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After looking through this site, I've noticed that there isn't much information in the car audio section, rather, just "what kind of amp should I use?" or "how will these speakers sound?".
I've done a little searching and I've decided to compile a little FAQ (frequently asked questions) list on I.C.E. (In Car Entertainment)

Where should I buy the components I want?
Most of the time, you will either buy from a local dealer, or from a mail-order house. Buying from a local dealer can be good because you get to deal directly with a person: you can show them your car, ask specific questions, haggle prices, get quick service when there are problems, get deals on installation, etc. But there can also be advantages to buying mail-order: generally cheaper prices, sometimes better service, etc. In either case, you should always check prices before you buy, inquire about warranty service, and ask about trial periods.

What mail-order companies are out there?

Crutchfield -- 800/955-3000
1 Crutchfield Park, Charlottesville, VA 22906 USA


Advantages:
Great customer service
Generally knowledgeable sales and tech support personnel
Custom mounting kits, wiring harnesses, etc. free of charge.

Disadvantages:
limited product line
generally higher prices than local shops

J.C. Whitney -- 312/431-6102
1917-19 Archer Avenue, P.O. Box 8410, Chicago, IL 60680 USA


Advantages:
Lots of "miscellaneous" items
10kW amps for $19.99

Disadvantages:
10kW amps that really only put out 1mW and break after first 10 minutes of use.

Parts Express -- 800/338-0531
340 E. First St., Dayton, OH 45402 USA


Advantages:
Large selection of electronics supplies at respectable prices.
Showroom prices said to be better than catalog prices.

Disadvantages:
Also carries some of the same quality-level components as J.C. Whitney.

Classic Research/Z-Box -- 520/571-0171
5070 E. 22nd St., Tucson, AZ 85711 USA


Advantages:
Creates custom door panels with car audio in mind.

Disadvantages:
Only services expensive sports and luxury cars.

MCM Electronics -- 800/543-4330
650 Congress Park Drive, Centerville, OH 45459-4072 USA


Advantages:
Sells lots of decently priced trinkets (fuses, fuse holders, wire, etc.)
Has excellent service and available technical support.

Disadvantages:
?
There are many other mail-order houses that can be found in the back of magazines, such as S.B.H. Enterprises, Speed and Sound and Smile Electronics, but people seem to have mixed feelings about these companies. The prices are very low, often due to the fact that these companies are not factory authorized -- this means that there could be problems getting the unit serviced by the manufacturer should it break. To get around this, these mail order houses will often provide their own service departments, to repair defective units. Generally, it is advised to be careful when dealing with any mail order companies, to protect yourself.

There are also a number advertisements for mail order houses (such as Apex Audio & Electronics or Insider's Audio) that offer special deals or free equipment if you buy their expensive catalog or pay a membership fee. While these ads may be enticing, keep in mind that they are often too good to be true! Usually you have to buy a large amount of equipment before you qualify for the "bonus" or the prices are very high for most equipment.

What tools should I have in order to do a good installation?

Electrical tape
Make sure you get some that can withstand extreme temperature ranges.

Wire cutters/strippers and crimpers
Get a big pair with stripper holes precut for individual wire sizes.

Angled screwdrivers
Makes taking dash and rear deck speakers out a lot easier.

Multiple size screwdrivers, both flathead and Phillips.
Magnetic screwdrivers can be a big help when trying to get screws into (or out of) tight spaces.

Various wrenches, pliers, and socket sets
The specific sizes you need will depend on your vehicle.

Metal drill and saw
You'll need these if you need to modify your vehicle for new speaker cutouts or to accommodate a new head unit.

Hot glue gun
Good for putting carpeting or door panel trim back in place after modifications.

Razor knife
Helps for detailed modifications of door panels or carpeting, especially when installing new speakers.

Wire
See section 2.3 What is the best power wire to use? [JSC], and See section 2.4 What is the best speaker wire to use? [JSC, JW].

Soldering Iron
Makes excellent connections, but can be messy if not careful.

Shrink wrap or flex tubing
Good for protecting wire, especially in the engine compartment.

Multimeter
Helps to diagnose installations.

Extra hardware
Screws, nuts, bolts, connectors, etc.

Fuse puller and extra fuses.
In addition to the fuses for your stereo system, check your car's fusebox to find the various sizes you'll need. Also, you can use needle-nosed pliers to pull fuses.

Wire ties
Helps to tuck wire away in otherwise exposed areas.

Small light source
A flashlight will do - you just want something that you can poke around the innards of your car with.

Tape measure

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What is "rear fill", and how do I effectively use it?
Rear fill refers to the presence of depth and ambiance in music. A properly designed system using two channels will reproduce original rear fill on the source without rear high frequency drivers. Since recordings are made in two channels, that is all you will need to reproduce it. What is captured at the recording session (coincident pair mics, Blumlein mic patterns, etc.) by a two channel mic array will capture the so called rear fill or ambiance. Many of the winning IASCA vehicles have no rear high frequency drivers. Also a lot of this has to do with system tuning. If rear high frequency drivers are added, however, the power level of the rear fill speakers should be lower than that of the front speakers, or else you will lose your front-primary staging, which is not what you want (when was the last time you went to a concert and stood backwards?). The proper amount of amplification for rear fill speakers is the point where you can just barely detect their presence while sitting in the front seat. Separates are not a requirement for rear fill; in fact, you may be better of with a pair of coaxial speakers, as separates may throw off your staging.

How do I set the gains on my amp?
The best way to do this is with a test tone and an oscilloscope Since most people have neither item, the following will work approximately as well.


Disconnect all signal inputs to the amp

Turn all sensitivity adjustments as low as possible

Turn head unit on to around 90% volume (not 100% or else you'll have head unit distortion in there - unless you've got a good head unit) with some music with which you're familiar, and with EQ controls set to normal listening positions

Plug in one channel's input to the amp

Slowly turn that channel's gain up until you just start to notice distortion on the output

Turn it down just a wee little bit

Disconnect current input

Repeat steps 4-7 with each input on your amp

Turn off head unit

Plug in all amp inputs, and you're done
If by some chance you do have an oscilloscope (and preferably a test disc), you do essentially the same thing as above, except that you stop turning the gains up when you see clipping on the outputs of the amplifier.

Note that if you are paralleling multiple speakers on a single amp output, you need to set the gains with all of the speakers in place, since they will be affecting the power and distortion characteristics of the channel as a whole.

How do I select proper crossover points and slopes?
Basically, this requires a degree of patience. The subwoofer should be started off at about 100Hz and adjusted until you are happy with the sound. Keep in mind that the higher the crossover point, the more power the driver on the high-pass will be able to handle but raising excessively may cause the low-pass driver to sound raspy or unnatural. The idea here is to first make rough selections to protect the drivers and then to fine tune crossover point selections to achieve optimum fidelity. It's all a matter of what sounds good to you after that, but remember that even minute changes in crossover frequency can make dramatic differences in the way your system sounds and images.

As a rule, subs should be crossed over no higher than 120Hz, a 6 1/2 mid should be able to handle about 90 Hz, a 5 1/4" should be okay with about 100Hz, a 4" -- about 500Hz, and tweeters vary from about 3500-5000Hz. These points all assume the use of a 12dB/octave crossover ... if you have a steeper roll-off a lower crossover point may be chosen. Remember, these are not hard and fast rules but rather a rule of thumb to help you get started (and so you don't blow up all your speakers when you are setting your gains!).

How do I flatten my system's frequency response curve?
First, you'll need a good quality equalizer - either a 2/3 octave (15-band) or 1/3 ocatve (30 band) equalizer or a quasi- parametric equalizer such as PPI's PAR 224 that allows you to choose the center frequency and bandwidth (Q) of each **** on the EQ. This will allow adjustments to very specific frequency ranges. Next, you'll need to get a hold of an RTA (Real Time Analyzer), which is an expensive piece of equipment that good shops will usually have. The shops can then equalize the system by making a measurement with the RTA, and varying the levels on the equalizer in order to make the overall response curve flat.

Unfortunately, most shops will not do this for free, since proper equalization can take anywhere from a half hour to many many hours.

Another method involves buying an SPL meter (available from Radio Shack for between $32 and $60) and a test disc (Autosound 2000 makes one that runs about $25) that plays discreet frequency ranges - in 1/3 octave groups. Then, moving through the range of frequencies, SPL measurements can be taken at each range, and you can plot out a "response" curve. You'll be able to see what frequency ranges need to be boosted and which need to be cut. This process will be time consuming (more so than an RTA, which can analyze the entire frequency spectrum simultaneously), but should be much less expensive than having it professionally done.

One last note: While a smooth curve will get the most points at an auto sound competition, you must NOT rely only on the RTA to tell you what sounds good. Use the RTA to get a good start, and then use your (better, use someone experienced in tuning systems) ears to do the fine-tuning.

How do I wire speakers "in series" and "in parallel?"
Wiring speakers in series involves connecting at least two speakers so that the first speaker's positive lead is connected to the amplifier's positive terminal, and the negative lead is connected to the positive lead of the second speaker. If there is a third speaker, its positive lead will be connected to the second speaker's negative lead ... and so on. The last speaker in the chain will have its negative lead connected to the amplifier's negative terminal.

Speakers that are wired in parallel are all connected to the positive and negative terminals of the amplifier. So, when two speakers are wired in parallel, you'll connect each speaker's positive lead to the amplifier's positive terminal, and you'll connect each speaker's negative lead to the amplifier's negative terminal.

Be careful when wiring multiple speakers in parallel or series so that you do not exceed your amplifier's rating. To calculate the effective impedance of a number of speakers, use the following formulas:

Series Connections: Z(t) = Z(1) + Z(2) + Z(3) + ... + Z(n)

That is, add up all of the impedances for each speaker to
get the total impedance. For example, with 3 4-ohm speaker
in series, the total impedance is 4 + 4 + 4 = 12 ohms.




Parallel Connections: 1/Z(t) = 1/Z(1) + 1/Z(2) + 1/Z(3) + ... + 1/Z(n)

That is, add up the inverse of the impedance of each
speaker and invert the sum to get the total impedance. For
example, with 3 4-ohm speakers in parallel, the total
impedance is 1 / ( 1/4 + 1/4 + 1/4) = 1 / (3/4) = 1.33 ohms.

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Are there any alternatives for Dynamat? It's too expensive!
In this question, "Dynamat" refers to all commercial products that are marketed expressly for reducing ambient noise in the car. Dynamat, Stinger RoadKill, et al. all have similar pricing, so this question is intended to give non-standard options.

There is a material known as "Ice Guard," which is used by roofing contractors. It is similar to Dynamat, both in thickness and density. It is self-adhesive on one side, and seems to work very well. Unfortunately, it is sold only in large quantities (225 ft^2 rolls), and runs about $70 for this much. Perhaps a few people could get together for a roll, or it might be possible to get scraps from a roofing contractor.

How many devices can I attach to my remote turn-on lead?
The remote turn-on lead that most head units will not provide very much current (usually 250-300mA), so there is a limit to the number of components you can activate with it. Generally, it is safe to hook up two devices to the lead without having to worry about problems. However, if you'll be activating more components, then you should probably use a relay.

How do I wire a relay in my system?
There are two types of relays that are commonly used in 12-volt automotive applications: Single-pole Double Throw (SPDT) relays, which have 5 pins, and Single Pole, Single Throw (SPST) relays, which have 4 pins. Depending on the application, you can use either of these; for remote turn-on leads See section 5.11 How many devices can I attach to my remote turn-on lead? , an SPST relay is fine, SPDT relays are often used in alarm installations. Make sure that you get a 12-volt relay -- this specifies the voltage required to make the relay "switch."

Pins 85 and 86 connect to the coil which causes the relay to switch. On both relays, pins 30 and 87 are normally disconnected. When the relay is activated (switched) pin 30 and 87 are then in contact. The difference with the SPDT relay is that in the "normal" state, pins 30 and 87a are in contact.

To hook up a relay (either kind) for a remote turn on, make the following connections:


Pin 30
+12 Volts (Battery +)

Pin 87
Amplifiers' remote turn-on terminal

Pin 86
Head unit remote turn-on lead

Pin 85
Ground
Pin 87a
No connection (SPDT only)

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How do I turn a stereo signal into a mono signal
Creating a mono signal is often necessary when you are powering a subwoofer by bridging the amplifier. Many people do not realize that bridging an amplifier does not always provide a mono signal -- many amplifiers will simply use only one input channel, which means that the subwoofer won't be receiving the full signal.

Some amplifiers have a switch that will allow you to combine the left and right channels into a mono signal. Some signal processors and head units provide a subwoofer-out channel that can be switched between stereo and mono.

If you don't have this feature on any of your equipment, you will need to provide a mono signal to the amplifier. The common thought is to use a Y-adapter to "combine" the left and right channels. However, by using a Y-adapter, you are actually summing the line voltages and directly shorting the left and right channels at the head unit, which could cause problems.

The correct way to create a mono signal is to cut off the ends of the RCA cables, combine the signal grounds (the outer shield), and then use a 1 kOhm (1/4 watt, 5% tolerance) resistor to each of the center conductors. Solder and insulate the resistors so that you don't short them prematurely, and then connect the two resistors together. Connect the summed signal ground to the shield of the new RCA plug, and the summed center conductor to the center pin of the RCA plug.

How do I determine a speaker's polarity?
If you have a speaker and the terminals are no longer marked, you can do a simple test to determine which terminal is positive (+) and which is negative (-). This test is useful for midrange/midbass/subwoofers, but not for tweeters.

Use a 1.5V battery (AA, C, D) and connect the (+) terminal on the battery to one terminal of the speaker, and connect the (-) terminal to the other terminal of the speaker.

If the cone moves OUT, then the battery is connected "properly," i. e., the (+) terminal of the battery is connected to the (+) terminal of the speaker, and the (-) terminal of the battery is connected to the (-) terminal of the speaker.

If, however, the cone moves IN, the battery has been connected "backwards," i. e., the (+) terminal of the battery is connected to the (-) terminal of the speaker, and the (-) terminal of the battery is connected to the (+) terminal of the speaker.

Why are kickpanels such a popular location for mounting speakers?
There is a lot more to mounting speakers in the kick panels than just equalizing the path length difference (PLD). Two of which are: on-axis response, and angling for pattern control. On-axis response refers to the fact that most speakers sound best when listened to on-axis, or as close to on-axis as possible. Second, after mounting your speakers in the kick panels you can then angle the speakers to take advantage of their off-axis response to use output level to overcome any PLD that is still present. The pattern control I am mentioning is one of the ways a horn loaded compression driver works very well, they not only use amplitude to overcome any PLD that is still present they minimize early reflections that can destroy imaging staging and spectral balance.

PLD can be improved more than marginally when you consider the stock locations in a lot of vehicles, or the locations most installers choose. Measure the PLD between tweeters when mounted high in the dash or at the front corner at the top of the door and you will notice its probably on the order of 24". This mounting setup requires a lot of amplitude adjustment to correct the problems induced by this difference. The nearer tweeter is out phase from the opposite side and is arriving much sooner and with much greater amplitude due to the fact is not as far away. When all these factors are added together, it is very difficult for even the most flexible DSP unit to correct. On top of that, not many people or installers have access to the necessary tools to properly set up time delays using a DSP -- TEF, MLSSA or other very expensive time domain measuring equipment are required to do the job properly.

There will always be trade offs involved and deciding which trade offs to take can be very hard. A small dropout due to phase cancellation will probably not be noticed by most people but most people will quickly notice when a vehicle is not imaging properly, and if you can move the problem to higher frequency where we determine localization more from amplitude rather than phase differences, it will be much easier to deal with. Also, if you minimize the time/phase difference it will be much easier to correct with amplitude.

Some people complain that kickpanel mounting gives a low sound stage. However, keep in mind that when any stereo system is imaging properly the point sources can no longer be localized. When our brains can no longer localize the point sources it will then hear things at eye level.

What's worse for a speaker, too much or too little power?
Problems occur (in everyday operation) when distortion is fed to a speaker. This occurs MUCH more often when you are dealing with an underpowered system -- typically the owner will turn up the volume too much or set the amplifier gains too high to try and get more volume from the system. These introduce distortion to the signal -- this will destroy *any* speaker.

When a speaker is overpowered, however, it is not nearly as common to have these kind of problems, so speakers aren't blown as much. Of course, it is certainly possible to destroy a speaker (thermally) by overpowering it, but you'll have a pretty hard time doing this on your own, especially with standard car audio amplifiers

Why is distortion harmful to my speakers?
Distortion is hard on speakers for two reasons.

Reason 1: Distortion causes the power spectrum to shift upwards in frequency. A bass note, when distorted, will have lots of high frequency energy. This will cause mid-ranges and tweeters to fry, if the amplifier is operating full range. It doesn't harm woofers, necessarily.

Reason 2: Distortion causes the average power to be much higher. Typically, a music signal that never clips has an average power level of 1/4 the peak power level for even the most compressed speed metal or pop. More dynamic music will be 1/8 the peak level or less on average. When you clip the amp hard, the average output moves up to the full-rated output of the amp or more. The peak to average ratio can be less than 2 to 1, with the peaks being at double the rated power of the amp, and the average being at the rated power of the amp or higher.

Thermally, the speaker can handle the average power being 1/4 the rated power of the amp (little to no clipping), but it will have a much harder time with the average power being the amp's rated power or more (massive clipping). As you might expect, this is pretty hard on the amp, too.

For transients, most speakers can handle a ton of power. But for long term signals, the power handling is much less.

What do all of those acronyms mean?
`A' is for amperes, which is a measurement of current equal to one coulomb of charge per second. You usually speak of positive current - current which flows from the more positive potential to the more negative potential, with respect to some reference point (usually ground, which is designated as zero potential). The electrons in a circuit flow in the opposite direction as the current itself. Ampere is commonly abbreviated as "amp", not to be confused with amplifiers, of course, which are also commonly abbreviated "amp". In computation, the abbreviation for amps is commonly "I".

`V' is for volts, which is a measurement of electric potential. Voltages don't "go" or "move", they simply exist as a measurement (like saying that there is one mile between you and some other point).

`DC' is for direct current, which is a type of circuit. In a DC circuit, all of the current always flows in one direction, and so it is important to understand which points are at a high potential and which points are at a low potential. For example, cars are typically 12VDC (twelve volts direct current) systems, and it is important to keep track of which wires in a circuit are attached to the +12V (positive twelve volts) lead of the battery, and which wires are attached to the ground (or "negative") lead of the battery. In reality, car batteries tend to have a potential difference of slightly higher than 12V, and the charging system can produce upwards of 14.5V when the engine is running.

`AC' is for alternating current, which is a type of circuit in which the voltage potential fluctuates so that current can flow in either direction through the circuit. In an AC circuit, it is typically not as important to keep track of which lead is which, which is why you can plug household appliances into an outlet the "wrong way" and still have a functioning device. The speaker portions of an audio system comprise an AC circuit. In certain situations, it is indeed important to understand which lead is "positive" and which lead is "negative" (although these are just reference terms and not technically correct). See below for examples. The voltage of an AC circuit is usually given as the RMS (root mean square) voltage, which, for sinusoidal waves, is simply the peak voltage divided by the square root of two.

`W' is for watts, a measurement of electrical power. One watt is equal to one volt times one amp, or one joule of energy per second. In a DC circuit, the power is calculated as the voltage times the current (P=V x I). In an AC circuit, the average power is calculated as the RMS voltage times the RMS current (Prms=Vrms x Irms).

`Hz' is for hertz, a measurement of frequency. One hertz is equal to one inverse second (1/s); that is, one cycle per second, where a cycle is the duration between similar portions of a wave (between two peaks, for instance). Frequency can describe both electrical circuits and sound waves, and sometimes both. For example, if an electrical signal in a speaker circuit is going through one thousand cycles per second (1000Hz, or 1kHz), the speaker will resonate at 1kHz, producing a 1kHz sound wave. The standard range of human hearing is "twenty to twenty", or 20Hz-20kHz, which is three decades (three tenfold changes in frequency) or a little under ten octaves (ten twofold changes in frequency).

`dB' is for decibel, and is a measurement for power ratios. To measure dB, you must always measure with respect to something else. The formula for determining these ratios is P=10^(dB/10), which can be rewritten as dB=10log(P). For example, to gain 3dB of output compared to your current output, you must change your current power by a factor of 10^(3/10) = 10^0.3 = 2.00 (that is, double your power). The other way around, if you triple your power (say, from 20W to 60W) and want to know the corresponding change in dB, it is dB=10log(60/20)=4.77 (that is, an increase of 4.77dB). If you know your logarithms, you know that a negative number simply inverts your answer, so that 3dB corresponding to double power is the same as -3dB corresponding to half power. There are several other dB formulas; for instance, the voltage measurement is dB=20log(V). For example, a doubling of voltage produces 20log2 = 6.0dB more output, which makes sense since power is proportional to the square of voltage, so a doubling in voltage produces a quadrupling in power.

`SPL' is for sound pressure level and is similar to dB. SPL measurements are also ratios, but are always measured relative to a constant. This constant is 0dB which is defined as the smallest level of sound pressure that the human ear can detect. 0dB is equal to 10^-12 (ten to the negative twelfth power) W/m^2 (watts per square meter). As such, when a speaker is rated to produce 92dB at 1m when given 1W (92dB/Wm), you know that they mean that it is 92dB louder than 10^-12W/m^2. You also know than if you double the power (from 1W to 2W), you add 3dB, so it will produce 95dB at 1m with 2W, 98dB at 1m with 4W, 101dB at 1m with 8W, etc.

`THD' is for total harmonic distortion, and is a measure of the how much a certain device may distort a signal. These figures are usually given as percentages. It is believed that THD figures below approximately 0.1% are inaudible. However, it should be realized that distortion adds, so that if a head unit, equalizer, signal processor, crossover, amplifier and speaker are all rated at "no greater than 0.1%THD", together, they could produce 0.6%THD, which could be noticeable in the output.

An Ohm is a measure of resistance and impedance, which tells you how much a device will resist the flow of current in a circuit. For example, if the same signal at the same voltage is sent into two speakers - one of which is nominally rated at 4 ohms of impedance, the other at 8 ohms impedance - twice as much current will flow through the 4 ohm speaker as the 8 ohm speaker, which requires twice as much power, since power is proportional to current.

What is meant by "frequency response?"
The frequency response of a device is the range of frequencies over which that device can perform in some fashion. The action is specific to the device in question. For example, the frequency response of the human ear is around 20Hz-20kHz, which is the range of frequencies which can be resolved by the eardrum. The frequency response of an amplifier may be 50Hz-40kHz, and that of a certain speaker may be 120Hz-17kHz. In the car audio world, frequency responses should usually be given with a power ratio range as well, such as (in the case of the speaker) 120Hz-17kHz +/-3dB. What this means is that given an input signal anywhere from 120Hz to 17kHz, the output signal is guaranteed to be within an "envelope" that is 6dB tall. Typically the extreme ends of the frequency range are the hardest to reproduce, so in this example, the 120Hz and 17kHz points may be referred to as the "-3dB points" of the amplifier. When no dB range is given with a frequency response specification, it can sometimes be assumed to be +/-3dB.

What is a "soundstage?" What is an "image?"
The soundstage is the position (front/back and high/low) that the music appears to be coming from, as well as the depth of the stage. A car with speakers only in the front will likely have a forward soundstage, but may not have enough rear fill to make the music seem live. A car with both front and rear speakers may have anything from a forward to a rear soundstage, with an accompanying fill from the softer drivers depending on the relative power levels and the frequencies reproduced. The high/low position of the soundstage is generally only obvious in a car with a forward soundstage. The music may seem to be originating in the footwells, the dash, or out on the hood, depending on how the drivers interact with the environment.

The stereo image is the width and definition of the soundstage. Instruments should appear to be coming from their correct positions, relative to the recording. The position of the instruments should be solid and easily identifiable, not changing with varying frequencies. A car can image perfectly with only a center-mounted mono speaker, but the stereo placement of the music will be absent.

What is meant by "anechoic?"
Anechoic means not echoing. It usually refers to a style of measuring a speaker's output which attempts to eliminate echoes (or "reflections") of the speaker's output back to the measurement area, which could alter the measurement (positively or negatively).

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The info in this section was obtained from Autosound 2000 by David Navone.

My speakers make this high-pitched whine which matches the engine's RPMs. What is it, and how can I get rid of it?

1. Check out the Amplifier(s)
After you have determined that there is noise in the system, determine if the amplifier is causing the noise. To do this, mute the signal at the inputs to the amp by using shorting plugs. If there is no noise, then the amp is fine, and you can proceed to level 2. However, if there is noise, then use a test speaker at the amp's output. If this stops the noise, then the problem is originating in the speaker wiring, or the passive crossovers. Check to make sure that none of these are shorting with the body of the car, and start again at level 1. If noise is still present when using the test speaker, then there may be a problem with the power supply on the amp. Try connecting an isolated power supply - if this does not get rid of the noise, then there is something seriously wrong with the amp, and it should be replaced. If the noise goes away, then there may be a problem with power supply filtering or isolation. This can be fixed by changing the amp's ground point or b adding external supply filtering.

2. Reduce the System
The amps have been determined to be noise free. If you have any processors between the head unit and the amps, disconnect them and connect the head unit directly to the amp. If this gets rid of the noise, then one (or more) of the processors must be at fault, so proceed to level 5. Otherwise, try running the signal cables over a number of different routes. If you are able to find one that does not produce any noise, permanently route the cables in the same manner, and proceed to level 5. If not, then you must isolate the head unit from the car's chassis (except for its ground!) -- don't forget to disconnect the antenna, since it is also grounded to the car. If isolating the head unit does not solve the problem, the move the grounding point of the head unit. Hopefully the noise will be gone, and you can install the head unit with a quiet ground and proceed to level 5, otherwise go on to level 3.

3. Move the Head Unit
The amplifiers are fine, but moving both the ground for the head unit and the signal cables does not solve the noise problem. Take the unit completely out of the dash, and put it on either the seat or carpet, and run new signal cables to the input of the amp. If this solves the problem, re-install the head unit, one step at a time and skip to level 5. But if the noise persists, then move the head unit as close to the amp as possible and use the shortest possible signal cables. This will verify that the original signal cables are not causing the problem -- assuming the noise is gone, reinstall the head unit one step at a time and go to level 5. Otherwise, there may be a problem with the power filtering for the head unit. As with the amps, power the head unit with an isolated power supply (again making sure that the head unit isn't touching the car's chassis at all). If the noise goes away, you can add power supply filtering or an isolated power supply; go to level 2. But if the isolated power supply does not solve the problem, then you can either replace the head unit and go to level 2, or check the car's electrical system in level 4.

4. Testing the Car
There does not seem to be a problem with either the head unit or the amplifier, and the car's charging system is suspect. To see if this is the case, we can use a system in a car that is already known to be "quiet." Bring both cars together as if you were going to jump one, and use jumper cables to connect the two batteries. Start the engine of the car with the noise problem, and listen to the "quiet" car's system. If the noise does not go away, there is a SERIOUS problem with your car's electrical system (possibly a bad alternator). Have a qualified mechanic check the charging system out. If there is no noise in the "quiet" car, then the "noisy" car's charging system is definitely quiet, so continue with level 5.

5. Adding Signal Processors
We have proven that the amplifiers are good, the head unit is good, and the car's electrical system is good. Now we need to reconnect each signal processor. Repeat this level for each signal processor used in your system; if you have added all of your signal processors, and there is no longer any noise, CONGRATULATIONS! You've removed the noise from your system! Connect the signal processor. If there isn't any noise, then go on to the next signal processor. Otherwise, try re-routing the signal cables. If this cures the problem, the route them permanently over the quiet path, and install the next processor. If not, then isolate the processor from the car's chassis except for a single grounding point. If this works, then permanently isolate the processor, and move on to the next processor. If isolation does not help, then advance to level 6.

6. Processor Isolation Tests
Now, noise enters the system when one particular processor is installed, but regrounding it does not help. Move the processor very close to the amp, and check for noise again. If there isn't any, then re-install the processor, carefully routing the cables to ensure no noise, and continue at level 5 with the next processor. Otherwise, use an isolated power supply to power the processor, making sure that no part of the processor is touching the car's chassis. If this solves the problem, the consider permanently installing an isolated power supply or possibly a 1:1 transformer, and go to level 5 with the next processor. Otherwise, separate the processor and isolated power supply from the car by many feet and re- test. If there is still noise, then there is a serious problem with the processor's design. Get a different processor, and continue at level 5 with it. If separating the power supply and processor from the car does solve the noise problem, then either the processor is damaged, or your tests were inaccurate. Repeat level 5.

Xsi

Great work man, keep it coming

spark plugs.

My system "pops" when I turn it off. What is happening and how can I get rid of it?
This kind of problem is often caused by transients in the signal processor as it powers down finding their way into the signal path, which the amplifier then transmits to the speakers.

Usually this can be solved by adding a little turn-off delay to the processor. This allows the processor to stay powered on for a short time after the amplifiers have powered down, thus preventing the pop.

Many components sold today (such as crossovers, equalizers, etc) have delays built-in. Read your manual to see if it is possible to set this delay on your piece of equipment or be sure to look for this feature during your next car audio purchase.

If your processor does not have this feature, you can build your own delay circuit with a diode and a capacitor. Add a 1N4004 diode in series with the processor's turn-on lead, striped side towards the EQ. Then add a capacitor in parallel, the (+) side of the cap connects to the striped (processor) side of the diode, the (-) side of the cap goes to ground (not the radio or EQ chassis - connect to the car chassis).

Experimenting with the cap value will give you the right amount of delay before the EQ shuts off. You don't want it too long, just long enough to make sure the amp is off before the EQ powers down. 220 - 1000 uF is about right, and make sure the cap is a polarized electrolytic, 16V or higher. Also keep in mind that the diode will introduce a 0.7V drop on the remote wire, which can cause the processor to power down before the rest of the system.

What is the best power wire to use?
There is much debate over the benefit of certain wiring schemes (oxygen-free, multistranded, braided, twisted, air core, you name it). However, most people do agree that the most important factor in selecting power wire is to use the proper size. Wire is generally rated in size by American Wire Gauge, abbreviated AWG, or commonly just gauge. To determine the correct wire size for your application, you should first determine the maximum current flow through the cable (looking at the amplifier's fuse is a relatively simple and conservative way to do this). Then determine the length of the cable that your will use, and consult the following chart, taken from the IASCA handbook See section 6.1 What is IASCA, and how do I get involved? [JSC, HK, IDB],

Length of run (in feet)
Current 0-4 4-7 7-10 10-13 13-16 16-19 19-22 22-28

0-20A 14 12 12 10 10 8 8 8
20-35A 12 10 8 8 6 6 6 4
35-50A 10 8 8 6 6 4 4 4
50-65A 8 8 6 4 4 4 4 2
65-85A 6 6 4 4 2 2 2 0
85-105A 6 6 4 2 2 2 2 0
105-125A 4 4 4 2 2 0 0 0
125-150A 2 2 2 2 0 0 0 00




If aluminum wire is used instead of copper wire, the next larger size (smaller number) should be used. You should also consider the installation demands: will you need to run the wire around corners or through doors or into the engine compartment? These sorts of problems in the car audio application require some special care in cable selection. You will want to have cable that is flexible; it should have thick insulation as well, and not melt at low temperatures. You don't want to install wire that is rigid and prone to cracks and cuts, or else the results could literally be explosive.

What is the best speaker wire to use?
Again, there is much debate over the benefit of the various schemes that are being used by different manufacturers. In general, however, you will probably want to upgrade your speaker wire from the factory ~20 gauge to something bigger when you upgrade your amplifiers and speakers. In most cases, 16 or 18 gauge should be sufficient, with the possible exception of high-power subwoofers. According to an example by Jerry Williamson, using 18 gauge instead of 12 gauge would only result in a power loss of 0.1dB, which is essentially undetectable by humans. Thus, other factors play more important roles in the selection of speaker wire. One issue is that different wires will have different line capacitances, which could cause the wire to act as a low pass filter. Generally, however, the capacitances involved are so small that this is not a significant problem. Be sure to heed the warnings above regarding cable flexibility and insulation, especially when running wire into doors and other areas with an abundance of sharp metal.

I heard that I should run my power wire directly to my car's battery. Why should I bother, and how do I do it?
For some components, like head units and equalizers, it's acceptable to use the stock wiring for power. However, amplifiers generally require large amounts of power, and accordingly will draw large amounts of current. The factory wiring in most cars is not designed to handle large amounts of current, and most wires have 10-20A fuses on them. Thus, you will almost always want to run the power line for your amplifier directly to the positive terminal of the battery. This could require drilling a hole through the car's firewall, or at least spending time hunting for an existing hole (the steering column is a good place to start looking). Always remember to place a fuse on your wire as near to the battery as possible! For various reasons, such as an accident or simple wear and tear, your wire's insulation may eventually crack, which could allow the conducting wire to make contact with the chassis of the car and short the battery through this wire, which could lead to a serious fire. The closer you place a fuse to the battery, the more protected you are. Also, when running wire through areas with sharp metal corners, it is a good idea to use rubber grommets to provide extra protection against tearing through your wire's insulation.

Should I do the same thing with my ground wire, then?
No. In almost every case, the best thing to do is to ground your amplifier to a point that is attached to the chassis of the car and is as close to the amplifier as possible. The ground wire should not need to be more than about eighteen inches long, and should be at least as large as the power wire. The point to which you make your ground connection should be an unpainted piece of bare metal.

Some cars (Audi, Porsche) have galvanized bodies, and in these cars, you must find one of the manufacturers' grounding points or else some noise can result.

When my car is running and I have the music turned up loud, my headlights dim with the music. Do I need a new battery or a new alternator?
The headlights will dim because of a momentary drop in the voltage level that is available to power the vehicle's accessories, including the headlights, amplifiers, the engine, etc. This voltage drop can be caused by a very large current demand by an accessory, such as an amplifier trying to reproduce a loud bass note.

The first thing to do is to get your battery and alternator checked for proper functioning. A failing battery can place undesirable loads on the alternator, leaving less power for your system.

If the power system appears to be working correctly, an improved alternator may be required for the large current demands of the audio system. When upgrading an alternator, be careful in your purchase, for there are some potential problems. An alternator which advertises a certain output level may only achieve that output at very high engine RPM ranges, for instance. Also, the new alternator must be adjusted to provide an output voltage within a reasonable range in terms of the voltage regulator.

If you find your car will not start after playing the stereo for long periods of time with the engine off, and the present battery is in good working order, then another, paralleled battery could prevent this embarrassing problem.

What do I look for when buying a capacitor?
The single most important attribute is the capacitance value (expressed in Farads). Put simply, more is better. Another important consideration is to make sure the maximum voltage rating of the capacitor safely exceeds the operating voltage of your vehicle's electrical system. In addition, ESR and ESL values may be provided with some capacitors to essentially indicate the amount of voltage drop that occurs when a capacitor is delivering current. Smaller values are better in this regard.

How do I install a capacitor?
If you conclude that your best course of action is to install a capacitor, it should be installed in parallel with the amplifier and, generally speaking, should be wired with approximately the same gauge wire used for a single amplifier (usually 8 ga. is sufficient even for rather large capacitors).

Before permanently installing it, it must be charged. Failure to do so could lead to blown fuses and lots of sparks! Some capacitors come with charging resistors. If yours does not, you can simply buy an automotive bulb and wire it in series with the capacitor's + lead while the capacitor is grounded. The bulb will continue to dim until the capacitor is fully charged. Once the capacitor is charged, it should be treated as you would a car battery; caution must be used to be sure not to short the terminals.

The final step is to permanently install it into the car. There's been much debate about where to install the capacitor. It's been argued that the placement is important because it requires shorter wire lengths. While this is true, there has never been any evidence supporting the notion that it should be installed as close (electrically) to the amplifier as possible. In fact, electrical theory demonstrates that it's more effective at quenching the dimming effects by installing it as close to the device exhibiting the symptom (ie. the headlights) rather than the device that's drawing the bulk of the current (ie. the amplifiers). However, the benefit to doing so is negligible. Therefore, hooking it directly to the battery, the amplifier terminals, or the distribution block are equally valid solutions as long as the mounting location is safe, the wire lengths are reasonably short, and there's an adequate ground present.

I have more than one amp in my audio system. Which one should I have the capacitor run?
The amplifiers are all connected in one way or another to the battery. In fact, unless you're running separate power wires to each amplifier all the way from the battery, they're usually connected at a more proximal site (a distribution block, for example). The effects of the capacitor are felt by the entire electrical system, including the amplifiers. Therefore, you cannot selectively dedicate a capacitor to a specific amplifier.

Will my bass response improve by adding a capacitor?
A capacitor serves to smooth the voltage fluctuations associated with transient current draw. As a result, the supply voltage presented to the amp during peak demands tends to be slightly higher than without the capacitor. For most amplifiers, this will increase the power output of the amplifier during transients. The degree to which it increases, however, typically leads to an inaudible improvement.

To illustrate, if you consider an amplifier that delivers 100 watts at 14v and 80 watts at 12v (these numbers are somewhat typical), the difference in output from the speaker will be at best 1 dB when the supply voltage fluctuates from 14v to 12v. However, when you take into account the fact that no practical amount of capacitance can completely eliminate this voltage drop during transients, the difference in output becomes even less pronounced. Further, if you take into account other factors such as loudspeaker power compression the equivalent series impedance of the capacitor, the length of the transient, and the human's decreased ability to perceive differences in intensity for shorter intervals, this difference in output becomes negligible.

spark plugs.

What do all of those specifications on speakers mean?
Input sensitivity is the SPL the driver will produce given one watt of power as measured from one meter away given some input frequency (usually 1kHz unless otherwise noted on the speaker). Typical sensitivities for car audio speakers are around 90dB/Wm. Some subwoofers and piezo horns claim over 100dB/Wm. However, some manufacturers do not use true 1W tests, especially on low impedance subwoofers. Rather, they use a constant voltage test which produces more impressive sensitivity ratings.

Frequency response in a speaker refers to the range of frequencies which the speaker can reproduce within a certain power range, usually +/-3dB.

Impedance is the impedance of the driver See section 1.1 What do all of those acronyms mean? typically 4 ohms, although some subwoofers are 8 ohms, some stock Delco speakers are 10 ohms, and some stock Japanese imports are 6 ohms.

Nominal power handling is the continuous power handling of the driver. This figure tells you how much power you can put into the driver for very long periods of time without having to worry about breaking the suspension, overheating the voice coil, or other nasty things.

Peak power handling is the maximum power handling of the driver. This figure tells you how much power you can put into the driver for very brief periods of time without having to worry about destroying it.

Are component/separates any better than fullrange or coaxials?
Usually, yes. Using separates allows you to position the drivers independently and more carefully, which will give you greater control over your imaging. For best results, try to keep the mid and tweeter as close together as possible -- this will make the two drivers act more like a single point source (which is ideal).

For rear fill applications, however, coaxial speakers will perform fine, as imaging is not a primary concern. However, it is very common to use a low pass crossover with the rear speakers (at 2500 Hz) since rear-fill is intended to produce "ambiance," and high frequencies (> 2500 Hz) can confuse the soundstage, making it appear that music is originating behind you.

What are some good (and bad) brands of speakers?
People will emotionally defend their particular brand of speakers, so asking what the "best" is is not a good idea. Besides, the best speaker is the one which suits the application the best. In general, however, various people have claimed excellent experiences with such brands as Boston Acoustics, MB Quart, a/d/s/, and Polk. Also, most people agree that you should avoid brands like Sparkomatic and Kraco at all costs.

What do all of those specifications on amplifiers mean?
Frequency response refers to the range of frequencies which the amplifier can reproduce within a certain power range, usually +/-3dB.

Continuous power output is the power output of the amplifier into one channel into a certain load (usually four ohms) below a certain distortion level (usually at most 1%THD) at a certain frequency (usually 1kHz). A complete power specification should include all of this information, e.g. "20W/ch into 4 ohms at < 0.03%THD at 1kHz" although this can also be stated as (and be assumed equivalent to) "20W/ch at < 0.03%THD". The amplifier should also be able to sustain this power level for long periods of time without difficulties such as overheating.

Peak power output is the power output of the amplifier into one channel into a certain load (usually four ohms) below a certain distortion level (usually much higher than the continuous rating level) at a certain frequency (usually 1kHz). A complete power specification should include all of this information, e.g. "35W/ch into 4 ohms at < 10.0%THD at 1kHz" although this can also be stated as (and be assumed equivalent to) "35Wch at < 10.0%THD". Consumer warning: some manufacturers will state the "peak power output" rating by including the amount of power which can be drawn from "headroom", which means power supply capacitors. They usually will not tell you this in the specification, however; indeed, they tend to prominently display the figure in big, bold letters on the front of the box, such as "MAXIMUM 200W PER CHANNEL!!!" when the continuous rating is 15W/ch and the unit has a 5A fuse.

Damping factor represents the ratio of the load being driven (that is, the speaker - usually four ohms) to the output impedance of the amplifier (that is, the output impedance of the transistors which drive the speakers). The lower the output impedance, the higher the damping factor. Higher damping factors indicate a greater ability to help control the motion of the cone of the speaker which is being driven. When this motion is tightly controlled, a greater transient response is evident in the system, which most people refer to as a "tight" or "crisp" sound. Damping factors above 100 are generally regarded as good.

Signal to Noise or S/N is the ratio, usually expressed in decibels, of the amount of true amplified output of the amplifier to the amount of extraneous noise injected into the signal. S/N ratios above 90 to 95dB are generally regarded as good.

nOOber

nice one Sparks.

how about a link/list to the major manufactures of head units, speakers, amps, prefab boxes/ kicks, processors, screens, cables, etc... ?

How about a sticky from our phantom mods ?

spark plugs.

i would post a list, but it'd be pretty much endless. The really kickass subs/amps are not really well known, too. I'll see if I can pull something together.

spark plugs.

Why should I bridge my amp?
For increased power. If your amp can handle the load, it will put out more power through a bridged channel than it would into through a non-bridged channel. Theoretically, a "perfect" amplifier that puts out X watts into Y impedance into each of two channels will put out 4X watts into Y impedance into one bridged channel. Be aware that some amps more closely approximate that perfect amp than others, and some manufacturers build current limiters into their amps to allow them to remain stable into difficult loads at the expense of power gains.

Why shouldn't I bridge my amp?
There are several reasons: you might need those extra channels; your amp might not be stable into the load your speakers present if the amp is bridged; you might be a hyper-perfectionist that can't stand the thought of an small increase in distortion; or perhaps you just don't need more power. Car audio power is relatively cheap, and if you are not trying to make a mega-gonzo system, you may not need to double your power.

What happens when an amp is bridged?
Basically, one channel's signal is inverted, and then the two channels are combined to form one channel with twice the voltage of either of the original channels.

Ohm's Law for Alternating Current states that I = V/Z where I is current, V is voltage, and Z is impedance. We also know that P = IV, where P is power. If we use Ohm's Law and substitute into the power equation, we get P = V(V/Z), which can be rewritten as P = (V^2)/Z. Therefore, power is the square of voltage divided by impedance.

Now, why do we care about all that? Because it explains precisely what happens when an amp is bridged. I'll give a practical example and explain the theoretical basis of that example.

Imagine you have a two-channel amp that puts out 50 watts into each channel when driven into a load of 4 ohms per channel. Since we know P and Z, we can plug these numbers back into our power equation and find V. 50 = V^2/4 -> V = sqrt(200). So, we're seeing a voltage of 14.1 volts across each channel.

Now, imagine we bridge this amp, and use it to push just one of those 4 ohms loads. When the amp is bridged, the voltage is doubled. Since we know the voltage (2*14.1 volts), and the impedance (4 ohms), we can calculate power. Remember that P = V*V/Z. That means P = (28.2)^2/4, which is 198.1 watts. It should be clear by now that the new power is approximately 200 watts - quadruple the power of a single, unbridged channel!

You can probably see that should be the case, especially if you look back at the power equation. Since P = V*V/Z, if you double V, you quadruple power, since V is squared in the power equation.

Now, all this assumes the amp is stable into 4 ohms mono. The mono channel is putting out four times as much power as a single unbridged channel, so it must be putting out twice as much as the two single channels combined. Since the voltage on the supply side of the amp is dependent on the car's electrical system, it doesn't change (OK, the increased current might cause a voltage *drop*, but let's not worry about that now). Looking at the first power equation, at the supply side of the amp, we see P = IV. Now, when we bridged the amp, we doubled the power, but the input voltage stayed the same. So, if we hold V constant, the only way to double the power is to double the current.

That means the amp is now drawing twice as much current when it's running at a given impedance mono than it would be running two stereo channels at the same impedance. There are only two ways the amp can do that - it can simply draw more through it's circuits, and dissipate the extra heat, or it can utilize a current limiter, to prevent the increase in current. Of course, using the current limiter means you don't get the power gains, either! So, if the amp can't handle the extra current, and it doesn't limit the current in some way, kiss it goodbye. For that reason, an amp is typically considered mono stable into twice the impedance it is considered stereo stable.

Does bridging an amp would halve the impedance of the speakers?
Impedance is a characteristic of the speakers. The speakers don't give a flip how the amp is configured: they have a given impedance curve, and that's that. It should be clear that when you bridge an amp, you are changing *the amp*. The speaker's impedance is *not* a function of the amp, but the amp's tolerance to a given impedance depends completely on the way the amp is configured. If you'll remember from section 4, an amp bridged into a given impedance draws twice as much current as it would if it were driving two separate channels, each at that impedance. So, a four ohm speaker stays a four ohm speaker, if it's hooked to one channel, a bridged channel, a toaster, or the wall socket. But, it is more stressful for the amp to drive any impedance bridged than unbridged.

So, why do people talk about the impedance halving? Well, it's a simple model that isn't correct but is easy to explain to people who don't know what's really going on. It goes like this: When you bridge the amp, each channel is "seeing" half the load presented to the amp. So, if you bridge an amp to 4 ohms, each channel "sees" 2 ohms. Therefore, each channel puts out twice as much power, and the combined output is quadruple a single channel at 4 ohms.

Why is that still wrong? Because each channel isn't really used as a single channel. You've used part of one channel, and an inverted part of another channel to create a totally new channel, the bridged channel. Also, there's no way for a channel to "see" only part of a circuit. If it's "seeing" half the speaker, it's "seeing" it all.

Second, it makes it awkward if people believe that the impedance is really, literally, changing. If you use that model, is it safe to run a 4 ohm mono stable amp into a 4 ohm speaker? It should be, but we just said the impedance halves, so that's now a 2 ohm speaker, and you can't use it. That's wrong, and confusing, and it makes people think they can't do things they really can.

Can I bridge my 4 channel head unit?
Generally, NO. Unless the manuals that came with your head unit specifically state that your head unit can be bridged, then do NOT attempt it -- this could destroy the head unit's internal amplifier, and possibly void your warranty.

What is "mixed-mono?" Can my amp do it? ]
Some amplifiers which are both bridgeable and able to drive low impedance loads also allow you to use mixed-mono mode. This involves driving a pair of speakers in stereo mode as well as simultaneously driving a single speaker in bridged mono mode off of ONE pair of the amp's channels.

To do this, you connect the mono speaker (typically a subwoofer) to the amp as you normally would in bridged mode, and then connect the left and right stereo speakers to the left and right stereo channels, respectively.

However, for this to work, the amplifier must actually use both input channels in bridged mode. Many amplifiers, when placed in bridged mode, will simply "copy" and invert either the left or the right channel. This practice ensures high output to the mono speaker, but eliminates the possibility of mixed mono since you lose one channel.

It is VERY important to use passive crossovers when configuring your amplifier in mixed-mono mode in order to keep from overloading the amp. The reason almost all new amplifiers are able to run in mixed-mono mode (even if they are only 2-ohm stable) is that the impedance seen by each channel of the amplifier is the same across the entire frequency spectrum when using passive crossovers. Here's how it works: Take a typical 2-channel amplifier that is stable to 2 ohms (stereo) or 4 ohms (mono). When the subwoofer is connected with a low-pass crossover (at 100Hz, for example) then the amplifier "sees" a 2 ohm load on each of its channels (see 3.5) from 100Hz and down. When the full range speakers are connected with a high-pass crossover (at 125Hz, for example), the amplifier "sees" a 4 ohm load on each of its channels from 125Hz and up. The passive crossovers prevent the amplifier from seeing more than one speaker on either channel at any given frequency. Of course, between the two crossover points the amp DOES see more than one speaker (and therefore the load on the amp dips to 1.33 ohms when using 4 ohms speakers).

What does "two ohm stable" mean? What is a "high-current" amplifier?
An X-ohm stable amplifier is an amp which is able to continuously power loads of X ohms per channel without encountering difficulties such as overheating. Almost all car amplifiers are at least four ohm stable. Some are two ohm stable, which means that you could run a pair of four ohm speakers in parallel on each channel of the amplifier, and each channel of the amp would "see" two ohms. Some amps are referred to as high-current, which is a buzzword which indicates that the amp is able to deliver very large (relatively) amounts of current, which usually means that it is stable at very low load impedances, such as 1/4 or 1/2 of an ohm. Note that the minimum load rating (such as "two ohm stable") is a stereo (per channel) rating. In bridged mode, the total stability is the sum of the individual channels' stability.

spark plugs.

any info you feel should be added or any questions...feel free to p.m. me

bassisliffe

EBP_SI

Lots of good info but i noticed a couple of things.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">What tools should I have in order to do a good installation?

Electrical tape
Make sure you get some that can withstand extreme temperature ranges. </TD></TR></TABLE>

I've never encountered a job whether it be a stereo install or anyhing to to with my work which is 90% electrical in which i've needed to use electrical tape. please dont tell me this is for making wire connections. what do you usually use it for?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">For some components, like head units and equalizers, it's acceptable to use the stock wiring for power. However, amplifiers generally require large amounts of power, and accordingly will draw large amounts of current
</TD></TR></TABLE>

this used to be true but with a lot of the new head units claiming to put out 60W x 4 or something similar, the manufacturers recommend running a separate 10awg wire directly to the battery. If you're using an external amp then this doesnt apply.

ShaunRR

This thread is a great idea

spark plugs.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EBP_SI &raquo;</TD></TR><TR><TD CLASS="quote">Lots of good info but i noticed a couple of things.


I've never encountered a job whether it be a stereo install or anyhing to to with my work which is 90% electrical in which i've needed to use electrical tape. please dont tell me this is for making wire connections. what do you usually use it for?

this used to be true but with a lot of the new head units claiming to put out 60W x 4 or something similar, the manufacturers recommend running a separate 10awg wire directly to the battery. If you're using an external amp then this doesnt apply.
</TD></TR></TABLE>

i agree completely with what you're saying, but there are those out there who either have NO experience with soldering or just won't be bothered and would rather use electrical tape. i don't recommend it. There are also a few instances (i'm not feeling to really think of any) where using a little electrical tape is necessary.
re: the 10 awg wiring for the head unit...in ANY installation, i recommend upgrading the wiring. better wiring does help produce better signal. as per now, i've only seen a few manufacturers that are requiring this wiring upgrade (i.e. alpine). it's always best to check with manufacturers specs.

Thanks: Xsi, n00ber, bassislife, and rochesterricer

spark plugs.

Should I buy a detachable faceplate or pullout CD player?
It is getting difficult to find pullout CD players any more, since detachable faceplates are much more convenient to carry around. However, there is the obvious trade off -- it is still possible to steal the chassis for the detachable face unit, when that is not possible with a pullout. Although some companies will advertise that it is very difficult to get replacement faces without the original receipt, thieves can still get the faceplates.

Some companies, such as Eclipse, are starting to offer alternative methods for preventing theft. Some Eclipse decks now offer ESN (Eclipse Security Network), where the owner chooses a "key" CD that must be inserted to "revive" the deck should it lose power. The entire deck stays in the dash, with nothing to carry around; this expands on the trend towards convenience while offering the owner peace of mind.

What are some good (and bad) brands of CD head units?
Generally, Alpine, Clarion, Eclipse, McIntosh, Phillips and Pioneer are considered to produce good quality CD head units. They all have their problems, but these brands seem to be common and relatively problem-free.

Bad brands include Kraco, Radio Shack, Rockwood and other "bargain" brands.

Can I use my portable CD player in my car? Won't it skip a lot?
You can use any portable CD player in a car provided that you have either an amplifier with line level inputs (preferred) or a tape deck. If you have the former, you can simply buy a 1/8" headphone jack to RCA jack adapter and plug your CD player directly into your amplifier. If you have the latter, you can purchase a 1/8" headphone jack to cassette adapter and play CDs through your tape deck. The cassette adapters tend to be far more convenient; however, there is a significant tradeoff: by using cassette adapters, you limit your sound to the frequency response of the tape head, which is sometimes as much as an entire order of magnitude worse than the raw digital material encoded onto the CD itself.

Portable CD players which were not designed for automotive use will tend to skip frequently when used in a car (relatively). CD players that are specially designed for automotive use, such as the Sony Car Discman, tend to include extra dampening to allow the laser to "float" across the bumps and jolts of a road. Some people have indicated success with using regular portable CD players in a car when they place the CD player on a cushion, such as a thick shirt or even on their thighs.

Are those FM modulator CD changers any good? What are my other options?
Almost all manufacturers offer an FM modulator for their changers. As with all equipment, some are good and some are not. A person thinking about using an FM modulator must take into consideration that the sound quality will only be as good as the tuner in your head unit. Also, FM is limited in its frequency response. There is usually a noticeable loss of the high frequencies, due to the nature of transmitting via FM.

If you do not want to use an FM Modulated CD changer, some manufacturers make controllers for changers that feature line-level (RCA) outputs. This allows you to connect the changer directly to an amplifier, bypassing the stock system altogether. Some models offer line-level inputs, allowing you to connect the stock system to the changer (so you can continue to use your radio/tape). Clarion, Sony, and Kenwood make such units.

Your third option is to use the aftermarket changer that corresponds to the stock unit in your car. Not all cars have this option, but it is becoming easier

What kind of changer will work with my factory head unit?
Many factory head units these days have the ability to control a remotely mounted cd changer. Generally, the head will have a button labelled "CD" to switch sources to the external changer. In this mode either the radio preset buttons and/or the tuner up/down buttons will control which CD and/or track is playing. Check your car's manual to make sure your head can control a changer and how the buttons work.

Once you know your head can control a changer, you wonder "What kind of changer will work with my factory head unit?" Of course, the one the dealer wants to sell you will work. However, the dealer makes lots of money selling you a changer, and there are often other after-market solutions, usually involving an adapter cable and a name-brand changer. The dealer will tell you that their solution is better and that's why it costs so much more (often more than twice as much as an aftermarket solution).

The car manufacturers are constantly changing the interfaces between their heads and changers, in an effort to get you to buy their solution. However, the after-market is constantly reverse-engineering the interfaces and providing alternative solutions for the cost-conscious consumer.

Two companies that make such adapters are Precision Interface Electronics (or PIE, http://www.pie.net) and Peripheral Interface Components (http://www.stinger-aamp.com/peripheral/s-ind.htm). Check their web sites to see if there's an adapter for your car's factory head. They also list which changer(s) will work with their adapters.

For example, many of Honda's late-model heads were made for them by Alpine, so the OEM changer you'd pay your friendly Honda dealer ~$700 for is essentially the same as Alpine's changers. The only difference is the interface wiring, where they swapped two pins, specifically so you'd have to get it from the dealer. (If you're interested in the details, see http://integra.cyberglobe.net/....html). The after-market adapters for this head simply swap the pins back, so you can use the regular Alpine changer, which can be bought for ~$300.

Once you know which adapter/changer combo will work, you can get it from your local car audio dealer or favorite mail order place. The advantage of getting it from a local dealer is that they'll be able to install it for you. However, if you have the time and are at all mechanically inclined, you should readily be able to install it yourself.

Why do I need a center channel in my car, and how do I do it?
If a proper center image isn't achievable via a two channel configuration, installation of a center channel can help. Since the majority of recordings are done in two channel, a two channel system designed correctly should be able to reproduce a center image which was captured during recording. A center channel is not simply a summation of the left and right channels, like bridging an amplifier; rather, it is an extraction of common signals from the left and right channels. This usually means the lead vocals, and perhaps one or two instruments. These signals will then be localized to the center of the stage, instead of perhaps drifting between the left center and right center of the stage. A signal processor is usually required in order to properly create a center channel image. The image should then be sent to a driver in the physical center of the front of the car, at an amplification level somewhat lower than the rest of the speakers. The correct frequency range and power levels will depend on the particular installation, though a good starting point is perhaps a pass band of 250-3000Hz at an amplification level of half the power of the main speakers (3dB down).

Should I buy a sound field processor?
Sound field processors (also known as DSPs) are fun toys to play with, and can have some use, but it is generally good to keep the KISS principle in mind: Keep It Simple, Stupid.

The fewer signal processors (this includes equalizers, and active crossovers) that are in your system, the less chance there will be for noise to enter your system. You'll also save money, have a lower noise floor. Surround sound processors and bass regenerators are nothing more than bells and whistles and are totally superfluous in a properly designed system.

I keep hearing that speakers for Company X are made by Company Y. What's the deal?
Many of the speakers you've ever purchased or ever will purchase have been assembled in plants "along side" speakers from other manufacturers, but that does NOT imply in any way, shape or form whatsoever that the two brands are even VAGUELY similar. This is often done in order to reduce costs because purchasing your own gaussing stations and mass producing your own drivers takes a LOT of money to implement.

EBP_SI

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by spark plugs. &raquo;</TD></TR><TR><TD CLASS="quote">

i agree completely with what you're saying, but there are those out there who either have NO experience with soldering or just won't be bothered and would rather use electrical tape. i don't recommend it. There are also a few instances (i'm not feeling to really think of any) where using a little electrical tape is necessary.
re: the 10 awg wiring for the head unit...in ANY installation, i recommend upgrading the wiring. better wiring does help produce better signal. as per now, i've only seen a few manufacturers that are requiring this wiring upgrade (i.e. alpine). it's always best to check with manufacturers specs.

Thanks: Xsi, n00ber, bassislife, and rochesterricer
</TD></TR></TABLE>

re: electrical tape

I understand abotu people not wanting to solder but what about going to your local hardare store and buying a dozen butt connectors if you're installing a head unit. its neater, it a better connection and its easier to do than electrical tape.

re: 10awg wire

i've seen that recommendation from pioneer too.

spark plugs.

again, i agree with you completely.
soldering is the best because:
1. it looks neater
2. it's the most reliable connection
3. provides the LEAST resistance through the line.
if you want to take your time and provide the best/cleanest/most reliable install, do what is necessary. EVERYONE has used electrical tape on their electrical needs at some time or another. if you say you haven't, you're only fooling yourself. i used to use it and it did it's work fine. i'm more knowledgeable now and take it a little more seriously, so i solder EVERY connection.

weezo182

ShaunRR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bassisliffe &raquo;</TD></TR><TR><TD CLASS="quote">make this topic STICKY! </TD></TR></TABLE>

I'm not sure that will happen.

I mean, is there even a mod for this section?

ShaunRR

They usually don't bother deleting posts like this from what I have seen.

If you want to contact a mod go ahead, but I think it would have to be a global mod.

EBP_SI

umm...hasnt this post been a sticky for a few days now??

spark plugs.

for the most part, i've seen that this forum is ignored by most. (i guess a lot of people don't have audio/security/video questions), but that's a good thing, right? i've just noticed that when someone DOES post a question, it takes a while to get an answer just because of the negligence towards this forum. i've just decided to compile a quick FAQ for those that can get some easy answers from it. i've spoken to a mod and it is a sticky. he will have to speak to other mods before they can decide if it will be a permanent sticky. Thanks for those who appreciate this thread! Hope it's helpful!

foz

frkn awsome, this forum has needed a thread like this one!

for Spark plugs

a good link for finding manufacturer's website is

http://www.meisearch.com it's a search site designed specifically for the 12V industry