Lectrosonics EQ1_EQ2 - Manual (Page 3)

27 Band Automatic Equalizer
GENERAL TECHNICAL DESCRIPTION
The EQ1/EQ2 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 EQ1
and EQ2 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
equalization 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 EQ1/EQ2. 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
TM process. The
signal path includes the switchable low cut filter, the 27 band 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
TM process). The programmable 1/3 octave bandpass filter and log converter allows post-EQ system re­
sponse to be measured as part of the AutoEQ TM process.
An RS-232 port is available to allow many of the functions of the EQ1/EQ2 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
REF MIC IN +
REF MIC IN –
GND
SERIAL
DATA LINK
RS-232 OUT
RS-232 IN
SERIAL
EEPROM
16dB GAIN
+15V PHANTOM
EQ OUT +
EQ OUT –
TO A/D
TO A/D
FROM POP SUPPRESSOR
FROM BANDPASS FILTER
EQ SOURCE
REF MIC SOURCE
FILTER
IN/OUT
NOISE OUT
EQ OUT
27 BAND 1/3 OCTAVE
CONSTANT Q
EQUALIZER
PINK NOISE
GENERATOR
PROGRAMMABLE
BANDBASS
FILTER AND LOG
CONVERTER
DYNAMIC POP
SUPPRESSION
FILTER
68HC705
uC
LOWCUT
FILTER
A/D
CONVERTER (EQ1 ONLY)
LCD DISPLAY
SAVE
SELECT
DOWN
UP
EQ1/EQ2 Block Diagram
Rio Rancho, NM – USA 3