Audio Basics

[The_Blur]

We're due for a good audio discussion on what makes audio great and how to implement it in a production car.

What makes JL so much better than JBL? Try to explain in plain enough terms that non-audiophiles can understand.

This thread will be updated as people post their wisdom. Get posting!


Sound

You know what sound is, but how is sound created for car audio?

It starts with some source of sound. Usually an artist and a band come together and record an album that you put on your iPod. You plug this iPod into your Camaro's USB port or auxiliary input. The sound is silent. It becomes an electrical signal that flows through the head unit, to the amplifier, to your speakers. Each of these components plays an important role. The head unit translates your iPod's file into an electrical signal. Your amplifier magnifies your tiny iPod's electrical signal so that it is big enough for your car. Your speaker translates this electrical signal into a sound that you can hear.

Each of these components is a translator speaking a different language. As a result, they have to be able to communicate, and the lines of communication must be good. First, your head unit has to speak to the iPod. Second, your amplifier has to speak to your head unit. Third, your speakers have to speak to your amplifier. If they are not attached in this order, they won't do their jobs.


Wattage

Your head unit will push power, measured in watts, to each speaker. For many people, an aftermarket head unit provides ample power by pushing a few watts to each speaker. My Subaru had a head unit that pushed 50W to each of 4 speakers in the car. This is a pretty average power rating for a head unit.

If you have an aftermarket amplifier or have more than 50W going to each speaker, it would make sense to upgrade the speakers in your car. The wattage requirement on the speakers should match the power going to them within a small range. If each speaker is designed for 100W, then receiving 110W is close enough that you won't experience a sound problem. Keeping these wattage numbers going out of the head unit and amplifier into the speaker close produces quality sound with limited distortion.


Speakers

Speakers produce sound. There are different kinds of speakers that will be important to this discussion.

Tweeters represent high frequencies in you car. Subwoofers represent low frequencies in your car. In between these are mid-range speakers which obviously produce the majority of frequencies heard in music.

Adding additional speakers of different classes can improve the depth of your sound system. When added correctly, they balance highs and lows. Unfortunately, most people do not add additional speakers correctly. The most common speaker addition is subwoofers. Some people really like the thump of a deep subwoofer at the expense of the rest of their system. This is common, but this is not correct. Subwoofers and tweeters can be added to a stock sound system without creating rattles or dominating the mid-range sounds.


Distortion

When the audio just doesn't sound right, people tend to describe the sound as distorted. This is one of the major ways of measuring sound quality.

Distortion occurs when more sound is pushed through a speaker than the speaker is equipped to handle. A great example can be found here. Basically, a speaker has limits, and pushing beyond those limits might create more volume but the distortion results in poor quality. Louder is not always better.

Frequently, your amplifier causes your speaker distortion. Rather than blaming your speakers for being of poor quality, try turning down your amplifier. Another cause of distortion is an overdriven amplifier.


Amplifiers

Amplifiers are very complicated. Regardless of what I post here, people should continue to post their additional wisdom.

I'll start by identifying the issue of efficiency, the measure of how much input gets applied to the output. As with all measures of performance, higher efficiency is better. Class A amplifiers have the poorest efficiency, capping at around 25%. Class B amplifiers have high efficiency but also very high distortion, so these tend to be a poor choice for anyone interested in quality. A good alternative is a Class AB amp, which usually has an efficiency in the range of 35% to 55%. Class D amps have up to 90% efficiency. Higher efficiency has the benefit of running cooler because less energy converts to heat instead of sound.

Noise

An inevitable result of amplifiers is noise. Noise is undesirable, but it is not the same as distortion. Basically, your amplifier magnifies sound much like a magnifying glass magnifies whatever is behind the lens.

For example, if you point a magnifying glass at a freshly installed carpet, you will see imperfections in your brand new carpet that you could not see with your eyes alone. Likewise, an amplifier can magnify sounds that you would not normally hear with your ears because other sounds were more dominant.

[Waco]

Distortion can occur due to an overdriven amplifier as well.

[strauchpete]

Really though good sounds is in the eye or ear for that matter of the beholder, Some people like stero sound some light hight tweeter some like flat line.
Me personally what I want to hear and they I love JL is because if you sit in a car done correctly with JL you would not know if you are listning to it from a CD or are at a concert listning to it live. That is what make a system good for me.

I mean we could get into more tech specs about it JL spends more time then anyone else doing DR on there speakers they hold more pattents on speakers then anyone else. There shit can be abused for years and still sound awsome, they have the lowest s:n ratio then any other company. ect ect. I could go on for hours.

[The_Blur]

Originally Posted by strauchpete

Really though good sounds is in the eye or ear for that matter of the beholder, Some people like stero sound some light hight tweeter some like flat line.
Me personally what I want to hear and they I love JL is because if you sit in a car done correctly with JL you would not know if you are listning to it from a CD or are at a concert listning to it live. That is what make a system good for me.

I mean we could get into more tech specs about it JL spends more time then anyone else doing DR on there speakers they hold more pattents on speakers then anyone else. There shit can be abused for years and still sound awsome, they have the lowest s:n ratio then any other company. ect ect. I could go on for hours.

Do go on for hours. Not everyone on the site knows what you do, and this thread is a work in progress. I'm going to try to build a definitive basics guide.