Ever had this experience? A friend drives over to show off the expensive new audio system in his vehicle. He slides in a CD and cranks it up, waiting for your reaction. The music hits you, and, even though his system cost more than your entire car, it sounds terrible! The highs are too bright, the bass is boomy, and you can't hear the vocals through all the nastiness. What's up with that?
 Whether you're a car audio novice or a seasoned competitor, these discs can help you find and cure weaknesses in your audio system. |
There's a science to tuning audio components to work well together. In the early 1990s, Autosound 2000 (a company founded by noted car audio experts Richard Clark and David Navone) created a series of five test discs to help you diagnose and cure problems in your audio system:
- CD101: Low Frequency Test CD
- CD102: Set Up and Evaluation of Sound System Imaging and Placement
- CD103: Evaluating Audio Components, Listening Environments, & your Listening Ability
- CD104: The Ultimate Amplifier Level Setting Disc
- CD105: Road Noise, System Noise, and Frequency Range Demonstrations
Finding weaknesses in your audio system
The first three tracks on CD101 contain reference tones designed to check the noise floor, headroom, and phase of your system. Since the purpose of the tracks is difficult to determine (and the liner notes were no help), I almost abandoned the project on the spot. But Tracks 4, 5, and 6 (a variety of sweeps from 20 to 20,000 Hz) made me realize two things: 1) my Infinity Reference tweeters were too loud, and 2) I had some rattling in my doors.
My well-used Polk db 10" sub really shone on Track 9 (a series of short, staccato, low-frequency tone bursts from 40 to 200 Hz), but I discovered a "hot spot" (an unnatural boost in response) around 80 Hz that I'd never noticed before. And Tracks 10-98 (30-second tone segments from 10 to 98 Hz) revealed several other vagaries in my low-frequency reproduction. Track 99 uses a 1,000 Hz sine wave to determine how loud your system will get before distorting. Wow, this was starting to get interesting.
And then it dawned on me — these Autosound 2000 test discs are great for pinpointing the weaknesses in your system. But without fairly sophisticated equalization and crossover capabilities (either built into your receiver or in outboard units) to correct any problems, there's no way to take full advantage of these discs. In other words, the more complex your system, the more these discs can do for you. Still, it was cool to discover flaws in a sound system which I'd previously thought was well-tuned.
CD102 had a few more surprises. The first six tracks gauge the focus of your stereo image by switching between stereo and mono presentations of the same material. Tracks 7-23 offer pink noise in various frequency ranges: bass, midbass, midrange, highs. If I had a crossover, I could adjust the relative levels of my components to increase playback accuracy.
The stark stereo drum recording on Track 24 sounded awesome, showing off my system's powerful stereo image. Out of curiosity, I activated my Pioneer receiver's Front Image Enhancer feature (which removes mids and high from the back speakers) to see if it actually improved the soundstage. The drums spread out dramatically, sounding even more mammoth. Cool. For people who like to crank it up, the rest of Disc Two is devoted to test tones designed to test your system's performance limits.
The first three tracks on CD101 contain reference tones designed to check the noise floor, headroom, and phase of your system. Since the purpose of the tracks is difficult to determine (and the liner notes were no help), I almost abandoned the project on the spot. But Tracks 4, 5, and 6 (a variety of sweeps from 20 to 20,000 Hz) made me realize two things: 1) my Infinity Reference tweeters were too loud, and 2) I had some rattling in my doors.
My well-used Polk db 10" sub really shone on Track 9 (a series of short, staccato, low-frequency tone bursts from 40 to 200 Hz), but I discovered a "hot spot" (an unnatural boost in response) around 80 Hz that I'd never noticed before. And Tracks 10-98 (30-second tone segments from 10 to 98 Hz) revealed several other vagaries in my low-frequency reproduction. Track 99 uses a 1,000 Hz sine wave to determine how loud your system will get before distorting. Wow, this was starting to get interesting.
 Even a relatively simple equalizer can help focus the sound of an improperly-tuned system. |
And then it dawned on me — these Autosound 2000 test discs are great for pinpointing the weaknesses in your system. But without fairly sophisticated equalization and crossover capabilities (either built into your receiver or in outboard units) to correct any problems, there's no way to take full advantage of these discs. In other words, the more complex your system, the more these discs can do for you. Still, it was cool to discover flaws in a sound system which I'd previously thought was well-tuned.
CD102 had a few more surprises. The first six tracks gauge the focus of your stereo image by switching between stereo and mono presentations of the same material. Tracks 7-23 offer pink noise in various frequency ranges: bass, midbass, midrange, highs. If I had a crossover, I could adjust the relative levels of my components to increase playback accuracy.
The stark stereo drum recording on Track 24 sounded awesome, showing off my system's powerful stereo image. Out of curiosity, I activated my Pioneer receiver's Front Image Enhancer feature (which removes mids and high from the back speakers) to see if it actually improved the soundstage. The drums spread out dramatically, sounding even more mammoth. Cool. For people who like to crank it up, the rest of Disc Two is devoted to test tones designed to test your system's performance limits.
 Separate component speakers give you more flexibility in achieving a powerful front soundstage. |
Stereo is where it's at!
If you're thinking of buying just one Autosound 2000 disc, CD103 is the one for you. The assortment of jazz and classical music contained in Tracks 1-6 is nothing I'd ever choose for my own listening, but each selection really shines on a well-tuned system. These well-recorded tracks are invaluable for checking out the stereo picture set up by your speaker system — and that's the whole point of these discs.
The ultimate goal of your speaker system is to disappear. Whether you're driving a car or sitting in your living room, a properly-tuned speaker system should not call attention to itself in any way, particularly as to the location of the individual speakers. It should produce a clean, clear sonic picture of the recording that's playing — a goal that's relatively easy to achieve in your home, much more difficult in the close confines of an automobile.
So, back to CD103. The liner notes ask you to listen for certain things in the first six tracks which might point out problems with your system. If you do hear problems, the remaining tracks on this disc help you track down the causes by checking for phase problems (caused by improper speaker wiring), relative volume of your speaker components, and so on. (Some tracks require special test equipment, but you can bypass these and still get good results.)
If you can beg, borrow, or steal a sound level meter (a worthwhile investment for any serious mobile audio fan), you can adjust your equalizer using Tracks 47-56 to flatten out the hot spots in your speaker system. If you're using separate components (tweeters, woofers, and subwoofers), use your crossover to get the proper balance between the various speakers. Hot tweeters, for example, may bring out the sizzle in your system, but they can make it impossible to achieve a realistic sonic picture. The last few tracks test distortion levels and the dynamic range of your system.
Mortal enemies of good sound — road noise and distortion
The fourth disc, CD104, is for the more technologically-advanced car audio fanatics out there. Its tracks help you adjust your amplifiers so that the highest musical peaks occur just before the onset of amplifier distortion — that's how the pros maximize system performance. This disc is not for a novice, but extremely useful for the knowledgeable audiophile or car audio competitor setting up a multi-amp system.
The most recent disc, CD105, is designed for trainers, retailers, salespeople, or anyone interested in general car audio concepts (some of which defy verbal explanation). This disc, while not particularly helpful in tuning your system, offers some informative, ear-opening audio demonstrations of road noise, frequency ranges, tonal balance, system noise, and distortion.
So, let's get back to your friend's car — what can these discs do for him? With a little bit of listening and some experimentation, he can adjust the system in his car to produce flat frequency response (with no unnatural cuts or boosts in the high, mids, or lows) and a clear, wide stereo image.
I hear you saying "But I like my bass, I don't want flat response!" And that's fine, because big, fat bass is what makes a car audio system sound great. But, once you tune your system to deliver flat response, you can change the tonal balance to your own taste without losing the power of a clean soundstage. Whether you're a novice with a nice stereo setup or a techno-freak with a competition-level system, these discs can help you get there.
Now picture this. It's Saturday night, and you're out in your friend's car. You slide in a disc, crank up the volume, and the music sounds so huge and in-your-face that it's almost like you're standing right in front of the band. You say under your breath, "Daaaaamn, that sounds good!" And that's what car audio's all about.
The fourth disc, CD104, is for the more technologically-advanced car audio fanatics out there. Its tracks help you adjust your amplifiers so that the highest musical peaks occur just before the onset of amplifier distortion — that's how the pros maximize system performance. This disc is not for a novice, but extremely useful for the knowledgeable audiophile or car audio competitor setting up a multi-amp system.
 Your system needs plenty of power to overcome road noise, even in a seemingly quiet vehicle. |
The most recent disc, CD105, is designed for trainers, retailers, salespeople, or anyone interested in general car audio concepts (some of which defy verbal explanation). This disc, while not particularly helpful in tuning your system, offers some informative, ear-opening audio demonstrations of road noise, frequency ranges, tonal balance, system noise, and distortion.
So, let's get back to your friend's car — what can these discs do for him? With a little bit of listening and some experimentation, he can adjust the system in his car to produce flat frequency response (with no unnatural cuts or boosts in the high, mids, or lows) and a clear, wide stereo image.
I hear you saying "But I like my bass, I don't want flat response!" And that's fine, because big, fat bass is what makes a car audio system sound great. But, once you tune your system to deliver flat response, you can change the tonal balance to your own taste without losing the power of a clean soundstage. Whether you're a novice with a nice stereo setup or a techno-freak with a competition-level system, these discs can help you get there.
Now picture this. It's Saturday night, and you're out in your friend's car. You slide in a disc, crank up the volume, and the music sounds so huge and in-your-face that it's almost like you're standing right in front of the band. You say under your breath, "Daaaaamn, that sounds good!" And that's what car audio's all about.