Handbook for Sound Engineers

Microphones 573

battery life of transmitters and portable receivers. By
driving the RF amplifier with a better efficiency, the
occupied RF spectrum will increase in an undesirable
manner.
If the data rate described above can be reduced, the
modulation scheme can be simplified and the amplified
RF can be used in a more efficient way to conserve
battery power and increase operational time.
To reduce the amount of digital data a compression
algorithm has to be defined. This algorithm will add
some latency to the whole data transmission process.
Low latency is especially important during a live perfor-
mance on stage. If the total latency in a PA system,
including contributions from digital mixing consoles,
effects, etc., is >10 ms, the timing of the band will be
thrown off. Furthermore, if streaming video is projected
to accommodate a large audience the picture and sound
will be out of sync.
New audio data compression algorithms show good
performance with a very low latency. However, audio
compression would introduce the possibility of audible
artifacts (at least with awkward signals).
As technology improves, there will be solutions to
the obstacles described above and digital will become
available for wireless transmission.
The key questions for a digital system at this time
are:

• Is data compression used?


• What RF spectrum is necessary and how will this
  impact multichannel systems?
  
  
  • What is the latency of the system?
  
  
  • What is the battery lifetime?
  
  
  
  

16.11.12 Conclusion

Large multichannel wireless systems demand excellent

planning, especially in the initial phase, and good tech-

nical support. Observing all the above-mentioned items,

perfect operation of a system can be guaranteed, even

under difficult conditions.

16.12 Microphone Accessories

16.12.1 Inline Microphone Processors

The overall sound of a microphone can often benefit

from signal processing, and most mixers provide some

basic equalization as a tool for customizing the sound of

the microphone. Digital mixers provide an even greater

set of tools, including parametric EQ, compression, gain

management, and other automated functions. Dedicated

signal processing for each microphone in a system

provides a real advantage for the user, and some manu-

facturers are offering this sort of custom processing on a

per-microphone basis via processors that plug inline

with the microphone. These include automatic gain

control, automatic feedback control, control for plosives

and the proximity effect, and integrated infrared gates

that turn the microphone on and off based on the pres-

ence of a person near the microphone. These

phantom-powered processors allow for targeted solu-

tions to many problems caused by poor microphone

technique.

16.12.1.1 Sabine Phantom Mic Rider Pro Series 3

The series 3 Mic Rider includes infrared gates that turn

the microphone on and off based on the presence of a

person. The heat-sensing IR module is mounted on the

gooseneck or is built in on the handheld version. The IR

sensor can be adjusted for both time to turn off of

5–15 s and for distances of 3–9 ft, Figs. 16-156 and

16-157.

16.12.1.2 Sabine Phantom Mic Rider Pro Series 2

The series 2 Mic Rider includes the adjustable IR Gate

plus three audio processors: automatic gain control,

proximity effect control for controlling increased bass

due to the proximity effect, and plosive control for

Figure 16-155. Constellation diagram of a 16 QAM modu-
lation.

Q

I

0000 0100 1100 1000

0001 0101 1101 1001

0011 0111 1111 1011

0010 0110 1110 1010