Khurram Bhai ... I feel a little reluctant to write on this issue since my gurus Madhouse/ STJ/ DrShaggy/ Mani1 will also be reading this .. however, let me give it a try
The thickness of a wire is measured in x gauge. The maximum diameter that I have personally seen in cars is 0 Gauge. In order to determine what diameter wire is appropriate for your system .. there are two factors ... RMS load and the distance between the battery and the amplifier.
For example ... a system with RMS power rating of 100 watts would require 10 Gauge wire for distance of upto 8 ft. If the distance increases from >8ft and <16 ft, then you will need power wire of 8 gauge. If the distance is >16 ft and <20 ft, then you need a wire of 4 gauge.
Another example, if your system power is RMS 1400 watts ... then for a distance of <4ft, you will will need a 4 gauge wire, but if the distance increases >4ft and <20 ft, you will need a 2 Gauge power wire.
In simple terms, a distributor is a "splitter" ... My car's system is designed to have 4 amplifiers. For this purpose, we need to have appropriate power wires running from the battery upto the amplifier. Attaching four thick wires to a single battery terminal is not a wise decision. It looks ugly and also results in loss of substantial power loss. For this issue, distribution blocks are used.
As you have seen the gold plated distribution blocks earlier in this thread, the input 2 gauge wire is connected at one end. This power is divided into 2 power outputs of 4 gauge. I am using the distribution blocks with two fuses each of 60 amperes. The output 4 gauge wires carry the current to the target amplifiers. The gold plated terminals ensure perfect conduction and current flow. Linked with previous part of my reply, the approximate distance between the distribution blocks and battery in my car will be approximately 5 meters, therefore, 2 gauge wire is required. Further down the circuit, distance of about one meter will be involved between the distribution blocks and the amplifiers, therefore, 4 gauge wire will be used for this shorter distance.
Heavy audio systems draw a large amount of power for their operation. When the low bass frequencies hit, the power consumption increases .. this results in sharp spikes in power consumption. You must have observed the headlights dimming and flickering when the low frequencies hit ... Most people think that a larger battery is the solution. I would tend to disagree. A battery is primarily used to start the engine. After the engine starts, the power is drawn directly from the vehicle's alternator. As per my knowledge, a car's alternator is designed to provide 30% more power than the average/ ordinary requirements of a vehicle. The alternators that come with the vehicle are not designed to meet the power requirements of heavy systems. Now when you have a heavy system, it draws heavy amount of current from the alternator .. but since the alternator does not have enough power, then the additional power requirement is met from the battery. This drains the battery and also reduces the battery life. For heavy systems, the cars need a larger heavy capacity alternator coupled with comparatively larger battery.
Now coming back to capacitor's function ... it is not a replacement for a large alternator or a large battery. It comes handy in meeting the "emergency" power peak requirements ...
The capacitor is installed as close to the amplifiers as possible, so that the quick/ emergency power requirement can be met through a shorter length circuit. In my car's system, 2 gauge wire running from battery will go to the capacitor installed in the trunk. The power wire from capacitor will feed the distribution blocks.
There is a simple formula to determine the power of capacitor, measured in Farad. For a system with RMS power requirement of up to 1000 watts needs a 1.0 Farad capacitor. For a system of RSM 2000 watts, you need a 2.0 Farad capacitor. My car's system requires a 2.0 Farad capacitor, but I have ordered a 10.0 Farad Hybrid capacitor. Having more power capacity of a capacitor does not hurt ... but it should not be below the prescribed formula of 1.0 Farad for each 1000 watts RMS power.
@ Gurus >>>> Please correct me if I have made a mistake in above post. I am a newbie in audio world ... so your guidance would be very helpful in my learning process.