Types of digital audio Cables
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With so much attention these days focused on the latest and greatest gear…
It’s easy to neglect some of the less-glamorous aspects of the studio…
Like cables, for instance.
Because once it’s all connected, and working as it should…
You forget they even exist. And that’s how it should be.
Getting to that point requires A LOT more knowledge than some might imagine.
Which is why, in today’s post entitled: The Ultimate Guide to Recording Studio Cables…
I’ve compiled an in-depth look at all the must-know facts of this important subject.
If you don’t know your cables yet, by the end of this post you will.
Analog vs Digital Signals
The first question every beginner asks is:
What’s the difference between analog and digital cables?
- Analog cables work by transmitting information through stream of electricity, and…
- Digital cables work by transmitting information through a long string of 1’s and 0’s (aka binary code).
For a detailed explanation on digital audio, check out this post. For now though, let’s focus on analog.
The Basics of Analog Cables
In the recording studio, there are 2 types of analog cables:
…that we use to transfer 3 levels of audio signal:
- Mic Level – (balanced)
- Instrument Level – (UNbalanced)
- line level – (balanced)
line level is the standard signal strength used with all pro audio equipment. Which is why mic/instrument level signals are first boosted to line level before entering the signal chain.
Instrument level signals, which come from electric guitar/bass, are sent through a standard guitar cable, which is then boosted to line level using a direct box.
Mic level signals, which come from your mics, are sent though a standard microphone cable, which is then boosted to line level using a mic preamp.
For more info on microphone cables in general, check out this post:
Balanced vs. Unbalanced Cables
The next most common question beginners ask is:
What’s the difference between balanced and unbalanced cables?
In terms of performance:
Balanced cables are relatively immune to noise from interference such as radio frequencies, electronic equipment, etc. Which is why they’re the standard for pro audio.
In terms of design:
BALANCED cables have 3 wires:
- Signal (+)
- Signal (-)
While UNBALANCED cables have only 2:
The addition of the 3rd wire in a balanced cable is exactly what makes noise-cancellation possible. Later in this post, I’ll explain how it works. For now though, let’s continue with the basics.
Analog Connectors Explained
One either end of a balanced analog cable, you will find 1 of 3 connectors:
- XLR Male – which connects to various hardware inputs.
- XLR Female – which connects to the microphone, and various hardware outputs.
- TRS – which connects to both inputs AND outputs.
Each of these connectors has 3 contact points which carry signals from the positive, negative, and ground wires previously mentioned.
- XLR male has 3 pins
- XLR female has 3 holes
- TRS has 3 surfaces known as Tip, Ring, and Sleeve
Unbalanced analog cables typically only use one connector, which is the TS connectors commonly seen on instrument/guitar cables.
TRS vs TS Connectors
The third common question folks ask is:
What’s the difference between TRS and TS connectors?
As you can see in the picture, TRS connectors have 3 contact points, while TS connectors have only 2.
The extra 3rd contact point on a TRS connector is what allows it to carry a balanced signal.
The balanced wiring for TRS goes:
- Tip = Positive
- Ring = Negative
- Sleeve = Ground
While the unbalanced wiring for TS goes:
How Balanced Cables Cancel Noise
Earlier I promised show you exactly how this works.
So here’s the explanation:
When audio enters a balanced cable…
Both the (+) and (-) wires receive identical versions of the signal…
The only difference is, polarity of the (-) wire is INVERTED.
As the two signals travel along the cable, BOTH wires gather noise, the same way unbalanced cables do, however…
Before re-combining them at the opposite end of the cable, the polarity of the negative wire is flipped BACK, to once again match the positive signal.
With the noise patterns now on OPPOSITE polarities, they cancel each other out, leaving the original signal noise-free.
Converting Signals from Unbalanced to Balanced
By now, you’re probably wondering:
If unbalanced cables are noisier, why use them at all?
Well the answer is…
Due to the design of electric guitars and other instruments, it’s not always possible to start off with a balanced signal.
But what you CAN do is convert them, as necessary. For example, because guitar cables get too noisy beyond 20-25 ft…
A direct box (aka DI, aka direct injection) is commonly used to change the unbalanced guitar signal into a balanced mic signal…
Which can then be extended for several-hundred-feet, through a standard XLR mic cable.
Balanced MONO vs Unbalanced STEREO
People often get confused, the first time they notice…
That are TRS connectors used on balanced cables…
And they wonder:
How can that be, when one is mono, and the other is stereo?
The answer is: STEREO headphone cables are UNblanced.
So unlike balanced MONO wiring, which has a (+), (-), and ground…