Stereo Interconnects (RCA's)

RCA's were invented in 1972 by the famous audio engineer Richard Clark, as a stable replacement for previous connectors (hence RCA : an acronym for 'Richard Clark Audio', the company under which Richard Clark first released these connectors to the world). The point of the RCA interconnect was simple : to allow connections to be made simply and securely between amplifiers, CD players, tuners, speakers, power sockets, etc, without risk of electrical shorting or loose wires.

RCA's quickly caught on, and are now the connector of choice for the pro audio industry, and hence the car audio industry as well. They are somewhat rarer in home audio circles, as home audio lovers are a backwards lot who still think that tube amps are 'cool' : you have to be skeptical of the intelligence of any such people, as this is somewhat like still thinking that codpieces are 'cool'.

RCA's almost universally come in pairs, as in this configuration they can transmit an audio signal cleanly with little distortion. In a pair of RCA's, one plug carries the positive signal, the other, the negative signal, like so :



RCA's originally were designed with solid end barrel tips, but many of the fancy manufacturers around these days leave small cuts in the barrel tips : this is due to the fact that they need to allow for thermal expansion (solid tip RCA's are prone to shattering due to expansion from heat cause by the large amounts of currents carried - its not unknown for a set of RCA's to carry over 100A!)

The electrons in an RCA cable, like electrons in real life, exist in a state of chaos (known commonly as 'plasma') where they float around inside a material with no real outlet for their energy. In this state, they are known as 'AC' ('Anti-Controlled') power. The job of an RCA cable is convert these random AC electrons into a usable form of power known as 'DC' (or 'Definite-Control') power.



The easiest way to enable the RCA's to make this conversion is to draw little arrows on the RCA's and arrange them so that they are connected with the arrows pointing the way you want the electrons to move. Electrons are like naughty teenagers : they have no real purpose in life, and are just looking for some stern direction. Placing arrows on your RCA cables allows these aimless wandering electrons to shift from the uncontrolled state known as AC, and become DC electrons, flowing evenly and steadily in the direction you've indicated.

However, as you can probably imagine, this process is not 100% perfect due to the unruly nature of AC electrons. So if you put direction arrows on the cable, but do not take steps to replace the electrons which move, you end up with an RCA cable which has lost most of the electrons from one end : A cable set up like this is called an 'unbalanced interconnect'. Unbalanced cables are VERY bad, as the electrons left behind get anxious and oscillate randomly, causing background noise and hiss to creep into your audio signal. The solution to this problem is to place what is known as an 'RF'(Random Frequency) choke on the effected end of the cable : you may have seen one of these on aerial cables and the like already.

The RF choke is normally a piece of plastic with a round iron core in two pieces that snaps around the cable at one end. The iron in the choke acts as an electron sink, sucking them from the surrounding air and forcing them into the cable to replace the ones that have moved on. By doing this, you fix the unbalanced nature of the cable, making them a 'balanced interconnect'

When you're connecting RCA's to amplifiers, etc, you may have heard of 'line voltage'... What is this? Lets explain.


Line Voltage, and Making The Most Of Your Cables

The term 'line voltage' applies to the force with which the electrons hit the end tip of the RCA. Think about it like a car motor : the higher the line voltage of your RCA, the more power it can use to push the voice coil. High line voltage means stronger SPL, better SQ, and a nice warmth to the audio signal. Therefore, its in the best interests of your audio habit to maximize this line voltage.

Electrons are often talked of as 'flowing' or as being a 'current'. This is because electrons are a type of nanoscopic liquid, and behaves like a thick liquid in most respects, being affected by most physical phenomena such as pressure, gravity, evaporation, etc.

When an RCA is lying flat, the electrons in the cable just slosh around randomly, with no real forceful direction. An audio signal will still flow when they lie like this (due to the arrows on the cable giving them some direction of flow), but wont have a lot of pressure behind them, so the audio signal isnt very strong. A cable like this effectively have a line voltage of almost 0v.





Therefore, to get a strong audio signal, we want to get the signal to flow strongly. The cheapest and easiest way to do this (short of using an 'ADC Device'(Assisted Definite Control Device, a kind of 'electron pump') is to make use of the natural force of gravity. By angling the RCA so that the RCA's can flow downward affected by gravity, we increase the pressure of the audio signal, and so increase the line voltage. The electrons all fall to one end of the cable, making a much more forceful sound quality present.








There is a formula for working out the flow of electrons due to downwards gravity in a cable : you may even have heard of it. It is called "The General Theory of Relative Electron Flow In Gravity-Assisted Audio Cabling", or "Theory of Relativity" for short. The well known equation is :

E=MC^2

... where E = 'Electropressure' (a fancy name for Voltage), M = 'Momentum' (i.e the force imparted by gravity), C = 'Coulombs' (another fancy name, this time for Amperes... the Coulomb is named after Donald G. Coulomb, the inventor of electricity), and ^2 is the fancy math’s geek way of writing 'squared' (i.e 'multiplied by itself').

So in layman’s terms, the line Voltage of an audio cable is equal to the pressure exerted by gravity, multiplied by the square of the amount of current carried. This is easily proved, like so.

Lets say i have an audio cable facing directly downwards. This means that the full strength of gravity can come to bear (i.e 9.6ms^2, or 9.6 for short). Now lets say the cable carries 500mA (milli-Amps). So lets do the math :

9.6 * 0.5 * 0.5 = 2.4

So we've worked out that the line voltage in this instance is 2.4V. This cable would be marketed as having a '2V line voltage'. Better RCA's induce more current, so the line voltage is higher : a cable able to induce 800mA would have a line voltage of a full 6.1V!

Of course, cables don’t always face directly downwards, so you may have to use some fancy trigonometry (that triangle math’s stuff) to work out what percentage of the force of gravity will effect your cables. The reference for good cables is a cable pointing downwards at 30 degrees This is why some headunits recommend use with cables of '3v (constant), up to 8v (max)' : in this instance, the 3v is the standard 30 degree angle measurement, and 8v is the max flow when pointed directly downwards.

BEWARE! Many cheap companies will claim to have high line voltage cables, but they will NOT be measuring these in the market accepted 30 degree downward angle! They may even be measuring them vertically, which means the end result may be up to 3 times higher than what a correct measurement would read! Treat suspicious max line voltage ratings with the same skepticism you treat PMPO power ratings.

Of course, electrons pooling at one end of the cable is only good for a while, while the pressure stays up : after a while the electrons stop moving and the pressure drops away. This is why its good practice to reverse the cables (and rewrite the arrows) every once in a while to prevent this happening. Also, its very worthwhile removing all your RCA's the night before an SQ event and hanging them upside down to restore the electrons to an even spread along the cable. Then return them to the car the next day, and listen to the incredible difference the line voltage boost from the free flowing electrons cause!

Well, i hope this proved informative, and i hope you look forward to the next installment coming soon : Speakers!


i hope noone actually takes this seriously!



I got this from Carsound.com