Let's start with the basics. Subwoofers play low notes. Subwoofers have what's called voice coils. Voice coils cause a magnetic field when energised, hence moving the cone. You can have a sub with a few different configurations, typically SVC and DVC. Voice coils will have an impedence, such as 4 ohm and two ohm. For some specialty speakers, they'll have 6 ohm voice coils.
Ohms are a measurement of resistance. For amplifiers, when you put more of a load, the distortion increases. Keep that in mind.
SVC stands for Single Voice Coil.
DVC stands for Dual Voice coil. Dual voice coils MUST
have both voice coils wired up, either in series or parallel.
Both positive leads are wired together, both negative leads are wired together, and leads go out to your amp or another speaker like so:
You'll notice that the speaker is a dual 4 ohm voice coil sub, and wired in parallel. When wiring voice coils in parallel, take the impedance of the voice coils, these being 4, and divide it by 2. That'll give you your impedence. For this example, your impedence will be 2 ohm.
Positive from Coil A is jumpered to the Negative of Coil B. The negative from Coil A and Positive of Coil B go out to your amp or another speaker like so:
You'll notice that the speaker is a dual 4 ohm voice coil sub, and wired in series. When wiring voice coils in series, take the impedance of the voice coils, these being 4, and double it. That'll give you your impedence. For this example, your impedence will be 8 ohm.
The most common dual voice configurations are dual 4 ohm and dual 2 ohm. A single dual 4 ohm sub can be wired to 8 ohm or 2 ohms. A single dual 2 ohm sub can be wired to 4 ohm or 1 ohm. Two dual 4 ohm subs can be wired to 4 ohm or 1 ohm, and two dual 2 ohm subs can be wired to 2 ohm or 1/2 ohm.
Amplifiers come in many shapes, sizes, colors, makes and brands. We'll do the most common ones. There are a few types. Class A/B amps are usually good for 2 ohm stereo or 1 ohm mono. Class D, X, Digital, etc... Are usually monoblocks and good for 2 ohms or less.
MAKE SURE TO CHECK WITH YOUR AMPLIFIER MANUFACTURER TO SEE WHAT LOADS YOU CAN OR CANNOT PUT ONTO YOUR AMP AND PROPER WIRING
Monoblocks are a 1 channel amp. Sometimes they have 2 sets of RCA's in, sometimes only one. Monoblocks are used primarily for subwoofers. These are your Class D, X, Digital, etc... amps. Most are good to 2 ohm. Some are good to 1 ohm, and very few are good to 1/4 amp. Some monoblocks are called High Current. They'll play with higher voltages to them, usually 14.4 volts.
Two Channel Amps:
These are a stereo amps, a left and a right channel. Most stereo amps are good for 2 ohms stereo, and most two channel amps can be bridged to play a subwoofer, and are usually good to 4 ohm.
Four Channel Amps:
Four channel amps are used to run 4 sets of speakers, usually front/rear. They have independent gains on the front and rear. Some 4 channel amps can be bridged to 3 channels or 2 channels. Some can do 2 ohm stereo, and those that can be bridged to 3 or 2 channels can usually run a 4 ohms.
Tuning your amps
The simplest and easiest way to get your amps tuned is to follow these simple instructions. Grab your digital multimeter and a calculator.
output = square root (watts * ohms)
First, take your amp's wattage at load. For example, let's say your amp does 300 watts rms at 4 ohm. That would be 1200. Take the square root of that and you'll get 34.64101615137755, so let's say 34.64. Take your multimeter and set it to AC
volts. Disconnect your speakers from the amplifier. Grab this file here - http://www.realmofexcursion.com/audio/testtones/20Hz_to_120Hz.mp3
- and burn it to a cd. Turn your eq's off, turn your volume to 3/4 of the way up, hook up your multimeter to the + and - of the speaker outputs and play the sine wave. Your peak voltage should hit at the beginning of the cd - adjust your gain till it reads the voltage you figured out earlier, then leave it. Hook your speakers back up, and your gain is set. Don't turn your volume up above this volume or else you'll clip.
Since your speaker outs are AC voltage, you have an AC wave, with a peak and a valley, usually symmetrical. When your signal is clipped, you'll have an extreme valley or peak, deadly for speakers.
Storage devices/Energy makers
Everyone gets the wrong idea about capacitors. THEY ARE NOT A BATTERY. They do store energy, but for car audio, they're used to fill valleys and level out peaks when you have a long bass note. They are used to clean the signal only.
Batteries, without them, your car won't start. Yellow top optimas and deep-cycle batteries are wonderful for car audio. They have higher storage than regular batteries, and they can be discharged and recharged safely. They are also a closed battery, and can safely be put inside a trunk without having fumes.
Our stock alternator puts out around 75 amps at an idle and 120 at around 2000 rpm. They do make higher output alternators but MAKE SURE YOU CHECK
and see what it puts out at an idle. Some will put out stock at an idle and make max at 3000 or 4000 rpm. Make sure the amperage is higher at an idle or else you could cook your alternator, battery, or both.
The BIG 3
This post here - http://www.j-body.org/forums/read.php?f=4&i=117446&t=113629#117446
- written by Wysiwig, is a wonderful resource on the Big 3. You'll notice less dim when the bass hits, quicker starting, and less strain on electrical devices.
This sums it up. If you should have any technical questions, myself, Wysiwig, Soundsgood, Lash, n8ball2013, cavi sedan ls, cavi in kc, unholysavage, and sweetnloud can help you out. If I forgot anything or anyone, I apologise.