AKG WMS BASICS

Signal propagation

As in a game of billiards, it is often impossible to reach a goal via a direct path. In the diagram on the left the red ball repre- sents the receiver, the while ball the signal, and the black ball an obstacle between the two. However, in practice we are not dealing with a single ball, but with very many simultaneously. Thus there is a comparatively high probability that at least one of the balls will reach its goal.

1.The signal hits the obstacle directly and fails to reach its goal.

2.The signal reaches its goal after being reflected off the wall.

3.If two signals reach their goal simultaneously, they cancel each other out in a situation referred to as dropout.

4.In spite of being reflected, the signal fails to reach its goal, and continues to be propagated until its energy is expen- ded.

fies it as necessary. An FM radio set – which everyone is familiar with – works on exactly the same principle.

Now that we have seen that a wireless micro- phone system functions just like an FM radio station on a narrow bandwidth, we can also see that it is subject to exactly the same phy- sical laws that govern the propagation of radio waves. The challenge here is to find a technical solution to the typical phenomena of wave propagation, such as cancellation, heterodyning, and absorption. Other factors such as RF interference, electrical and elec- tromagnetic fields, and intermodulation are also severely disruptive, and have a negative impact on the transmission quality of a wire- less installation, significantly impairing the quality of the radio link and the audio signal. But more about that later!

It is particularly important to choose the right antenna and set up the antenna and receiver

correctly if we wish to avoid loss of quality. The rule of thumb is that the best radio transmission path is always the line of sight. Antennas and receivers should therefore never be hidden behind walls or other objec- ts – it is vital to have a free line of sight bet- ween them! Problems with wireless systems during club gigs are frequently caused by incorrectly positioned antennas, although everything functioned perfectly during the sound check. In this case the audience forms an imaginary “wall” between the transmitter and the receiver, severely attenuating the radio signal. The best thing you can do is position the antenna high enough above the audience to avoid such a situation.

Do not place the antenna behind gratings, metal surfaces, or behind curtains if you can, as the signal will be unable to penetrate such obstacles. Even neon lights, dimmers, lighting systems, electronic equipment with strong RF radiation, like computers and stage

effects, power switching equipment, keybo- ards, etc. are potential sources of interferen- ce. They produce high-frequency harmonics, and are therefore totally unsuitable for use near the antennas of wireless systems. The minimum distance between walls and anten- nas should not be less than 3 feet, and the recommended minimum distance between transmitter and receiver is 10 feet.

You can get even better results by using diversity systems, carefully selecting the car- rier frequency band (UHF or VHF), and pla- cing the antenna(s) carefully to prevent any dead spots. If none of the above methods alone improves the situation, try them in dif- ferent combinations. If this still does not help, you should secretly check that the receiver is connected to power, and that fresh batteries have been inserted in the transmit- ter! But seriously, even professionals have made this mistake in the commotion of set- ting up the equipment for a gig!

Positioning the receiver

One of the most common mistakes in practice is failing to take the audience into account when positioning the receiver. The basic rule of thumb is: always maintain a line of sight between the transmitter and the receiver. In order to prevent the signal from being absorbed by the audience, always place the receiver as high as possible and in the vicinity of the transmitter – ideally on the stage itself.

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AKG Acoustics WMS 4000 manual Signal propagation, Positioning the receiver

WMS 40, WMS 400, WMS 4000 specifications

AKG Acoustics has long been recognized as a premier brand in the professional audio industry, particularly in the realm of wireless microphone systems. Among its celebrated offerings, the WMS 4000, WMS 400, and WMS 40 series stand out for their advanced technology and robust performance, catering to a range of applications from live performances to studio recordings.

Starting with the WMS 4000, this system is engineered for versatility and reliability. It features a sophisticated transmission diversity system that minimizes dropouts and ensures clear audio quality. The WMS 4000 offers an extensive frequency range, accommodating diverse environments and frequencies. A standout feature is its digital pilot tone, which automatically mutes the transmitter when it is switched off, effectively preventing unwanted noise during transitions. With a range of up to 300 meters, the WMS 4000 is ideal for large venues, allowing performers ample space to move without compromising sound quality.

Next, the WMS 400 series maintains the high standards set by its predecessor while providing a more accessible option for mid-level performers. It combines ease of use with quality audio performance, boasting a user-friendly interface that simplifies setup and operation. The WMS 400 employs an efficient frequency management system, which automatically scans the environment to select the best frequencies available, ensuring optimal performance with minimal interference. The system also features a rugged metal chassis, enhancing durability for live applications.

The WMS 40 series serves as an entry-level solution, perfect for beginners and small venues. It is lightweight and features a straightforward design, making it easy to operate for users without extensive technical knowledge. One of its most notable characteristics is its plug-and-play functionality, allowing for quick setup without complicated configurations. The WMS 40 series also offers excellent sound quality through its crystal-clear audio transmission and robust reception, making it a popular choice for schools, theaters, and small events.

All of these systems benefit from AKG's heritage in sound engineering, incorporating advanced audio processing technologies that ensure superior sound fidelity. They also come with a variety of microphone options, including handheld, lavalier, and headworn microphones, providing flexibility to meet different performance needs. Whether for a professional stage or an intimate setting, the AKG WMS series delivers outstanding performance, reliability, and user-friendly features that cater to a wide range of audio applications.