Lexicon PCM 42 - 4.1.1 Echo; SLAP AND AMBIENT ECHO SETTINGS

patch diagrams are intended enly as suggested starting
points. By a means experiment and derive your own
favorite effect
In the following front pane! drawings, darkened but-
tons are engaged foiessed in}. Control settings are
marked on the knobs ex cae where the setting does not
alter the basic effect (e.g., wherever VCO DEPTH is at
“O" the WAVEFORM sit RATE settings are
4.1.1 Echo
irrelevant). Input level is not shown as this must be set
up for the specific source in use. For setups that use
sweeping delay times, the numbers indicated in the
display window are to be set up with the DEPTH control
set at ‘0’; then DEPTH should be raised to the level i:
dicated for that effect. Generally speaking, the Belay
times shown need not be precisely emulated to achieve
the desired effect, and the longer the delay time in-
volved, the less critical the setting.
DEPTH WENEF ORM RATE
lexicon
oe digitat
pati delay
PPOCESSOr
‘ "Le
VCO. SWEEP
Figure 4.5-a — SLAP ECHO
This set-up adds rhythmic interest by doubling the attacks, and tonal interest by doubling the sustains. Sending the
output through a fuzztone circurt will produce a more dramatic distortion.
This mode simulates an acoustic echo, in which
sound bouncing off a hard surface is heard as a distinct
repetition of the original. The level of delayed sound
relative to direct sound gives the ear information about
the hardness and size of the reflecting surface. Natural
echoes have losses in the upper frequencies due to air
absorption: it may be desirable to use the DLY X2 push-
CELAT KZ
LEVEL FEEOBACK FUTER
button with its 6 KHZ rolloff when simulating a distant
echo even when the delay time is within the limit im-
posed by full-bandwidth operation. An external equal-
izer may also be inserted between the delay and the out-
put mix using the MIX CONTROL jack (See Section 4.4,
“Interfacing to Other Units’'). Delay times of 75 to 100
ms create what is commonly known as ‘‘slap echo”
DEPTH WAVEFORM.
Figure 4.5-b — AMBIENT ECHO
These settings simulate echoes from a medium-sized hard room. The reverb time will be a function of the FEEDBACK
setting. The proper amount of VCO modulation varies with the material, and can be quite high with a pure vocal track.
Ambient echo effects simulate sound reflections from
room surfaces. In true reverberation there are many ran-
dom reflections, a gradual decay of overail level, anda
gradual narrowing of bandwidth. While the PCM 42
only simulates reverberation with its ambient echo ef-
fects, there are situations where the results are
reasonably convincing and quite desirable.
lf the reflected sound continues to bounce back and
forth between surfaces, it provides a long decaying
+5
“tail’’. To produce this effect, use 30 to 150 ms of delay,
in conjunction with some recirculation. Experiment with
the H! CUT filter and the FB INV function to simulate
the absorption characteristics of different reflecting sur-
faces. To further enhance diffusion of the echoes, try
very small amounts of VCO modulation at slow rates.
With musical programs that have few sharp attacks, the
ambient echo cdn closely resemble true reverberation.