Better Safe Than Sorry

Tips and techniques on documenting your system parameters.

For serious competitors, there are a number of considerations that should never be overlooked or neglected. Even a slight lack of attention to detail in an area can be the catalyst to a season of lackluster performance in the competition arena. Ensuring the best possible chance of winning involves many tasks.

Things like an up-to-date photo book, a polished and practiced presentation, and an immaculate attention to detail are all very critical to winning sound quality contests, but they’re also very obvious. And, without a doubt, the most important factor is superb sound quality. High SQ scores can place a system at the top of the class, while even minor SQ flaws can send the scores to the bottom of the barrel.

As important as sound quality is to the overall scoring potential of a system, there’s one area about it that seems to elude many competitors’ checklists. That would be complete documentation of the system parameters and tuning specifications, written, stored in a file, or otherwise.

While it may seem like a very boring thing to do, it’s one of those simple, obvious, and often overlooked things that can save your you-know-what someday.

Think about these things:
1) How many times have you re-tuned a system in an attempt to improve it’s SQ? Then, after several hours (or days), you realize that the original settings sounded better, but now they’re gone. Ouch!

2) Ever accidentally bump an EQ setting while detailing the processor area, then not known exactly how to reset it? Oops!

3) What about changing out a component like an EQ or crossover, then having to start from scratch on the tuning because the original settings weren’t saved?

It’s a fact that even a fraction of a decibel change to a particular setting can significantly affect how the system sounds. So, any of these situations could range from a minor inconvenience to a total disaster, depending on when and where they might occur. And be assured that at least one of these will occur during your career in car audio competition. However, with a complete documentation history of the system, these situations can all fall into the minor inconvenience category.

When tweaking a system, we can probably get away with making a change to a single parameter and be fairly confident that we can reset it if needed. But, if the changes you have planned involve more than one parameter (like a gain level along with multiple EQ settings), or if you’re going to swap out a component, you should definitely document what you have in place first, just in case the changes don’t work out. This is exceedingly critical when the system has matured to the point where it sounds great, but further improvements will necessitate major changes to the tuning. The changes may improve one area but detract from another. If so, and the result is less desirable than the initial settings, it’s easy to get back to where it was. If the settings aren’t recorded, then you’re just out of luck. Also, record the system settings several times during the initial tuning process so you can go back to a previous set up to compare the two settings more closely. Then you can choose the best one. And, most importantly, record the settings as soon as they system is in it’s final tuning state. This can save you many hours of panicked re-tweaking the night before a show if something gets accidentally out of whack.

So, how can the settings be preserved? There are several options. Some are easy, some more precise, and they all carry different price tags. Which ones you use depends on the situation and the level to which you’re committed to preserving the settings for the long haul.

The simplest system is to write down exactly how every gain adjustment knob, EQ filter, crossover point, etc., is set. A visual accounting, backed up by written documentation, takes only an hour at most, but can save your scores in a pinch. Keep the records in a safe, accessible place with the vehicle. It doesn’t do you any good at a show if the records are at home on the desk.

Another method is to use a permanent fine-point marker to locate the settings on the components with small dots. This is a good method that allows for quick visual inspection without having to keep track of and read the settings off of a piece of paper.

For those with digital processors, it’s a whole lot easier, but don’t get lazy. Make sure to write down all the settings, or store them to a disc if possible. If the processor glitches or, for some reason, dumps the settings, or you accidentally overwrite them, you’ll still need to back up.

More precise records can be developed using electronic measurements. It doesn’t matter how good our eyes are, trying to visually set a gain knob to where it was before a change was made will always have some error involved. However, a simple Digital Volt Meter and a test CD can work wonders. Let’s say you want to record the gain levels of the crossover outputs. Get your hands on a good level-setting CD like Autosound 2000’s CD 104 and a DVM. With the CD playing a 1 kHz test tone, measure the signal level at the input to the crossover. Set it to a known reference level, maybe 1 volt or so. Record this level! Now, without readjusting anything, select a track that represents a frequency in the subwoofer output pass band. Record the output level of the subwoofer section of the crossover. Do the same for all other pass bands using the appropriate tracks.

This technique also works great when you need to change out a component. If, for example, you need to swap out an amp or a crossover and you have the gain level of the old component, you can install the new one with absolute assurance that its output will match that of the old one exactly. Of course when testing amplifiers, you’ll want to use a voltage divider on the output or simply disconnect the speaker altogether. Test tones at even moderate levels can damage speakers if not used carefully. And besides, a 1 kHz test tone is really annoying to listen to for very long.

The ultimate choice for recording system settings involves some investment in time and a potentially high price tag. But in the world of top-end competition, involving systems with thousands of hours and dollars invested in the installation, this option is often worth pursuing. You don’t necessarily need to buy the equipment to do it — you can gain access to and pay someone that can take the measurements for you.

To truly and accurately record all system settings, there’s nothing like a dedicated electronic analysis computer system. There are several available from companies like Audio Precision, HP, B&K, TEF, etc. These systems can allow you to record every facet of the electronic performance of your audio system. From gain settings, to frequency response, to phase response, to delay settings, etc. — there’s nothing about the system’s electronic response that cannot be measured and recorded and saved for later reference.

I can’t tell you the number of times using these techniques has saved me in various situations. I also can’t tell you how many times before I started using them that I wish I had known better. Whether you’re planning on making any changes that can even remotely impact the SQ of the system, or (especially) if you’re done tuning the system to the point where it will never be touched again, it’s critically important to maintain records of all system settings.

Keeping records of your system settings is like having insurance — It’s not much fun to keep track of, but if you’re in a situation where you need it and have it, you’re in good shape. If you don’t have it, well, you know...