AMS RMX 16 User manual

RMX 16 : Digital Reverberation System
User Manual
Issue 2
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Table of Contents
Intro.................................................................................................................................................4
RMX 16 S reenshot...........................................................................................................................5
The Basi Prin iples of Reverberation...............................................................................................6
Understanding Reverberation ...........................................................................................................6
The Fundamentals of Reverberation...................................................................................................6
Stereo From a Mono Source..............................................................................................................7
Operating Instru tions.....................................................................................................................8
Operation.........................................................................................................................................9
Input Output Level And Level Monitoring Section...............................................................................9
The Pot Control Section....................................................................................................................9
Program Selection...........................................................................................................................9
Keypad Entry..............................................................................................................................9
Using The Nudge Keys.................................................................................................................9
Pre-Delay Entry...............................................................................................................................9
Keypad Entry............................................................................................................................10
Using The Nudge Keys...............................................................................................................10
Pot Control Entry.......................................................................................................................10
Decay Time Entry.......................................................................................................................... 10
Keypad Entry............................................................................................................................10
Using The Nudge Keys...............................................................................................................10
Pot Control Entry.......................................................................................................................10
Decay Filter Controls......................................................................................................................10
Dry Wet .....................................................................................................................................11
Keypad Entry............................................................................................................................11
Using The Nudge Keys...............................................................................................................11
Pot Control Entry.......................................................................................................................11
Using the RMX 16 .........................................................................................................................11
Pre-Delay................................................................................................................................. 12
Decay Time.............................................................................................................................. 12
Decay Filtering..............................................................................................................................12
Keyboard text Entry.......................................................................................................................12
Spe ifi ations.................................................................................................................................13
Electrical.................................................................................................................................. 13
Appendix B.....................................................................................................................................14
Program Index..............................................................................................................................14
Program 1 AMBIENCE................................................................................................................14
Program 2 ROOM A1..................................................................................................................15
Program 3 HALL C1...................................................................................................................15
Program 4 PLATE A1..................................................................................................................15
Program 5 HALL B3....................................................................................................................15
Program 6 CHORUS...................................................................................................................15
Program 7 ECHO.......................................................................................................................16
Program 8 NONLIN 2.................................................................................................................16
Program 9 REVERSE 1................................................................................................................16
Program 10 REVERSE 2..............................................................................................................17
Program 11 FREEZE...................................................................................................................17
Program 12 ROOM A0................................................................................................................17
Program 13 ROOM B1................................................................................................................18
Program 14 HALL A1..................................................................................................................18
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Program 15 PLATE B1................................................................................................................18
Program 16 DELAY....................................................................................................................18
Program 17 IMAGE P1................................................................................................................18
Program 18 NONLIN 1...............................................................................................................19
Appendix C.....................................................................................................................................19
High and Low Frequency Decay Characteristics..................................................................................19
Nominal High Frequency Decay Control Characteristics...................................................................19
Low Frequency Decay Control Characteristics................................................................................19
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Intro
The AMS RMX16 was the world’s first mi ropro essor ontrolled,
full bandwidth digital reverberator and hara terized an enormous
number of seminal re ordings from the 1980s onwards. Its
designer’s love for musi and experien e in the aerospa e industry
meant it was way ahead of its time on release.
It has remained an essential pie e of kit for any self-respe ting
world- lass studio ever sin e, and the units sell today for a
substantial proportion of their original ost due to their great
desirability.
Designed from the outset to be musi al rather than simply
implementing mathemati al algorithms, ea h program was tuned
and re-tuned to provide as wide a “sweet-spot” of settings as
possible by means of “ arpet graph” parameter tables,
intera tively linked ontrol by ontrol. It was designed by ear over
an extended period of time and from first prin iples and this is
what has made it a lassi . Despite its longevity, there is little
more any present-day design ould better and its sound is unique
and instantly re ognisable.
Now available in a plug-in, the sound on e available only to
premier studios is now on tap for a mu h wider user base.
In addition to the 9 programs that the AMS RMX16 has as standard
there are a rare series of aftermarket programs that were made
available to AMS RMX16 users if they ould get their hands on the
unique and now elusive RMX16 remote ontrol with bar ode
reader input. These 9 extra programs are in luded in the AMS
RMX-16 Digital Reverb Expanded Plugin.
Image of an original RMX16 remote ontrol Image of an original
with bar ode reader bar ode hart
Note: The following text is reprodu ed verbatim from the original
user manual.
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RMX 16 S reenshot
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The Basi Prin iples of Reverberation
Understanding Reverberation
The acoustic phenomenon known as reverberation accompanies nearly all of the
sounds we hear, in fact we are so conditioned to hearing the accompanying
reverberant field that on hearing sound totally lacking in reverberation (in anechoic
chambers, well damped studios, etc.) we are immediately struck by its unnatural
character.
Natural reverberation not only adds a certain amount of character, or coloration, to
the actual sound it is accompanying, but also 'tells' our ears from which direction
the sound is coming; approximately how far away the sound is; how loud the initial
sound was; what type of acoustic space we are in; how large the space is; what the
boundaries are like (hard walls, curtained walls, etc.) and so on.
'Dead Room' acoustics, approaching anechoic proportions, are found more and
more in modern studio designs and because of the resulting lack of natural
reverberation, a good reverberation system has been found to be mandatory in
modern recording studios. 'Good reverberation' is not enough however, since the
studio must be capable of reproducing all types of reverberant situations from
'sitting rooms' to 'great halls'. Only modern digital systems with carefully designed
programs and large memory capacity, such as the RMX 16, are capable of
producing such a wide variety.
The Fundamentals of Reverberation
Let us say you are in the centre of a small hall and someone, standing a few feet
away, claps their hands. Immediately the resulting sound wave will radiate in all
directions at an approximate rate of one foot every millisecond. The first sound you
will hear will be that which comes directly towards you from the clapped hands.
Thanks to our well developed binaural hearing this 'Direct Sound' will tell us where
the sound source is.
Next come the 'early reflections'; remember sound was radiated in all directions and
some of this radiated energy, on striking room boundaries (walls, floors, ceilings,
etc.), will again be directed towards your ears. These early reflections may be
slightly different in character from the original sound since not only is some of the
energy absorbed by the boundary upon which the wave strikes, but this absorption
also varies depending on the frequency.
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These early reflections can extend from 5ms in a small room to some 200ms in a
large hall. Even at 200ms, if the sound is not impulsive, we are unable to pick out
individual reflections during this period, but we are able to extract important
psycho-acoustic information about the type of hall and the type of boundaries
involved.
These reflections eventually build up into an extremely dense, omni-directional
reflection pattern called the 'reverberant period'. At this stage so many reflections
are arriving at once that a pleasing diffuse sound is heard which slowly dies away.
Stereo From a Mono Sour e
Another important aspect of sound in any acoustic space is its binaural nature.
Sound occurs in three dimensional space and even a single hand clap is heard in
stereo, even though emanating from a single source. The stereo image is created
by each ear receiving a slightly different pattern of reflections, coming from
different directions at different times. The 'stereo image' in artificial reverberation is
an extremely important concept and should not be ignored. We never hear truly
mono sounds in nature.
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Operating Instru tions
With digital reverberation one can simulate mathematically any real environment
and also any 'old fashioned' artificial reverberant character such as 'plates', or
'springs'. Digital reverberation techniques are the first to offer such sophistication.
The RMX 16 digital reverberation system employs sophisticated micro-programmed
parallel processing of 16 bit data offering an 18kHz bandwidth; 90dB dynamic
range and 0.03% distortion in delay mode; independent control of each program's
fundamental reverberant parameters; alphanumeric program descriptions for ease
of use and 'at a glance' understanding of how the RMX 16 is currently programmed
as all data, including the variables (pre-delay, decay time, high frequency decay
profile and low frequency decay profile), are continuously displayed on the reverb
front panel.
The RMX 16 is designed to be simple to operate with nine factory programs
simulating different reverberant environments with the ability to control all
parameters.
A calculator styled keypad is provided for entry of user definable variables. Note,
the 'C' and 'D' buttons on the keypad have no function.
Both input and output levels are adjustable to accommodate sources and
destinations sending or requiring non-standard signal levels. Overflow indication on
digital processing is provided as well as the standard 'traffic signal' LEDs enabling
fine adjustment of input level for optimum signal to noise performance.
When changing basic reverberation programs, the output is muted so that 'memory
flush-out' is not output to the audio chain. A useful feature incorporated into the
RMX 16 reverberation system is the use of 'Nudge Buttons'. These buttons
increment or decrement data for all selectable functions.
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Operation
This section is intended to familiarise the user with the front panel controls of the
RMX 16 reverberation system. Frequent reference to the front panel drawing at the
front of the manual is therefore recommended when following this section.
Input / Output Level And Level Monitoring Se tion
When the unit is switched on, the front panel LEDs will illuminate. Between the
Input level and Output level control knobs there are four LEDs (green, yellow, red
and red). The first three (i.e. green, yellow and red) are basic 'traffic signal' level
LEDs. The red LED is illuminated 6 dB, the yellow LED 12 dB and the green LED
18dB before clipping. In normal operation, with a signal present, the input level
should be adjusted so that the red LED is illuminated only when the highest
programme peaks occur. The remaining red LED indicates processing overflow.
Should this occur, due to exceptional program material, 'backing off' the input level
slightly will prevent internal clipping of the signal.
Once the input signal has been 'level matched' using the traffic signal LEDs, the
output (stereo) can be adjusted to give a good match on the output.
The output from the RMX 16 is true stereo and while these outputs may be used
singly, a more solid spatial sound will be obtained by using the stereo pair.
The Pot Control Se tion
Depressing the decay time, pre-delay or Dry Wet keys, hands control of that
parameter over to the rotary control knob above the actual pot key. This facility can
only be used once that parameter key function has been selected.
Program Sele tion
To select one of the reverberation programs first push the 'program' key, the LED
on this key will now illuminate. Actual program selection can be accomplished in
two distinct ways:
Keypad Entry
To select a reverberation program using the keypad, enter a single or two digit
number between 1 and 18 followed immediately by the 'enter' key (#); the
required program will then be loaded. Once a program number has been selected
the LED on the 'program' key will flash until the 'enter' key (#) is pressed. If the
program number selected is not available (e.g. greater than 18), then the error
message (E) will be displayed above the 'program' key. No change in program will
result and therefore the program LED will still flash. Re-pressing of the 'program'
key will clear the error condition from the display.
Using The Nudge Keys
The 'nudge' keys are very useful for jumping from one program to another. Once
'program' has been selected, a nudge up will increase the program number while a
nudge down will decrease the program number. It should be noted that when
changing between basic programs, the output is muted for a short period so that
'memory flush-out' is not output to the audio chain.
Note: Any ustom settings made to a program are lost when hanging
between programs.
Pre-Delay Entry
Pre-delay, delays the onset of reverberation giving the impression of distance from
the sound source. To introduce a pre-delay before reverberation occurs, first push
the 'pre-delay' Key.
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The LED on this key will now illuminate. Again, actual pre-delay setting can be
accomplished in three distinct ways:
Keypad Entry
Using the keypad, enter the amount of pre-delay required followed by the the enter
key (#). The amount (ms) of pre-delay will be displayed above the 'pre-delay' key
and as information is entered from the keypad the LED on the 'pre-delay' key will
flash. If the requested pre-delay time is within certain limits, the output will be
delayed with respect to the input by this amount and the LED will stop flashing. If
the requested pre-delay time is greater than that which is available using the
program selected, the error message (E) will be displayed above the 'pre-delay'
key. No change in the program will result so the 'pre-delay' LED will continue
flashing. To clear this error the 'pre-delay' key should be pressed again.
Using The Nudge Keys
If the Nudge Keys are used, the pre-delay amount will be increased or decreased;
the step size being program dependent. It is important to remember that the
maximum available pre-delay time depends on the basic reverberation program in
use. The maximum pre-delay time for each reverberation program is given in the
program notes at the back of this manual (see APPENDIX B).
Pot Control Entry
You can also vary the pre-delay using the pot control. Once the pre-delay function
has been selected, control of the pre-delay is immediately available to the rotary
pot directly above the pot key.
De ay Time Entry
To vary the decay time first push the 'decay time' key. The LED on that key will
now illuminate. There are three ways of adjusting decay time:
Keypad Entry
Decay time may be selected using the keypad. Both the minimum and the
maximum decay times are dependent upon the program selected. Fractions of a
second are entered by using the '*' key as a decimal point. Hence 2.8 Seconds
would be entered by first pressing the 'decay time' key followed by the '2' key, the
'*' key, the '8' key and finally the enter key (#).
Using The Nudge Keys
Once the 'decay time' key has been pressed, an increase or decrease in the decay
time can be accomplished by the use of the nudge keys. Depressing the nudge up
key will result in the illumination of the nudge up LED and an increase in the decay
time. Depressing the nudge down key will result in illumination of the nudge down
LED and a corresponding decrease in the decay time. The decay time will increase
or decrease in 0.1 second steps.
Pot Control Entry
You can also vary the decay time using the pot control. Once the decay time
function has been selected, control of the decay time is immediately available to
the rotary pot directly above the pot key.
De ay Filter Controls
The availability and use of these controls is dependent upon the basic reverberation
program in use (See Appendix B).
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For example PROGRAM 1 allows use of both the high and low filter controls while
PROGRAM 3 allows for use of the high filter control only.
A positive filter setting will produce an increase in reverberation time in the
selected frequency band while a negative value will give a decrease. A low
frequency filter setting of, say +9, will give a large increase in reverberation time
in the low frequency band.
To select negative values the '*' key must be pressed prior to entering the
numeral. If the '*' key is not pressed a positive value is assumed.
The decay filter controls may be changed by using the nudge buttons.
Dry/Wet
These two buttons control the balance between the reverb processor and the
source signal when Wet Solo mode is inactive.
The Dry Wet mix is indicated in the Numerical Display as a percentage. A value of
50 produces an equal blend of the wet and dry signals. Values greater than 50
emphasize the wet signal, and values less than 50 emphasize the dry signal.
Keypad Entry
Dry Wet mix may be selected using the keypad. Hence 50.5% would be entered by
first pressing the 'Dry Wet' key followed by the '5' key, the '0' key, the '*' key then
the '5' key and finally the enter key (#).
Using The Nudge Keys
Clicking the nudge down button once will decrement the value by one percent;
clicking nudge up once will increment the value by one percent. To increase the
fine resolution when adjusting these controls, hold SHIFT (on the computer
keyboard) when clicking the controls. Shift+click will decrement (nudge down) and
increment (nudge up) by a value of 0.1 percent instead of one percent.
Pot Control Entry
You can also vary the Dry Wet mix using the pot control. Once the Dry Wet
function has been selected, control of the Dry Wet is immediately available to the
rotary pot directly above the pot key.
The Dry Wet controls are typically used when RMX 16 is inserted on individual
channels. When RMX 16 is used on a group bus in a typical reverb send return
configuration, set to 100% WET or activate Wet Solo mode.
Using the RMX 16
Once the RMX 16 has been correctly 'level matched' decide which basic program is
needed for the effect you require. Reading through the program list in APPENDIX B
will help if you are already familiar with basic reverberation sounds. If you are not
it is advisable to listen to all of the basic pre-set programs using the material you
wish to record as the source.
You will then be able to select the basic program nearest to the effect you require.
Do not use source material with a fundamentally different frequency character than
the material you will eventually record, this will give you a false impression of the
final sound. Almost all reverberation types, especially when using large amounts of
frequency contouring, are dependent upon the frequency character of the source
material.
Press the 'program' key and nudge up or down through the programs to the one
required. The program number appears on the left of the display, the program
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name on the right. Whether nudging up or down, the output will be muted for a
short time. Mute time is not compounded i.e. is the same regardless of how many
programs are nudged through and which program you are nudging to or from.
There are nine factory pre-set programs; choose the one you wish to use and refer
to the program notes at the back of this manual (APPENDIX B). These notes give
the maximum pre-delay, the maximum decay time and the decay filter ranges
available when using each particular program.
Pre-Delay
Pre-delay offsets the output of the RMX 16 relative to the input. When mixing the
original with the output of the reverberation system a variety of material can be
enhanced by adding pre-delay; knowing when to use pre-delay and how much to
use comes with experience.
De ay Time
Increasing decay time effectively increases the length of the final phase of
reverberation i.e. the reverberant period. By using the 'pot' control the decay time
may be varied at any time during a mix.
De ay Filtering
The effectiveness of these controls depends to a large extent on the frequency
character of the source material. The high frequency filter will have no effect at all
on low range instruments like the bass guitar whereas cymbals, violins, etc., will
be affected to a large degree; there is no substitute for experimentation.
Keyboard text Entry
Text entry can be used to change any of the parameters displayed on the
numeric displays. Click on the display parameter you want to modify and use
the keyboard to type a new value followed the enter key.
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Spe ifi ations
Ele tri al
Distortion: Less than 0.03% at 1KHz, full output.
Dynamic Range: 90dB.
Frequency Response: 20Hz to 18KHz : - 3dB, + 0dB.
S N Ratio: Dependent upon reverberation program selected
but typically 86dB.
Nudge:
Program: Will nudge through programs allowing quick selection of
program required.
Pre-delay: Nudges from 0 to maximum in steps of 10 milliseconds.
Decay time: Nudges from 0 to maximum in 0.1 second steps.
Decay filtering: Nudges up and down in single digit steps.
Keypad Control:
Program Entry: Keypad entry 1 to 18.
Pre-delay Entry: Keypad entry 0 to maximum (dependent upon program
selected), least significant digit = 1mS
Decay Time Entry: Keypad entry least significant digit = 0.1 Second '*' acts
as decimal point.
Filter settings: Keypad entry of signed single digit numeric. '*' acts as
minus sign. Positive value implied if digit not preceded by
'*'.
Display Comprises: 11 x 7 Segment digital characters with 8 x 17 Segment
star burst alphanumeric characters.
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Appendix B
Program Index
Program Title Number
1 Ambience
2 Room A1
3 Hall C1
4 Plate A1
5 Hall B3
6 Chorus
7 Echo
8 Nonlin 2
9 Reverse 1
Additional Programs in the AMS RMX16 Expanded Plugin
10 Reverse 2
11 Freeze
12 Room A0
13 Room B1
14 Hall A1
15 Plate B1
16 Delay
17 Image P1
18 Nonlin 1
Program 1 AMBIENCE
This program is a very useful and flexible general purpose program with an effect
somewhere between a hall and a plate. It is useful for increasing reverberation time
on material with existing reverberation, or producing unobtrusive reverberation on
dry material.
It differs from a hall in that dimensional elements are deliberately minimised, and
differs from a plate in its lower coloration.
Pre-delay to 200ms is selectable and low and high frequency profiles can be
modified.
Two special features of the program are that a setting of 9.9 on the decay controls
gives an almost infinite decay time, and if the filters are set to their zero positions,
the decay continues with all original harmonic information without air absorption
simulation. This allows voices to be added into the sound one at a time to create a
“choir” effect. This can also be described as a 'freeze' setting and can be initiated by
selecting 'pot' on the decay control and rapidly turning from minimum (0.0) to
maximum (9.9) settings as the sound you wish to 'freeze' occurs.
CAUTION
Since internal multiplying parameters are unity in this mode, after a long period of
time in this condition - several minutes, or tens of minutes - the output dynamic
range may limit due to very small DC offset voltages building up. The overflow LED
will illuminate to show this. The condition is simply cleared by returning the decay
setting to zero momentarily. In any case the effect is available for ample time for all
useful purposes without problem.
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Program 2 ROOM A1
This program is designed to replicate a 'live' room with all the attendant
colourations.
Decay time should be kept short for most realism (to 1 or 2 seconds), and a high
degree of high frequency damping sounds best (say -7,-8). Low frequency
equalisation is not provided for this program.
Colouration is made deliberately high to simulate standing waves in real rooms. All
types of material are suitable for this program. Pre-delay to 300 milliseconds is
selectable.
Program 3 HALL C1
This hall program has strong initial reflections thus defining the size of the hall
distinctly, giving high presence, making it very useful for vocals.
For example: for 'topping up' material already recorded in halls, a more neutral
program such as Ambience is recommended, to avoid two possibly conflicting sets
of early information.
Control of both high and low frequency profiles is provided as in program 1 above.
Program 4 PLATE A1
This is a program with high diffusion, similar to that produced by plate
reverberators.
Percussive sounds are rapidly smoothed with this program. Colouration is medium
and decay even, as with standard plate reverberators.
Decay times of up to 5 seconds are useful for normal use, and above for special
effects.
Indicated decay times are accurate to about 5 seconds, but it should be noted that
perceived delay time will depend greatly on the frequency spectrum of the input
program material referred to the filter settings. Pre-delay of up to 300ms is
selectable.
Control of high and low frequency decay times is available.
Program 5 HALL B3
This program is similar to Hall C1, but has lower energy initial reflections.
Pre-delay of up to 200ms is available.
Control of both high and low frequency equalisation is available.
Program 6 CHORUS
This is a five voice program which is very useful for 'filling out' voices and certain
instruments.
The five voices are panned across the stereo image and are separated from each
other by randomised delays operating on each voice. In addition, a basic separation
is also selectable to bring the voices 'closer' together or to 'spread out' the image in
time and space.
The program is controlled as follows:
The PREDELAY control affects the separation of the voices, as described above. The
nudge control increment in steps of 1ms instead of the normal 10ms because of the
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short delay nature of this program. The maximum value selectable is 50ms which,
over the five voices, gives a total spread of 250ms.
At settings below about 6ms useful phasing flanging tunneling effects are available.
These effects are especially evident if the outputs are summed to mono.
The 'depth' of the randomising and pitch changing effect is controlled by the DECAY
control.
High frequency filtering of all voices is available.
NOTE:
(1) Phase cancellation and addition are very strong in this program by design,
which can mean that slight adjustment of the input level control may be
necessary dependent on program material to avoid overflow conditions.
(2) This program is designed to be used mainly with voices. Program material
with pure notes or large amounts of high frequency energy may introduce
varying amounts of interference signal components due to discrete stepping
of time increments as in other reverberation systems. This may be reduced
by use of the high frequency filtering control.
In most cases however, very good effects can be obtained from this
program as long as care is taken in choosing the relevant source material.
Program 7 ECHO
This program provides two high quality, completely independent and programmable
outputs from a single input. Control of decay is via PREDELAY, of feedback level
(regeneration) via the DECAY control and high and low filtering can be selected in
the decay path in the normal way.
To select which output to program, the 'A' or 'B' keys should be depressed as
appropriate. The program title will reflect this selection, displaying ECHO A or ECHO
B accordingly.
To allow the greatest flexibility in generating effects with this program, the
maximum delays selectable on each output have been set differently –
ECHO A : 1.2s and ECHO B: 400ms.
This program can be used to great effect for double triple tracking, longer delays
simulate tape echo, and very long delays with high degree of feedback allow a
musician to effectively 'play along' with himself by laying a new bar on top of
previous slowly decaying bars to build up a very full sound. Since the regeneration
is accomplished in the digital domain, a very clean effect is generated. Both high
and low frequency profiles can be modified.
Program 8 NONLIN 2
This is an unusual program for special effects or loudness enhancement, in which
the sound decays only very slightly for a period of time (set by the decay control),
and then dies away very rapidly. It is especially useful on drums, and at small
settings of decay produces a very good room effect. The decay values are not
calibrated in this mode, but values may be used for reference. Unlike NONLIN 1,
the output is in stereo, and filtering at high frequencies is available.
Program 9 REVERSE 1
This is another special effects program with dispersed reflections on the left output
and more discrete reflections on the Right output.
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Dependent on the setting of the decay control, the reverberating sound builds up
for a period of time then suddenly stops - the reverse of natural reverberation.
Again decay settings are not calibrated but may be used for reference.
A pre-delay is selectable before the start of the reverb build up.
Program 10 REVERSE 2
This is another special effects program with two outputs of separate character. One
output has discrete reflections (output 2), the other has a more diffused character
(output 1). Either output may be used but it should be noted that this feature is
designed to offer maximum flexibility, and it is not intended that both variations are
used together as a stereo pair.
Dependent on the setting of the decay control, the reverberating sound builds up
for a period of time and then suddenly stops - the reverse of natural reverberation.
Again, decay settings are not calibrated but may be used for reference.
A predelay is selectable before the start of the reverb build-up.
Unlike REVERSE 1, the output is in stereo and filtering at high frequencies is
available.
Program 11 FREEZE
It has always been possible to select an infinite decay to which further input may be
added on the RMX 16. This was achieved by setting the AMBIENCE program to
maximum decay with high and low filters set flat to zero. This feature has been
made easier to control with the FREEZE program.
The program is controlled as follows:
The only control that is necessary is the decay control. The following settings only
are effective:
0.0 Clear - this setting allows the 'frozen' setting to be released
0.2 Freeze add - in this position, the program will accept and freeze incoming audio
0.1 Freeze mute input - in this position the algorithm continues at infinite decay
time, but gates out incoming audio.
Although the above may sound complicated, in practice it is a very easy operation
using the nudge button on decay. By using first and second fingers to switch
between the three values - adding audio when ready at 0.1 and gating out when
the required amount of extra signal has been introduced, very concise control of the
effect is available.
All settings above 0.2 give the Freeze add condition - therefore the use of the
decay pot is not of much value with this program.
Program 12 ROOM A0
This is the original version of ROOM A1 - shipped with very early RMX 16 units. The
program was later modified to restrain the very top end of the response, which
could be a little difficult with certain program material. However, a number of well
respected users had utilised this program to great effect and have asked to be
given access to it once more.
Controls are as for ROOM A1.
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Program 13 ROOM B1
This room has constant diffusion density with time, and utilises a completely
different algorithm to ROOM A1. Maximum decay time is of the order of 700ms, and
because of the constant diffusion rate the impression of size of room is altered by
the DECAY control.
This program is very useful when very short decay times are required, and also for
drama dubbing where fine control is required over the perceived dimensions of
particular environments.
High frequency control is provided to simulate the amount of HF damping in the
room.
Program 14 HALL A1
This program has a similar history to ROOMA0. Used by some to great effect,
especially on vocals - it was replaced to allow greater smoothness in decay, but this
feature was liked by some.
Low frequency control of decay profile is not available on this program. Predelay to
300ms can be selected.
Program 15 PLATE B1
This is a program with high diffusion, similar to that produced by plate
reverberators. Percussive sounds are rapidly smoothed with this program.
Colouration is medium and decay even as with standard plate reverberators.
Decay times of up to five seconds are useful for normal use, and above for special
effects. Indicated decay times are accurate to about 5 seconds, but it should be
noted that perceived decay time will depend greatly on the frequency spectrum of
the input program material referred to the filter settings.
Predelay of up to 300 milliseconds is selectable.
Control of high and low frequency decay times is available.
Program 16 DELAY
This program gives very high quality delays of up to 810 milliseconds. The delay
required is set by selection of predelay. The decay time control then acts as a
feedback control, zero decay time giving a single repeat echo whilst above zero
regenerative echo effects may be obtained.
When used for this function the decay time control is not calibrated. Since the
feedback is achieved digitally, no degradation of the repeated sound occurs, and the
effect is quite remarkable for its clarity.
This delay appears on output 2 only. Output 1 is 'straight through' the
Analog-to-Digital-and-back-again chain. (For 2 channel operation; ECHO splits the
available delay time between the channels, with independent control over delay and
feedback).
Short delays may be used for automatic 'double tracking' or 'doubling' (up to about
40-50ms) longer delays to simulate tape echo, and very long delays coupled with a
high degree of feedback allow a musician to effectively 'play along' with himself by
laying a new bar on top of previous slowly decaying bars to build up a very full
sound.
Program 17 IMAGE P1
This program is the first of a series of IMAGE programs which are designed for very
special effect. IMAGE P1 is a program similar to the NONLIN series, except that the
reverberation produced pans between the stereo outputs as it proceeds. The length
of time of the effect is selectable by the decay controls between a few milliseconds
and about 0.6 seconds and can produce some very startling image effects which
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obviously have no equivalent in natural environments.
Control of the brightness of this program is achieved via the HI FILTER control.
If the stereo outputs of this program are summed to mono, an effect similar to
NONLIN will be obtained.
Program 18 NONLIN 1
This program is for special effects or loudness enhancement, in which the sound
does not decay for the first period of time set by the decay control, then very
rapidly dies away. The decay values are not calibrated in this mode, but values may
be used for reference.
A predelay before the reverberation begins is also selectable.
The program has two outputs - one having discrete reflections (2), the other having
a more diffused character (1). Either output may be used at short decay times for
multiplying percussive sounds like hand claps - the smoother program at short
decay times for a certain type of room simulation.
Appendix C
High and Low Frequen y De ay Chara teristi s
High and low frequency profiles may, for many programs, be modified as specified
below. These figures apply to the final, reverberant phase of the decay or each
program, but early reflections are also affected in certain programs, so the figures
should be used as a guide only. The final setting should be selected by ear.
Nominal High Frequen y De ay Control Chara teristi s
Setting Half de ay time frequen y
0 18 kHz (flat)
-1 15 kHz
-2 10 kHz
-3 8 kHz
-4 6.5 kHz
-5 5 kHz
-6 3.5 kHz
-7 2 kHz
-8 1.5 kHz
-9 1 kHz
Low Frequen y De ay Control Chara teristi s
The low frequency filter control affects the decay time of the reverberant phase of
the programs at a frequency of 350Hz, varying nominally from a quarter of the
indicated time at a setting of -9, to four times at +9. Program material content
varies the subjective effect of this control considerably; again it is best set by ear.
RMX-16 Digital Reverberation System - 19 - Issue 1