Shure UK Pro Audio Group Manager, Tuomo Tolonen walks us through the key differential factors that separate how digital and analogue wireless systems sound. Read the article below, or scroll down to watch the Whiteboard Video.
The analogue vs digital wireless debate is a highly subjective topic that evokes a lot of emotion. We’ve covered the key technical differences before, and so today’s session focuses more specifically on the difference in sound between analogue and digital systems.
In the interest of brevity (and taking subjectivity into account) we’ll be assuming comparison of a high-end analogue system with an equally high-end digital system. After all, if we were to put a high-end analogue system up against an entry level digital system, the results would be quite easily skewed.
Ultimately, when comparing the audible difference between analogue and digital wireless, there are some key elements we should consider:
Radio Frequency Modulation
Analogue wireless systems have an ever-modulating RF carrier, whereas a digital system works with binary code. Please check our previous session for details on how these different modulation systems work. The key factor to remember is that with analogue wireless systems, the amount of modulation invariably depends on the strength of our audio signal, whereas digital systems always modulate in discrete steps.
One other important variable we must consider when comparing analogue and digital wireless systems, is the application for which the system was designed. For the purpose of this demonstration, we’ll be assuming the use of a system designed for live stage applications, where the sound source is likely to have highly dynamic sounding material, such as a guitar or bass.
All analogue systems feature a type of compression in the form of a compander. A compander allows analogue wireless systems to handle the inherent limitations of analogue modulation schemes (again, more on this in our previous session). Digital systems do not require a compander and therefore typically allow for a more natural and accurate reproduction of the audio signal at the receiver.
How the various companding schemes sound, depends — once again — on the source material. In speech applications, for example, you’d be unlikely to hear a compander. On the other hand, Sound sources with wide frequency ranges and broad dynamics (such as an electric or bass guitar) are more likely to produce some artifacts from compander compression. In a digital system, we’re able to achieve a clean 20Hz – 20KHz frequency response, which means those very low bass guitar notes stand a much greater chance of sounding natural and clean.
Carrier to Noise Ratio
The final point to cover when considering the difference in sound between analogue and digital wireless is the inherent ability for digital systems to maintain a better signal to noise ratio — particularly in harsh RF environments.
In short, as digital and analogue signals reach the RF noise floor, they each behave differently. Analogue systems will slowly degrade, picking up more noise before they cut out; digital systems retain perfect audio right up until the last second. In other words, digital signals are binary by definition, they’re either on or off.
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