How to Tune a Car Audio System

[usctrojan]

I'm upgrading my G35's audio system but leaving the head unit / navigation alone. So I was told I needed to get the Rockford Fosgate 3Sixty as a signal processor to take the head unit's output, clean them up, and then send the signal to the amplifiers. Well I'm reading the manual on the 3Sixty and you can adjust / tune any speaker using a Palm OS device. Of course I'm going to let the professional installers tune my system after installing the amplifiers and replacing the OEM speakers. But I wanted to understand what is that tuning process like. How do the professionals tune a car system? Is it some guy with 20 years experience and his ears making adjustments to each individual speaker to what he thinks sounds good? Any help on understanding this would be great. Plus there are crossovers on the 3Sixty along with crossover slope? I think I semi understand crossovers, but my DLS Iridium 8.3 component speakers also have a box filter for crossovers. And the amplifiers also have selectable crossovers and crossover slopes. Isn't all that crossover redundant then? Which ones are set and again, how do they make sure everything sounds optimal? Thanks for the feedback.

[EW]

This is a very basic explanation- Most systems end up using both electronic and passive crossovers to direct the proper frequency range to the proper speaker. Human hearing is generally accepted to be 20Hz to 20,000Hz. The sub range is approx 20Hz-80Hz. The midrange is approx 80Hz-3000Hz. High frequency range is approx 3000Hz-20,000Hz. The crossover in your sub amp is known as a low pass filter because it lets the low frequencies pass (play through) to the subs but not mid or high frequencies. The low pass filter (LPF) in the amp is electronic and does not affect the amount of power (wattage) going to the woofers.Your mid/high amp also may have a crossover and it would be used as a high pass filter (HPF). It is electronic and allows frequencies above the crossover setting to play through to your speakers. There is nothing wrong with playing the mid from 80Hz-20,000Hz but the tweeter will not like frequencies below 2500Hz or so. The component set includes a passive crossover. The passive crossover usually prevents the mid from playing above a certain frequency (3000Hz), and prevents the tweeter from receiving signal below a certain frequency (3000Hz). A passive crossover can reduce the power getting to the speakers by as much as 20% and there are phase issues depending upon the type of passive crossover used. You can remove the passive crossover from the system if you add another amp and possibly an electronic crossover(depending upon how elaborate each amps built in crossover is) to the system. There are also radios out there with 2 way and 3 way crossovers built in like the Alpine CDA-9887.

Again, this is over simplified and there are MANY variables to what I listed above.

Modified by EW at 1:20 PM 10/30/2007
Modified by EW at 1:23 PM 10/30/2007