Tips For Setting Up A Killer Audio System

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posol

RETIRED
normally i won't post this here... but hey, anyway. a lot of you have stereos, including myself.

this is actually a repost from ECDS :)
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The following has been complied by a friend of mine from Washington state. He is a professional installer, and has been for over 11 years. His knowledge is beyond overwhelming. Here's some tips to getting your system to sound killer.
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As most of you know I have an extensive back ground in the installation bay. However, I also have a back ground in IASCA sound quality judging and setting up high end audio systems once they have been installed. I would like to share a few tips on how to set up and plan a high end car audio system.

Most think that the sound quality comes from the brand name on the gear they buy. Realistically, this is not the highest priority on the list of things to accomplish when you design your system. When it comes right down to it there are three major components in the design process. First, is speaker placement. I don't care if you buy the highest end gear in the world and spend thousands for it, if you don't place the speakers right they will sound like all other speakers. Second, is speaker choice. Not to be confused with speaker brand name. What I mean is, you need to get the right size drivers to recreate the entire music spectrum. The average human ear picks up between 25Hz and 16kHz pretty well, and music averages between 30Hz(at the extreme low end) to 20kHz. This is what you want to focus on in recreating your music no matter what you listen to. Third is the power distribution to these drivers. Once you have picked out the speakers and there placement you need to maximize their power handling to give you the headroom needed to avoid clipping at high volume and extend the life of the speakers, making your system very reliable. All these above tips should be all considered first before any purchasing or installing. A competition "quality" system generally takes more time to plan than to install.

Choosing the right size of speakers takes a little bit of research and in car listening. Sound rooms at the local retailer are the worst place to accurately judge the sound quality of a speaker. However here are some tips to help choose the right speaker. First, knowing the spectrum we want to create, we split it up into 4 groups, treble, midrange, mid bass, and sub bass. The frequency ranges on these will vary depending on the speakers you pick. They are determined by the crossover points of each group. The crossover points are dictated by the drivers frequency response and power handling at this range. An average 3 way system has a crossover point in between the sub bass and the mid bass, then another one between the midrange and the treble. This makes the mid bass and the midrange play through the same speaker. A two way system uses a single point between to treble and the midrange making the woofer play everything except treble. The 4 way of course have three crossover points separating all 4 parts. Because of the constraints and the shape of the interior of a car, you don't see very many 2 way systems that reproduce every thing including sub bass. The most common is a 3 way system, usually consisting of a coax of separates in the front and a subwoofer. Since we know that speaker placement is the most important part of the systems sound quality, what do you think comes second? It's the crossover points! Because you can't just change the crossover points on any speaker and get away with it, it is necessary to purchase the right speakers for the job. (Again not paying attention to brand name) The most critical crossover point in the spectrum in the point between the midrange and the treble. The reason is because this is the point where the vocals are, along with a lot of the melody. A poorly placed crossover point here will define the way the vocals sound. If the crossover point is too high, the vocals begin to sound congested. Try singing with a cold and a stuffed up nose :) The trick is to get this point below the vocals so that its your tweeter(the most accurate speaker in the system) can play the vocals. This brings up some issues with speaker choice. In order to accomplish this, it generally requires the purchase of some pretty high and speakers.(MB Quart, Boston Acoustics, Diamond Audio, ADS, ...etc.) Most of these high end manufacturers take this into account in there designs. You will find a lot of these speakers use a crossover point around 2500Hz or lower of their tweeter. In order to accomplish this the tweeter has to be able to take large amounts of power, after all its also the smallest voice coil in the system also. This makes the tweeters more expensive. Other manufacturers like Image Dynamics, Crystal, and USD use a compression horn to avoid this crossover point all together. The frequency response of an average horn is around 500Hz to 40kHz making one driver capable of reproducing both midrange and treble without a crossover point in between. This makes the rest of your system require only a mid bass and a sub bass driver. The crossover point between the mid bass and the midrange is not as critical, however it is still important. This point will determine how accurate your mid bass and midrange transition. In judging, there is a term we use called transparency. The transparency of a system when the listener can listen to a system without being to clearly identify all the individual parts. When a single part of the system becomes over powering or is too weak, the way the rest of the system sounds is affected by it. When the sound of a midrange driver and a midbass driver overlap, it creates a spike in the frequency response at the crossover point. The way these two drivers react to each other differs from vehicle to vehicle. In a car that naturally reproduces this frequency well, the result of the overlap is a very muddy sounding midbass. On the flip side it could sound very weak giving the music no real kick. The kick of most of the drums comes from midbass, so if this is weak, so is the way the song sounds. If you have a car that sound muddy in this area, the trick is to put a gap between the crossover points to reduce the spike. An example would be to crossover the mid bass at 175Hz and the midrange at 200Hz. The overlapping area electrically would be wider but the way it sounds in the car would be smoother. If your midbass is of the weak variety I wouldn't recommend over lapping the crossover points more, this will create phase cancellations and other problems with the sound quality. The solution is to either add more drivers or more power. Good mid bass systems use 6", 8", or dual 6" drivers. Which brings me to the last crossover point. The transition between mid bass and sub bass can give your system the illusion that the bass is coming from the front of the car if done right. This requires getting this crossover point down around 50Hz or lower. If you have a mid bass driver(s) capable of playing down this low, then this is the way to go. By keeping you sub woofer below 50Hz you reduce the directionality of it. This makes the bass appear to come from the front of the car where the rest of the music is. The only other way to get this is the install the subwoofer in the front of the car. This crossover point is not going to break your score in a competition, but if the judge can make this distinction he/she will make note of it. Well, I think this covers crossover points :)

The way to properly set up a system has a lot of opinions :) It seems every one has a certain disc that they think is a good reference or a good "test" disc. I had a customer once that played his "awesome test disc" it was rap. (I had a good chuckle at that) When a system it complete and it is installed and set up right, it will be able to play ANY music you put in it correctly. If your system can't do this then it is not finished or not set up right. When it comes to test software the right stuff is music recorded with a true stereo microphone. Most of the music out there is recorded in a studio using a microphone for each instrument. This makes it possible for a mixer to manipulate the sound of the song. You also need a recording that uses the full music spectrum. When your listening to this test software you should be able to pick out the instruments and there locations accurately, and be able to reproduce the entire spectrum with balance. Some good test software is anything recorded by Telarc or Sheffield Labs. The IASCA test discs are the best. Once you have taken all the necessary steps and there done right your will be able to play anything from metal to opera, from rap to country, from polka to jazz and it will sound spectacular and the way it was meant to be listened to(and yes, your bass will thunder, too).

I hope this helps in the future with some of your systems. The system I am currently building in my car if a very tedious step by step process. I am taking every part of the system and maximizing its effectiveness based on my experience with IASCA and the years I have spent building systems like this. When it's all said and done it should sound phenomenal.
When it comes to your system, the more time you spend designing and planning, the less time you spend trouble shooting and tweaking with it.

Scott,
Bellevue, Wa
 
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