Car Audio - Starting with Sound Advice

Figure 1-2: A wild system looks great but can leave you with no trunk space.

Upgrade your factory-installed system
If you really want to stay on the mild end of the scale and keep from altering your car too much — as well as protect against theft — you can keep the factory radio and add components such as amplifiers and subwoofers. Inversely, you could always change out your factory radio and keep your factory speakers intact.

I did this in one of my own vehicles, a 1997 VW Eurovan Camper that’s a family mobile. After talking it over with my installer, we decided I could get the sort of performance I needed in the vehicle (after all, my wife mostly drives it, and I can’t really crank it up with the kids around) just by swapping out the radio. This also gave me the option to add satellite radio and an auxiliary input that allowed me to easily jack in an iPod. And I could always decide to upgrade the speakers and add an outboard amplifier later.

There are several options for upgrading your factory audio system. You should consider these first if you’re primarily looking for better sound. The easiest and least expensive path to better sound is to swap the factory speakers for higher quality aftermarket ones. Many car audio manufacturers offer drop-in speakers that are specifically designed to fit factory provisions in a vehicle with a minimal amount of hassle and little to no modification. Often it’s just a matter of taking out the factory speakers and dropping in new ones.
This approach generally offers the most bang for your buck because many stock car audio systems use cheap and poor performing speakers, and even inexpensive aftermarket speakers can offer a dramatic difference in sound quality.

Car Audio - Choosing between Mild and Wild

For many people, car audio is as much about show as it is about sound. After all, chrome wheels won’t make your car go any faster, but they look good, they’re fun, and they tell people you care about your car. Nothing wrong with that. After all, people have been pimpin’ their rides for years.

If you want a flashy car audio system, go for it. Just keep in mind that there are trade-offs. If your car is a daily driver and you use it to haul people and other things, then going with a flashy system may be impractical. For instance, I once put a show system in my 1996 Chevy Impala for a cross-country promotional trip I did for a magazine. It was the first time I installed a huge system in my own personal car after nearly 10 years in the car audio business. Although the interior was kept pretty low-key except for custom door and rear-deck panels for the speakers, the car’s trunk was turned into a veritable car audio showcase.

It included five amps in a rack in the floor and three 10-inch subwoofers in a bandpass box with a see-through Plexiglas panel under the rear deck. A massive 100-disc CD changer was installed against the driver’s side trunk wall, with a bank of capacitors and power-supply accessories on the other. It was all trimmed with custom vinyl-covered wood and Plexiglas panels.

It sounded great and looked awesome. The car was a hit at the shows I attended and my neighbors would bring their friends over just to see it and listen to it. It was covered in magazines several times, and it was cool to have a celebrity car.
But the car didn’t handle and accelerate the same due to all that extra weight from the car audio components. About a year or so later, after my first child was born, my wife and I couldn’t even fit a baby stroller in the trunk because of all the car audio gear.

The reason I relate this story is to show you both sides of the coin. You can go with a mild system, like the one shown in Figure 1-1. Or, go nuts with a system like that in Figure 1-2. If you want that showy system, by all means, you should have one. But a great-sounding but more discreet system can usually serve the same purpose. Plus, with a showy system you run the risk of attracting the wrong kind of attention: from thieves.

                   Figure 1-1: A mild system can sound good and leave you with trunk space.

Exploring the World of Car Audio

Taking the Car Audio Plunge
For my money, there’s no better place to listen to music than in a car. When you’re listening at home, the phone always rings or someone tells you to turn it down. Even with headphones, distractions occur and the music is all in your head, so to speak. But the car is like your own private listening room: a mobile sound cocoon that isolates you from the outside world. You can turn it up as loud as you want (as long as you’re not disturbing others) and feel the visceral impact that comes from the music pulsing around you.I’ve been fortunate enough to hear some ultra high-end home-audio systems and I’ve been in state-of-the-art recording studios and witnessed some amazing live performances. But none of these live up to the feeling I get while listening to a well-designed car audio system in a cool car on a fun road. Music justseems to sound better when asphalt is flying under your feet!

The best time ever for car audio fans
There’s never been a better time to be a mobile music lover. Not only have components such as amplifiers and speakers reached an apex of performance and offer more bang for the buck than ever, but the recent explosion in media options has made the DVD radios that were state-of-the-art a decade ago seem almost antiquated now. The advent of MP3 has freed music from a disc based format so that now you’re able to carry your entire music library on a small portable player such as an iPod. Alternatively, you can load hundreds of songs onto a single disc or even a USB thumb drive. Satellite radio has gained ground against traditional terrestrial radio, while high-definition (HD) radio promises to make AM and FM better and offer more content. Plus, in just a few short years, mobile video has turned “Are we there yet?” to “Are we here already?”

Your roadmap to awesome car tunes
Consider Car Audio For Dummies your roadmap to awesome car tunes. You know that there’s this wonderful world of car audio out there, but you don’t know how to get started planning a sound system, shopping for components, or installing everything, let alone getting the most out of your system, protecting it, and fully enjoying it. In this book, I take you through each step of the process so that you can make informed decisions without wasting time and money and so that you’ll ultimately end up with a car audio system that will give you years of listening pleasure.

You’ve come to the right place
You probably heard someone’s car audio system — a friend’s, your older sibling’s, or maybe one at a car show — and now you want something similar. You used to think your car’s system sounded pretty good, but now that you’ve heard something better, it just doesn’t stack up. I’ve always referred to this as the ice cream theory. After you’ve tasted Ben & Jerry’s, for example, you can’t go back to the grocery-store brand. It’s just not the same.

Unbalanced / Balanced Plugs.

How an unbalanced mono plug is connected to a one-conductor shielded wire. Or, in other words, to a wire that has one internal conductor which is surrounded by a shield, that also functions as the ‘ low ’ side for the audio signal.
The same fi gure also shows how an unbalanced stereo plug is connected to a two-conductor shielded wire. That is, to a wire with two internal conductors, both of which are surrounded by a shield. The two signals are discrete, but share a common ground.
The two signals could be left and right of a stereo signal or they could be two totally unrelated signals, so the nomenclature of ‘ stereo guitar plug ’ is ubiquitous, but not really accurate. Hopefully, with the aid of the previous picture, you now have a clear concept of how unbalanced audio is connected. The same rules apply whether you are using guitar plugs, RCA plugs or whatever the ‘ plug dejour ’ happens to be today.
But what about balanced audio? Why is it called ‘ balanced ’ , and how does it differ from an unbalanced signal? This is where we come to some very clever voodoo.

Balanced audio is created by splitting the audio signal into two separate but equal parts, and then inverting (flipping) the phase of one of the two.
Your instantaneous question may be ‘Why bother?’. The reason is that when the in- phase and the out-of-phase signal are properly recombined (by uninverting the flipped phase side in a particular way), the result is that our desired audio signal is not only amplified, but any stray noise it has picked up is immediately nullified, leaving only the pure signal.
This is such an important concept that I’m going to repeat it in different words, hoping that it will embed itself deeply in your minds.

Balanced audio reduces or eliminates unwanted noise picked up in wires by flipping (inverting) the phase of one of the two conductors that carry the signal. When the signal is properly recombined, its amplitude (volume) is increased and the unwanted noise is nulled out.Yet another way to describe this is that when the plus (+) noise is summed (added) to the minus (-) noise, the result is no noise. Or at least very little noise.

What this means is that balanced audio runs can be hundreds of feet long without degrading the signal by adding noise to it. Pretty cool, huh?
Figure 2.3.6 shows a balanced mono guitar plug, and also the noise cancelling concepts we’ve talked about above. Pay particular attention to it, as the subsequent discussion in this section is based on you having a clear understanding of how balanced audio works.
Hopefully, I ’ ve now tossed this information at you in enough different ways that you’ve got a decent grasp of it. Let’s put it in still another way.
Balanced audio lines help cancel out interference of many types. Not only hum (ground loops), but also buzz (60 Hz harmonics), thermal sound (white noise), digital clock jitter and lots of other bad stuff, too numerous to mention.
Next up is an example of a typical balanced  +4 dBu audio connection, the kind of connection you might make from a pro-level recording console to a pro-level audio recorder – analog or digital. This example is shown in Figure 2.3.7 for an XLR type (three-pin) connection.
You don ’t have to pay too much attention to the voltage values – they represent an ideal you might see on your DVOM, on a clear day with a favoring tailwind.
The only function of the voltages in this diagram is to give you some idea of what you might encounter in the real world, and reinforce the concepts of balanced audio.
With luck – and attention on your part. you’ve now seen the advantages of balanced audio. You will restrict your unbalanced connections to short runs and, if given the option, always wire gear in balanced mode, right?

Now we come to the real mind-blowing part. Electrical power is basically an audio frequency signal! We’re all painfully familiar with the sound of 60 Hz hum. it’s ubiquitous. No matter where you go, you hear it – anywhere within the AC power grid, and often up to several miles away from it.
But is our regular run-of-the-mill 120 V, 60 Hz electrical power distributed in a manner similar to balanced audio in a studio, to reduce noise pick-up? No! Regrettably, all standard 120 V power distribution systems are wired in an unbalanced mode – this makes them highly susceptible to picking up all kinds of crud!
Every time you hear 60 Hz (or any other noise) in an audio system, it’s
degrading the sound quality and robbing your amplifiers of power.
This brings us to our next section in this module. The truly observant among you noticed that the last fi gure included a credit to something called Equi=Tech. In the next part, you ’ ll fi nd out why that mysterious credit is there. Can you wait that long?

Audio - Unbalanced/Balanced Wiring

Unbalanced/balanced wiring is after we take a quick peek at a couple of guitar plugs to show you the physical difference between balanced/unbalanced connectors.

What you ’ ll see next are the solder tab ends of a stereo and mono guitar plug, followed by the ‘ business end s of the plugs that actually get inserted into guitars, amplifi ers and other gear. And if you guessed that the mono plug is unbalanced, while the stereo plug can be wired balanced, you get a gold star!
There are always caveats and this example is no exception. The so-called ‘stereo’ guitar plug can be wired as a single balanced connection, or two unbalanced mono connections that share a common ground. So don’t assume, always check.

A close-up of the two solder tabs on a stereo male guitar plug is shown in Figure 2.3.2 . I ’ ve drawn two arrows to show exactly what part(s) I ’ m talking about. The longer part, that extends to the upper left in this picture, is both a strain relief for the wire and the part that the shield/drain gets soldered to.

                                          Figure 2.3.2 Solder tabs of stereo male guitar plug.

Let ’s call the two tabs I show the ‘ upper ’ and ‘ lower ’ tabs in this picture.The lower tab goes down to the tip of the plug. It ’s the high/hot conductor.The upper tab goes to the ring of a stereo plug, but is omitted (not present) in a mono plug. It ’s the low/cold conductor. As a general rule, tip is high, ring is low, and the long barrel of the plug is used for drain/shield. Since I want everyone to be totally clear on the difference between stereo and mono plugs, I ’ ve got a couple of side-by-side comparisons ready.

These pesky plugs are so shiny I had to put some white artist ’s tape behind the solder tabs, so you could see them against the strain relief behind them ( Figure 2.3.3 ). I hope it ’s all clear. On the left is a mono plug with one tab. On the right, a splendid example of a stereo plug with two solder tabs. Now that we ’ re straight on the tabs, let ’s see the whole plug ( Figure 2.3.4 ). Here we can see the business ends of our plugs – mono on the bottom and stereo on the top. Notice the ring on the stereo plug? That ’s the part thelow conductor is connected to – and is clearly omitted in the mono plug below it. So one tab no ring, mono plug. Two tabs has ring, stereo plug. And remember, a stereo plug can be wired as unbalanced stereo or balanced mono – the wiring will look thesame.

                                                 Figure 2.3.3 Mono/stereo comparison.

Balanced and unbalanced audio and AC power

After much skull scratching and soul searching, I decided to combine several concepts into one section, because they are so intimately interconnected. No, not that intimately, they ’ re just good friends. So in this section I ’ ll talk about unbalanced and balanced audio, unbalanced and balanced AC power, and the best ways to wire and clean up the sound (and picture) of your studio/disco/home theater/whatever.

Unbalanced/balanced audio
Let ’s start with audio; a nice, simple bit of audio – a sine wave. Some of you may have seen a sine wave on an oscilloscope or in a picture. They all look more or less like the one in Figure 2.3.1 .

Since the sine wave is AC (alternating current), it will start at 0 V (zero volts), rise to a positive peak, then reverse itself, cross the 0 V reference line again, and rise (inversely) to its negative peak. Or it will do what I’ve shown here: start negative and fl ip positive. And it will keep doing this, over and over, until we get bored and turn it off.

If the sine wave repeated this action 1000 times in a second, we ’ d say it has a frequency of 1000 Hz (hertz) or, in older terminology, 1000 cps (cycles per second). We audio folks got tired of saying ‘ see-pee-ess ’ and renamed the unit of measurement ‘hertz’ as it ’s shorter.
Higher frequency sine waves will appear more squished together horizontally;
lower frequency sines will look more spread out. The reason for this is that the horizontal axis in an oscilloscope is the ‘ time base ’ – it shows the progression of the waveform from the past into the future. The more times a signal reverses polarity, the higher its frequency and the more reversals present in a given period of time.

All sound (almost) is made up of complex combinations of AC (alternating current) waveforms, most of which are not sine waves. The only exception is a DC (direct current) pulse, which will make a one-time ‘ click ’ when connected to a speaker or headphone, but not much else.

We use sine waves for measurement because they ’ re easy to quantify.
I hope you are now fine with sine, as it were, and ready to see how this applies to real-world situations.There are only two ways that an analog audio signal can be carried along in a wired connection. For the sake of brevity (and sanity – mine), I ’ m not going to expound on digital or RF transmission of audio.
The simplest way for an audio signal to be carried on a wire is as an unbalanced signal. This means that there is a center conductor (hot), and (typically) shield and ground are combined in the outer layer of the wire. So half of the signal path is (sort of) shielded by the outer layer, and the outer layer itself is tragically vulnerable to interference from sources in the outside world.
What this means is that unbalanced audio is basically limited to runs of 20 feet or less, and even then it lacks the ability to null out induced noise, hum and the other crud we encounter with great ah, frequency.

Balanced audio, on the other hand, can survive runs of hundreds of feet, so all pro audio facilities use balanced mic lines, balanced transmission lines, and do most of their internal wiring in a balanced manner. We ’ ll explore what unbalanced/balanced wiring is after we take a quickpeek at a couple of guitar plugs to show you the physical difference between balanced/unbalanced connectors.