I Need What Kind Of Cable? – Making Sense Of Audio Cables And Their Use
Experts do it without even thinking about. Make sure the line levels of all their input devices are correct. All the RCA cables are connected correctly. The XLR cable from the dynamic microphone runs through the DI box to boost and clear the signal to be plugged into the back of the audio interface. You choose to connect your audio interface through the FireWire cable to the computer instead of the USB, as it carries the signal that much faster.
But let's be honest. There was a time when, for all of us, the above paragraph might as well have been written in Greek. At some point, we all looked at our newly bought audio equipment and small mountain of cables with nothing but a sense of sheer bewilderment.
So if you find yourself overwhelmed, its perfectly normal. You will find yourself at ease with all these cables and ports a lot quicker than you might think. In this article the majority of cables and ports will be covered to help you better understand each one's function and use in your home recording studio.
First we need to look at the 2 types of signals carried in cables, and their associated uses.
The Two Signal Types
The signals travelling through your cables can either be digital or analogue. They differ not only in the way the signal travels, but also in speed and quality.
Analogue Signals And Cables
Analogue signals use a continuous wave form, varying from positive to negative, in an electrical charge. They do not suffer from latency (speed or lack of it) issues, unlike many digital interfaces, which still make them the connection of choice for my recording studios.
These analogue waves are susceptible to picking up noise and other external interference. Longer cables tend to weaken the signal strength as well. (This is why the use of balanced cables and connections are so important, as well as DI boxes to boost and balance the signal. More on that later.)
In the past, most signals between audio devices used to be analogue. Today we find an increasing number of digital cables connecting your high end audio devices, but these devices and connections are quite expensive. As a result, many traditional and home studios still stick with analogue connections.
The most important cables and connections associated with analogue signals are:
XLR Connections: These connections are normally associated and used for connecting a microphone with the audio interface. Either a dynamic or condenser microphone can be used with this cable. (A dynamic microphone is "passive" and does not require external power. A condenser microphone is "active" and requires an external power source. XLR cables are able to provide this power directly through the cable with what is called "phantom power".)
XLR signals are balanced with 3 contact points. (Balanced cables use 3 signals to reduce noise. They have a positive and negative charge that balance the noise out, as well as a ground signal.) The contact points can be either male or female.
RCA Connections: These connections are normally associated with connections between hi-fi equipment, but are also used to connect devices like electronic keyboards and traditional turntables to the line-in connections of audio interfaces and mixers.
These cables normally carry 2 signals for stereo input or output, with color-coded connectors for the left and right channel. (Normally red for right, and black or white for left). Sometimes a third connection (yellow) is added for the now familiar composite video with stereo audio connection. Like XLR connections, they also have both male and female connectors. These cables are still very popular with camcorders and older DVD players.
(Please note that RCA cables can sometimes be used for carrying a digital signals as well.)
TRS Connections: These cables are used to carry a single balanced signal, normally from an audio instrument to the audio interface or mixer. The connectors look very similar to your stereo headphone jack and normally come in 2 sizes (3.5mm and 6.35mm).
Just don't make the mistake of confusing TRS connections with the connections at the end of a stereo headphone cable. Headphone connections are not the same and the 3 signals they carry are for the left, right and ground signals. (TRS connections use the 3 signals for the positive current, negative current and ground signal in a order to create a balanced signal.)
Apart from the above mentioned connections, you get quite a few other analogue connections, but many of them are not that relevant anymore, and many others are used in high-end studios, which should not come into play when setting up your home studio.
Digital Signals And Cables
Digital signals also travel via an electrical current, but unlike analogue signals, they make use of binary code (a series of ones and zeros). The result is that there is no loss in signal quality, and it's not influenced by the length of the cable or external sources.
However, they did suffer from latency problems in the past. Sometime the delay between the audio interface and computer can be as long as 0.5 to 1 second. USB 2, and especially FireWire and Thunderbolt connections come close to eliminating the problem completely. With the integration of USB 3, latency should not be an issue at all anymore.
Apart from the digital connection between audio interface and computer, many high-end audio components use digital cables to connect to each other, but are mostly used in top end studios and are quite expensive. Since we are focusing on the more basic and home recording studio, I'm not going to make things more confusing by addressing these connections in this article.
The main digital connections that's really of importance, take place between the audio device and computer. There are mainly three type of digital connections: USB, FireWire and Thunderbolt.
USB Connections: The Universal Serial Bus (USB) was developed by a consortium of computer manufacturers to standardize the input an output ports of all connected devices (printers, scanners, mice, keyboards etc.) It was introduced in 1996, but only really started being widely used in 1998 with USB 1.1 providing a speed of 12 Mb/s. It also provides power of up to 20V to external devices like mice, hard drives, and in the case of audio devices, condenser microphones and low powered PC speakers.
This speed was still too slow to properly handle multiple audio signals, so latency was a problem from the start. Things started changing with the introduction of USB 2 in 2000 when the transfer speed was increased to 480 Mb/s which dramatically increased its performance. The real game changer though, is USB 3 which was introduced in 2008, with the current version 3.2 producing an astonishing speed of 20Gb/s (1 Gigabyte = 1024 Mb). This technology is still finding its way into audio devices, but once they do, any latency problems should be a thing of the past.
FireWire Connections: Apple Computers started developing this connection as a high speed interface to peripherals as far back as 1986. Like USB, it's also able to provide power of up to 30V to components.
It only really started being used commercially in 1995, with FireWire 400 providing speeds up to 400 Mb/s. It also went through many iterations throughout the years. The latest versions though, the S1600 and S3200 were released with respective speeds of 1.5 Gb/s and 3.1 Gb/s to compete directly with USB 3.
It has been struggling to gain popularity though, and is not nearly as popular as USB. (Steve Jobs went as far a declaring FireWire dead in 2008.) Some high-end audio systems make use of them though.
Just a word of caution: If you think of investing in an audio device just because it supports FireWire and you still need to upgrade you computer to support it, just think twice and maybe hold back a little. With the future of FireWire a bit uncertain, you may run into support and upgrade problems should the technology suddenly fall completely out of favor with manufacturers.
Thunderbolt Connection: The newest of the 3 technologies, Thunderbolt was co-developed by Intel and Apple and the first commercial use of the technology was in 2011. It can be used in optical and copper cables. In its current iteration, Thunderbolt 3, it is capable of deliver speeds up to 40 Gb/s, making it arguably the fastest of the three digital connections.
Although its unable to provide power to peripherals on its own, Thunderbolt 3 is able to bypass this problem by using the USB-C adapter on its copper cables. With this adaption, it's able supply up to 100 watts of power.
Thunderbolt 3 is fully supported by Apple and has already been incorporated into many other devices since 2015, so it is definitely a safe technology to invest in with currently unparalleled speed delivery.
As you can see, there are many options available, on both the analogue and digital side of things. It may still be a bit confusing, even after reading this article, but with a little more exposure, things should get a lot less complicated.
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Catch you in the next article and happy recording!