Lexicon PCM 42 - SECTION TWO CONTROLS & INDICATORS; 2.1 Front Panel Controls

SECTION TWO
CONTROLS & INDICATORS
2.0 INTRODUCTION
ly describes the PCI
ee A a AA
aicators. More cet
d applications is conta
2.1 FRONT PANEL
E
F
GH
J
M
P
VW
Figure
2.1 —
PCM
42
Front
Panel
When
the
button
is
out,
the
unit
is
set
for
the short
Re nEROROOM lore range (O0-1200 ms standard, 0-2400 ms with memory op-
The HEADROOM display monitors the audio level tion) and 16 kHz bandwidth. Pushing the button selects
after the INPUT LEVEL and FEEDBACK controls. The the long range (0-2400 ms standard, 0-4800 ms with
display has 5 LEDs which indicate peak levels relative to memory option) with 6 kHz bandwidth, illuminating the
converter overload. The input stage operates normally 6 kHz LED (Fig. 2.1, Q). The numeric delay display
up to 3 dB below the absolute limit, where a 5:1 com- always indicates the actual delay time.
pression ratio comes into play. At 0 dB, the input stage
limits, and further increases in input level will produce C. INPUT LEVEL
no additional input to the digitizer. Even extreme input
levels produce only a soft distortion, rather than clip-
ping. The Headroom Display follows the compressor/
limiter, indicating the audio level actually seen by the
analog-to-digital converter; thus it becomes non-linear
with respect to the input signal when the O-dB LED is lit.
The INPUT LEVEL control adjusts the input gain for
proper matching of the PCM 42’s sensitivity to the input
signal. Set this control so the HEADROOM display
occasionally indicates 0 dB on program peaks, with
average levels at about -12 dB (in the green zone).
NOTE: A rear panel switch provides an additional
BE PEEE TENGE 20 dB of gain for low level inputs, such as the output of
The DELAY X2 switch determines whether the PCM an instrument pickup. For details, see Section 2.2,
42 is in the short (X1) or the long (X2) time delay range. paragraph “|”.