Legend Audio ISA 828 - Manual (Page 6)

Mode 1 Mic Gain Range 0-30
With the 30-60 switch off, the stepped gain dial operates over a gain range of 0dB to +30dB, the level of gain chosen
being indicated on the front panel by the outer arc of yellow numbers around the gain knob.
Mode 2 Mic Gain Range 30-60
With the 30-60 switch on (illuminated), the stepped gain dial operates over a gain range of 30dB to 60dB, the level of
gain chosen being indicated on the front panel by the outer arc of yellow numbers around the gain knob.
An additional 20dB of gain can be applied to the signal after the mic/line Gain knob using the Trim knob. (See the
‘Trim’ control text below for a full explanation.)
Line Input Gain
With the line input selected, the user has access to gain settings ranging from –20dB to +10dB, indicated on the front
panel by the arc of white numbers around the gain knob. The 30-60 switch is inactive when the line input is selected,
as the gain range for Line level inputs is restricted to –20dB to +10dB in 10dB steps. An additional 20dB of gain can be
applied to the signal after the mic/line gain knob using the Trim knob. (See the ‘Trim’ control text below for a full
explanation.)
Instrument Input Gain
With the instrument input selected (inputs 1-4 only), gain is applied to the input signal by using the trim control only,
which allows +10dB to +40dB of gain range. The level of gain chosen is indicated on the front panel by the outer arc of
yellow numbers around the gain knob. This input is suitable for high impedance sources such as guitar or bass pickups
(which may be connected directly without the need for an external DI box) or vintage synthesizers with high impedance
outputs.
Trim
The Trim control provides additional variable gain of 0dB to +20dB when mic or line inputs are selected. The level
of gain chosen is indicated on the front panel by the inner arc of white numbers around the gain knob. The additional
20dB of gain that can be applied to the mic or line signal is very useful for two reasons:
When high gain is required
Using trim in conjunction with the mic gain of 60dB gives a total of up to 80dB of pre-amp gain, making it very useful
for getting good digital recording levels from very low output dynamic and ribbon microphones.
Gain adjustment during recording
When small amounts of gain adjustment are needed to correct performance level variations during recording, use the
trim knob rather than the stepped mic/line gain knob, as switching the 10dB gain steps would be much too intrusive.
It is therefore good practice to apply some Trim gain before using the 10dB stepped gain knob to find the optimum
recording level so that the Trim control can be used to gently add or take away gain later, if so required.
+48V
Pressing the +48V switch provides phantom power, suitable for condenser microphones, to the rear panel XLR
microphone connector. This switch does not affect the other inputs. If you are unsure whether your microphone requires
phantom power, refer to its handbook, as it is possible to damage some microphones (most notably ribbon microphones)
by providing phantom power.
Phase
Pressing PHASE inverts the phase of the selected input to correct phase problems when using multiple microphones,
or when incorrect wiring polarity has occurred.
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