Lexicon Prime Time 93 User manual

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MODEL93
DIGITAL DELAY
PROCESSOR
OwnerS Manual
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PRIME TIME MODEL 93 OWNER'S MANUAL
CONTENTS
FIG.
1.0 FRONT AND REAR PANELS
(PHOTO)
1.0 INTRODUCTION AND INSTALLATION
1.1 INTRODUCTION
1.2
UNPACKING AND INSPECTION
1.3
INSTALLATION
1.4 POWER REQUIREMENTS
1.5
VOLTAGE CHANGEOVER
1.6 CONNECTOR REQUIREMENTS
FIG
1.1 CONNECTOR DETAILS
FIG. 2.0 PRIME TIME BLOCK DIAGRAM
2.0 SUMMARY OF CONTROLS
2.1 POWER SWITCH
2.2 DELAY SELECTION
DELAY SELECT
Delay Display, PRIME Indicator, OVERRANGE Indicator
DELAY MULTIPLY
DELAY ADJUST, UNCAL Indicator
2.3
MIXERS, THE IN'S AND OUT'S
INPUT MIX
2.4 vco
HEADROOM Indicator
OUTPUT MIX
OVERLOAD Indicator
PHASE INVERT
DELAY ADJUST, UNCAL Indicator
Function Generator
FREQUENCY
DEPTH
2.5 DELAY BYPASS
2.6 REPEAT HOLD
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2.7 REAR PANEL
Inputs
Gain Switches
Outputs
External Controls
3.0 OPERATION AND APPLICATIONS
3.1 THE BASICS: STRAIGHT DELAY
FIG. 3.0 SCHEMATIC REPRESENTATION OF STRAIGHT DELAY
Delay Phenomena
Initial Control Settings
FIG. 3.1 STRAIGHT DELAY
REAR PANEL CONNECTIONS
FRONT PANEL GAIN SETTINGS
SLAP ECHO
EARLY REFLECTIONS
DOUBLING, TRIPLING
LOCALIZATION
AUX INPUT
3.2 VCO, DELAY BYPASS
FIG. 3.2 VCO AND DELAY BYPASS
VARIABLE DELAY
PITCH SHIFTING
FLANGING
FUNCTION GENERATOR
DELAY BYPASS
FIG. 3.3 SCHEMATIC REPRESENTATION OF DELAY BYPASS
3.3 DELAY MULTIPLY, REPEAT HOLD
SOFT REFLECTIONS
FIG. 3.4 DELAY MULTIPLY, REPEAT HOLD
REPEAT HOLD
3.4 RECIRCULATION, ROLLOFF, PHASE
ECHO
REVERBERATION
FIG. 3.5 RECIRCULATION, ROLLOFF, PHASE
FIG. 3.6 SCHEMATIC REPRESENTATION OF RECIRCULATION AND ROLLOFF
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FIG. 3.7 SCHEMATIC REPRESENTATION OF SCHROEDER SECTION
FIG. 3.8 SCHE~~TIC REPRESENTATION USING EXTERNAL REVERB UNIT
RESONANCE
FLANGING
HUM FILTERING
3.5 STEREO AND QUAD
FIG. 3.10 SCHEMATIC REPRESENTATION OF STEREO SYNTHESIS
3.6 ~OUND REINFORCEMENT
FIG. 3.11 SOUND REINFORCEMENT IN HALL
3.7 EXTERNAL FUNCTIONS
3.8 TWO M.93'S
3.9 RESEARCH TOOL
3.10 M.93 "LIVE"
4.0 EFFECTS
SPATIAL EFFECTS
ECHO
4.1 SLAP ECHO
4.2 RECURRING ECHO
4.3 BOUNCING ECHO
4.4 DELAYED ECHO SEND
AMBIANCE
4.5 REVERBERATION: MONO/STEREO SYNTHESIZER
4.6 ROOM EXPANDER: SYNTHESIZED STEREO
4.7 ROOM EXPANDER: STEREO SOURCE (QUAD SYNTHESIS)
SPECIAL EFFECTS
4.8 DOUBLING AND TRIPLING
4.9 VIBRATO
4.10 FLANGING: POSITIVE (AND NEGATIVE)
4.11 "DOPPLER" PITCH SHIFTING (PLUS FLANGING)
4.12 DOUBLE RESONANT FLANGE
4.13 RESONANCE
4.14 SIREN (RESONANCE)
4.15 FUGUE EFFECT
4.16 DOUBLE DELAY LINE FLANGING
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5.0 IN CASE OF DIFFICULTY
5.1 UNIT WILL NOT POWER UP:
FUSE REPLACEMENT
5.2
SERVICE PRELIMINARIES
FIG. 5.0 INTERIOR VIEW
5.3
UNIT FUNCTIONS ONLY AT ZERO DELAY SETTING
5.4
PROBLEMS AT ONLY ONE DELAY TAP
5.5
HEADROOM INDICATOR NORMAL BUT NO AUDIO
5.6
HEADROOM INDICATOR ACTS ERRATICALLY
5.7
COMPONENT LEVEL TROUBLESHOOTING
5.8
RETURNING UNITS FOR REPAIR
5.9
MODULE RETURN
5.10 REPLACEMENT PARTS
6.0 LIMITED WARRANTY
7.0 SPECIFICATIONS
8.0 APPENDIX
8.1 LIST OF AVAILABLE DELAY SELECTIONS
8.2 STUDIO APPLICATIONS OF TIME DELAY, AN-3
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1.0 INTRODUCTION AND INSTALLATION
1.1 INTRODUCTION
The PRIME TIME Model 93 is a sophisticated digital delay system incorporating
a high performance delay 1
ine, specia1 effects capabilities, an·d versati 1e
mixing functions.
The heart of M.93, its digital delay circuitry, is the
very
same as that of our professional DELTA-T series• Model 92 with one im-
portant exception: there•s more delay -- twice as much, over ~ second, at
the full bandwidth and up to 16 times as much, over 2 seconds, at reduced
bandwidth
(utilizing an optional memory extension).
For special effects M.93 incorporates a delay time modulator (VCO), feedback
equalization, phase inversion, a repeat-hold function (for unlimited repeti-
tion without degradation) and more. Multiple inputs and outputs and indepen-
dent four-function input
and output mixers make M.93 an extraordinarily flex-
ible instrument. M.93 is capable of reverberation enhancement or distant
echoing, of flanging or doppler pitch shifting, of musical vibrato or dis-
cordant resonance -- of nearly anything that can be done with time delay.
1.2
UNPACKING AND INSPECTION
Remove M.93 from the packing material taking care to avoid breaking or bend-
ing any of the many switches, levers, and knobs. Thoroughly inspect both
the
unit and packing carton for indications of shipping damage and report any
damage found to the carrier. If in good condition, be sure to save the car-
ton
and packing materials in the event it becomes necessary to reship the
machine.
1.3
INSTALLATION
M.93 is designed to be rack mounted in a standard 19 inch relay rack (unit
dimensions: 3~
11
H X 12
11
D), but it can also be rested on a flat surface. If
the unit is to be shipped while rack mounted, it may be desirable to support
the
rear of the chassis to protect it from mechanical shock. Be sure to
leave
ventilation space around the top and bottom covers since electronic
equipment lasts longer and is more reliable if kept cool~
1.4 POWER REQUIREMENTS
M.93 can be operated from either 115 or 230 volts at 50 or 60 Hz, provided
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that the voltage changeover switch located inside the unit is set to the
appropriate
position and that the unit is appropriately fused: 3/4 A for
115V, 3/8 A for 230V. See section 1.5 for voltage changeover instructions.
But beware that voltages are normally set at the factory and should not be
changed except by a qualified service technician. The unit will draw a
maximum of 35 Watts and will tolerate line voltage variations of +10%.
1.5 VOLTAGE CHANGEOVER
The M.93 can be set to operate at either 115V, 50-60Hz or 230V, 50-60Hz
+10%. The voltage set at the factory will be indicated on the rear panel.
To change the operating voltage, first remove the power cord to avoid con-
tact with power line voltages. Remove the top cover screws and the top
cover. Locate the
clear plastic High Voltage protection shield in the front
left hand corner (facing the unit) through which the voltage changeover
switch can
be viewed. First look to verify that the switch does not indicate
the desired voltage.
If not then remove the plastic shield by depressing
each (one
at a time) of the small locking barbs on the three nylon standoffs
while simultaneously
lifting the shield at the nearest corner. The barb
can
be depressed with a small pliers or screwdriver. Change the fuse, F2,
located beneath the shield to a type 3AG 3/8 Amp slow blow for 230V operation
(or
to 3AG 3/4 Amp slow blow for 115V operation). Then flip the voltage
changeover switch, S6, to expose the
correct voltage setting (230 or 115).
Snap the insulating plastic shield back onto the nylon standoff making sure
that all the barbs lock in place. Refit the cover. Finally, plug in the
power cord, and verify correct operation.
1.6
CONNECTOR REQUIREMENTS
Standard versions of M.93 require male 3 pin XLR connectors to mate with the
two inputs:
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INPUT
11
and
11
AUX INPUT
11
• The MASTER OUTPUT requires a female
3 pin
XLR connector. All other rear panel connections require ~~~ standard
phone plugs. An optional version uses tip/ring/sleeve type ~~~ phone jacks
for the
two inputs and main output instead of XLR connectors.
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XLR connections at inputs and outputs are as follows:
Pin 1 : ground
Pin 2 :
signal, high
Pin 3 :
signal, low
For single-ended (unbalanced, two-conductor) connections, connect the ground
(low side) to both pins 1 and 3.
Optional
TIP/RING/SLEEVE~~~ phone jack connections are as follows:
Tip :
signal, high
Ring : signal, low
Sleeve : ground
For single-ended connections use standard ~~~ phone jacks:
Tip :
signal, high
Sleeve : ground,
low
Cl I
PHONE
TIP RING
@I' • M"~t!~~E/
MALE TIP/RING/SLEEVE
FEMALE STANDARD
FIG. 1.1 CONNECTOR DETAILS
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lJ'illli L.£'lEJ.. llA.lll. s.EIIlJ:lli
+1.3 to +18 dBm
0 dB
-18 to +1.3 d8m
20 dB
WAVEFORM PHASE INDICATOR: ~
POWER SUPPLY
POWER
~H
~
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HEADROOM
INDICATOR
0
MEMORY
PROCESSOR
VOLTAGE
CHANGEOVER
POWER TRANSFORMER
DISPLAY
CONTROL
LOGIC
DELAY
SELECT
B
PROGRAMMABLE oE-
1
FUNCTIONS x I
DELAY
MUL Tl PLY
INPUTS
AUX
+15V
ANALOG
GROUND
-15V
+5V
DIGITAL
GROUND
v
INPUT
GAIN
020 dB
AUX
GAIN
020 dB
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FREQUENCY
.1-20Hz
vco
CRYSTAL
OSCILLATOR
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FUNCTION
GENERATOR
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FIG. 2.0 PRIME TIME BLOCK DIAGRAM
•
MASTER
TO AID
INPUT
MIXER
BUFFER~
OUT
~
-1
I 1
OVERLOAD
...
EXTERNAL
DELAY
BYPASS
LEVEL
~
ADJ. A
t--..
DELAY
8-18dBm _ A
OUT
~
LEVEL
ADJ. B
DELAY
8-18dBm _ B
OUT
g
EXTERNAL
DELAY
ADJUST
m<J
REPEAT
HOLD
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2.0 SUMMARY OF CONTROLS
This section is a brief run-down of the functions of all controls and indi-
cators to be followed in the next section by a more comprehensive set of
operating instructions. See FIG. 2.0 for reference.
2.1 POWER SWITCH
M.93 comes on with the opening of a blue eye in its push-push type power
switch. It switches both sides of the power line, consistent with good
safety practice.
Note: The REPEAT. HOLD function may occasionally be activated dur-
ing power-up disabling other
M.93 functions. If the REPEAT
HOLD indicator lights, simply press the REPEAT HOLD button to
return to
normal operation.
2.2
DELAY SELECTION
Each of the delay selectors, A and B, selects one of 60 possible delay set-
tings which is then displayed (in milliseconds) in the display window. If
the delay time selected is a prime value, the "prime" indicator will light.
The maximum delay for a standard M.93 occurs at the 128 msec position. How-
ever, there are seven more positions, up to 256 msec, for those machines
equipped with optional memory. When without optional memory and beyond 128
msec, an overrange indication is given by a decimal point in front of the
delay time displayed.
When in the overrange condition, the actual delay is
128 msec, the maximum allowed, regardless of the longer delay setting appear-
ing in the
window.
The indicated delay settings can be multiplied by factors of 2, 4, and 8 with
the
DELAY MULTIPLY switch to achieve delay times up to 128 msec X8 =1.024
seconds (or
256 msec X8 = 2.048 seconds for machines with optional memory).
The l, 2, 4, and 8 positions also program the system bandwidth so that the
12kHz bandwidth (available at the DELAY MULTIPLY lX position) becomes 6kHz
at the 2X position, 3kHz at the 4X position, and 1.5kHz at the 8X position.
In addition to the discrete display selection described above, one can select
any delay from a continuous sweep using the DELAY ADJUST control. It can

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be continuously adjusted from the displayed value down to 50% of that value,
e.g. 128 msec can be adjusted down to 64 msec. A maximum sweep range of one
second is possible with optional memory. Uncalibrated delays set with
DELAY ADJUST are indicated with a bold UNCAL light centrally located in the
display
window. With DELAY ADJUST in the detented
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(cal)
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position, M.93
locks into an accurate crystal time base for the actual indicated delay
time (the displayed value times the
multiplier).
2.3 MIXERS, THE IN'S AND OUT'S
The INPUT MIX supplies the input signal to the digital delay processor. It
consists of four functions with independently adjustable level controls and
a MASTER control which determines the level of the resultant blend. The four
functions are
two identical but independent inputs,IN and AUX, and two delay
taps, A and B. The delay taps are recirculated from the outputs through
variable 6 dB/octave ROLLOFF filters which adjust the high end rolloff
frequency from 15 kHz to 800 Hz.
Monitoring the delay processor input, the HEADROOM indicator displays peak
signal levels on a sequential array of five LED's indicating from 40 dB
below limit to 0 dB (limit). When the 20 dB LED just comes on, for example,
there is 20 dB of dynamic range left before limit, i.e. 20 dB of headroom.
Optimum levels can be achieved by proper adjustment of the INPUT MIX MASTER
control which provides up to 6 dB of gain and up to 25 dB of attenuation.
The OUTPUT MIX supplies signal to the MASTER OUTPUT. Like the INPUT MIX,
it blends four functions of which two are the inputs, IN and AUX, and two
are the delay taps, A and B. The overall level is adjusted with the MASTER
control which can provide from zero to infinite attenuation. When in danger
of overloading the output stage, the OVERLOAD indicator will light. The
OVERLOAD function indicates the levels of the four mixer functions only and
is not affected by the MASTER control. For additional flexibility IN, A, and
B functions can be inverted with their respective PHASE INVERT switches be-
fore the
OUTPUT MIX. The PHASE INVERT switches also determine the phase of
the
recirculated delays to the INPUT MIX.
2.4 vco
The voltage controlled oscillator (VCO) provides continuously variable delay
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whenever the DELAY ADJUST control is out of its counterclockwise detent
"(cal)". The UNCAL indicator lights when M.93 is in the VCO mode and serves
to
remind the user that the indicated delay times are no longer accurate.
Rather, the delay times
are a function of the VCO frequency which can be
varied over a 2:1 range resulting in a delay sweep from 1 times the indi-
cated delay settings to .5 times the indicated settings. The VCO (and
hence the delay time) can be varied manually with the DELAY ADJUST control,
controlled externally with a pot or voltage, or modulated by an internal
triangle function generator.
The frequency of the triangle waveform is determined by the FREQUENCY con-
trol (. 1 Hz to 20Hz), while its amplitude is determined by the DEPTH con-
trol. The DEPTH control pans between the manual DELAY ADJUST and the tri-
angle function generator. The DEPTH control can thus select either all
manual control, all function generator control, or a mix of the controls.
Normally, the triangle waveform extends up and down from the manually se-
lected DELAY ADJUST level unless the waveform excursion exceeds the limits
of the range. In that case the level shifts towards the middle so that
there are no settings which will force the VCO outside of its correct op-
erating range. In addition, the VCO will not alter the signal bandwidth
and it will not cause aliasing problems.
2.5
DELAY BYPASS
The DELAY BYPASS sends the output of the INPUT MIX directly to the OUTPUT
MIX MASTER control bypassing the delay electronics and disabling the OUTPUT
MIX and RECIRCULATE functions. The DELAY BYPASS indicator lights when in
the bypass
mode. The DELAY BYPASS can also be operated externally.
2.6 REPEAT HOLD
The REPEAT HOLD function repeats an audio segment idefinitely without de-
gradation.
The repeated segment consists of the audio entered into the
delay
line just before pressing the REPEAT HOLD button. Pressing the button
again
deactivates the REPEAT HOLD, outputting the contents of the delay line
to make room for new input. When activated, the REPEAT HOLD blocks addition-
al input to the delay
line memory so that no f~rther delay processing (in-
cluding delay recirculation) can occur. The repeating segments from A and
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r
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B delay taps can be mixed with new source material from IN and AUX in the
OUTPUT MIX. In addition, when 0 delay is selected, new source material can
be entered into A orB delay taps so that the source can be bandwidth limit-
ed and recirculated though it cannot be delayed.
The length of the repeated segment is the product of the DELAY MULTIPLY
setting, the VCO settings, and the maximum displayed delay setting, 128
msec (256 msec with optional memory). In the calibrated delay mode (VC9
off) the segment lengths
can be tabulated:
SEGMENT LENGTH
(msec)
DELAY MULTIPLY STANDARD MEMORY OPTIONAL MEMORY
lX 128 256
2X 256 512
4X
512 1024
8X 1024 2048
While REPEAT HOLD is activated, changes in the DELAY MULTIPLY setting cause
corresponding changes in the
segment length as well as octave related pitch
shifts. Variations in the VCO settings also cause variations in segment
length and pitch. The DELAY SELECT switches determine the relative timing
between the two delay taps A and B so that they will be in synchrony only
if they are at the same delay setting.
2.7 REAR PANEL
The inputs, IN and AUX are on the left side of the rear panel. Located be-
low each of these two balanced inputs is a switch which sets either 0 dB or
20 dB of input gain. The 0 dB position accommodates peak signal levels from
+1.3 dBm to +18 dBm while the 20 dB position accommodates peak levels from
-18 dBm to +1.3 dBm. This yields a 36 dB input range for optimum perform-
ance with a
variety of input sources.
The Master Output is transformer coupled (balanced) from the OUTPUT MIX
and can deliver up to +18 dBm, as determined by the OUTPUT MIX MASTER control
setting, into 600 ohms.
CAUTION
It is possible to overload
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the inputs without being aware
of it, since there are no input
overload indicators.
Additional outputs are the INPUT MIXER OUT which comes from the INPUT MIX
MASTER control, the DELAY A OUTPUT and the DELAY B OUTPUT. Delay A and B
outputs each
have level adjustments for peak output levels anywhere from
+8 to +18 dBm. These additional outputs are single-ended (unbalanced) and
can also drive 600 ohm loads.
Three functions
can be controlled externally via rear panel jacks. Delay
Bypass can be activated by a closure to ground through the DELAY BYPASS
jack using a single pole, single throw switch. External delay adjustment
can be achieved by plugging a 50k ohm potentiometer or a 0 to lOV source
(including a function generator source) into the
EXTERNAL DELAY jack. And
a closure to ground, using a normally open momentary switch, through the
REPEAT HOLD jack will enable or disable the REPEAT HOLD function.
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3.0 OPERATION AND APPLICATIONS
During the following instructions, it may be helpful to consult FIG. 2.0,
the M.93 BLOCK DIAGRAM.
3.1 THE BASICS: STRAIGHT DELAY
MIX
DELAY
LlNE
A
B
FIG. 3.0 SCHEMATIC REPRESENTATION OF STRAIGHT DELAY
MASTER
OUTPUT
Because it takes time for sound to travel in air, there is a delay from the
time a
sound is made to the time it reaches a listener's ears. This delay
is the basis of many perceptual phenomena. Perhaps the most obvious example
of delayed sound is that of an echo, a reflection of sound occurring perhaps
seconds
after the original. Less distinct but also striking are the delay-
ed sounds reflected from the walls of large halls or cathedrals which follow
the
direct sound by about 50 or more milliseconds.
The delayed sounds immediately following the direct sound are called early
reflections. Following the early reflections are multiple reflections which
become increasingly dense in time and space. So long as they are less than
30 - 50 msec apart, they are perceived as a continuous sound and are known
as reverberation. Early reflections which follow within 30 - 50 msec of
the direct sound are similarly perceived as continous so that they appear
to be part of the original sound. These reflections determine the room
15

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r-------- OVERRANGE
r OVERLOAD
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IN AUX A
L...J L..J
A
SOURCE DELAY
POWER
DELAY SELECT-ms l:~~~:rl&!i.MC41 -- II'BiF'..IIIS:-- - -1::::~;:;:;~-:;:~;:;:;:::~m;:;:::::::::~::l -OUTPUT MIX-
FIG, 3.1 THE STRAIGHT DELAY
I J J 1 }

ambiance, a
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live
11
or reverberant room being one in which many reflections
take place before dying away.
Another effect is that of localizing a source using
11
interaural" time dif-
ferences. For example, a sound reaching the right ear before it reaches the
left ear will be perceived as coming from the right. Delays less than one
millisecond can produce this effect. This is a factor in determining one's
spatial orientation, and,along with reverberation and echo, can be simulat-
ed on M.93.
Before starting, set controls as follows:
REPEAT HOLD: Off
DELAY ADJUST: Cal.
DEPTH: CCW (fully counter clockwise)
INPUT MIXER AUX,A, B: All down
DELAY MULTIPLY: lX
INVERT IN, A,B: All left (normal)
DELAY BYPASS: Off
These
controls will not be used further in this section. See FIG. 3.1
REAR PANEL CONNECTIONS
Plug an audio source into the INPUT from a mixing console, microphone, gui-
tar, tape, record, or radio, etc. Make sure that appropriate equalization
of the source is done before putting it into M.93 (e.g. connect a turntable
to a phono preamp and phono preamp to M.93). To start, use a simple source
such as a
single voice, guitar, or other instrument so that the effects of
delay will be readily discernable. Set the INPUT GAIN to OdB initially.
Connect the MASTER OUTPUT to a monitor amplifier and speaker or headphones
(all M.93 outputs can drive high impedance headphones, 600 ohms or more,
directly if necessary).
FRONT PANEL GAIN SETTINGS
With all MIXER controls down to avoid overloading the circuitry, and M.93
plugged in, push the POWER switch on. With the audio source playing, bring
the
IN control of the INPUT MIXER up. (If
11
0dB
11
of the HEADROOM INDICATOR
lights (and the MASTER control is down) then the input level is too high;
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see section 2.7.) Bring up the MASTER control so that "lOdB" of the HEAD-
ROOM INDICATOR 1ights on peaks but so that "OdB" does not 1ight at a11. If
the level is still not high enough, increase the INPUT GAIN to 20dB and reset
the MASTER control for the correct HEADROOM indication.
Now bring the IN control of the OUTPUT MIX (the source) up to the third
division. Bring up the OUTPUT MIX MASTER control until a comfortable vol-
ume is reached. Set DELAY SELECT A for 128 msec and bring up the OUTPUT_MIX
A control until the echo can be heard distinctly. Be sure not to light the
OVERLOAD light with too much level from the OUTPUT MIX sources (the OUTPUT
MIX MASTER control does not effect OVERLOAD).
SLAP ECHO
M.93 is now simulating a 128 msec single echo ("slap echo••) which can be
thought of as a very short mountain-like echo or as the first reflection
from a distant wall of a cathedral. The closer the volume of the delayed
sound to the original, the harder seems the imaginary surface from which
it was "reflected
11
• If the delayed sound is as loud or louder, however,then
the
situation seems unnatural.
EARLY REFLECTIONS
Keeping the delayed level lower than the original, reduce the delay time to
make the simulated space become smaller. Below 30 - 50 msec the delayed
sound is no longer discernable as separate from the original. It is per-
ceived as crude ambiance: crude because only
one reflection is represented.
Another
"reflection
11
can be derived from M.93 by setting Delay B to, say,
about twice the time
of delay A and bringing up the OUTPUT MIX B control to
an amplitude somewhat smaller than that of A. That is, the longer the delay,
the smaller the amplitude.
The second delay tap can also enhance the echoes
which are perceived at longer delay times.
DOUBLING, TRIPLING
So-called "doubling .. can be achieved by setting one delay to about 40 msec
or less and to about the same volume as the source (OUTPUT MIX IN). Since
the sounds
merge at such short delay times, the effect of doubling is to
thicken
and intensify the source. When using voice as a source, this is
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known as
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VOcal doubling
11
•
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Tripling
11
is done by adding a second delay.
The second delay time does not have to be within 40 msec of the source
as long as
it is within 40 msec of the first delay. So by making the second
delay longer than the
first, the sound is
11
thickened
11
even more. Doubling
and Tripling are different from simulated reflections because levels of
the delayed signals are not reduced.
LOCALIZATION
Using delay to perceive the direction of a sound can be accomplished with
a modified
set-up. Connect the input via the INPUT MIXER OUT to the left
channel of the monitor amplifier and connect the MASTER OUTPUT to the right
channel. Now by using only one delay of short duration, the sound will ap-
pear
to be coming from the left (the input). The longer the delay, (but less
than about 30 msec) the more the effect is enhanced. One can also achieve
the
effect by monitoring the two delays, A and B, one in each channel from
their rear panel outputs (instead of INPUT MIXER OUT and MASTER OUTPUT}.
The location of the sound can then be moved from left through center to right
by changing the relative delays. In this way single instruments or voices
can
be positioned in the mix-down of complex multi-track recordings. It is
the left and right discrimination which can be accomplished with time delay
that enables the synthesis of stereo from a mono source.
AUX INPUT
M.93 accomodates two independent inputs, IN and AUX, which can be used
interchangeably or in combination in the
INPUT MIX. Thus all functions de-
scribed using the
IN source can be performed with the AUX source or with a
combination
of IN and AUX sources equally well. IN and AUX can also be com-
bined in the OUTPUT MIX to provide direct signal output from either one or
both sources.
To connect a second source use the AUX INPUT on the rear panel.
The effects in this section, including echo, reverb, stereo simulation, and
vocal doubling will all be discussed again using more sophisticated tech-
niques
available with M.93. But the basic principles are here in the straight
delay.
3.2
VCO, DELAY BYPASS
See FIG. 3.2
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