Adjusting Input Gain; First Stage Gain; Second Stage Gain Controls - Benchmark ADC1 Instruction Manual

The ADC1 has a very large dynamic range
(especially when operating at 24-bit output
word lengths). It is wise to use some of this
dynamic range to provide more headroom as
insurance against clipping. Leave some extra
headroom between your highest anticipated
peak and the red 0 dBFS LED.
To select the meter scale and
peak hold function
• Set the Meter Switch to "H" (up) to enable
the Peak Hold function and set the scale
to 1 dB/step.
• Set the Meter Switch to "1" (center) to
disable the Peak Hold function and set the
scale to 1 dB/step.
• Set the Meter Switch to "6" (down) to
disable the Peak Hold function and set the
scale to 6 dB/step.

Adjusting Input Gain

Input Gain Stages

First Stage Gain

Each channel on the ADC1 is equipped with a
3-position first-stage gain switch. The first
gain stage provides exceptional noise
performance at gains of 0 dB, +10 dB, or +20
dB. This stage is followed by a second-stage
having a continuously variable gain range of
-1.3 dB to +22 dB. This gain structure
provides ultra-high performance at any gain
setting between -1.3 dB and +42 dB. The
higher gain settings will allow direct
connections from many instrument pickups
(no DI box required).
ADC1 Instruction Manual
To select the first stage gain
• Set the Gain Switch to "0" (center) to
select 0 dB gain (unity gain) for the first-
stage.
• Set the Gain Switch to "10" (down) to
select 10 dB gain for the first-stage.
• Set the Gain Switch to "20" (up) to select
20 dB gain for the first-stage.

Second Stage Gain Controls

The second gain stage of each channel has a
41-detent Gain Control Knob, and a 10-turn
Gain Calibration Trimmer. Each channel also
has a 2-position Second-Stage Gain Switch.
The switch selects either the Gain Control
Knob or the Gain Calibration Trimmer. Both
controls have a useable range of
approximately -1.3 dB to +22 dB.
To use the Gain Control Knob to
adjust second stage gain
Set the Secondary Gain Switch to Variable
(up) as shown in the diagram below.
Up Position
To use the Gain Calibration
Trimmer to adjust second stage
gain
Set the Secondary Gain Switch to Calibrated
(down) as shown in the diagram below.
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