Introduction - AKG CEQ1/1 Manual

1. Introduction

The CEQ1/1 is a 27 band, constant-Q, automatic equalizers. The CEQ1/1 has a 2 line LCD screen
for user interface, while the EQ2 is a blank faced unit. Both of the units have the capability to inject
pink noise into a sound system, and to measure and adjust the system equalization to a user speci­
fied target curve. In addition, a dynamic pop suppressor minimizes breath pops. The CEQ1/1 has
an RS-232 port for remote set-up or control by a computer or other RS-232 compatible controller.
The CEQ1/1 uses a straightforward analog signal path to provide excellent audio performance. 27
bands of constant-Q equalization allows systems to be accurately equalized. The constant-Q
topology means less interaction between adjacent EQ bands, which in turn means less "tweaking"
of the EQ settings to achieve the desired EQ curve. The CEQ1/1 have a programmable pink noise
generator and a programmable 1/3 octave measurement filter. These provide the capability to
stimulate a room with pink noise, and measure its response. A sophisticated automatic equaliza­
tion algorithm is used to equalize the room, typically to within +/-2dB of a user selected target
curve. This process takes just over one minute.
A fixed frequency, switchable low cut filter combines with Dynamic Pop Suppression (DPS) circuitry
to give precise control over system low frequency performance. The DPS system is a dynamic
high-pass filter, which reacts only to low frequency transients. Breath pops or bass boost from
speaking too close to a directional microphone are both significantly reduced. Since the filter is
dynamic, it has no effect on the normal frequency response of the system.
Figure 1. shows the block diagram of the CEQ1/1. Balanced inputs are available for both the line
level input to the EQ and the reference microphone. Note that either input may be used as the
source for the AutoEQ
equalizer, the DPS system, and a balanced output driver. The output source may be switched
between the normal signal path and the pink noise generator (used for the AutoEQ
The programmable 1/3 octave bandpass filter and log converter allows post-EQ system response
to be measured as part of the AutoEQ
An RS-232 port is available to allow many of the functions of the CEQ1/1 to be controlled either by
a computer or a dedicated control system (such as the AMX or Crestron systems).
THRU OUT +
THRU OUT –
GND
EQ IN +
EQ IN –
GND
+15V PHANTOM
REF MIC SOURCE
16dB GAIN
REF MIC IN +
REF MIC IN –
GND
TM
process. The signal path includes the switchable low cut filter, the 27 band
TM
process.
EQ SOURCE
LOWCUT
FILTER
FILTER
IN/OUT
FROM POP SUPPRESSOR
FROM BANDPASS FILTER
Figure 1 - CEQ1/1 Block Diagram
CEQ1/1 und CEQ1/1BB
PINK NOISE
GENERATOR
27 BAND 1/3 OCTAVE
DYNAMIC POP
CONSTANT Q
SUPPRESSION
EQUALIZER
PROGRAMMABLE
BANDBASS
FILTER AND LOG
CONVERTER
TO A/D
SERIAL
DATA LINK
A/D
CONVERTER
15
TM process).
NOISE OUT
EQ OUT
FILTER
TO A/D
RS-232 OUT
RS-232 IN
68HC705
uC
LCD DISPLAY
SERIAL
EEPROM
(EQ1 ONLY)
EQ OUT +
EQ OUT –
SAVE
SELECT
DOWN
UP