LA Audio EQX20 - Manual (Page 17)

Page 17
6.0 CIRCUIT DESCRIPTION
Audio
input
High pass
filter
Audio
output
Clip
Equaliser
Bypass Bypass
Fig: 6.0.1 Block diagram of the LA EQX20 showing the main signal paths
AUDIO PATH
The input signal first passes through the electronically balanced input stage
which provides RF filtering and rejection of common mode noise signals.
The signal then passes through the High pass filter and equalisation stages
and is output via the ground compensated output amplifier.
FILTER
The filter section is a standard 2 pole, -12dB/octave high pass design
optimised for minimum ripple in the pass band. The -3dB frequency for this
filter is 75Hz.
EQUALISER
The equaliser section is based on a State Variable Filter which provides
variable Gain, Frequency and Q with very little interaction between the
controls. There are 3 stages in series for each channel.
OUTPUT
The output stage is a balanced impedance, ground sensing amplifier which
provides level matching and a low impedance output. The outputs are also
RFI protected.
MONO mode
In MONO mode the output of Channel 1, pre output stage is fed directly
into the EQ section of Channel 2.
Signal is still output from Channel 1 but has not been affected by the EQ
settings of Channel 2.
BYPASS and 75Hz filter switching is controlled by Channel 1, Channel 2's
switches are disabled. Only one filter is used in this mode.