4
R
TA
S
ERIES II
I
NTRODUCTION
A real-time audio analyzer (RTA) is an audio measurement tool that graphically
shows two kinds of information:
1. The frequency response of an audio system or device, and
2. The frequency response of the listening environment.
This kind of information is very useful for equalizing a P.A. system, finding
feedback hot spots, or "nodes", in reinforcement situations, and flattening the
frequency response of other audio equipment.
RTAs that show both the entire audible frequency spectrum (20 Hz to 20 kHz)
and its entire dynamic range (loudness from 0 dB to 120 dB) are called spec-
trum analyzers. RTAs that show portions of the dynamic range are called
“window” RTAs.
ABOUT THE DOD RTA
The DOD Electronics RTA Series II is a window-type RTA. It covers the audi-
ble frequency spectrum (20 Hz to 20 kHz), and has a five LED level meter for
each of the 31 audio frequency bands that it covers.
The RTA Series II includes a calibrated audio measurement microphone. This
microphone is equipped with a 40 foot cable which enables you to position the
microphone in several locations in the reinforcement area as you make your
evaluations of the audio system. ONLY THIS MICROPHONE SHOULD BE
PLUGGED INTO THE JACK ON THE FRONT OF THE PANEL OF THE RTA. Other
microphones may be damaged or give inaccurate readings.
The sensitivity of the RTA can be modified using the input level control, and
the window of the RTA may be widened or narrowed using the Resolution
switch. This switch allows you to choose the LED display range in dB per
LED. You can choose either a 1 dB per LED step (for a 4 dB wide window) or
a 3 dB per LED step (for a 12 dB wide window).
MAX
MIN
PINK
NOISE
MAX
MIN
INPUT
GAIN
20K
16K
12.5K
10K
8K
6.3K
5K
4K
3.15K
2.5K
2K
1.6K
1.25K
1K
800
630
500
400
315
250
200
160
125
100
80
63
50
40
31.5
25
20
2/6
1/3
0/0
-1/-3
-2/-6
ON
1dB
OFF
3dB
WINDOW
RES.
PINK
NOISE
CALIBRATED
MICROPHONE
RTA
series
II
real
time audio analyzer
Signal Processors 18-0121-B 6/8/99 10:24 AM Page 4
