6. STEREO PHONO/LINE INPUT MODULE
Inputs and Sensitivity
This module features a stereophonic input stage with RIAA compliant pre-amplifier for phono
signal levels (1.77 to 56.2mV) and a line input stage (0.100 to 10V). Selecting one of these two inputs
(featuring RCA connectors) is done with the PHONO/LINE push-button switch. This selects one of
the input pairs on the rear panel. A green indicator lights up when the PHONO input is selected and a
yellow indicator does when the LINE input is selected. The nominal input sensitivity of the PHONO
input is 10mV (-40dB). To this input you can connect a turntable equipped with a phono cartridge
capable of delivering between 1.77 and 56.2mV. This input has a quite large overload capacity, thus
admitting higher output cartridges. The Phono Input features a PHONO/LINE switch (25) at the back
panel, which lets you use this same input (23) to connect low line level audio sources as well. All
SCLAT mixers are factory-set with the switch in PHONO position. Regarding the LINE input, its
nominal input sensitivity can be switched from -5dBV to +5dBV, via the LOW/HIGH switch found on
the rear panel. For high signal levels such as CD players, DATs or MINIDISCs use +5dB. For low
signal levels use -5dB (Cassette players, tape recorders, tuners...) These modules are factory-set
with the switch in LO position.
GAIN (4) Input Gain Adjustment
On the front panel you can find a channel gain potentiometer which is common for both
inputs. Its adjustment range is ±15dB. This control is useful when compensating for level differences
in the signals to mix with already on-air music or music on another channel. This operation can be
accomplished either visually (via the left VU-METER) or by pre-listening via headphones (comparing
both signals successively using the PFL buttons).
Each module additionally features a set of internal jumpers (see fig. 1) which allow you to
reduce the gain range from ±15dB to ±5dB, thus minimizing the risk of damage of transducers in
"high risk" installations.
ATTENTION: The modification of the input gain range must be carried out by a qualified
technician.
TREB (5), MID (6), BASS (7) Tone Control
Three band tone control with -30dB to +10dB adjustment range for bass and treble and -25dB
to +10dB range for the mids.
Each module additionally features a set of internal jumpers (see fig.1) which allows you to
reduce the upper gain limit from +10dB to +6dB, minimizing the potential risk of putting such broad
gain ranges for all three bands in hands of a novice operator. This type of mixer usually drives
expensive high performance power audio systems. A +5dB gain limit practically eliminates any
possibility of damage.
ATTENTION: The modification of the tone control gain limit must be carried out by a
qualified technician.
BAL (8), Balance control
Its mission is to adjust the signal level between the left and right channel
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