Here's something I wrote up for my home forum. Some is covered above. This is a very basic faq that I have been adding to on my home forum in my spare time:
The golden rules:
1) 90% install 10% product
2) ALWAYs, ALWAYS unplug your battery whenever you do any kind of electrical work
Also, don't forget, a system isn't a subwoofer and amp, it's a well rounded stereo system including head unit, speakers, sub, and amps.
If you have a what to get question, feel free to include a few helpers:
1) match oem colors
2) price range
3) what functions do you need from it? ipod, processor control, navigation, etc
4) any experience you've had in the past (had x head unit and y subwoofer / first timer and have no experience)
5) sacrafices you're willing to make (cost, size, sound, functionality)
What should I buy? threads
It depends on a lot of factors. How much are you willing to spend? How good of an install can you perform? Most will recommend head units first, then speakers, then amps, then subs.
If you're happy with the sound of the stock system but want a little more, personally, I advocate using sound deadening on the doors. It's the cheapest and probably most cost effective if you're happy with stock. Brands include elementaldesigns.com secondskinaudio.com raamaudio.com dynamat, and peel and seal (roofing tape)
Audio basics: head units
There are many great brands. The most recommended will always be Pioneer and Alpine. Other great brands include Eclipse, Nakamichi, and the Excelon line of Kenwoods.
Some headunits have more functionaliy than others. Some let you do everything from your seat. Others, you have to have post-headunit equipment to do all the sound manipulation work for you. Some, like some Alpines and the Pioneer P9, let you attach processors directly to the unit and have all the control from your seat.
What kind of controls can you get? Well, crossovers, equalizers, and time alignment are the most common. What are they?
-Crossovers block frequencies from reaching the speakers. There are two types of filters. One is a Low Pass which lets all of the low speakers "pass through" the filter. You use this for subwoofers and depending on your install, midwoofers. High pass lets all of the high music go through and blocks low frequencies. This is for some midwoofers and tweeters. You use a crossover to block sounds that the speaker can't produce properly or may damage the speaker. Most head units don't have equalizers, but the good ones do. Crossovers aren't brick walls, however. They have what's called slopes. These slopes change the rate that sound drops off, the higher the slope, the faster the drop-off rate. Here's how to set your crossovers.
-Equalizers allow you to increase or decrease certain frequencies. The human ear can hear 20-20,000 hz (lower the hz the deeper the note). Say you're lacking output in the 500hz region, you can bump it up. Most headunits typically have bass, treb, and high equalizers. 100hz, 1000hz and 10,000-15,000hz typically. The more levels of equalization you have, the better you can adjust the sound. Equalization is NOT a means for producing more bass. It can't fix unproperly set up equipment. This can be often done by a well trained ear, however[url=http://www.diymobileaudio.com/forum/showthread.php?t=17] here's how to do that, right.[/b]
- Time alignment lets you tell the head unit to pretend a speaker is closer or farther away from you. This adjusts the pathlengh of the speaker (distance away from you) to make it seem like all of the speakers are equal distances from you. Most head units don't have this, although the good ones do.
- Other features: most head units give you rca out and few give you optical out. These are connections that run to either amplifiers or external processing and are VERY helpful when setting up a stereo system. The difference is RCAs use an analog signal while toslink/optical use a digital signle that's completely immune to noise. Voltage of the RCAs don't make much of a difference and should only be your deciding factor if everything else is dead even (and you're using amplifiers). RCA's can be substituted by using a line out converter, which converts speaker wires into RCAs. Line out converters can also be used for using the stock headunit with an aftermarket system.
How to hook up a head unit:
Headunits don't require anything fancy to turn on and opperate. At the bare minimum they need power, ground, accessory, and wires to the speakers. Power is just a +12v signal from the battery. Ground is a wire going to the chassie. Accessory is a +12v signal wire that turns on whenever the key is in the accessory (or on) position.
Unless you're doing a custom install, the easiest thing to do is get a wiring harness adapter. These typically run 10-20 dollars and can be found any any Walmart, Best Buy, Pep boys, Circuit city, etc. They attach the special propreitary (only for this specific unit) head unit harness to the stock harness without cutting or splicing any wires. On MOST harness adapters, the colors are coordinated with the headunit's wire colors (these are standard, so just match the colors and the stripes). Most also have the description of the wire's function printed on the wire itself.
Wires on the harness adapter are as follows:
red: accessory - VW harness does have an accessory wire, except the new metra harnesses don't correctly tap into it. You MUST run a new wire if you use the metra harnesses. If you use an older harness, you can use the in-harness accessory line. For running a new line, the easiest places are a black wire with a gold stripe behind the fuse box under the dash, or a brown wire with a red stripe in the ignition column. The black with gold stripe is just a switched 12v line. The brown/red wire is the key-in wire. Once the car has been turned off, as long as the key is in the ignition, the radio will still operate (similar to the power windows).
black: ground - This wire needs to go directly to the chassie. See below for good grounding procedures.
yellow: power (or mem or vmem) - this wire always gets 12v from the battery. It's how your radio keeps it's time and settings.
orange: illumination and/or brightness - usually useless. I personally haven't ever seen them work. Illumination slightly dims the headunit when the head lights are turned on and brightness adjusts the brightness of the head unit in conjunction with the brightness of the interior lights. brightness rarely if ever owrks
Blue: Accessory out - this is for turning on external amplifiers and units. When the radio is on, this wire gets a 12v signal. You should string no more than 3 devices to this wire unless you use a relay (see below)
blue-white stripe: power antenna - some vehicles have an antenna that extends whenever the radio is turned on - that's what this is for
green/white/purple/gray and stripe - these are for the interior speakers. white spkr wires: driver-side front
gray: pass side front
green: driver side rear
purple: pass side rear
Audio Basics: Speakers
There are millions of these for every application imagineable - more than you would realize and more than I care to remember. They fit every application and price range. These are best left to specific thread details, however, here's a few points
- Each speaker is an electronic device called an inductor. At rest, the speaker has a fixed resistance. This resistance is a good tool in measuring the power applied to the speaker. The most common resistance is 4-ohms. As the number of ohms increases, the resistance increases. 0-ohms is a direct short. The resistance of the speaker changes with several factors, including the design of the enclosure, heat of the speaker, frequency played, amount of power applied, and natural resistance (impedeance) curve of the speaker.
Amp or head unit power?
- head unit power typically works but amped will ALWAYS sound better
Midbass vs Midrange vs Tweeter
- midbass are woofers specifically designed to play almost subwoofer frequences to the top of most male vocals. Midrange are for most of your vocals and most of the music you hear. Tweeters are for high sounds, cymbals, beeps, boops, etc. Most midrange also function as midbass.
Component vs coaxal vs braxial
- component have a crossver between the tweeter and woofer (inbetween amp and speakers) and the tweeter is a seperate unit from the midwoofer. Coaxial have the tweeter mounted directly on the midwoofer and crossover built into the speaker. Braxial are a mix of both, sometimes having a crossover, sometimes not, but the tweeter can be mounted anywhere or on the midwoofer like a coaxial.
2-way coaxial vs 3-way and 4-way and etc
- Anything past 2-way coaxials just add supertweeters to play really high frequencies. They're typically really harsh sounding and a pure marketing gimmic to lure in the gullable.
Oval vs round (vs square and whatever shape)
- Oval (6x9's) have more surface area than round speakers, however, distort much easier making them sound worse. The best theoretical shape for speakers is round as it provides the best ridgitiy.
How much power can the speaker take?
- Each speaker is different in the amount of power it can handle. Some can handle more than advertised power, and some can't ever handle advertised power. This comes from how the speaker is tested - which there is no industry standard for. How much power the woofer can take relies on the cooling abilities, design of the enclosure, and quality of materials the speaker can handle. Usually rated power is close to what should be applied, however, in extreme cases, some speakers can handle over 10kw of power.
Heat and Cooling
- Each speaker naturally cools itself. If it didn't it would burn up right away. The movement of the speaker is what forces air over the internal components. When a speaker is driven too hard and the cooling can't keep up, then parts begin to break down and the speaker will die.
Matching speakers and amplifiers
- My amp does 50wrms and my speakers are advertised to take 50wrms. Is this safe? Most likely. Advertised numbers are usually conservative to begin with. What you have to realize is there are several factors at play. Typically advertised power for the speaker is thermal, meaning a value for heat, whereas the power for amplifiers is just that, the power it produces. Next, amplifiers RMS power is the maximum unclipped power the amplifier produces times .707. As a personal rule, I always use an amplifier that's capible of producing more power than the speaker is capible of. I do this because I like the headroom and ability not to go into clipping (see below).
Audio Basics: Amplifiers
The only thing really you can say about amps is they go between the headunit and speakers to provide more power to the speakers. That and you get what you pay for. Some amps are really high quality, some are better used as door stops or target practice. Amps to avoid are Sony, Boss, Pyle, Pyramid, Audiobahn (avoid everything from them) and anything else really cheap.
Amplifiers power is displayed as RMS power. This is the maximum unclipped power times .707. Clipping is when the sound wave producted (normally a nice smooth curved sin wave) starts to square off. When this squaring occours, the amplifier produces twice the total power. You would think this is a good thing, more power, however, due to the nature of the wave, it will actually damage your speakers. The best way to control clipping is properly setting your gains, as seen here
. Clipping not only damages your speakers, but will also damage your amp.
Some amps have crossovers in them, some have other features. Mostly these extra (non-crossover) features are a marketing gimmic.
Some amps make rated power (what you're told) and most don't. Most amps are tested at 14.4v, which in a car you will never get. You'll get approximately 13-13.5v. The good amps are rated at 12v and will actually make more power than advertized. The better companies send sheets that show the actual power produced by the amp, called a birthsheet.
Amps put out certain power at certain "loads". A load is how much resistance a speaker has. Typically, the lower the load (smaller the number), the more power an amp will make. Most amps are stable to two ohms, some only 4, and some as low as .24ohms. In contrast, most speakers are four ohms. When the load is too low, the amplifier can go into protect mode, which is a "safe mode" for the amplifier that it may or may not come out of.
Some amps are bridgeable. What this means is that you can turn a two channel amp (left and right) into a single channel and get more power out of it.
Placement of amplifiers depend greatly on the amplifier. Some amplifiers get hotter than others, though, so their placement options are limited. Most amplifiers can be mounted anywhere or in any position. The heatsink of most amplifiers are designed for the amp to be most effective when the amp is mounted vertically. As long as there is airflow over the amplifier, it can be mounted in any position. This is how in show cars the amplifier can be mounted under plexy or in ampracks.
Audio Basics: Subwoofers
Sub x vs Sub y - search for the name of a sub, then post. Like woofers, this is better handled in a case-specific thread.
Things to look for:
SPL vs SQ
- this is how loud a woofer gets vs how good it sounds. Some can do both. What a sub can do is 100% dependant on the enclosure type
Sealed vs Ported vs Freeair vs Bandpassed.
- Sealed is just a sealed box, no holes. They're sonically accurate but inefficient and require more power to get louder
- Ported is a box with a hole in it, but the length and size of the hole are tuned to get extra output at a specific frequency. The box is more efficient, but requires lower power and the ability to properly design the enclosure.
- Freeair is no box, the woofer just sits there. It's not good for your speakers because you won't get any noticeable output and will damage the woofer.
- Infinate baffle is similar to free air except better =). It's technically 10x VAS (which just means a really really big sealed box. They are not very efficient (don't get as loud) and require lower power, but with the right woofer, can be sonic bliss
- Bandpass is simlar to a sealed box except the woofer fires into another box, which has a port tuned for a certain frequency. These are very efficient, the loudest of the boxes, at the cost of sound quality. They can achieve a flat response, but can have all kinds of delay and/or phasing problems.