A Quick Explanation of Shielding for Audio Cables and How to Choose it.
You might have noticed that, on our website, you can filter cables by type of shielding. If you're still not sure about what type of shielding you need for your cable or don't know what shielding is, then this guide is for you.
What is cable shielding used for?
Shielding protects your signal from electromagnetic interference (EMI). Indeed, electric cables naturally produce electromagnetic fields which can interfere with your cable signal. Therefore, those electromagnetic and radio-frequency interferences (EMI/RFI) could impact the signal quality, causing data loss, or completely disrupt the signal, resulting in equipment failure. Consequently, we use shielding to reduce interference.
For every alternative current, a pair of electromagnetic waves are generated (and vice versa, an electromagnetic wave will induce a current). Meaning that if 2 cables are next to each other, their respective electromagnetic waves will induce a current into the other one. So this current has a direct impact on the data stream contained into the cable. In conclusion, the shielding's purpose is to decrease such impact.
Braided shielding, like its name suggests, is an interwoven set of thin tin or copper wires grouped together to protect the cable from electric interference. This type of shielding provides low-path resistance to the ground but does not guarantee full isolation from interferences. Braided shielding covers between 70% and 95% of the cables and is suitable for applications using low or medium frequencies.
- Strong and flexible
- Efficient against low and medium frequency interference
- Does not offer 100% coverage
- Less efficient against high-frequency interference
- More expensive
Spiral shielding is similar to braided shielding, except that, instead of groups of thin wires woven together, single strands of copper are twisted around the inner conductors of a cable to form what looks like a spiral. In short spiral shields are easier to terminate than braided shields.
Spiral shields work well in the audio frequency range and, thus, are mostly found in microphone and audio cables.
- Easier to terminate and more flexible than braided shields
- Effective in the audio frequency range
- Higher shield coverage between 95% and 99%
- Its efficiency can be reduce if the cable is bent while it is in use
Foil aluminum cable shielding
Foil aluminium shields consist of a light sheet of aluminium wrapped around the cable conductors. In addition, foil shields provide a wire, which is called a "drain wire", to ground the shield when the cable is terminated.
- Offers 100% shielding coverage
- Quick and inexpensive to produce
- Effective at low and high frequencies
- Fragile and less durable
How to Choose the Right Cable Shielding?
Knowing what the difference is between each type of cable shielding is all well and good, but how do you which one is best for your application?
As a rule of thumb, remember this: choose spiral shielding for microphone and audio cables. If you are working with high frequencies where there is a lot of EMI, make sure to use foil aluminum shielding. Braid shields can be used to minimize low frequency interference and offer a better physical protection than other types of shielding.
|Braided Shielding||typically between 70% and 95%||Flexible||Difficult||High||Reduces low-frequency interference and has lower DC resistance than foil shields.|
|Spiral Shielding||95% to 99%||More flexible than braided shielding||Easier than braided shielding||Medium||Microphone and audio cables. Not recommended for signals above the audio frequency range.|
|Foil Aluminium Shielding||100%||More flexible than braided shielding but shorter flex life than spiral or braid||Easiest shielding to terminate thanks to the drain wire||Low||Better than braid shields in higher frequency ranges.|
Ideal to block electromagnetic interference (EMI).
- Types of Cable Shielding - AlphaWire
- Shielding Types Comparison Chart - Lapp Tannehill
- Shielding - Procab
- Shielded Cable: Foil Shielding vs. Braided Shielding in Cable Assemblies - Iconn Systems
- Foil Shielding vs. Braided Shielding - Iconn Systems
- Understanding Shielded Cable - Mouser
- Cable Shielding: When? Why? - New England Wire Technologies
- What is the function of a drain wire? - Quora