Ski_Banker said:
I'll be Joe Schmoe here, since I don't know squat about car audio. Despite Hugh's frightening going-out attire, his "buy an equalizer, and play with it till you find what you like best" advice makes sense to me. The SPL meter results (have no idea what that means) would only get you to a good starting point quicker, right? Meaning, it's just a time saving device, no?
CL65captain said it but I will break it down and make it even simpler. A perfect human ear hears from 20Hz to 20,000 Hz. 1 Hz is one "cycle" of sound per second. One full wave going up and down. 20 Hz is the lowest bass frequency you can hear, and 20,000 Hz (or 20KHz) is the highest high. Most people's hearing however is much more limited than that.
An ideal stereo, would be capable of producing all these frequencies, all these sound waves, equaly. It would not exagerrate any particular part too much, or take any particular part AWAY too much. If you have no subwoofer for example, you probably won't get a lot of response from the system below 100 Hz. If you have no tweeter, you won't get much in the 10Khz area.
When you install a stereo system, you have to make sure that the tweeters, mids, woofers, subwoofers, all do their part right, and that their interaction with the "room", in this case the NSX cabin, produces a resonable response. When we talk about a "flat" response, all we are saying is that the frequencies are all produced equaly, at the same level (same loudness).
An SPL meter (Sound Pressure Level), just measures how loud a sound is. Thats all. The test disc, gives you tones... centered around frequencies such as 20 Hz for example, the next track a bit higher at 30Hz (a bit higher bass), and so on... all the way up. You simply sit in the cabin, and measure so that you know where a sound is louder, and where it is quieter. An increase in 3db (decibels) is roughly equivalent to a doubling of volume. So if you meausure and at 100Hz you have 90 dB, and everywhere else you are at 85 dB, you clearly have a "peak" at 100 Hz. It is too "loud" at around 100 Hz. And so you use the equalizer settings to lower the bass at 100Hz enough to bring it in-line with other frequencies.
Tuning a system is almost impossible by ear where there are a lot of problem areas, if you are not starting with a fairly clean sheet, a system with a fairly flat response. It is, like CL65captain said, very difficult to guess that you have a huge peak or dip at 5KHz, without measuring. All you know is something is not right. So instead of cutting at 5Khz, you may inadvertantly boost what is around it... at 7.5Khz, etc.
My advice for system tuning, is to just measure the response in your cabin. With a cheap SPL meter from Radio Shack (that I will state again is fairly accurate, especially for our use here), and a test disc like the stereophile (stereophile is a magazine) one to see what is going on. Once you have that info, there are plenty of experienced people on this forum that can look at the list of equipment, their placement and settings, and make suggestions as to what to do. If there is any area that a novice may screw it up, it is in this tuning area.
This is similar to for example sticking an wideband 02 sensor on your car, getting A/F ratios, plotting them, and then telling someone like Dynomike or the FactorX guys what you are getting. They can then help get the tuning right, and that is much better than sitting in your car with a laptop and "guessing" about how to set your A/F parameters.
This is a very general post and I know there are technical aspects that can be argued, I am refraining from doing so as I hope the more technical people here do as well.
I hope this was simple enough to understand.
