An automotive interior is one of the harshest environments for an audio system, and a truck presents an even more difficult landscape. There are so many barriers in a truck, including the limited locations where speakers can be mounted, interior materials, and those less-apparent obstacles, such as your legs, that often block the path of sound. This is where Alpine's new Imprint sound processing technology comes in to play. Imprint offers an advanced solution to sound processing that was developed to recreate the sound intended by the recording artist.
Before going into specifics about Imprint, let's first walk through some of the basics of sound processing. Sounds are signals, or waves, with a specific time pattern, called a frequency. Sound processing electronically alters the music signal to achieve a result dictated by the desired atmosphere and personal taste. This is typically accomplished through a series of mathematical algorithms and computational tools built into processors.
A general term used to describe the device that is used to manipulate the audio signal is a sound processor. Common names for these are signal processors, equalizers, crossovers, and DSPs. These are often standalone units, but can also be found in head units, amplifiers, and as peripheral devices. Each of these sound processors are developed with a different purpose or function in mind, with uses varying from frequency level adjustments, frequency filtering, and time-domain alterations.
Why should you use a sound processor? Let's create a basic scenario in a truck. The front speaker system consists of a pair of coaxials, one in each door. The driver side coaxial is closer to the driver's ears than the passenger side coaxial. What occurs here is an imbalance between the left and right signals because of the variation in distance, resulting in music that sounds like it is louder on the left side of the listener. Also, the positioning of the speaker makes music sound like it is below the listener. To correct this, you will need to delay the electrical signal going to the closest speaker. In this case, it's on the driver side. By doing so, the left and right arrival time of the left and right sound waves will be equalized, raising the apparent direction of the sound up closer to head level and eliminating the left side sound bias. As your system increases in complexity-by adding component speakers, front and rear, and a sub-the time alignment becomes a much more difficult task.
Audio systems are also often plagued by frequency response evils that can inhibit coherent audio reproduction. To improve a system's frequency response, you will need an equalizer. Equalizers are generally broken up into predetermined frequency bands that limit their adjustability. This means that any anomalies in the response must be at-or near-the set band for it to be effective. The results, however, can be quite stunning when an equalizer is placed in the right hands. Also, in most cases, the sound can be tailored for a more accurate representation of the original recording or to your personal liking.
Easy Does It
If all of the aforementioned adjustments sound time consuming, that's because they are. But, Alpine's Imprint is different. It accomplishes the same tasks as the two previous processors mentioned, and it's easy enough for almost anyone to use.
Imprint optimizes equalization for any vehicle in order to accurately recreate the original sound of the music recording. Imprint automatically analyzes between 4 and 32 reference points in the acoustic environment of a vehicle, through the use of a microphone that is included with every Alpine unit that uses Imprint. Once the measurement process has completed, Imprint derives a detailed model of the listening space. At this point, Imprint automatically determines the optimum corrections necessary-including equalization, time corrections, and channel levels-and applies them to each speaker. In fact, it is so accurate, even minute differences between trim levels can be accounted for.
Let's go back to the earlier example of speaker locations in a truck, however, this time in a standard-cab. In this vehicle, our speaker locations are in the bottom front corner of the door panels. The rear speakers, in the B-pillar, are right by the listener's elbow and closer to the listener than the front speaker, making the music sound like it's coming from behind. Imprint can make the music sound like it is coming from in front of the listener with the musicians spread across a stage, which is often how the music is recorded.
Choices
Alpine's Imprint technology is currently available in a variety of products. The first is the PXE-H650 sound processor that can be used with a factory or aftermarket head unit. Factory head units will send their high-level input signals directly through the processor's AntEQ. This cleans up the output of the factory source by removing any built-in processing and sums the necessary channels for a full bandwidth signal. MultEQ then corrects the acoustical environment by creating EQ filters and setting the time domain for each speaker through each channel and signal. Of course, to use the PXE-H650, you will need to use aftermarket amplifiers and speakers.
Alpine's CDA-9887 is the first head unit to incorporate the Imprint technology. This unit includes the same MultEQ function as the PXE-H650. However, to use Imprint in this head unit, it must be tuned by PC-based software.
After several Imprint demonstrations, it had yielded the single biggest improvement we have heard to an audio system. You can really hear the difference between regular sound processing and Imprint sound processing. Alpine's claim to deliver music as the artist intended seems to be accurate-it truly sounds amazing. So, now you can bring a movie to life, or have it sound like an actual live band is performing inside of your truck.