Rocktron VOODU Valve User manual

Voodu Valve
TUBE DRIVEN PROGRAMMABLE 24-BIT DSP GUITAR PREAMP
™
USER'S MANUAL
May be covered by one or more of the following: U.S. Patents #4538297, 4647876, 4696044,
4745309, 4881047, 4893099, 5124657, 5263091, 5268527, 5319713 and 5333201.
Other patents pending. Foreign patents pending.
HUSH
®
licensed by
®

PRECAUTIONS
NOTE: IT IS VERY IMPORTANT THAT YOU READ THIS SECTION TO PROVIDE YEARS
OF TROUBLE FREE USE. THIS UNIT REQUIRES CAREFUL HANDLING.
All warnings on this equipment and in the operating instructions should be adhered to and all
operating instructions should be followed.
Do not use this equipment near water. Care should be taken so that objects do not fall and liquids
are not spilled into the unit through any openings.
The power cord should be unplugged from the outlet when left unused for a long period of time.
DO NOT ATTEMPT TO SERVICE THIS EQUIPMENT. THIS EQUIPMENT SHOULD BE
SERVICED BY QUALIFIED PERSONNEL ONLY. DO NOT MAKE ANY INTERNAL AD-
JUSTMENTS OR ADDITIONS TO THIS EQUIPMENT AT ANY TIME. DO NOT TAMPER
WITH INTERNAL ELECTRONIC COMPONENTS AT ANY TIME. FAILURE TO FOLLOW
THESE INSTRUCTIONS MAY VOID THE WARRANTY OF THIS EQUIPMENT, AS WELL
AS CAUSING SHOCK HAZARD.
POWER REQUIREMENTS
This unit accepts power from the 9VAC/3.4A adaptor supplied with the unit. This 9 volt RMS AC
voltage is internally processed by a voltage doubler which generates a bi-polar ±15 volts to maintain
the headroom and sound quality of professional, studio quality equipment. Using an external power
source such as this minimizes excessive noise and hum problems often associated with internal
transformers, providing optimal performance for the user.
OPERATING TEMPERATURE
Do not expose this unit to excessive heat. This unit is designed to operate between 32° F and 104°
F (0° C and 40° C). This unit may not function properly under extreme temperatures.
Copyright ©1995 Rocktron Corporation.
All rights reserved.

Contents
1. Introduction .................................................................................................................................. 1
2. Quick Setup .................................................................................................................................. 2
3. Front Panel ................................................................................................................................... 3
4. Rear Panel .................................................................................................................................... 6
5. Connections ................................................................................................................................. 9
Using the Voodu Valve with a stereo power amp and guitar cabinets .................................................. 9
Using the Voodu Valve direct into a mixing console .......................................................................... 10
6. Operating Format ....................................................................................................................... 11
Voodu Valve Functions and Parameter Descriptions ......................................................................... 12
GLOBAL Function ................................................................................................................................. 13
MIXER Function .................................................................................................................................... 14
HIGH GAIN Function ............................................................................................................................. 15
LOW GAIN Function .............................................................................................................................. 16
HUSH® Function ................................................................................................................................... 17
PRE EQ (EXPERT) Function ................................................................................................................ 18
POST EQ (EXPERT) Function .............................................................................................................. 19
COMPRESSOR Function ...................................................................................................................... 20
SPEAKER SIMULATOR Function ........................................................................................................ 21
WAH-WAH Function .............................................................................................................................. 22
PHASER Function ................................................................................................................................. 23
FLANGER Function ............................................................................................................................... 24
TREMOLO Function .............................................................................................................................. 25
PITCH SHIFT Function ......................................................................................................................... 26
CHORUS Function ................................................................................................................................ 28
DELAY Function .................................................................................................................................... 30
REVERB Function ................................................................................................................................. 32
7. Voodu Valve Configurations .................................................................................................. 33
H-GAIN, CRS, DLY, REV Configuration ................................................................................................ 33
H-GAIN, FLAN, DLY, REV Configuration .............................................................................................. 36
H-GAIN, TREM, DLY, REV Configuration ............................................................................................. 39
H-GAIN, PSHF, DLY, REV Configuration .............................................................................................. 42
WAH, H-GAIN, DLY, REV Configuration ............................................................................................... 45
PHAS, H-GAIN, DLY, REV Configuration ............................................................................................. 48
L-GAIN, CRS, DLY, REV Configuration ................................................................................................ 51
L-GAIN, FLAN, DLY, REV Configuration ............................................................................................... 54
L-GAIN, TREM, DLY, REV Configuration .............................................................................................. 57
L-GAIN, PSHF, DLY, REV Configuration .............................................................................................. 60
WAH, L-GAIN, DLY, REV Configuration ................................................................................................ 63
PHASE, L-GAIN, DLY, REV Configuration ............................................................................................ 66
8. Operating the Voodu Valve .................................................................................................... 69
Selecting a preset ................................................................................................................................. 69
Changing preset parameters .................................................................................................................. 70
Storing changed preset parameters ....................................................................................................... 71
Selecting a configuration ....................................................................................................................... 73
Editing a preset title .............................................................................................................................. 75
Controller Assignments ......................................................................................................................... 77
Tap Delay .............................................................................................................................................. 81
Program Changes .................................................................................................................................. 84
MIDI Channels ....................................................................................................................................... 86
MIDI Dump/Load ................................................................................................................................... 88
Factory Restore ..................................................................................................................................... 94
Restoring a single factory preset: .......................................................................................................... 94
Restoring a single factory preset: .......................................................................................................... 96
Restoring the Voodu Valve controller assignments: .......................................................................... 97
Selecting a Power On Preset ................................................................................................................ 98
Using the Voodu Valve with a Rocktron All Access in REMOTE mode ......................................... 99
9. Appendix ................................................................................................................................... 102
ERROR MESSAGES .......................................................................................................................... 102
MIDI IMPLEMENTATION ................................................................................................................... 103
TECHNICAL DATA .............................................................................................................................. 104
VOODU VALVE FACTORY PRESETS ........................................................................................... 105

1
1. Introduction
1. Introduction
Congratulations on your purchase of the Rocktron Voodu Valve! The Voodu
Valve is a 24 bit DSP professional tube guitar preamp providing 12 unparalleled
effect algorithms and superb sound quality never before heard from a digital tube
guitar preamp. Complete programmability and full MIDI implementation are coupled
with a user friendly operating format to ensure that designing unique and useful
preset sounds is as simple as possible.
In addition, the Voodu Valve also features:
• Advanced Speaker Simulation provides a strikingly realistic
approximation of a miked speaker cabinet at line-level for
direct mixer input or headphone listening.
• Full parametric Pre and Post EQ gives the user complete EQ
control over each preset.
• Hush Systems’ HUSH® Noise Reduction provides noise reduc-
tion while playing and complete silence when not.
• "Variac" Simulation, like a conventional Variac, adjusts the
level at which the preamp begins to distort. This provides
more gain in high-gain applications, and allows for full-bodied
cleaner presets which just begin to distort when the strings
are attacked harder.
• Internal Wah-Wah allows the player to use an expression pedal
for Wah-Wah effects instead of running long audio cables out
to a conventional Wah-Wah pedal.
• High-quality Digital Effects, including:
-Reverb -Phasing -Tremolo -Flanging
-PitchShifting -Compression -Chorus -Delay
• XLR Outputs for direct mixer input.
For a thorough explanation of the Voodu Valve and its features, please read
this manual carefully and keep it for future reference. After removing the Voodu
Valve from the box, save all packing materials in case it becomes necessary to
ship the unit.

2
2. Quick Setup
2. Quick Setup
STORINGCHANGEDPARAMETERS
STEP 7 Press the STORE button to start the storing
procedure.
STEP 8 If you wish to save the altered preset in the
current preset location, press the STORE button a
second time.
If you wish to store the altered preset in a different
preset location, turn the PRESET control to the
desired preset number, then press STORE a second
time.
STEP 9 When storing into a different preset location, the
Voodu Valve™ will display "COPY TITLE
TOO?". If you wish to copy the title from the
previous preset, press STORE a third time. If you
do not wish to copy the title, turn any knob to exit
the storing procedure.
SELECTINGAPRESET
STEP 1 Turn the PRESET control to the desired preset.
STEP 2 Press the RECALL button to call up the selected
preset.
CHANGINGPRESETPARAMETERS
STEP 3 Turn the FUNCTION SELECT control to the
desired effect or utility function.
STEP 4 Turn the PARAMETER SELECT control to the
parameter you wish to alter under the selected effect
or utility function.
STEP 5 Use the PARAMETER ADJUST control to select
the new parameter value.
STEP 6 The COMPARE button may be used to compare the
sound of the altered value to the stored value.

3
3. Front Panel
3. Front Panel
1POWERswitch
2RECALLbutton
This button is used to recall the displayed preset.
3PRESET control
This control scrolls through the successive presets.
4CONFIG button/led
The status of this button determines whether the Voodu Valve™
will display either the preset number and title or the configuration
of the currently displayed preset. The configuration display indi-
cates the effects that the displayed preset executes and, in most
cases, the order in which they are executed.
The LED above the CONFIG button is lit when the configuration
is displayed.
5DISPLAY panel
The DISPLAY panel provides 16 characters consisting of 14
segments each.
6EFFECT BYPASS button/led
When lit, the Pre and Post effects are bypassed and only the Com-
pressor/Preamp signal is passed to the Voodu Valve™ outputs.
This button does not affect the condition of the Speaker Simulator.
7COMPARE button
The COMPARE button may be used to compare an altered param-
eter value to its stored value.
This button may also be used to compare between the altered and
stored values of multiple parameters under the same function
heading (i.e. "Reverb", "Mixer", etc.).

4
Note: If comparing an altered value to the stored value and the stored
value is currently being viewed, turning a knob or pressing a button that
changes the parameter value displayed will cancel the previous altered
value. This will also occur if a MIDI control change is received while
viewing the stored value(s).
8PARAMETER ADJUST control
This control is used to adjust a displayed parameter value. When
the parameter is changed from its original value, the LED above
the STORE button will light until either the new value is stored, a
new preset is selected or the parameter is returned to its original
value.
9STORE button/led
This button is used to store values into the Voodu Valve™ memory
when altered. See "Storing Changed Preset Parameters" in Chapter 8
for more information on this procedure.
10 PARAMETER SELECT control
When adjusting parameter values, this control will scroll through
the available parameters under the current function heading.
In the "Title Edit" function, this control will scroll through the
character locations to be edited.
11 FUNCTIONSELECTcontrol
This control allows access to each function of the Voodu Valve™.
Depending on what configuration is currently recalled, these
functions include:
Global Pre EQ (Expert) Phaser Delay Footswitch
Mixer Post EQ (Expert) Flanger Reverb Program Changes
High Gain Compressor Tremolo Config Select MIDI Channels
Low Gain Speaker Simulator Pitch Shift Title Edit MIDI Dump/Load
HUSH Wah-Wah Chorus Controller Assig Factory Restore

5
12 SPEAKER SIMULATOR indicator
When lit, this LED indicates that the Speaker Simulator is activated
for the current preset.
13 OUTPUT LEVEL control
This control is used to adjust the output level of the unit at the
unbalanced outputs.
14 INPUT LEVEL meter
These LEDs provide visual indication of the peak level of the input
signal when in the Preset Select mode. For the optimal signal-to-
noise ratio, it is best to adjust the input level so that the last LED
(0dB) is rarely lit. This will guard against the possibility of
overdriving the unit.
These LEDs also display the final digital mixer output levels when
any other functions are selected. This will help you to guard
against clipping the output of the mixer at the digital-to-analog
converter.
15 INPUT LEVEL control
This control adjusts the unit’s gain to match the signal level at the
input of the Voodu Valve™. Use the INPUT LEVEL meter to
determine the setting of this control.
16 INPUT jack
This standard, unbalanced mono 1/4" jack is used to provide input
to the unit. It is front panel mounted for easy access.

6
4. Rear Panel
4. Rear Panel
1BALANCED OUTPUTLEVEL control
This control determines the output level at the XLR BALANCED
OUTPUTS. Note that the balanced outputs pass the same signals as
the unbalanced outputs, except that the levels are independently
adjustable.
2(L) BALANCED OUTPUT connector
This balanced XLR connector provides the left balanced output of
the Voodu Valve™ for direct use into a mixing console.
3(R) BALANCED OUTPUTconnector
This balanced XLR connector provides the right balanced output of
the Voodu Valve™ for direct use into a mixing console.
4(L) UNBALANCED OUTPUT jack
This 1/4" unbalanced RTS jack provides the left unbalanced output
of the Voodu Valve™ for use with a guitar amplifier or rack
system setup.
In addition, this jack also allows for the connection of stereo
headphones (600Ωimpedance or greater).
5(R) UNBALANCED OUTPUT jack
This 1/4" unbalanced RTS jack provides the right unbalanced
output of the Voodu Valve™ for use with a guitar amplifier or rack
system setup.

7
6FOOTSWITCH jack
This 1/4" mono jack allows for the connection of a momentary
footswitch to control the Tapped Delay feature of the Voodu
Valve™. The Tapped Delay feature allows the player to set (or
reset) the current delay time by tapping the footswitch. The new
delay time will be based on the length of time between two taps.
For more information on this feature, refer to the "Tap Delay"
section in Chapter 8.
7REMOTE jack
This 7-pin DIN connector is provided for the connection of a
Rocktron All Access™ MIDI footswitch, which can be configured
to act as a dedicated remote footswitch for the Voodu Valve™.
This feature allows the user to access Voodu Valve™ functions
and parameters via the remote footswitch.
8PHANTOM POWER jack
This 2.5mm PIN jack offers the ability to power Rocktron MIDI
foot controllers from a 7-pin MIDI cable which connects from the
Rocktron MIDI foot controller to the MIDI IN jack on the rear
panel of the Voodu Valve™. This eliminates the need to find an
AC outlet near where the footpedal would be placed during a
performance, or the need to run an extension cord out to the
footswitch. Instead of inserting the AC adaptor into the "POWER"
jack of the footswitch as you would normally, plug it into the
"PHANTOM POWER" jack on the Voodu Valve™. This will
power the Rocktron MIDI foot controller through pins 6 and 7 of
the MIDI cable connecting the two units. A 7-pin MIDI cable must
be used and is available from your Rocktron dealer.
9MIDI IN jack
This 7-pin DIN connector must be connected to the MIDI OUT
jack of the transmitting MIDI device via a standard MIDI cable, or
to the MIDI THRU jack of the preceding device (if the Voodu
Valve™ is within a chain of MIDI devices).
Pins 6 and 7 of this connector carry the phantom power to power a
Rocktron MIDI foot controller when a 7-pin MIDI cable is used.

8
10 MIDI THRU/OUT jack
This standard 5-pin DIN connector can be connected to the MIDI
IN jack of another device via a standard MIDI cable. There are
limitations to the number of devices that can be chained (or series
connected) in this fashion.
Note: Inherently in MIDI there is a limit to the number of devices which
can be chained together (connected in series). With more than 3 devices,
a slight distortion of the MIDI signal can occur (due to signal degradation)
which can cause an error in MIDI signal transmission. Should this prob-
lem arise, a MIDI Thru box can be used which connects directly to the
MIDI device which transmits MIDI information and has multiple connec-
tors for the multiple devices receiving MIDI. MIDI cables should not
exceed 50 feet (15 meters) in length.
11 POWER jack
This 4-pin DIN connector accepts power from the 9VAC adaptor
supplied with the unit.

9
5. Connections
5. Connections
Using the Voodu Valve with a stereo power amp and guitar cabinets

10
Using the Voodu Valve direct into a mixing console

11
6. Operating Format
The Voodu Valve provides 254 stored sounds called presets. Any of the
254 presets can be called up at any time via the front panel PRESET control (used
to select a preset) and RECALL button (used to call up the selected preset), or by a
remote MIDI footswitch.
The root of each presets sound is its configuration. The configuration
determines both the effects available for a given preset and the order in which
those effects are executed. The Voodu Valve provides 12 fixed configurations to
achieve a wide array of preset sounds, any of which may be instantly called up at
any time.
Voodu Valve™ Configurations:
• High-gain Distortion - Chorus - Delay - Reverb
• High-gain Distortion - Flange - Delay - Reverb
• High-gain Distortion - Tremolo - Delay - Reverb
• High-gain Distortion - Pitch Shift - Delay - Reverb
• Wah - High-gain Distortion - Delay - Reverb
• Phase Shift - High-gain Distortion - Delay - Reverb
• Low-gain Distortion - Chorus - Delay - Reverb
• Low-gain Distortion - Flange - Delay - Reverb
• Low-gain Distortion - Tremolo - Delay - Reverb
• Low-gain Distortion - Pitch Shift - Delay - Reverb
• Wah - Low-gain Distortion - Chorus - Delay - Reverb
• Phase Shift - Low-gain Distortion - Delay - Reverb
To see the configuration of each preset, press the CONFIG button on the
front panel of the Voodu Valve - the LED above the CONFIG button will light
and the display will show the configuration for the current preset. Turning the
PRESET control will then scroll through each successive preset (displaying its
configuration instead of its preset number and title).
The configuration of each preset can also be changed from within the
desired preset. For more information on selecting a configuration, see Selecting
a Configuration in Section 8, "Operating the Voodu Valve".
6. Operating Format

12
VooduValve™ FunctionsandParameterDescriptions
Each Voodu Valve preset is divided up into individual blocks called
functions (such as "Mixer", "Reverb", etc.). Within each function of each configu-
ration is a set of controls which allow you to manipulate various aspects of that
function. These controls are called parameters. It is the setting of each of the
parameters which determines the overall sound of each preset.
The Voodu Valve is set up to allow you to first access each function (via
the FUNCTION SELECT control), then the parameter list for each function (via the
PARAMETER SELECT control) and finally the adjustable value for each parameter
(via the PARAMETER ADJUST control).
Step 2:
Turn to select a parameter
within the selected function.
Step 1:
Turn to select a function.
Step 3:
Turn to alter the value of the
selected parameter.
The functions available for each preset are dependent upon which configu-
ration is currently recalled. The remainder of this section will describe each of the
effect-based functions and the associated adjustable parameters they provide.
The remaining functions are utility-based, and are described in Section 8,
"Operating the Voodu Valve".

13
GLOBAL Function
The first function displayed after turning the FUNCTION SELECT control is
the Global function. The parameters provided in this function affect all presets
(i.e. the settings stored for these parameters are the same for all presets).
The PARAMETER SELECT control will allow you to access these Global parameters:
The OUTPUT parameter determines whether the output of the Voodu
Valve™ is a stereo (left and right) signal or two mono signals.
This SPEAKER SIMULATOR parameter under the Global function
allows you to globally (all presets) lock the Speaker Simulator off
(LOCKOFF) so that it will always be off for all presets - regardless of
the status of the “SPKR SIM” parameter under the Speaker Simulator
function. It may also be locked on for the left channel (LOCK L) or on
for both channels (LOCK B).
Note: The Voodu Valve™ will only recognize the “SPKR SIM”
parameter under the Speaker Simulator function when this parameter is
stored as UNLOCK.
The HUSH OFFSET parameter allows you to globally (all presets)
adjust the HUSH® Expander Threshold. This means that if this param-
eter is altered from 0dB to +3dB, the Expander Threshold will be 3dB
higher for all presets. This feature can be useful when switching from a
quiet guitar with passive electronics to a noisy guitar with active
electronics - as the active guitar would require a higher Threshold level
in all presets.
The MUTE parameter allows you to mute the output of the Voodu
Valve™. This feature is especially useful when changing guitars during
a live set. If a Rocktron All Access™ is used in remote mode with the
Voodu Valve™, a single All Access™ button can be configured as a
momentary switch which will mute the output when it is held down.
(See "Using a Voodu Valve™ with a Rocktron All Access™ in
REMOTE mode" in Chapter 8 for more information.)
OUTPUT
SPKR SIM
HUSH OFFSET
MUTE

14
MIXER Function
The next function displayed after turning the FUNCTION SELECT control is
the Mixer function. The Mixer function parameters are included in all presets -
regardless of which configuration is currently recalled - although the parameter
values stored in this function are only for the currently recalled preset.
This digital mixer allows you to control most signal levels pertaining to each
presets configuration and stores these levels for each preset.
The PARAMETER SELECT control will allow you to access these Mixer parameters:
The VOLUME parameter determines the overall signal level of the
current preset.
The LEFT OUT LEVEL parameter allows you alter the level of the left
channel output of the current preset independent of the right channel.
The RIGHT OUT LEVEL parameter allows you alter the level of the
right channel output of the current preset independent of the left
channel.
The DIR/EFF MIX parameter is used to define the ratio of direct signal
level to effect (Chorus, Flange, Pitch Shift) signal level.
The DIRECT PAN parameter allows you to pan the direct signal to the
left or right.
The DELAY LEVEL parameter determines the overall level of the
delayed signal at the output relative to the direct signal and other effect
signals. This parameter can also be accessed from the Delay function
parameter list.
The REVERB LEVEL parameter determines the level of the reverb
signal at the output relative to the direct signal and other effect signals.
This parameter can also be accessed from the Reverb function param-
eter list.
VOLUME
LEFT OUT LVL
RIGHT OUT LVL
MIX DIR/EFF
DIR PAN
DELAY LVL
REVERB LVL

15
HIGH GAIN Function
The HIGH GAIN function is only accessible in configurations which display
"H-GAIN" in the configuration title. The preamp stage in these configurations is
set up to provide high gain levels for maximum sustain and distortion.
The PARAMETER SELECT control will allow you to access these High Gain parameters:
The TUBE GAIN parameter sets the amount of drive at the input of the
tube stage.
The GAIN parameter determines the gain value in the distortion stage.
The VARIAC ADJUST parameter adjusts the level at which the preamp
stage in the Voodu Valve™ begins to distort. A Variac is a voltage-
attenuating device that plugs into an AC wall outlet and adjusts the
voltage level to any device which is plugged into it. For years, many
guitarists have plugged their amplifier heads into a Variac and reduced
the voltage coming into the amplifier from the AC wall outlet. This
allows the amplifier tubes to reach saturation at a lower input level and
increases the gain produced. The VARIAC ADJUST parameter
operates in a similar manner as a conventional Variac - where lowering
the parameter value lowers the level at which saturation will take place.
The post BASS LEVEL parameter adjusts the amount of low frequency
information at the output of each preset. This parameter is also acces-
sible from the "Post EQ (Expert)" function. (In the Post EQ function,
the center frequency and bandwidth of this EQ section are also adjust-
able.)
The post MID LEVEL parameter adjusts the amount of mid frequency
information at the output of each preset. This parameter is also acces-
sible from the "Post EQ (Expert)" function. (In the Post EQ function,
the center frequency and bandwidth of this EQ section are also adjust-
able.)
The post TREBLE LEVEL parameter adjusts the amount of high
frequency information at the output of each preset. This parameter is
also accessible from the "Post EQ (Expert)" function. (In the Post EQ
function, the center frequency and bandwidth of this EQ section are also
adjustable.)
The post PRESENCE LEVEL parameter also adjusts the amount of
high frequency information at the output of each preset. This parameter
is also accessible from the "Post EQ (Expert)" function. (In the Post EQ
function, the center frequency and bandwidth of this EQ section are also
adjustable.)
TUBE GAIN
GAIN
VARIAC ADJUST
BASS LVL
MID LVL
TREBLE LVL
PRESENCE LVL

16
LOW GAIN Function
The LOW GAIN function is only accessible in configurations which display
"L-GAIN" in the configuration title. The preamp stage in these configurations
provides four distortion types, and can also be used for clean tones.
The PARAMETER SELECT control will allow you to access these Low Gain parameters:
TUBE GAIN
GAIN
TUBE
BASS LVL
MID LVL
TREBLE LVL
PRESENCE LVL
The TUBE GAIN parameter sets the amount of drive at the input of the
tube stage.
The GAIN parameter determines the gain value in the distortion stage.
The TUBE parameter allows you to select between four different tube
distortion types - Hard Clip, Soft Clip, Class A, Class B. The Hard Clip
setting provides the hardest clipping, while the Soft Clip type provides a
softer clipping and the Class A and B types provide the softest clipping.
The Class A setting produces non-symmetrical clipping - therefore
more even harmonics are produced. Conversely, the Class B setting
produces symmetrical clipping. The differences between these types
are most pronounced at moderate gain settings of about 30dB or less,
where Class B produces the least amount of upper harmonics.
The post BASS LEVEL parameter adjusts the amount of low frequency
information at the output of each preset. This parameter is also acces-
sible from the "Post EQ (Expert)" function. (In the Post EQ function,
the center frequency and bandwidth of this EQ section are also adjust-
able.)
The post MID LEVEL parameter adjusts the amount of mid frequency
information at the output of each preset. This parameter is also acces-
sible from the "Post EQ (Expert)" function. (In the Post EQ function,
the center frequency and bandwidth of this EQ section are also adjust-
able.)
The post TREBLE LEVEL parameter adjusts the amount of high
frequency information at the output of each preset. This parameter is
also accessible from the "Post EQ (Expert)" function. (In the Post EQ
function, the center frequency and bandwidth of this EQ section are also
adjustable.)
The POST PRESENCE LEVEL parameter also adjusts the amount of
high frequency information at the output of each preset. This parameter
is also accessible from the "Post EQ (Expert)" function. (In the Post EQ
function, the center frequency and bandwidth of this EQ section are also
adjustable.)

17
The HUSH® function is accessible in all presets - regardless of the configu-
ration currently recalled.
HUSH® is Hush Systems patented single-ended noise reduction system. The
HUSH system contained in the Voodu Valve, though modeled after the latest
analog HUSH design, is a fully digital implementation achieved through Digital
Signal Processing (DSP).
The low level expander of the HUSH system operates like an electronic
volume control. The analog version of the HUSH utilizes a voltage-controlled
amplifier (VCA) circuit which can control the gain between the input and the
output from unity to 30, 40 or even 50dB of gain reduction. When the input
signal is above the user preset threshold point, the VCA circuit remains at unity
gain. (This means that the amplitude of the output signal will be equal to that of
the input signal.) As the input signal level drops below the user preset threshold
point, downward expansion begins. At this point the expander acts like an elec-
tronic volume control and gradually begins to decrease the output signal level
relative to the input signal level. As the input signal drops further below the
threshold point, downward expansion increases. A drop in the input level by
20dB would cause the output level to drop approximately 40dB (i.e., 20dB of gain
reduction). In the absence of any input signal, the expander will reduce the gain
so that the noise floor becomes inaudible.
The HUSH circuit is located after the A/D converter in the signal chain to
reduce any noise generated from the guitar and the A/D converter. This ensures a
quiet input signal to the preamp section. Because the preamp section of the
Voodu Valve is digital, it is virtually noise-free (even in the high-gain mode).
Therefore, a quiet input signal to the preamp will result in a quiet output signal.
The PARAMETER SELECT control will allow you to access these Hush® parameters:
HUSH®Function
HUSHI/O
HUSH THRESH
The HUSH I/O parameter simply determines whether the HUSH®
circuit is active for the current preset.
The HUSH THRESHOLD parameter determines the level at which
downward expansion begins. For example, if the HUSH THRESHOLD
was set at -20dB and the input signal dropped below -20dB, downward
expansion would begin.