Related Manuals for AKG WMS61
Summary of Contents for AKG WMS61
- Page 1 WMS61 & & WMS81 Wireless Microphone Systems...
- Page 2 The WMS61 system operates in the VHF band, while the WMS 81 operates in the UHF band; otherwise, the two systems are virtually identical in execution and performance. The available frequency sets for the WMS 61 correspond to TV channels 7, 8, 9, 10, 11, 12 and 13.
- Page 3 FM has been used for broadcast transmission of high quality audio since the mid-1950s, and its primary advantages are wide audio bandwidth and relative freedom from external electrical disturbances as compared to AM (amplitude modulation). The chief factors that determine the ultimate performance characteristics of an FM system are RF signal strength at the receiver and the modulation index (FM frequency deviation divided by modulating frequency) of the signal at the transmitter.
- Page 4 (This same basic principle is used in Dolby noise reduction in Cassette recorders.) Figure 3. Details of Companding (compression-expansion) processing in a wireless microphone system. Figure 4. Compander characteristics in the WMS61/81 systems. Pre-emphasis curve in the transmitter (A); de-emphasis curve in the receiver (B).
- Page 5 Another technique for minimizing noise under marginal operating conditions is known as squelching. When the level of the incoming RF signal drops below a certain threshold, the system becomes prone to interference and may even pick up spurious signals. In older systems, the squelching threshold is a manual adjustment. The WMS 61 and 81 systems use a pilot tone sent from the from the transmitter, which “instructs”...
- Page 6 7. Color coded rings (part number CCS-1): Included in the package is a set of color coded rings and matching rectangular snap-on color chips. These accessories help you keep track of which microphone corresponds to which receiver. For example, you can replace the black ring (the one you removed earlier) with the yellow ring, and snap its corresponding yellow rectangular chip on the lower front center of the receiving unit which is tuned to the same frequency.
- Page 7 3. Mute indicator: When this red status light is on, the system is muted, indicating low or no RF signal from the transmitter. The squelch action operates with a pilot tone from the transmitter and requires no manual adjustment at the receiver.
- Page 8 Trying Out the System: A Typical Setup: Now that you have been introduced to the basic functions of the WMS 61 and 81 units, let’s proceed with a typical setup. We’ll choose the bodypack and use it with a clip-on lapel microphone such as the AKG Model CK 77 WR-L. (The L in the model number indicates that this model has the proper locking-type plug-in jack for wireless use.) Mount the small microphone element onto the lapel clip by gently pushing the wire just below the microphone capsule into one of the notches on the lapel clip.
- Page 9 Using Handheld Transmitters: The same setup routine and precautions as we used for the bodypack apply here as well. Since a given handheld transmitter may be used by a number of speakers it is recommended that the initial checkout be made using the loudest of the speakers to ensure that the system can handle those maximum speech peaks.
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Page 10: Specifications
Specifications PT61 bodypack transmitter: Audio bandwidth: 50 Hz to 20 kHz Modulation method: Radiated RF power: 10 mW Frequency stability: ±10 ppm Antenna: Flexible, quarter-wave wire Rated deviation: ±30 kHz Signal-to-noise ratio: Typical 50 dB (A weighted) Input impedance: 220 kohms, 600 pF Audio input: Mini 3-pin XLR;... - Page 11 1.4 x 9.4 in dia. (36 mm x 240 mm) Net weight: 9.8 oz. (245 g) AKG Acoustics, U.S. • 1449 Donelson Pike • Nashville • TN 37217 • Tel: (615) 360-0499 • Fax: (615) 360-0275 SR81 receiver: Receiver type:...