Now that the basic stuff is out of the way, let's move onto the more advanced. When you move onto a system that surpasses the typical 4 speaker/CD/amp/sub, things are going to change as far as equipment and sound shaping as well as the sound type you are going for.
Types of systems and/or combinations
SQ- Sound quality, the ultimate pursuit of creating a lifelike concert in your car
SPL- The ultimate pursuit of making your car as loud as possible, not my favorite, and not recommended for a daily driver
Balanced- Using carefully selected equipment in order to achieve a combination of both above
Performance oriented- Kind of a new field when I left installing, some companies are making equipment weighing the least amount possible using a lot of aluminum and carbon fiber to create a new niche in the market. (Basically trying to pull some of the "tuners" into the car audio realm).
Value oriented- Getting the best sound for money spent
Three things that will affect all the above are source, power, and sound.
Source- Everything before the amplifier including the material you are listening to, the head unit, equalizers, signal conditioners, etc.
Power- Terminal gear (including the battery), capacitor(s), and the amplifiers
Sound- components, crossovers, co-ax speakers, subs
The thing to remember about the above is that your system only works as well as your worst piece of equipment.
Source- Normally when I buy a headunit now, I'm looking for one with dual 24 bit digital to analog
convertors. This will ensure that you are getting all the nuances of the music you are listen-
ing to. A good system will reveal things in the music you've never heard before, and might
open you up to new music. I also look for some type of digital signal processing.
Many headunits now have microphones (Pioneer) included to automatically adjust the DSP
for your vehicle in order to try to attenuate the resonant frequency. Resonant frequency
is the frequency at which your vehicle absorbs all the energy of that frequency and invests it
in vibration. Dynamat can help in reducing resonant frequency to a certain extent. Because
all of the invested power is being to used to vibrate, this causes a "hole" in the audio
spectrum, normally in the midbass region of frequency. Many people opt out of a built in
DSP and go for an equalizer. This is kind of older technology. They will allow you to
manually adjust frequencies, and sometimes can boost signal output as high as 17 volts.
The only disadvantage to this is having to adjust for different music types, maybe even ind-
vidual tracks. Generally speaking, a higher signal output voltage means the amplifier has
to do less "work" to achieve desired volume output. However, some amplifiers may not be
built to handle this much voltage, and it increases the liklihood of picking up some kind
of noise. Unfortunately, many head unit companies are changing focus to ipod, video, aux inputs, and sound quality units are hard to find and very expensive ($300+).
Power- Good power terminals are very important. Voltage drops are the enemy. All of your
connections should be at tight as possible, the most important being a solid ground
contact point to the chassis. Usually a seatbelt mounting point works great, just make sure
your contact point has the paint stripped away with a wire cup brush. Make sure that if you do choose an alternative grounding spot, that the panel has good welds to the main chassis, and is not joined by the factory "glue". You also want to make
sure you are using the right size wire. I normally recommend 4 gauge at least for runs of
15-18 feet. Too small a power wire can cause as much as a .5 volt drop, which will create
performance loss in the amp. All told, a combination of small wiring, bad ground, and poor
connections can drop your battery to trunk voltage by 3-4 volts in bad cases. This can cause the amp/amps to go into protect mode the first time you crank on them. As for amp quality, the general consensus among the audio elite is that no human can tell the difference between amp quality. I'm not sure I buy into this. I try to stick with amps that have a good reputation, and price range in the medium-high range. Brands like Rockford Fosgate, JL, Infinity come to mind. Like just about everything in life, you get what you pay for.
Sound- Now for the most important part- speakers. Think of speakers like tires, you can have a blown Hemi (source), and a bomb proof tranny (power terminals), but if you are rolling on 4 spares you aren't going anywhere. Price is always going to be an issue, but generally speaking the majority of your car audio budget should be in the speakers. If you are going with a system in the price of this post, I'm assuming you are going to be using at least two amps, one for the interior speakers, and one for the sub/subs. You want a speaker that has low sensitivity. The reason for this is that with plenty of power from the amps, a speaker with lower sensitivity is going to be able to play the subtle nuances of the music. A system at this level should have a component set up front, possibly no rear speakers (or rear speakers with power cut significantly as well as response cut down by a crossover). As far as SQ systems, most systems will not have a huge sub set up, most of the time two at most. Some people go with 2 10"s, or a single 12" sub with good response (mine). Sub enclosure is another thing to mention. There are multiple types of enclosures, I'm going to mention the most popular 3 here.
1. Sealed- great response, natural roll-off due to subwoofer mechanical structure and "buoyancy" of the "air spring" at higher volumes. Boxes tend to be smaller. The disadvantage of the sealed enclosure is that lack of bottom end volume (can be a negative or positive depending on amp power). I use sealed, but I'm starting to miss the next one.
2. Ported- "dialed in" enclosure. This enclosure can be tuned to specific frequencies, and generally play lower than the above. They require less power to achieve desired volume output. Volume output will be higher than sealed at any lower frequency. The disadvantage to this setup is higher bass extension, and the extra wear and tear on the sub without the "air spring" effect of the sealed enclosure. There are subs on the market that are built to deal with the ported enclosure. JL and OZ audio come to mind. They have larger voice coils, better cooling, and larger surrounds.
3. Bandpass- High volume, and a built in crossover effect. The disadvantage is that these are extremely hard to get right. You never want to buy a pre-assembled bandpass box if you are an SQ fan, as they should be crafted to individual sub specs. Many in the audio community shun this enclosure unless the system was made by the manufacturer to the specs of the included sub.
There are tons of speaker companies out there. My pics in order of quality are OZ, Focal, Infinity, MB Quart, JL.
Car Audio 201
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