As we all know, noise issues are a common and frustrating challenge in sound systems like those used in stage performances and live sound reinforcement. The types of noise generated by these systems can vary widely, originating from numerous sources. As a sound engineer, it’s essential to analyze and address each specific situation carefully. Generally speaking, the main sources of noise can be categorized into three areas: first, improper connections between devices; second, inherent noise within the devices themselves; and third, interference noise from the power supply.
**Tip 1: Eliminate Noise Caused by Improper Equipment Connections**
In any audio system, the proper connection of devices is critical. Incorrect connections can lead to degraded performance, noise, and even malfunctions. Here are some key considerations when making connections:
Firstly, ensure impedance matching. In professional audio equipment, most devices are designed to operate in a bridging configuration, where the output impedance is low and the input impedance is high. This approach minimizes the impact of load changes on signal quality. When the signal source is designed as a constant voltage source, and the load significantly exceeds the internal impedance of the source, this setup works well. Most professional audio gear follows these principles, ensuring compatibility through standard jumpers. Impedance matching is particularly important when connecting multiple devices to a single output. For example, if an amplifier's output needs to drive two different speakers, it should be connected directly to a preamp's output to maintain the correct impedance balance.
When pairing amplifiers and speakers, match the nominal output impedance of the amplifier with the input impedance of the speaker. Amplifiers typically have outputs rated for 4 ohms and 8 ohms, allowing them to connect to either type of speaker. Connecting a 4-ohm speaker will result in higher output power compared to an 8-ohm speaker. Similarly, two 8-ohm speakers can be connected in parallel to achieve a 4-ohm load.
**Tip 2: Address Inherent Device Noise**
A sound system consists of multiple components, including microphones, DVD players, mixers, effects processors, equalizers, compressors, crossover units, amplifiers, and speakers. Each component has the potential to generate noise. To identify the source of the noise, test each unit individually.
To begin troubleshooting, turn on the system following the signal flow sequence. If noise is present immediately upon powering up, try turning off the wireless microphone receiver and listen for a change. If the noise disappears, the issue likely stems from the wireless microphone receiver. If noise persists, continue testing other components.
**Tip 3: Mitigate Power Supply Interference**
One of the most significant sources of power supply noise comes from theatrical lighting setups that use thyristors. These devices control brightness levels by adjusting the conduction angle of the alternating current rather than varying the voltage from 0 to 220V. This process alters the sine wave of the AC current, creating a sawtooth waveform instead of a smooth curve. This results in substantial 50Hz ripple noise, which manifests as noticeable noise in the sound system.
To reduce this interference, the most effective solution is to allocate one phase of a three-phase power supply to the lighting system and reserve the remaining two phases for the sound system. This separation minimizes the impact of thyristor-generated noise on the audio equipment.
By addressing these common noise sources—improper connections, inherent device noise, and power supply interference—you can significantly improve the clarity and reliability of your sound system.
Dongguan Zhonghe Electronics Co., Ltd. , https://www.zhonghesleeving.com