Lexicon PCM 42 - DETAILED INPUT;OUTPUT SPECIFICATIONS; 6.3 Controls and Indicators; MIXING CONTROLS; MODULATION CONTROLS

Input Level
With adjustable INPUT LEVEL control and 20 dB
GAIN switch on rear panei, fees im input ievels of
from -12 dBV to +720 dBV (0. to 10 V rms} can be
accommodated (0 dBV = 1.0 volts rms}.
Input Limiting
The main input is subject to two step compres-
2 n/timiting. Between preamp/mixer and anti-aliasing
iter isa compression Stage with a threshold at +9 dBV
srt a compression ratio of 5 an Between the filter and
the pie le-and-hold, there is a limiter wi are threshold
at 12 dBV.
Auxillary Inputs (See also Remote Jacks)
Two audio control jacks function as secondary input
points. The tip portion of the Feedback ‘Control | Jack is
mixed at unity gain with the main inputs signal, after the
compression stage but before the anti-aliasing filter and
limiter. This input has an impedance of 20 kilohms. The
tip of the Mix Control Jack connects to the CW side of
the OUTPUT MIX control.
The normal connection of delayed audio is broken
when a 1/4” phone plug is inserted in this jack. Input
impedance is 30 kilohms.
Output Type
The Main, Direct and Delay outputs are unbalanced,
and have standard 1/4” Tip-Sleeve phone jacks. The
delayed signal ts also available at the Ring portion of the
Recirculation and Mix control jacks.
Output Impedance
Main Out: 100 ohms actual source impedance.
Direct & Delay Out: 600 ohms actual source
impedance.
All outputs are intended for driving high impedance
loads, but are operable with loads as low as 600 ohms.
Output Level
Main Output: +18 dBV (9 V rms) maximum. Will
drive loads of 2 kilohms or greater at full level. An Out-
put Level control varies the output level.
Di rect Ok Varies with system level. This output is
compressed, but not limited. Nominally +12 dBV at
limit point.
Delay Out: Varies with system level. Limited to + 12
dBV
Remote Jacks
Rear panel 1/4” phone ja ommodate external
jack
switches and controls as follov
O
S acc
Al
FB Control: When ecnies ted es a stereo phone plug
to Lexicon A-41-CP Foot Pedal, allows external control
of recirculation
Mix Control: Allows control of delay volume level in
main output with Lexicon Foot Pedal.
Clock: This is a TTL level timing pulse that is syn-
chronized to the Infinite Repeat interval. This may be
used to cue a musician or clock an external sequencer
or rhythm unit.
Bypass: When the Tip and Sleeve of the (mono)
phone jack are shorted together, the PCM 42 is placed
in bypass mode.
Infinite Repeat: When the Tip and Sleeve are
momentarily shorted, the PCM 42 captures a segment
of the input and holds it in repeat mode. A subsequent
momentary contact of Tip and Sleeve releases the seg-
ment, returning the unit to normal operation.
VCO: This stereo phone jack may be connected
either to a potentiometer or to a voltage source;
whenever a plug is inserted in the jack, the MANUAL
VCO SWEEP control is replaced by the external control.
For control by a voltage source a range of Oto +10 Vis
required.
6.3 CONTROLS AND INDICATORS
Mixing Controls
Level: Rotary control sets level of signal from the
main input.
Feedback: Rotary control set level of delay output
mixed into the input signal.
| CUT: Switch inserts single pole low pass filter at
4 kHz cutoff into feedback path.
FB INV: Switch inverts the phase of the delayed
signal fed to input.
DLY INV: Switeh inverts the phase of the delayed
signal fed to the output.
Output Mix: Rotary control sets blend of direct and
delayed signal at Main Output.