School of CAR Audio

Audio/video systems, electronics, GPS, seats, fabrics etc.

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Post by Neo » 25 Aug 2006, 2:07 am


I guess this is it. Been planning to have a sticky for Car audio. I know already a topic exists with similar name. However, I would rather have the AUDIO SETUP for posting specification and questions regarding installation setup only. I hope this thread would help everyone who is looking forward to understand basics of car Audio. So you all could possible choose or even install a new car audio system yourself. The information will come in installements so you can read, understand, ask questions and move on to the next level.

About me
Not a master of Car Audio but I have a fair understanding of basics and few years experience in installation and troubleshooting. I have got some training from Rockford Fosgate on their product line. I am still in the learning process since there is always something new to work on and look forward to.

Most of the information have been complied from the study material which helped me learn. I decided to keep the original statements since my sentence construction often leads to confusion than conclusion. I shall avoid detailing since it will be beyond the scope of this topic . However if you have questions I am nore than willing to answer.

Good luck all... Let this be a reference point, hence dont try to read this at a stretch and claim this to be boring.

Head Unit

The head unit is the radio, cassette player, or CD player that sends the signal to the rest of the system. Some head units have amplifiers built in
(in which case you must make sure your speakers are efficient enough to play loudly with the relatively small amount of power in most head units).

Most of the HU's claim +/- 50w of output Per channel, Honestly these are just +/- 15W RMS per channel. On a budget? Buy speakers first. Better speakers can make your stock head unit sound really good. You can upgrade it later.

One thing to keep in mind: make sure the head unit has pre-amp outputs when you buy it. You'll need them when you’re ready to add amplifiers later. Normal system comes with two preouts these days, Left and Right channel. You should be looking at six pre out, Two for the front channel, two for the rear channel and two for the Sub woofer. With this facility you can control the Amplifiers right on your head unit.u

Signal Processor

The signal processors gained much popularity recently. The best HU always had the capability to do the same function. As the automotive manufacturers increasingly make their source units (radios) an integral part of the vehicle,it becomes harder to change them out and upgrade your system.The Singal Processor makes it possible to utilize the vehicle source unit and still create the sound experience that fits you. With easy to functions or controls, the signal processor connected to your vehicle’s source unit and an amplifier, you can create a sound stage that is personally tuned to your vehicle, sometimes not even possible by the best HU.The sound processor gives you all the benefits of creating the best system possible without compromising the manufacturer’s integrated source system. Also these units could be considered as Active crossover in a certain way (read cross overs for more info).


Ultimately, the head unit source sends its signal to the speakers. Your speakers determine how your whole system will sound. No equalizer, amplifier, or processor can compensate for poor (or poorly installed) speakers. Even if you’re on a budget, you should plan on spending the bulk of your allotted expenses on your speakers. (And if you’re really on a budget, plan on a head unit and a set of speakers now, and worry about amps and processors later.)

Coaxial/three way speakers are two or more speakers built into the same frame. These are inexpensive and easy to install, often fitting into vacated factory locations. But they lack the flexibility of seperate components, since you can't aim them and has simple crossovers built-in;you get stuck with them for the rest of your life.

Components are sets of separate woofers and tweeters with an external crossover having system flexibility and better crossover facility. Resulting in better quality audio.

It is known fact that round speakers are better than Oval speakers. Period


Subwoofers are the speakers that deliver the lower frequencies of the audio spectrum. Subwoofers need power. They need more power than anything else in your system. This is simply because they are bigger, and need more power to move their cones farther than other types of speakers. If you have an amp supplying 50W to each of your four front and rear speakers, you can bet on needing at least 100W for your sub(s). And you need to use a lowpass crossover to block the high frequencies from getting to your subwoofer and messing up the mix. the lowpass crossovers are built into the Amplifiers these days.

Low frequency signals reproduced by subwoofers are “non-directional.” That is, it’s most difficult for humans to tell where lower frequencies are coming from. So you can (theoretically) put a subwoofer anywhere without worrying about a loss of sound quality due to poor aiming and direction. To make bass response more effective, subwoofers must be housed in a “subwoofer enclosure.” That would be a box. With a subwoofer in it. Because of this, subwoofers are most often placed in a car’s trunk..

Based on the enclosures the following are the classification. Maybe if I get a good response from you all I will post the details with the enclosure pics.
Free air, Sealed, Ported and Bandpass. Also there is complicated system known as Dual Reflex Bandpass, Multiple Drivers, Isobaric etc....

Crossovers (Passive & Active)

A crossover is a key element in the overall design of a multiple-driver system. It is designed to filter sound into frequency ranges the way a prism filters light into colors. There are two common types of crossovers, "passive" and "active". Both types of crossovers consist of a single (or group) of electronic parts responsible for dividing or "blocking" frequencies.

Once the frequencies are divided or "blocked", they are routed to the correct speakers.

Passive Crossovers are non-powered components. They consist of capacitors (and/or) inductors placed in-line with the speaker leads located between the amplifier and the speaker

Active Crossovers are powered components. They are typically electronically powered "black boxes" placed in-line with the RCA signal cables located between the source unit and the amplifier(s). (Could be a Signal processor)

Crossovers Types
There are three primary types of crossover filters: high-pass, low-pass, and band-pass. For special applications, there is a fourth filer called a subsonic-filter.

High-Pass Crossovers allow high frequency information to be passed to the speaker (Tweeters) while the low frequency information is attenuated in amplitude as the frequency decreases.

Band-Pass Crossovers are the combination of high pass and low pass filters. Band pass filters assign a specific band of frequencies to pass through to the speaker. The most common use of a band pass filter is the mid-bass frequencies (100 Hz - 275 Hz).

Low-Pass Crossovers allow low frequency information to be passed to the speaker (woofers or subs_ while the high frequency information is attenuated in amplitude as the frequency increases.

Subsonic Filters are high-pass crossovers centered around 25-30Hz. They are designed to block out subwoofer frequencies that are not useful in the automotive environment. This saves valuable amplifier power and improves woofer control.


Your vehicle's electrical system was designed to operate stock; the way it rolled off the showroom floor: Any additional drains on the stock system destabilize the stock engineering. When you add any electrical device like an amplifier or other accessories, you need to boost your electrical system to prevent problems and maximize performance.

Capacitors are designed to help stabilize and re-engineer your electrical system to handle your additional components. By providing intermediate power (small current bursts,) a Capacitor reduces the pressure (current demand) on your electrical system. This helps to improve the performance of your vehicle and your system, getting you the most 'bang' for your buck.

The general rule-of-thumb when selecting capacitors is 1 Farad Per 1,000 Watts. This rule is not exact for every condition and primarily designed to assist you with selecting capacitor-to-amplifier combinations.

One or Two Amp Systems
Up to 500-watt system 0.5-Farad cap
400-watt to 1000-watt system 1-Farad cap

MultiAmp and Competition Systems
700-watt to 2000-watt system 25-Farad competition cap
1500-watt to 4000-watt system 40-Farad competition cap
2000-watt to 5000-watt system 50-Farad competition cap
3000-watt to 8000-watt system 100-Farad competition cap


Amplifiers can really turn your system on. With more power you’ll achieve a
cleaner, more dynamic sound at higher volumes. An amplifier boosts your signal power, resulting in a cleaner sound and more volume. And because more power is a good thing, an amplifier might be the next thing on your list. Be careful, though, because if you are planning on adding several high power amplifiers you may need to upgrade your car’s electrical system with upgraded capacitors, battery, and finally alternator. The topic is vast and discussion on amplifiers can go on and on. So later on more specific details will be covered.


You’ll need RCA cables to carry pre-amp (low line level) signal, usually from your head unit to your amp and processors (crossovers, equalizers, etc.). Get ‘em well-built, flexible and shielded, with sturdy connector ends that will withstand the stresses of car audio connections. It pays to buy
quality cables.

Amplified signal (especially when it’s going to your subwoofer) is much stronger, and requires a more capable cable. There’s a lot of current zipping out of your amps. That’s why they make speaker cables. Be sure to use cable that is 16 to 8 AWG (gauge) for subs and coaxes. (The lower
the number, the thicker the wire, the less resistance;thicker is better.) Tweeters and mids can use thinner cables (16-12 AWG).

For battery connections, a power distribution block can make wiring multiple electronics a breeze. Run a 4 to 6 AWG power cable from your battery to a power distribution block and use its multiple outputs for each component.
Some power distribution blocks even come with their own fuses to protect your components. You can also find battery terminals that have secondary
connectors to let you easily hook up the extra power cables. Sometimes the power requirement is so high, you even end up running 0 AWG or 0/2 AWG wires.


Trust your ears, not the specs.
Specs can tell you how a speaker will sound, but they can’t tell you what a speaker sounds like. Trust your ears. And if you don’t know what to listen for, trust someone with listening experience. Good luck.


The above information is for reference and not meant to be read at a stretch. More information to follow later on, but these are must know basics that will help to understand that might follow later on.

Hope you enjoyed as much as I enjoyed compiling it.
Corrections and Questions are welcome.

Last edited by Neo on 01 Sep 2006, 8:38 pm, edited 1 time in total.

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Post by Neo » 25 Aug 2006, 8:52 pm


Free Air (Infinite baffle)

Free air subwoofers use the whole trunk as their enclosure. If you’re driving a hatchback (stop this now) this won’t work, since the trunk has to be sealed as tight as possible for the woofers to get any benefit. Free air subs are not very accurate and are unpredictable— sometimes they sound good, sometimes they sound really really bad—and they require a lot of power. An infinite baffle design is defined as an enclosure that contains a greater volume of air than the Vas of the driver.



Sealed enclosures are the most common kind of box, and the easiest to build.When the volume of air within a sealed enclosure is less than the Vas of the driver, the air trapped within the enclosure acts as an acoustic spring that adds to the restoring force of the speaker. This system is called acoustic suspension, also referred to as a sealed enclosure. They deliver the flattest frequency response and best sound quality. Make sure you get the size right, since a box that’s too small will deliver tighter bass but suck up more power from your amp, and a box that’s too big will simply sound muddy. Use about 1kg of loosely packed damping material per cubic foot of enclosure volume when you’re building one, being sure to keep the fill out of the speaker’s pole piece vent.A well designed sealed enclosure will exhibit smooth frequency response with excellent cone control at sub-bass frequencies.

Vented/Ported Enclosure


Vented enclosures are also known as ported, bass reflex, tuned, or tuned ported. A vented enclosure is essentially a sealed enclosure with an extra opening that allows the back wave to interact with the front wave. By changing either the length or surface area of the opening, we change the tuning frequency of the enclosure. Ported enclosures are usually bigger than sealed enclosures and feature a “tube” or port that lets air out of the box. The theory is that a speaker port pushes and pulls the air at the same time as the woofer, thus reinforcing the bass. The box itself can often act like amplifier,sometimes adding 3 to 4 dB to bass levels. Again, about 1 kg of loosely packed damping material is recommended per cubic foot of enclosure volume (be sure to keep it away from the port).This system offers some performance advantages and disadvantages over a sealed enclosure. The advantages are, for a given enclosure volume, deeper bass extension or higher output. Another advantage is that near the tuning frequency, almost all output is from the vent so cone movement is controlled to the point of almost no movement. The disadvantage is that below the tuning frequency, the speaker no longer has the restoring force of the air in the enclosure, and therefore the cone acts as though it is in free air.

Single Reflex Bandpass


Bandpasses enclose a woofer between a sealed and a ported box. Sometimes both parts of the box are ported. Bandpass enclosures yield more bass than sealed or ported boxes (especially at lower frequencies), but over a narrower frequency range. The enclosure acts to block upper and lower frequencies. Bandpasses are big, hard to build, and can be messy when precise volumes and port sizes are not followed.

Due to the fact that all the sound from this type of enclosure is produced by the vent, sound quality may not be as good as that of a properly designed sealed or ported enclosure. However, there are times when bandpass enclosures are the best choice to use. In a sedan application, bandpass enclosures are often used due to the inability to have multiple drivers mounted in the rear deck. In a limited space situation, efficiency can be sacrificed to gain deeper bass extension. In a situation where ultimate SPL is the goal, you can sacrifice bass extension, and enclosure size to produce a very efficient enclosure. Efficiency gains in the range of 5-10dB are not uncommon! As with any enclosure design, there is no free lunch. As you change one parameter to gain another, many times sound quality is degraded as well.

Dual Reflex Bandpass


A dual reflex enclosure can be described as a speaker with a ported cabinet on both sides. This system has the advantage of making use of both the front and the back wave of a speaker, and can attain great efficiency. However, like a vented enclosure, when operating below the tuning frequency of the enclosure, the driver may move beyond its excursion limitations. Combine this with the fact that all information is produced by the ports, so, we can’t hear the distortion until it is too late.

Multiple Driver


It is often possible to attain better sound quality and higher output for a given airspace by using multiple smaller speakers rather than a single large one.

When designing an enclosure that will use multiple speakers, be sure that you are doubling the air space that you would have used for a single driver. If the speakers will be given the same signal, a divider is not necessary. If the speakers will be operated by two different signals, be sure to use a divider to separate the two enclosures, or cancellation will result.

Multiple Driver (IsoBaric)


By combining two woofers to act as one, either by mounting them gasket to gasket, or gasket to magnet or magnet to magnet, we create an isobaric system. An isobaric system acts as one speaker, but requires an enclosure volume that is half of what one singular driver would take. The output capability of this system is limited to what a single speaker would be in a cabinet of twice the size of the isobaric system. The reason that an isobaric system requires only half of the enclosure volume is that the Vas is half of the single driver. This is due to having two suspensions on the same diaphragm.

More to follow....

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Post by Alpha » 29 Aug 2006, 3:54 pm

Absolutely awesome. I hope the School would be of great help for our sound-systems-inspired members. We've been waiting for a School as such.


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Post by don_homie » 02 Sep 2006, 4:08 pm

Excellent work gonna read each 'n every word on this im still a beginer :$ ..........

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Post by 3mro » 21 Sep 2006, 12:57 am

Hey neo do u hav ur own audio shop ??

Actually i got a system for my car
its a kenwood bass tube 1000W
and its connected witg a 250W amp ... i actually dont get tht fact :(

and plus cud u tell me like how much it wud cost me to take out my audio system from my car to another car
and my xenon as well ... ??

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Post by Neo » 24 Sep 2006, 7:24 pm

3mro wrote:Hey neo do u hav ur own audio shop ??

Actually i got a system for my car
its a kenwood bass tube 1000W
and its connected witg a 250W amp ... i actually dont get tht fact :(

and plus cud u tell me like how much it wud cost me to take out my audio system from my car to another car
and my xenon as well ... ??
Hey dude,
I checked ur message couple of days back however i didn get time to post a reply.
if u read thru the details, i had explained why therez difference of power in the speaker and amplifier.

Lets say, u have a 12 volt bulb and u connect it to 6 volt battery. Obviously the bulb wud glow, but the brightness wud be less.
Connect the same bulb to 12 V and u will see the rated brightness.
However if u connect it to 14 Volts the bulb mite still work and maybe more bright. But the life wud be reduced and it mite burn out any moment.

If u saw the bass tube to be 1000W and AMP to be 250W the definitely the Sub is underpowered. Bcoz the AMP rating is PMPO , so is the sub.

Unless the car is really different, i mean unless ur transferring from a Civic hatchback to a Landcruiser, there wont be much difficulty and cost. Same goes for the Xenons too... I wud have done the work for u.. but i am not in UAE at the moment.


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Post by 3mro » 10 Oct 2006, 12:39 am

hey neo

thanx alot for ur help ..
i already spent almost 150 on getting the xenon and the woofer out of my car ...

i want ur recommendation .. wht do u think? wht power amp shuld i use wid my 1000W woofer ... coz its fitted in a tube...

and if ur back cud u help me wid getting in back into my new car

i had an Epica :$ and my accord 2007 is coming in by wednesday ..

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Post by Arnie » 28 Mar 2007, 4:19 pm

this school reminds me of my bro whos also a sound engineer teaching me the stuff :P

damn good school.....if you dont mind might wanna add this sound handbook from DLS for more serious sound setup...and even useful tips!!.....

btw...that PDF had some hardcore formulas too...if your interested that is :D

but that pdf is got everything if you wanna build a high Definition audio (High Clarity) system or SPL Setup (High Volume for DB Drag Races)...
if different sub woofer boxes as neo mentioned..

Hope this helps too..


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Post by prossett » 26 Nov 2007, 8:43 am

That's an excellent write-up, Mr Neo! 8)

Very useful for a newbie who just joined, like me - all the info in one place, clear and easy to read... (Y)

Maybe as I get to know the members more we can do a few more on different subjects, sharing the collective knowledge.

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Post by Neo » 29 May 2009, 10:29 pm

Thanks... This is something for the community.
There is more to add... But i am finding almost no time or patience in write ups...

We need to do more on different subjects.

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Post by .Zohair » 29 May 2009, 10:34 pm

Great stuff mate, I learned from it.

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Post by jstyezy » 15 Mar 2015, 12:35 pm


I recently did a DIY of connecting my Existing subwoofer tube (with built-in amp, 250W) to another JBL 1000W tube and threw in some LED to light up the interior with the bass. I also installed a flip switch to turn on the JBL tube and the LED when required. Everything worked fine as required, but my only problem is when I turn on both tubes with the LED, everything works fine for like 10 mins and then the fuse in the amp (15ohm) blew. I replaced the fuse with a 30 ohm and everything worked fine for a week or two until one day when I played some loud music and the whole system turned off leaving me with playing music through the normal speakers. This has been going on for a while and when that happens my amp gets very hot. I disconnected all the mods and been looking around for a fix. Kindly adivce as I am not an expert :$


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