weight of the cone assembly is easy: it’s just the sum of the weight of the cone assembly components. The driver radiation mass load is the confusing part. In simple terminology, it is the weight of the air (the amount calculated in Vd) that the cone will have to push.

 

EBP This measurement is calculated by dividing Fs by Qes. The EBP figure is used in many enclosure design formulas to determine if a speaker is more suitable for a closed or vented design. An EBP close to 100 usually indicates a speaker that is best suited for a vented enclosure. On the contrary, an EBP closer to 50 usually indicates a speaker best suited for a closed box design. This is merely a starting point. Many well-designed systems have violated this rule of thumb! Qts should also be considered.

 

 

Xmax/Xlim Short for Maximum Linear Excursion. Speaker output becomes non-linear when the voice coil begins to leave the magnetic gap. Although suspensions can create non-linearity in output, the point at which the number of turns in the gap (see BL) begins to decrease is when distortion starts to increase. Eminence has historically been very conservative with this measurement and indicated only the voice coil overhang (Xmax: Voice coil height minus top plate thickness, divided by 2). The Xmax figures on this website are expressed as the greater of the result of the formula above or the excursion point of the woofer where THD reahes 10%. This method results in a more real world expression of the usable excursion limit for the transducer. Xlim is expressed by Eminence as the lowest of four potential failure condition measurements: spider crashing on top plate;vVoice coil bottoming on back plate;vVoice coil coming out of gap above core; or the physical limitation of cone. A transducer exceeding the Xlim is certain to fail from one of these conditions. High pass filters, limiters, and enclosure modeling software programs are valuable tools in protecting your woofers from mechanical failure.

 

 

Sd This is the actual surface area of the cone, normally given in square cm.

 

 

Usable frequency range This is the frequency range for which Eminence feels the transducer will prove useful. Manufacturers use different techniques for determining ‘Usable Frequency Range’. Most methods are recognized as acceptable in the industry, but can arrive at different results. Technically, many loudspeakers are used to produce frequencies in ranges where they would theoretically be of little use. As frequencies increase, the off-axis coverage of a transducer decreases relative to its diameter. At a certain point, the coverage becomes ‘beamy’ or narrow like the beam of a flashlight. Following is a chart that demonstrates at what frequency this phenomenon occurs relative to the size of the transducer. If you’ve ever stood in front of a guitar amplifier or speaker cabinet, then moved slightly to one side or the other and noticed a different sound, you have experienced this phenomenon and are now aware of why it occurs. Clearly, most two-way enclosures ignore the theory and still perform quite well. The same is true for many guitar amplifiers, but it is useful to know at what point you can expect a compromise in coverage.

 

 

Power handling This specification is very important to transducer selection. Obviously, you need to choose a loudspeaker that is capable of handling the input power you are going to provide. By the same token, you can destroy a loudspeaker by using too little power. The ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. To use an automobile as an analogy; you would not buy a car that could only go 55mph if that were the speed you always intended to drive. Generally speaking, the number one contributor to a transducer’s power rating is its ability to release thermal energy. This is affected by several design choices, but most notably voice coil size, magnet size, venting, and the adhesives used in voice coil construction. Larger coil and magnet sizes provide more area for heat to dissipate, while venting allows thermal energy to escape and cooler air to enter the motor structure. Equally important is the ability of the voice coil to handle thermal energy. Eminence is renowned for its use of proprietary adhesives and components that maximize the voice coil’s ability to handle extreme temperatures. Mechanical factors must also be considered when determining power handling. A transducer might be able to handle 1,000W from a thermal perspective, but would fail long before that level was reached from a mechanical issue such as the coil hitting the back plate, the coil coming out of the gap, the cone buckling from too much outward movement, or the spider bottoming on the top plate. The most common cause of such a failure would be asking the speaker to produce more low frequencies than it could mechanically produce at the rated power. Be sure to consider the suggested usable frequency range and the Xlim parameter in conjunction with the power rating to avoid such failures. The Eminence power rating is derived using an EIA 426A noise source and test standard. All tests are conducted for eight hours in a free-air, non-temperature controlled environment. Eminence tests samples from each of three different production runs and each sample must pass a test exceeding the rated power by 50 to 100W. The Eminence music program is double that of our standard Watts rating.

 

Sensitivity This data represents one of the most useful specifications published for any transducer. It is a representation of the efficiency and volume you can expect from a device relative to the input power. Loudspeaker manufacturers follow different rules when obtaining this information — there is not an exact standard accepted by the industry. As a result, it is often the case that loudspeaker buyers are unable to compare 'apples to apples' when looking at the sensitivities of different manufacturers’ products. Eminence sensitivities are expressed as the average output across the usable frequency when applying 1W/1M into the nominal impedance. ie: 2.83V/8 ohms, 4V/16 ohms.