Focusrite ISA Two Rackmount 2-Channel Microphone Preamp - Manual (Page 9)

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English
Z In - Input Impedance (6)
Pressing the Z In switch steps through each of the four transformer preamp input impedance values,
as indicated by the corresponding LEDs. By selecting different values for the impedance of the ISA
Two transformer input (mic or line), the performance of both the ISA Two preamp and the microphone
connected can be tailored to set the desired level and frequency response.
The impedance values are as follows:
• Low – 600 Ω
• ISA 110 – 1.4 kΩ
• Med – 2.4 kΩ
• High – 6.8 kΩ
Phase (7)
Pressing the Phase switch (illuminated when active) inverts the phase of the selected input to correct
phase problems when using multiple microphones, or when incorrect wiring polarity has occurred.
Filter (8)
Pressing the Filter switch (illuminated when active) makes the high pass filter active in the audio
path. This is useful for removing any unwanted bass caused by proximity effect or rumble.
High Pass Filter Control (9)
The high pass filter is adjustable between 16 Hz and 420 Hz, with an 18 dB/octave roll-off.
Insert (10)
Pressing the Insert switch (illuminated when active) routes the insert return socket to the output
instead of the direct mic, line or instrument signal. The input signal is permanently routed to the
insert send output on the rear panel. Insert allows the input signal to be routed to other hardware
for processing before returning back into the ISA Two.
Metering (11)
ISA Two’s two front panel LED meters display the peak level at the output, after any insert processors,
and are calibrated to meter the dBFS scale.
Calibration
The LED meters can be calibrated using the PEAK METER CALIBRATION control on the rear panel
(see the Rear Panel diagram for the exact location) enabling the 0 dBFS point on the LED meters to
correspond with that on an external A/D converter. The meters are calibrated in the following way:
LED Meters
To calibrate the LED meters, use the rear panel PEAK METER CALIBRATION control. With the control
in the default central (‘detented’) position, 0 dBFS is equivalent to an analogue audio level of +22 dBu.
Rotating the control in either direction sets a new value for 0 dBFS from +16 dBu (fully anticlockwise)
to +24 dBu (fully clockwise). When performing a factory reset, the peak meter calibration control
must be in the central (‘detented’) position .