Crest Audio IPRO TWO User manual

IPro Two™
Intelligibility Processor

2
Intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s
enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.
Intended to alert the user of the presence of important operating and maintenance (servicing)
instructions in the literature accompanying the product.
CAUTION: Risk of electrical shock — DO NOT OPEN!
CAUTION: To reduce the risk of electric shock, do not remove cover. No user serviceable parts inside. Refer
servicing to qualified service personnel.
WARNING: To prevent electrical shock or fire hazard, do not expose this appliance to rain or moisture. Before
using this appliance, read the operating guide for further warnings.
Este símbolo tiene el propósito, de alertar al usuario de la presencia de “(voltaje) peligroso” sin ais-
lamiento dentro de la caja del producto y que puede tener una magnitud suficiente como para constituir
riesgo de descarga eléctrica.
Este símbolo tiene el propósito de alertar al usario de la presencia de instruccones importantes sobre la
operación y mantenimiento en la información que viene con el producto.
PRECAUCION: Riesgo de descarga eléctrica ¡NO ABRIR!
PRECAUCION: Para disminuír el riesgo de descarga eléctrica, no abra la cubierta. No hay piezas útiles dentro.
Deje todo mantenimiento en manos del personal técnico cualificado.
ADVERTENCIA: Para evitar descargas eléctricas o peligro de incendio, no deje expuesto a la lluvia o humedad
este aparato Antes de usar este aparato, Iea más advertencias en la guía de operación.
Ce symbole est utilisé dans ce manuel pour indiquer à l’utilisateur la présence d’une tension dangereuse
pouvant être d’amplitude suffisante pour constituer un risque de choc électrique.
Ce symbole est utilisé dans ce manuel pour indiquer à l’utilisateur qu’il ou qu’elle trouvera d’importantes
instructions concernant l’utilisation et l’entretien de l’appareil dans le paragraphe signalé.
ATTENTION: Risques de choc électrique — NE PAS OUVRIR!
ATTENTION: Afin de réduire le risque de choc électrique, ne pas enlever le couvercle. Il ne se trouve à l’intérieur
aucune pièce pouvant être reparée par l’utilisateur. Confiez I’entretien et la réparation de l’appareil à un réparateur
Crest agréé.
AVERTISSEMENT: Afin de prévenir les risques de décharge électrique ou de feu, n’exposez pas cet appareil à la
pluie ou à l’humidité. Avant d’utiliser cet appareil, lisez attentivement les avertissements supplémentaires de ce
manuel.
Dieses Symbol soll den Anwender vor unisolierten gefährlichen Spannungen innerhalb des Gehäuses
warnen, die von Ausreichender Stärke sind, um einen elektrischen Schlag verursachen zu können.
Dieses Symbol soll den Benutzer auf wichtige Instruktionen in der Bedienungsanleitung aufmerksam
machen, die Handhabung und Wartung des Produkts betreffen.
VORSICHT: Risiko — Elektrischer Schlag! Nicht öffnen!
VORSICHT: Um das Risiko eines elektrischen Schlages zu vermeiden, nicht die Abdeckung enfernen. Es befinden
sich keine Teile darin, die vom Anwender repariert werden könnten. Reparaturen nur von qualifiziertem
Fachpersonal durchführen lassen.
ACHTUNG: Um einen elektrischen Schlag oder Feuergefahr zu vermeiden, sollte dieses Gerät nicht dem Regen
oder Feuchtigkeit ausgesetzt werden. Vor Inbetriebnahme unbedingt die Bedienungsanleitung lesen.

3
IPro Two™
DESCRIPTION:
The IPro Two is a two microphone, two stereo line input, all analog processor that is especially designed to optimize
audio signals (low or high impedance) for recording or live applications. It is loaded with features that distinguish it from
other units.
The dual full featured mic inputs can be set up as a stereo pair, or independently panned/mi ed in the stereo field.
Phantom power, pad, polarity, low cut, gain, and enable are separately provided for each mic. Added to these inputs are
a high impedance stereo line input, which can be mi ed with the mic signals, or used by itself. The output of the mic/line
mi is routed through stereo insert jacks which have an enable switch. This provides an additional unprocessed output
(the tip signal is always present), if one is required, as well as a place to insert alternate effects.
The equalization is comprised of two wide range, fully parametric filters. A cut and boost of 15 dB, a bandwidth of 2
to 1/6 octave and a frequency adjustment range of 40 Hz to 15 kHz will shape the sound as needed. Each parametric
equalizer has its own on/off switch to route the signal around it if it is unused.
The second parametric equalizer has an additional feature. It can be moved out from the main signal path into the
dynamic section’s side-chain path, where it is in series with (after) the side-chain insert jacks of the RMS detectors. By
setting it up in this mode, it can be used to define the frequencies that control the dynamics’ circuitry (e pander,
compressor, and limiter). This is used for de-essing, for removing rumble modulation, or for specifying a problematic
frequency band to compress. When configured in this manner, any e ternal signals brought in through the side-chain
insert jacks pass through this equalizer before being sent to the detector to allow frequency shaping to be applied to that
source as needed. The on/off switch still bypasses this filter even in this mode, just as you would e pect.
A key part of the IPro Two is its true RMS summed, stereo-linked dynamics section. Using state-of-the-art integrated
circuits for the voltage controlled amplifiers and true RMS detectors, it has very low distortion and noise. Incorporated in
the processing is a downward e pander, a compressor, and a limiter. Each has an independently adjustable threshold
control. The e pander and compressor sections also have ratio controls. There are side-chain inserts in the detector
path that can be enabled from the front panel (see previous paragraph). The e pander is of soft knee topology, and has
a ratio control to allow it to be used as a gentle-slope noise reduction circuit (low ratio), or a gate (high ratio). A threshold
LED illuminates when the e pander is active. The compressor is also soft knee, but has a more gradual knee action for
even smoother transitions. It can be adjusted from no compression (1:1) to limit (infinite:1). The limiter is a compressor
with a fi ed infinite:1 ratio, a faster knee transition, and an LED to show when it is functioning. All have preset (program
dependent) attack and release times. A twelve segment gain reduction meter displays all VCA activity (e pander,
compressor, and limit) so that control action is easily seen, making adjustments a snap.
Heavy compression will give the perception of darkening the signal, since the low frequency components (which
have the most energy) dominate the compressor action. As the signal is compressed, the treble material is reduced at
the same ratio as the bass, causing it to lose definition. To compensate for this apparent loss and to add a new sheen to
signals which do not have much high frequency content, the SmarTube™Enhance process was developed. This is a
high frequency harmonic generator based on our SmarTube tube simulation circuitry. A unique feature of the circuitry is
that it behaves as a tube does in its distortion characteristics and is level dependant. This means that more harmonics
are created at higher levels, which decrease as the source fades out, just as a natural sound would. It is tunable and will
add pleasing high frequency detail not found in the source. It can bring a mic to the front of a mi , or add atmosphere to
an instrument.
There may be an occasion when certain frequencies must be compressed then added back to the original “dry”
signal, similar to using the IPro Two as one of the bands of a multi-band compressor. A blend control was added so that
this could be done without having to sacrifice an e ternal mi er channel (if one is available) to accomplish this feat.
Simply turn it to “wet” and set up the frequency band and dynamic action that you want processed, then blend this with
the “dry” signal to taste. By compressing the bass and adding it back to the original, a “fatter” sound can be created.
A headphone monitoring function with an independent level adjustment is included. This is especially needed when
the unit is used as a stereo channel recording preamp. Its signal is picked up before the main level control, and drives a

4
front panel headphone jack. In addition, a track input has been provided to monitor an e ternal source (click/cue track,
soundcard output from a digital audio workstation, tracks from a multi-track deck, etc.). This signal only appears in the
headphone jacks and is independent of the headphone level control. The main level control sets the IPro Two™s main
balanced and unbalanced outputs. It will adjust from “off” to +10 dB of gain. Dual twelve segment meters monitor either
this output or the pre-amp signal, depending on the meter switch setting. In the pre-amp position, it allows metering of
the “dry” signal so that the mic or line gain can be properly adjusted to the 0 dBu reference level. The main output has
both a 1/4" unbalanced phone, and an XLR balanced left and right connectors on the rear panel.
The unit is powered by an internal transformer, and has a standard IEC mains connector.
CONTROL FUNCTIONS:
1. +48V: Turns on the +48V phantom power for mics that require it. Do not enable phantom power if an
unbalanced low impedance mic is used, since the mic could be damaged. The LED will light if phantom power is
present.
2. POLARITY: The polarity of the mic input can be reversed in the event that the signal is out of phase with either
the line or other signals. This can happen when miking the top and bottom of the soundboard of a piano, or both
sides of a speaker cabinet or a drum head.
3. PAD: If the input level is too hot, and the gain control cannot be turned down far enough to avoid distortion,
engage this switch. This attenuates the input signal by 20 dB. It reduces the level of the input stage to avoid pre-
amp clipping, which could occur when close miking loud sources.
4. MIC ON: Enables the XLR input. If the mic input is not used, it should be turned off. This will improve
the signal-to-noise ratio by removing all residual mic pre-amp noise from the signal path. This switch can also be
thought of as a mic mute, if the mic must be turned off temporarily when it is active. The LED will light when the
mic input is live.
5. LO CUT ON: Places the low cut filter in the mic signal path. This will reduce the boom and thump of
pro imity breath effects, stage rumble, and handling noise. It has an 18 dB per octave slope with a corner
frequency of 75 Hz. This filter is before the insert point, so it will affect the “dry” signal throughout the unit.
6. GAIN: This control sets the gain of the mic pre-amp, and should be adjusted to provide a nominal signal level
of 0 dBu at the “dry” output. This is the optimum level for the rest of the circuitry that follows. This control should
be adjusted by turning off the other input sources, setting the output meter select switch to “pre-amp” and
adjusting it for a 0 dB average level.
7. MIC PAN: Sets the position of the mic signal at any place in the stereo field. If two mics are used for a stereo
recording, pan one fully left and the other fully right.
8. LINE INPUTS: Left and right high impedance (200 k ohms, balanced, 100 k ohms unbalanced) 1/4" TRS input
for line-level signals, including wireless mics, basses, guitars, and synths. If a mono signal is used, connect it to
the L/Mono input, which will automatically sum it to both the left and right inputs. Plugging anything into the right
jack forces it into a normal stereo mode.
12 4 12 19 20 22 24 282515 13
810 11 14 30 17 18 21 23 26 27 29
9
6
75
3
31 32

5
9. LINE LEVEL: Used to set the nominal input levels for the stereo line input. Adjust for a nominal level of
0 dBu for best results. If the line input is not used, this control should be turned off to remove any line pre-amp
noise from the signal path.
10. BALANCE: Use this control to balance the stereo line signal in the left and right stereo field. If the line input is
mono (no right input jack connected) this control becomes a pan control.
11. INSERT ON: The pre-amp signals are routed through the rear panel insert jacks (TRS) before continuing to the
first parametric filter. This switch activates the inserts; an LED shows the status. The insert jacks will always
have the pre-amp signals at the send (tip) contact irregardless of the setting of this switch, letting them be used
as “dry” outputs if one is required.
12. PARAMETRIC LEVEL: Adjusts the amount of cut or boost applied to the signal at the frequency specified by the
frequency control and the bandwidth set by the octave control. The ma imum range is +/-15 dB. Most uses will
require a cut. Both parametric equalizers are fully stereo.
13. PARAMETRIC FREQUENCY: Sets the center frequency of the parametric filter. The range of adjustment is
wide: 40 Hz to 15 kHz. The two filters’ adjustment ranges are identical.
14. OCTAVE: Adjusts the bandwidth (Q) of the parametric filter. It is variable from 2 octaves (wide bandwidth,
broad tuning) to 1/6 octave (narrow bandwidth, critical tuning) as measured at the state-variable filter’s output.
Narrow bandwidth is usually used to notch out (cut) problematic feedback frequencies; wide bandwidth can be
used to boost or to cut.
15. PARAMETRIC ON: To activate the parametric filter, press this switch. An LED will indicate that it is on line.
The second filter’s enable switch functions even when it is used in the side-chain mode to enable side-chain
processing.
16. PARAMETRIC TO SIDE-CHAIN: This switch allows the second parametric filter to be inserted into the side-
chain of the dynamics processor (after the side-chain insert jack return). This provides the ability to either
remove frequencies from the detector path (making the dynamic’s circuitry LESS sensitive to that part of the
audio information), or to boost them (causing the detector to be DOMINATED by those frequencies). Uses would
include de-essing (a side-chain boost at high frequencies) to help reduce sibilance, or the removal of rumble
modulation (a side-chain cut at low frequencies) which can cause pumping and breathing. It can also be set so
that the compressor will only respond to certain frequencies to even out the effects of resonance (primarily in
guitars and synths) that cause some notes to be much louder than others. Since the e ternal side-chain input is
routed through this filter when this switch is engaged, it can be used to bandwidth limit a keying signal.
17. EXTERNAL SIDE-CHAIN ON: The side-chain is another name for insert points in the input of the dynamic
section’s RMS rectifiers. Normally, the same audio signal is applied to the voltage controlled amplifier and its
detector, causing all processing to be controlled by the input, however there are instances when this is not what
is desired. If the control is to be given to another signal (to duck, for e ample), the input of the detector must
look at another input. A standard TRS insert jack is provided on the rear panel and is activated by this switch.
Any signal applied at the jack will not be seen unless the side-chain is enabled. This switch does not affect the
“parametric to side-chain” function which is always available. The e ternal signal will be modified by the
parametric filter if it is active, however.
18. EXPANDER THRESHOLD: The e pander is actually a downward e pander that adds attenuation to the signal
as it decreases in level, following defined set points and curves. It behaves oppositely of compression. This
adjustment sets the level at which it begins operation. An LED indicates that this threshold has been crossed
and downward e pansion has begun. If the input signal drops below the threshold’s set point, the e pander
fades it out according to the slope (ratio) set by the ratio control. The soft knee design smoothes the transition
from off to active by dynamically shifting the slope through the transition point. The attack and release times are
preset for best response.
19. EXPANDER RATIO: The e pander ratio is determined by dividing the input level by the output level. A ratio of
1:5 signifies that the output level has dropped five times as fast as the input. Ratios of 1:1.2 to 1:2 are typically
used to eliminate background noise and to dampen room reverberations. Higher ratios are used when gating is
required, and usually require lower thresholds to keep from cutting off the source too soon.

6
20. COMPRESSOR THRESHOLD: A compressor is a circuit that reduces (or compresses) the dynamic range of
the input signal. A great change in volume is shrunk to a more manageable one. This particular adjustment sets
the point that this compression action begins. Any signal above this threshold will be compressed by the amount
set by the ratio control. If it drops below this point, the compressor has no effect. At the ma imum threshold
setting, the compressor will be out of circuit for all signals e cept very high peaks. At the minimum setting, the
source will be almost continuously compressed. The attack and release times are optimized for vocal
applications and are program dependent.
21. COMPRESSOR RATIO: The action of the compressor is determined by the compression ratio, which is the
ratio of the input level to the output level. A ratio of 3:1 signifies that the input level has increased three times as
fast as the output (the dynamic range is compressed by a factor of three). If the ratio is 1:1, the output e actly
tracks the input, and there is no compression. Ratios of 2:1 to 4:1 are typically used for vocals and musical
instruments. Higher ratios provide a soft limiting function, since the compressor uses a soft knee design with a
more gentle transition than the e pander or limiter.
22. LIMITER THRESHOLD: The limiter is an infinite ratio compressor. The threshold control defines the point that
absolute limiting begins. The limit LED will light when this threshold has been e ceeded. To disable limiting, set
this control to ma imum. The attack and release values are preset.
23. COMPRESSOR GAIN: Adjusts the post-processing gain to make up for compression loss. It does not change
the input level to the dynamic’s section. After the ratio and threshold controls have been set, adjust this for a
0 dB average indication on the output meters with the main level control centered and the blend turned fully
CW (wet).
24. MAIN LEVEL: The master output level control of the IPro Two™. The center position is unity gain, with as
much as 10 dB gain available.
25. ENHANCE LEVEL: The SmarTube™Enhance circuitry generates pleasing high frequency harmonics from the
source signal. Using our SmarTube technology, we have designed it to give a “tube” brightness to the source
that was not in the original material. It will add crispness to vocals, or add clarity to a dull recording. Start with
the control centered and tune the frequency to where it sounds good. Then adjust the level to add the e tra
sheen. It works well in recovering highs that get squashed in the compression process. Be careful of adding too
much! It can get unpleasant if used in e cess!
26. ENHANCE FREQUENCY: This is the tuning adjustment for the SmarTube Enhance effect. It can be set to
generate second order harmonics from the source range of 2 kHz to 10 kHz (4 kHz to 20 kHz harmonics). For
most uses, this control will be set near the center of its rotation.
27. BLEND: Pans between the “dry” pre-amp signal and the fully processed “wet” signal. When set fully CW, the
output will be 100% processed, with all functions on line. At the CCW position, only the pre-amp signal will be
present. Any in between settings will be a blend of these e tremes. This control will allow the IPro Two to be
used as a single band of a multi-band compressor. To fatten an input, set the processes to boost the bass, set a
high compression ratio and a moderate compression threshold, and then blend it back into the dry signal. Many
specialized functions are possible.
28. HEADPHONE: The headphone level control picks up the main left and right signals before the main level
control so that an independent setting is possible. The headphone jack is a standard TRS 1/4" stereo jack.
29. TRACK LEVEL: An alternate stereo input is provided on the rear panel to monitor a sync/cue track, a
computer soundcard output, or other source. This control sets the level sent to the headphones, and is
completely independent of the headphone level control. The track signal is not sent to the main outputs.
30. GAIN REDUCTION METER: A twelve segment LED array that tells how much gain reduction is being applied to
the signal. It is very useful for making adjustments, since the action of the e pander, compressor, and limiter
controls is easily seen. If there is no activity, the signal’s amplitude is unchanged. Since the left and right
channels are linked with true RMS summing, the same gain reduction is applied to both.
31. OUTPUT LEVEL METER SELECTOR: The output meter can monitor either the output signal (default) or the
output of the pre-amp. It is used to set the optimum (0 dBu) internal level and to show the amplitude that is sent
to the output jacks.
32. OUTPUT LEVEL METER: This is a peak indicating meter that indicates the level of the signal picked by the
meter selector switch. The 0 dB point corresponds to 0 dBu for the 1/4" jacks and +4 dBu for the XLR output
jacks.

7
REAR PANEL JACKS:
33. MIC INPUT: XLR low impedance input jacks that will accept a wide range balanced input. Pin 2 is the positive
phase input.
34. LINE INPUT: Left/mono and right 1/4" (TRS), high impedance, balanced input jacks. The left/mono jack (if used
alone) automatically sums to the left and right inputs. The tip is the positive input and should be used for
unbalanced applications.
35. SIDE-CHAIN INSERT: Left and right 1/4" stereo (TRS) jacks which allow an e ternal device or another audio
input to be inserted into the detector’s signal path to control the VCA circuitry. The tip has the send signal; the
ring is the return input. A switch in the jack normally connects the return (ring) to the send (tip) until a plug is
inserted. This jack is enabled by a front panel switch (see #16).
36. MAIN OUTPUTS: Both balanced XLR and unbalanced 1/4" jacks are provided to interface with any type of
equipment. The XLR connectors have 4 dB more output to match the +4 dBu industry standard level. Pin 2
(and Tip) is the positive phase.
37. TRACK INPUTS: Unbalanced left/mono and right 1/4" input jacks that feed the track level control. The
left/mono jack (if used alone) automatically sums to the left and right inputs. This is where the computer output
or sync track is connected for track monitoring while laying down new tracks.
38. AC MAINS INPUT: Connect the line cord to this connector to provide power to the unit. Damage to the
equipment may result if improper line voltage is used. Operate only with the specified AC input voltage and
frequency applied.

8
IPRO TWO™SPECIFICATIONS:
Input Specifications
Function Input Z
(Ohms)
Min.
Input gain
setting Bal/ Unbal Connector
Min** Nom. Max***
Input Level, dBu*
Microphone 2.2 k Max. Gain -70 dBu -60 dBu -39 dBu Bal. XLR:
150 Ohms 56 dB Pin1 Grd
Min. Gain -16 dBu -6 dBu (>30 dBu Pin2 (+)
6 dB w/pad) Pin3 (-)
Line (Hi Z) 200 k Max. Gain -30 dBu 0 dBu +24 dBu Bal. 1/4" TRS;
20 dB Ring (-)
Sleeve Grd
Insert 10 k N/A -10 dBu 0 dBu +22 dBu Unbal. 1/4 "TRS
Return 0 dB Tip Send,
Ring Return
Sleeve-Grd
Side Chain 10 k N/A N/A 0 dBu N/A Unbal. 1/4" TRS;
Return 0 dB Tip Send
Sleeve-Grd
Ring Return,
Sleeve-Grd
Track 10 k Max. Gain N/A 0 dBu N/A Unbal. 1/4" Phone
13 dB Tip (+)
** Min. input level (Sensitivity) is the smallest signal that will produce nominal output (0 dBu) with input and master level
controls set for maximum gain.
*** Nominal settings are defined as all controls set at 0 dB (or 50% rotation for rotary pots) except the gain adjustment pot,
which is as specified.

9
IPRO TWO™SPECIFICATIONS:
Output Specifications
Function Minimum
Load Z
(Ohms)
Bal/
Unbal
Connector
Nom. Max***
Output Level
Main 600 0 dBu +22 dBu Unbalanced 1/4" Phone
XLR:
+4 dBu +26 dBu Balanced Pin1 Grd
Pin2 (+)
Pin3 (-)
Insert Send 600 0 dBu +22 dBu Unbalanced 1/4" TRS:
Tip Send,
Ring Return
Sleeve Grd
Side Chain 600 0 dBu +22 dBu Unbalanced 1/4" TRS:
Send Tip Send,
Ring Return
Sleeve Grd
Headphone 8 0 dBu +22 dBu Unbalanced 1/4" TRS:
Output (no load) Tip Left,
Ring Right
Sleeve Grd
0 dBu = 0.775 V (RMS)

10
Controls:
Equalization:
CONTROL ADJUSTMENT RANGE
Parametric (1 and 2) Cut/Boost -15 dB +15 dB, detent = flat
Parametric 1 Freq 40 Hz to 15 kHz
Parametric 2 Freq 40 Hz to 15 kHz
Bandwidth (1 and 2) 2 oct to 1/6 oct
Dynamics:
CONTROL ADJUSTMENT RANGE
E pander Threshold <-80 dBu to +10 dBu
E pander Ratio 1:1 (off) to 1:5 (gate)
E pander Attack (to gate open) 2 msec (fi ed)
E pander Release (to gate closed) 175 msec (fi ed)
Compressor Threshold -40 dBu to +20 dBu
Compressor Ratio 1:1 (off) to infinite:1 (limit)
Compressor Attack 5 msec (fi ed)
Compressor Release 175 msec (fi ed)
Limiter Threshold 0 dBu to +22 dBu
Limiter Attack 5 msec (fi ed)
Limiter Release 175 msec (fi ed)
Make-up Gain 0 dB to +20 dB
Frequency Response:
Mic Input to Output: 15 Hz to 45K Hz +0 dB / -1 dB
Line Input to Output: 10 Hz to 35K Hz +0 dB / -1 dB
Total Harmonic Distortion plus Noise (THD+ N):
< 0.01% 20 Hz to 20 kHz Mic to Output (10 Hz - 80 kHz BW, dry)
< 0.02% 20 Hz to 20 kHz Mic to Output (10 Hz - 80 kHz BW, dynamics enabled)
Signal to Noise:
88 dBu (+4 dBu reference level, all functions enabled, all levels at nominal, mic input at min gain)
MIC Equivalent Input Noise (EIN):
-129 dBu (Input terminated with 150 Ohms)
Common Mode Rejection Ratio (Mic Input):
77 dB typ @ 1 kHz, ma gain
Meters:
12 segment gain reduction indication
Dual 12 segment, peak reading output (0 dB= 0 dBu @ 1/4” out, +4 dBu @ XLR out)
Dimensions:
19” W 9.5” D 3.5” H
eight:
8.7 lbs
Power Requirements:
DOM: 120 VAC 60 Hz 15 Watts Nominal
EXP: 230 VAC 50/60 Hz 15 Watts Nominal

11
DYNAMICS CONTROL SETTING PROCEDURES
(EXPANDER, COMPRESSOR, LIMITER)
If you are starting from scratch, or have gotten something out of whack and do not know e actly what to adjust, begin by
setting the controls so that all functions are disabled.
Here are the control positions for this:
EX THRESH: min (off)
EX RATIO: min (1:1)
COMP THRESH: ma (+20dB)
COMP RATIO: min (1:1)
LIMIT: ma (+22)
CMP GAIN: min (0dB)
Naturally, the controls that need to be adjusted will depend on what you want accomplished. Here are some suggestions
to get you up and running - just follow the order listed, and leave the controls in the above (disabled) positions if that
particular function is not required.
1. Determine the ma imum output level and adjust the LIMIT THRESHOLD so that at the loudest peaks the output
level never e ceeds this point. (The action of the limiter can be seen on the GAIN REDUCTION METER and at
its own LED threshold indicator. If these never activate, there is no limit activity.) One way to accomplish this is
to deliberately increase the mic input gain (or line level control) past the desired ma imum level, then turn the
LIMIT THRESHOLD control CCW until it limits it to the correct level, then reset the input(s) to normal operating
levels.
2. To set up a noise gate, first turn the EXPANDER RATIO control fully CW (1:5). During quiet passages of the
source (between songs, when the mics are not being used, etc.) adjust the EXPANDER THRESHOLD CW until
gain reduction is indicated (a reduction of –12 dB is a good starting point). Re-adjust the EXPANDER RATIO to
set the desired gating action when the source changes from noise to signal. Low threshold settings have little
action and can tolerate a higher threshold without coloring the sound. The ma imum of 1:5 will cause an abrupt
turn on and off when the signal changes and will probably need a lower threshold setting to prevent the signal
from dropping off when you don’t want it to. You may have to go back and adjust the threshold after the ratio has
been changed, since the soft knee circuitry has more effect at lower ratios, making the transition point less
obvious.
3. For typical vocal compression, set the COMPRESSOR RATIO control to 3:1 (a range of 2:1 to 6:1 is common)
and adjust the COMPRESSOR THRESHOLD until the desired amount of gain reduction is seen on the meter.
This is a personal preference, but continuous gain reduction greater than -9 dB (especially with higher ratios)
could be e cessive and could create an unnatural sound. Lower ratios have a more gentle effect.
4. After all other settings are made, adjust the COMPRESSOR GAIN control for a 0 dB average on the output
meter to recover any level losses due to compression.

12
PRACTICAL APPLICATIONS
There are many uses for the IPro Two™, limited only by your imagination. Here are some suggested uses to inspire your
creative talents. The main ingredient is the IPro Two’s ease of setup and use. With mic and line pre-amps, two
parametric equalizers, full dynamics, SmarTube™Enhance, and headphone outputs all connected and in one place,
there is nothing easier to use. These procedures assume that all settings default to a disabled (or non-influencing) state
and are adjusted per instructions. (The LOW CUT is set at 10 Hz, SmarTube Enhance is off, main level is centered,
blend is set fully CW, line and mic gain controls are minimum, and all on/off switches are off.)
RECORDING FROM A MIC (COMPLETE SETUP): One of the most common uses is as a pre-amp for recording, either
with an analog tape machine or a digital recorder (such as a computer or digital multi-track tape machine). This unit has
all the functions necessary. Here is the setup:
1. Begin with all the functions off (see above).
2. Connect the mic to one of the XLR inputs and turn on phantom power if required.
3. Set the output meter select switch to pre-amp to check the front end levels and adjust the mic gain control to
give a 0 dBu average level. The 20 dB pad may need to be enabled if the signal is too hot. Pan the mic to its
desired stereo position.
4. Engage the dynamics section and set the limiter so that it prevents the output from e ceeding the ma imum
output level desired. This can be checked by turning up the mic gain until the gain reduction LEDs begin to light.
With the meter switch set to check the output, watch the ma imum levels and adjust the limit level to hold it to
the desired level. Then repeat step #3 to set the mic to the nominal 0 dBu level.
5. If there is too much low frequency energy getting into the mic (stage rumble, wind noise, breath e plosives, or
pro imity effects) turn on the low-cut filter.
6. Engage the parametric filters and adjust to taste. Always remember – a little is better than a lot, especially when
it comes to EQ! Usually slight notches with moderate bandwidths in the 200 Hz and 2 kHz areas are all that is
required. (Unless you are shooting for that AM radio sound!)
7. Let the mic pick up background noise and set the e pander ratio to 1:2. Gradually raise the e pander threshold
until 9 or 12 dB (or even more if the noise level is high) of gain reduction is seen on the dynamics meter. Then
add the source material and listen for e cessive dropouts or cut-off syllables. The e pander threshold may need
to be lowered if artifacts are heard. All we want is background noise reduction, not necessarily gating.
8. Normally, vocalists have such a great dynamic range that it is difficult to adequately record them. We can
overcome this problem by adding compression. A good starting point is to set the compressor ratio to 3 or 4 to 1,
and bring down the compressor threshold until 6 to 9 dB of gain reduction is seen on the meter. Add more or
less to achieve the sound you want. Adjust the dynamic’s gain control to restore the signal level to the nominal
0 dBu.
9. Because compression is driven primarily by the low frequency content of the source, the highs tend to get
swallowed up in the gain reduction. A special circuit has been built into the IPro Two to compensate for this
apparent loss. It is the SmarTube Enhance section, which generates high frequency harmonics from the source
material and adds them back in to brighten and sharpen (add sheen) the source. Start with the frequency and
level controls centered and adjust as needed. Again, less is better! This circuit can get obno ious quickly, if the
level is set too high! Tune the frequency control for the most pleasing harmonics, different sources may need
different settings to add what they don’t have.
10. Set the output level with the main level control.

13
SETTING UP A DE-ESSER:
The human voice has a lot of sibilance. The high frequency content of certain consonants can quickly overload a system
with harshness. To help reduce this problem, the compressor can be configured as a de-esser, or a compressor that
primarily responds to high frequencies. When the offending “SSSS” is detected, the gain is automatically reduced to
lessen its effect, leaving a more pleasing voice. Setup is very easy.
1. Begin with all the functions off. Set up the mic input for normal operation (gain, low cut, phantom power, etc.) If
any EQ is needed, adjust with Parametric EQ # 1.
2. Monitor the processed output and set the controls of Parametric # 2 this way: Octave = centered, Frequency =
4 kHz, Level = 3 o’clock. The sibilance energy should dominate, you may have to tweak these controls to get it
e actly right. Then set Parametric EQ # 2 in the Side Chain mode (The yellow LED will light.)
3. Set the Compression Ratio control to 6:1 or higher. Adjust the compressor’s Threshold CCW until the gain
reduction meter indicates 9 to 12 dB of reduction (set as necessary). The high frequency content of the source
should be suppressed.
4. Recover compression losses with the Dynamics Gain control.
5. Set the main output to the desired level.
REMOVING RUMBLE MODULATION FROM THE COMPRESSOR:
Since low frequencies take control of the compressor action by virtue of their dominate energy; undesirable mic handling
noise, stage rumble or wind noise can severely modulate the compressor, causing pumping and breathing effects. To
overcome this problem, we set up the compressor’s Side Chain to overlook the low frequency content and focus on the
vocal range.
1. Set up the mic normally (see Recording paragraph).
2. Set Parametric EQ # 2 like this: Frequency = 150 Hz, Octave = centered, Level = -12 dB.
3. Then set Parametric EQ # 2 in the Side Chain mode. (The yellow LED will light.)
4. Adjust the compressor controls as you normally would and tweak Parametric # 2 to taste. With the low
frequencies reduced, the signal will sound more natural when heavily compressed.
Stereo In-Ear monitors (limiting and compression a must!)
Bass guitar (frequency shaping and compression)
Guitar (electric or acoustic) (frequency shaping and compression)
Mastering mi down tool (slight EQ tweeks to clean up, and SmarTube™Enhance a mi )
Multi-tracking with computer software/hardware (using the track inputs)

14
CREST AUDIO LIMITED WARRANTY
Effective Date: November 1, 2000
What This Warranty Covers
Your Crest Audio Warranty covers defects in material and workmanship in Crest Audio products purchased and serviced in the U.S.A.
What This Warranty Does Not Cover
The Warranty does not cover: (1) damage caused by accident, misuse, abuse, improper installation or operation, rental, product modification or
neglect; (2) damage occurring during shipment; (3) damage caused by repair or service performed by persons not authorized by Crest Audio; (4)
products on which the serial number has been altered, defaced or removed; (5) products not purchased directly from Crest Audio or from an
Authorized Crest Audio Dealer.
Who This Warranty Protects
This Warranty protects only the original purchaser of the product.
How Long This Warranty Lasts
The Warranty begins on the date of purchase by the original retail purchaser. The duration of the Warranty is as follows:
Product Category Duration
Amplifiers 5 years
Consoles 5 years
Signal Processing 2 years *(+1 year)
Enclosures 3 years *(+2 years)
“Crest Performance” 2 years *(+2 years)
[*Denotes additional warranty period applicable if optional Warranty Registration Card is completed and returned to Crest Audio by original purchaser within 90
days of purchase.]
[**Denotes all products sold under the “Crest Performance” brand including amplifiers, consoles, signal processing, enclosures and any other product
category.]
What Crest Audio Will Do
We will repair or replace (at Crest Audio’s discretion) products covered by warranty at no charge for labor or materials. If the product or component
must be shipped to Crest Audio for warranty service, the consumer must pay initial shipping charges. If the repairs are covered by warranty, Crest
Audio will pay the return shipping charges.
How To Get Warranty Service
(1) Take the defective item and your sales receipt or other proof of date of purchase to your Authorized Crest Audio Dealer or Authorized Crest Audio
Service Center. OR
(2) Ship the defective item, prepaid, to Crest Audio, 100 Eisenhower Dr., Paramus, NJ 07652. Include a detailed description of the problem, together
with a copy of your sales receipt or other proof of date of purchase as evidence of warranty coverage. Also provide a complete return address.
Limitation of Implied Warranties
ANY IMPLIED WARRANTIES, INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED
IN DURATION TO THE LENGTH OF THIS WARRANTY. Some states do not allow limitations on how long an implied warranty lasts, so the above
limitation may not apply to you.
Exclusions of Damages
CREST AUDIO’S LIABILITY FOR ANY DEFECTIVE PRODUCT IS LIMITED TO THE REPAIR OR REPLACEMENT OF THE PRODUCT, AT CREST
AUDIO’S OPTION. IF WE ELECT TO REPLACE THE PRODUCT, THE REPLACEMENT MAY BE A RECONDITIONED UNIT. CREST AUDIO SHALL
NOT BE LIABLE FOR DAMAGES BASED ON INCONVENIENCE, LOSS OF USE, LOST PROFITS, LOST SAVINGS, DAMAGE TO ANY OTHER
EQUIPMENT OR OTHER ITEMS AT THE SITE OF USE, OR ANY OTHER DAMAGES WHETHER INCIDENTAL, CONSEQUENTIAL OR
OTHERWISE, EVEN IF CREST AUDIO HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Some states do not allow the exclusion
or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you.
This Warranty gives you specific legal rights, and you may also have other rights which vary from state to state.
If you have any questions about this warranty or service received or if you need assistance in locating an Authorized Service Center, please contact
Crest Audio at [phone] and ask for the service department.
Features and specifications subject to change without notice.

15
IMPORTANT SAFETY INSTRUCTIONS
WARNING: When using electric products, basic cautions should always be followed, including the following:
1. Read all safety and operating instructions before using this product.
2. All safety and operating instructions should be retained for future reference.
3. Obey all cautions in the operating instructions and on the back of the unit.
4. All operating instructions should be followed.
5. This product should not be used near water (i.e., a bathtub, sink, swimming pool, wet basement, etc.)
6. This product should be located so that its position does not interfere with its proper ventilation. It should not be placed flat against a wall
or placed in a built-in enclosure that will impede the flow of cooling air.
7. This product should not be placed near a source of heat such as a stove, radiator, or another heat producing amplifier.
8. Connect only to a power supply of the type marked on the unit adjacent to the power supply cord.
9. Never break off the ground pin on the power supply cord. For more information on grounding, write
for our free booklet “Shock Hazard and Grounding.”
10. Power supply cords should always be handled carefully. Never walk on or place equipment on power supply cords. Periodically check cords
for cuts or signs of stress, especially at the plug and the point where the cord exits the unit.
11. The power supply cord should be unplugged when the unit is to be unused for long periods of time.
12. If this product is to be mounted in an equipment rack, rear support should be provided.
13. Metal parts can be cleaned with a damp rag. The vinyl covering used on some units can be cleaned with a damp rag or an ammonia-based
household cleaner if necessary. Disconnect unit from power supply before cleaning.
14. Care should be taken so that objects do not fall and liquids are not spilled into the unit through the ventilation holes or any other openings.
15. This unit should be checked by a qualified service technician if:
a. The power supply cord or plug has been damaged.
b. Anything has fallen or been spilled into the unit.
c. The unit does not operate correctly.
d.The unit has been dropped or the enclosure damaged.
16. The user should not attempt to service this equipment. All service work should be done by a qualified service technician.
17. This product should be used only with a cart or stand that is recommended by Crest Audio, Inc.
18. Exposure to extremely high noise levels may cause a permanent hearing loss. Individuals vary considerably in susceptibility to noise induced
hearing loss, but nearly everyone will lose some hearing if exposed to sufficiently intense noise for a sufficient time. The U.S. Government’s
Occupational Safety and Health Administration (OSHA) has specified the following permissible noise level exposures.
Duration Per Day In Hours Sound Level dBA, Slow Response
890
692
495
397
2 100
1 1/2 102
1 105
1/2 110
1/4 or less 115
According to OSHA, any exposure in excess of the above permissible limits could result in some hearing loss. Ear plugs or protectors for the ear
canals or over the ears must be worn when operating this amplification system in order to prevent a permanent hearing loss if exposure is in excess
of the limits as set forth above. To ensure against potentially dangerous exposure to high sound pressure levels, it is recommended that all persons
exposed to equipment capable of producing high sound pressure levels such as this amplification system be protected by hearing protectors while
this unit is in operation. SAVE THESE INSTRUCTIONS!

Features and specifications subject to change without notice.
Crest Audio Inc. • 100 Eisenhower Drive • Paramus, NJ 07652 USA
TEL: [phone] • FAX: [phone] • www.crestaudio.com
©2001 Printed in the U.S.A. 04/01
80304725