Line Drivers

One thing that’s inherently hard in building mobile audio systems is the amount of crosstalk that impinges the audio signal being transmitted, such that when it arrives on the sound medium, the reproduced sound’s noise floor is evident. This is a serious aspect on wiring audio systems on wider topography such as a movie theater or an auditorium setting. But on mobile setting, such as in car audio, the problem of crosstalk and noise floor is on another platform.

Especially in car audio system, audio signals are very much hampered by the excessive amounts of noise floor, thermal noise, blackbody, sound bleeding, and crosstalk available. This could be signal distorted by the running engine, the temperature of engine, and the amount of shock it produces.

The problem is further escalated when the amplifiers not only pick up these low voltage audio signals, the amps also picks the noise floor the signal has picked up along the way. And you know that the lower the input voltage a signal has, the greater the gain will be to produce certain loudness. And the larger the gain is, the more evident those hums and buzzes will be. And sometimes you’ll never know that the problem is the noise floor and the crosstalk.

Gain is, by the way, the mean ratio of the signal output from the signal input of a system.

And the Line Driver is the device that, should they be implemented correctly, may help eliminate woes concerning those infernal noise floor.

Professional audio installers prefers to use balanced line drivers, because of all the designs of line drivers, balanced line drivers have the highest probability to produce the least distorted sound. And you should know by know there’s no way to effectively eliminate these noise floor and crosstalk. You only have to lessen its amount of effect. This line driver info should hopefully help you plan for the best disparity free audio system.

Let’s start by marking out the difference of standard (or unbalanced) line drivers to balanced line drivers. Standard line drivers, the ones that are usually encountered on conventional hi-fi system, use an RCA connector where it feeds the audio signal through a coaxial cable. If you have understanding about coaxial cables, you’d know that coaxial cables are excellent materials in preventing interference. The inner core of the coaxial cable carries the audio signal. The outer sheath that wraps around this inner core is a screen that prevents RF interference (in the form of general airborne noise) from being picked up by the audio signal.

The only problem is that, signals do attenuate, and when it attenuate, no amount of sheathing can protect it from picking up general airborne noise. Also, since we are talking about low voltage electricity, one of its most common and a dreaded aspect is the ‘hum’, signifying the attenuation of a signal. Line drivers serve to eliminate all these by signal amplification. As was said earlier, the lesser the gain in an audio signal, the less amount of noise floor will also be evident.

Another problem with audio signals, or for a more general term: electricity is that they are ruled by governance that makes them take the shortest paths of least resistance. So when two pieces of wirings are bind close, they generate signal garble what you will hear on the speakers as “hum”. If ever there’s a sound of void, that hum would be it.

Quality line drivers normally a high output impedance, around 30 ohm. Line drivers such as this are able to transmit a signal boost of up to 20 decibels. On a car audio system, this is fairly enough to ‘mute’ the surrounding interference and yes, lower the needed gain for amplifiers.