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Getting to Know the ISA430
Power
Applies power to the unit. Turn on the ISA430 before powering up
devices to which the outputs are connected.
Bypass
The EQ and Dynamics processing modules can be globally switched
out using the BYPASS switch, providing a direct route (except for
the protection of the multi-band limiter which remains in the
circuit) from Line Input or External Input to the A/D inputs. This
enables the unit to be used as a 24 bit, 96k stereo converter for
final mastering or for analogue transfer to digital.
Listen LED
This illuminates when LISTEN is selected on the Compressor,
Expander/Gate or De-Esser and indicates that the unit is
monitoring the selected side chain frequencies. Note that the VU
meter continues to show the signal chosen by VU SELECT and not
the LISTEN signal. What you are watching and what you are
hearing can be two different things!
O/L LED
This LED illuminates when the peak signal level reaches or exceeds
+20dB, or when the peak signal level reaches 6dB below clipping.
The signal is monitored at four points: after the input gain TRIM,
after the EQ module, after the Dynamics module and after the
Insert Return, since each module could cause clipping if incorrectly
set up.
Occasional short-duration peaks which may cause the LED to blink
will not normally cause audible distortion, but if the LED is lit
constantly, the level in the appropriate module should be reduced
to prevent overloading.
Inst I/P
Instrument sources may either be connected via the rear panel, or
via this front panel jack.
Metering
VU Select
The VU Meter can display input level, insert return level, or the
compressor gain reduction. Press VU SELECT to step through the
three sources as indicated by the corresponding LEDs. For the
Input and Insert Return, 0VU corresponds to +4dBu. For the
Compressor the meter indicates the amount of gain reduction
caused by compression, from 0VU (no compression) to -20VU
(corresponding to 20dB of gain reduction).
Digital Output Meters
Two LED bargraph meters monitor the Internal signal and the
External signal (whatever is connected to the “Ext I/P A/D Direct”
XLR input) at a point after the Limiter but before the A/D input.
The meters provide a wide range with the O/L LED (lower right
side) acting as an Overload indicator to warn of excessively high
levels at the input of the A/D converters.
Input Stage
Three input options are provided to give compatibility with Mic,
Line or Instrument sources.
An immediately-post-mic pre balanced output (“Post Mic OP”)is
provided on the rear panel giving an ultra-short signal path to allow
for the cleanest possible recordings.
Select
Pressing SELECT steps through each of the three inputs as
indicated by the corresponding LEDs. When the Mic LED is lit, the
Mic input is active etc. Only one of the ‘Mic’, ‘Line’ or ‘Inst’ inputs
can be used simultaneously.
Mic
Mic input sensitivity is switched from -60dB to +6dB in 6dB steps.
Phantom power is available on the rear panel XLR for condenser
mics when +48V front panel switch is pressed.
Line
A Line input is available on XLR, with a switched gain control giving
a range of +/-18dB in 6dB steps.
ISA 430 Manual (multilanguage) 20/1/2000 9:06 am Page 3
