PreSonus GTX44 User Manual

GTX44

Four Channel Gate/Expander

User's Manual

VERSION 1.1

PreSonus Limited Warranty

PreSonus Audio Electronics Inc. warrants this product to be free of defects in material and workmanship for a period of one year from the date of original retail
purchase. This warranty is enforceable only by the original retail purchaser. To be protected by this warranty, the purchaser must complete and return the enclosed
warranty card within 14 days of purchase. During the warranty period PreSonus shall, at its sole and absolute option, either repair or replace, free of charge, any
product that proves to be defective on inspection by PreSonus or its authorized service representative. To obtain warranty service, the purchaser must first call or
write PreSonus at the address and telephone number printed below to obtain a Return Authorization Number and instructions of where to return the unit for service.
All inquiries must be accompanied by a description of the problem. All authorized returns must be sent to the PreSonus repair facility postage prepaid, insured and
properly package. Proof of purchase must be presented in the form of a bill of sale, canceled check or some other positive proof that the product is in within the
warranty period. PreSonus reserves the right to update any unit returned for repair. PreSonus reserves the right to change or improve design of the product at any
time without prior notice. This warranty does not cover claims for damage due to abuse, neglect, alteration or attempted repair by unauthorized personnel, and is
limited to failures arising during normal use that are due to defects in material or workmanship in the product. Any implied warranties, including implied warranties of
merchantability and fitness for a particular purpose, are limited in duration to the length of this limited warranty. Some states do not allow limitations on how long an
implied warranty lasts, so the above limitation may not apply to you. In no event will PreSonus be liable for incidental, consequential or other damages resulting from
the broach of any express or implied warranty, including , among other things, damage to property, damage based on inconvenience or on loss of use of the product,
and, to the extent permitted by law, damages for personal injury. Some states do not allow the exclusion of 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 form state to state.
This warranty only applies to products sold and used in the United States of America. For warranty information in all other countries please refer to your local
distributor.

Limited Warranty Outside of The U.S.

PreSonus Audio Electronics products are warranted only in the country where purchased, through the authorized PreSonus distributor in that country, against defects
in material and workmanship. The specific period of this limited warranty shall be that which is described to the original retail purchaser by the authorized PreSonus
dealer or distributor at the time of purchase. PreSonus does not, however, warrant its products against any and all defects: 1) arising Out of materials or
workmanship not provided or furnished by PreSonus, or 2) resulting from abnormal use of the product or use in violation of instructions, or 3) in products repaired or
serviced by other than authorized PreSonus repair facilities, or 4) in products with removed or defaced serial numbers, or 5) in components or parts or products
expressly warranted by another manufacturer. PreSonus agrees, through the applicable authorized distributor, to repair or replace defects covered by this limited
warranty with parts or products of original or improved design, at its option in each respect, if the defective product is shipped prior to the end of the warranty period
to the designated authorized PreSonus warranty repair facility in the country where purchased, or to the PreSonus factory in the U.S., in the original packaging or a
replacement supplied by PreSonus, with all transportation cost and full insurance paid each way by the purchaser or owner. All remedies and the measure of
damages are limited to the above services. It is possible that economic loss or injury to person or property may result from the failure of the product; However, even
if PreSonus has been advised of this possibility, this limited warranty does not cover any such consequential or incidental damages. Some states or countries do not
allow the limitations or exclusion of incidental or consequential damages, so the above limitation may not apply to you. Any and all warranties, express or implied,
arising by law, course of dealing, course of performance, usage of trade, or otherwise, including but not limited to implied warranties of merchantability and fitness
for a particular purpose, are limited to a period of two years from either the date of original retail purchase or, in the event no proof of purchase date is available, the
date of manufacture. Some states or countries do not allow limitations on how long an implied warranty last, so the above limitations may not apply to you. This
limited warranty gives you specific legal rights, and you may also have other rights which vary from state to state, country to country.

PreSonus Audio Electronics, Inc.
7257 Florida Blvd.
Baton Rouge, LA 70806
225-216-7887
www.presonus.com

Table of Contents

1 Overview

1.1 Introduction

1.2 Features

2 Controls & Connections

2.1 Front Panel Basic Layout

2.2 Gate/Expander Controls

2.3 Bypass & Link

2.4 Patch Panel

2.5 Power

3 Basic Setup & Applications

3.1 Basic Applications

4 Technical

4.1 Specifications

5 Troubleshooting

1.1 INTRODUCTION

Thank you for purchasing the PreSonus GTX44 four channel dynamics processor. This process or was designed using state of
the art components to deliver crystal clear compression and limiting for an infinite period of time. We believe that it is an
exceptional sounding unit as well as an exceptional value. Feel free to contact us at 1-800-750- 0323 anytime for any reason
whatsoever. We value your suggestions and your comments!

Please pay close attention to how you connect your GTX44 to your system. Improper grounding is the most common cause
of noise problems found in studio or live sound systems. We urge you to at least scan this manual before hooking up your
GTX44 to become familiar with its features and various applications.

Good luck and enjoy your GTX44!

1.2 FEATURES

The following is a summary of your GTX44's features:

Full Featured Gate/ Expander

Each channel of yourGTX44 can be used as a frequency specific gate or expander, depending on your needs and settings.

Channel Linking

Using the Link function, you can link together two channels of the GTX44 for stereo operation. When linked, the processor
follows the setting of linked channel to the left, which becomes the master. When two channels are linked the sidechains are
summed.

Separate Bypass for Each Channel

All four channels have a separate bypass for listening to 'before and after' pe rformance tests.

Insert Sidechain on Each Channel

Each channel of your GTX44 was designed with a special jack for spectral processing, and ducking applications. Sidechaining
is useful for automatically ducking tracks behind a narrator for 'auto mixing' a service, broadcast or performance.

Duck Mode

Ducking lowers the level of the audio signal based upon the level of a second sidechain audio signal.

Balanced XLR and Unbalanced 1/4" Tip/Ring/Sleeve Input/Output

Your GTX44 accepts XLR connectors for balance d or a single 1/4" TRS for unbalanced inputs and outputs.

+4dBu or -10dBV Insert Switch

The operating level of your GTX44’S inserts can be switched between +4dBu (pro levels) to -10dBV (line levels) for ease of
use with external equipment in any situation.

To Get Help

Call Us: 1-800-750-0323, 9AM to 5PM, CST
Visit our World Wide Web site: http://www.presonus.com
Email Us: [e-mail]

2.1 FRONT PANEL BASIC LAYOUT

Notice that the front panel is divided into four identical sections. These are the four signal processing channels of the
GTX44. Each channel contains:

Gate/Expander
Lo/Hi Filter
SideChain Monitor
Link & Bypass Control
Duck Mode

2.2 GATE/EXPANDER CONTROLS

Lo/Hi Filter

There are many situations, especially with drums, when other instruments open up the gate instead of the instrument being
gated. For example, tom-tom mics are generally placed very close to the cymbals on a drum kit, creating the possibility of
the cymbals opening up the tom-tom gates. The Lo/Hi Filters allow the user to specify which frequencies are ‘eligible’ for
gating. Therefore the cymbals may be removed from ‘eligibility’ by using a high cut filter to filter out the high frequencies of
the cymbals. The gate will no longer open up during cymbal crashes, leaving th e low frequencies of the tom-tom to properly
open the gates.

Threshold

The gate threshold sets the level at which the gate opens. Essentially, all signals above the threshold setting are passed
through unaffected, whereas signals below the threshold setting are reduced in level by the amount set by the ratio and/or
range control.

Ratio

The expansion ratio sets the amount of noise reduction applied to a signal once the signal has dropped below the expansion
threshold. For example, a 2:1 expansion ratio attenuates a signal 1dB for every 1dB it drops below the threshold. Ratio’s
4:1 and higher act like a noise gate. Note: The Range Control overrides the ratio control. For example: If the Expander calls
for 40dB of attenuation but the Range is set to 20 dB of attenuation, the signal will be attenuated by 20dB.

Range

The range is the amount of gain reduction that the processor closes down to. Therefore, if the range is set at 0dB, there will
be no change in the signal as it crosses the threshold. If the range i s set to -60dB, the signal will be attenuated (reduced)
by 60dB, etc.

Attack

The gate attack time sets the rate at which the gate opens. A fast attack rate is crucial for percussive instruments, whereas
signals such as vocals and bass guitar require a slower attack.

Hold

Hold time is used to keep the gate open for a fixed period of time following the signal going below the gate threshold. This
can be really useful for effects such as ‘gated snare’ where the gate remains open after the snare hit for the duration of the
hold time then abruptly closes. Hold is only available when the ratio knob is set to GATE.

Release

The gate release time determines the rate at which the gate closes. Release times should typically be set so that the natural
decay of the instrument or vocal being gated is not affected. Shorter release times help
to clean up the noise in a signal but my cause ‘chattering’ in percussive instruments. Longer release times usually eliminate
‘chattering’ and should be set by listening carefully for the most natural release of the signal.

SC Mon

The SideChain Monitor allows you to hear the frequency range that the Lo and Hi Filter are operating on.

Link

Using the Link function, you can link together two channels of the GTX44 for stereo operation. When linked, the processors
follow the setting of linked channel to the left, which becomes the master. Remember, when two channels are linked, the
sidechains are summed!

Duck

Ducking lowers the level of the audio signal based upon the level of the sidechain audio signal. If the unit is in gate mode,
then you can DUCK according to what the range setting.

A typical application is paging: A ducker senses the presence of audio from a paging microphone and triggers a reduction in
the output level of the main audio signal for the duration of the page signal. It restores the original level once the page
message is over.

Bypass

All four channels have a separate bypass for listening to 'before and after' performance tests.

2.5 BYPASS & LINK

Bypass

Activating the bypass effectively removes all processing being performed by your GTX44 and returns the signal to unity
gain. You should use bypass often when setting up your GTX44 to compare the 'before and after' results of the signal
processing affecting your audi o signal. Bypass affects the gate and all its functions. When in Bypass the Link function is still
engaged, but both channels are set to Bypass Mode.

Link

When the Link button is pushed in, the channel to the left becomes the master controller of both channels. The channel to
the right's controls become disabled and metering becomes summed left and right, i.e. stereo mode. IMPORTANT: When the
two channels are linked (link button pushed in), all of the right channel's controls are inactive.

2.6 PATCH PANEL (BACK)

Input/Output

The input/output jacks are unbalanced tip/sleeve or ring/sleeve connectors or balanced XLR connectors. The XLR
inputs/outputs can handle up to +24dBu unbalanced or balanced.

+4/-10 Switch

This switch adjusts the insert operating le vel of the sidechain of your GTX44 when it is connected to line level (0dB = ­10dBV) gear. With the switch in the '-10' position, the sidechain signal is raised internally. The main audio path is not
affected, only the processing level is. When the switch is in the '+4' position, the signal is not changed since this matches
the internal sidechain operating level of your GTX44. The +4/- 10 does not change the audio level through the GTX44. . It is
important to remember that Pro Gear has a hotter +4 level, whe reas consumer gear runs at the lower level of -10.

Sidechain

It is sometimes impossible to set a noise gate to open precisely when an instrument sounds in a noisy environment. Most
gates feature an external gate key that will allow the gate to be opened u sing an external signal, in effect ‘triggering’ the
gate to open. For example a bass guitar gate might be ‘triggered’ using the kick drum to tighten up the low end of a mix. Or
a snare track might be ‘triggered’ using a click track or sequencer to place th e snare right in time with the music.

2.7 POWER

Power Connection

The power jack on your GTX44 accepts a standard IEC cord like those found on most computers and professional recording
equipment. Your GTX44 contains a custom built in power supply, no wall wart. This way you can be assured of clean power
combined with rugged construction that has been designed to last!

Power Switch

I = ON, 0 = OFF.

3.1 BASIC IDEAS AND APPLICTIONS

Why Do You Need Noise Gates?

Problems arise when there is noise or instruments in the background of the vocal mic that became more audible after the
lower end of the dynamic range was raised. (air conditioner, loud drummer, etc.) You might attempt to mute the vocal
between phrases in an attempt to remove the unwanted signals; however this would probably be disastrous. A better
method is to use a noise gate. The noise gate threshold could be set at the bottom of the dynamic range of the vocal, say ­10dBu, such that the gate would ‘close’ out the unwanted signals between the phrases. If you have ever mixed live you
know well the problem cymbals can add to your job by bleeding through your tom mics. As soon as you add some highs to
get some snap out of the tom the cymbals come crashing through, placing the horn drivers into a small orbit. Gating those
toms so that the cymbals no longer ring through the tom mics will give you an enormous boost in cleaning up the overall
mix.

Expansion

There are two basic types of expansion: dynamic and downward. Expansion increases the dynamic range or level of a signal
after the signal crosses the expansion threshold. Dynamic expansion is basically the opposite of compression. In fact,
broadcasters use dynamic expansion to
‘undue’ compression before transmitting the audio signal. This is commonly re ferred to as ‘companding’ or COMPression
followed by expANDING. By far the most common use of expansion is downward expansion. In contrast to compression,
which decreases the level of a signal after rising above the compression threshold, expansion decreases the level of a signal
after the signal goes below the expansion threshold. The amount of level reduction is determined by the expansion ratio.
For example, a 2:1 expansion ratio reduces the level of a signal by a factor of two. (e.g. if a level drops 5dB below the
expansion threshold, the expander will reduce it to 10dB below the threshold.) Commonly used as noise reduction,
expansion is very effective as a simple noise gate.
The major difference between expansion and noise gating is the fact that expansion is dependent on the signal level after
crossing the threshold, whereas a noise gate works independent of a signal’s level after crossing the
threshold.

Noise Gating

Noise gating is the process of removing unwanted sounds from a signal by attenuating all signals below a set threshold. As
described above, the ‘gate’ works independent of the audio signal after being ‘triggered’ by the
signal crossing the gate threshold. The gate will remain open as long as the signal is above the threshold. How fast the g ate
opens to let the ‘good’ signal through is determined by the attack time. How long the gate stays open after the signal has
gone below the threshold is determined by the hold time. How fast the gate closes is determined by the release. The range
determines how much the gate attenuates the unwanted signal while closed.

Patching Using a Patch Bay

When using a patch bay to extend the GTX44's patch panel for easier access, the following should be considered:

1. Lowest noise is achieved when using balanced patch bays.

2. The input and output jacks should not be normalled (the send routed
back to the return).

3. The sidechain jacks must be normalled.

Gating Drums or Percussion Instruments

Adjust the Gate on the snare to stop those other drums from 'bleeding' through the snare mic: Turn the gate release knob
to about the middle position, turn the gate attack knob to fully counter- clockwise, set the gate range to -60dB, adjust the

gate threshold slowly clockwise until you begin to hear those other drums disappearing. Too high of a threshold setting
might disrupt the snares natural sound; too low will let those other drums open the gate. You need to adjust the gate's
threshold and release to suit your drumming taste.

This simple application applies to any percussive instrument of course. Experiment.

4.1 SPECIFICATIONS

Number of Channels 4
Dynamic Range >115dB
Signal to Noise Ratio >95dB
Headroom +24dBu, Unbalanced; +24dBu Balanced
Frequency Response 10Hz to 50kHz
Gate Attack Range 10mS to 500mS
Gate Thr eshold Range 40dBu to +15dBu
Gate Release Time 0.01sec to 2sec
Gate Attenuation Range 0dB to -80dB
Input Impedance 10kOhms
Output Impedance 51 Ohms
THD + Noise <0.05%
Gate Metering -3dB to - 30dB
Sidechain Output Impedance 51 Ohms
Sidechain Input Impedance 10kOhms
Internal Operating Level +4dBu = 0dB
Sidechain Level +4dBu or- 10dBV, Switchable
Input/Output Connectors 1/4", Tip / Sleeve, Unbalanced or XLR Balanced
Sidechain Connector 1/4", Tip Ring Sleeve
Power Supply Internal, Linear Supply
Power Requirements 100/120/220/240VAC (Factory Configured)
Power 24 Watts
Weight 7 lbs.
Size 1U Rack

TROUBLESHOOTING

Ghost Meters

The inputs of the CL44 are not designed to be overdriven. In the event that you do overdrive the inputs on one or two
channels, the meters of the other two channels (if not in use) may show activity. This “ghost activity” is not signal bleed, it
is sidechain crosstalk. It will not change or affect the processing power or ability of your unit.

Installing the GTX44 int o an Existing Rack

If you are installing your CL44 into an existing equipment rack, it may be necessary to purchase some additional cabling.
Most dynamics processors use a 1/4” TRS Y shaped insert cable to connect to a console. The CL44 is designed to connect to
a console using one 1/4” TRS cable. A 1/4” TRS Y male to dual female cable may need to connect the CL44 to an existing
audio snake. Once the cabling is connected, you only need to press the FLIP switch if the sends/returns are not matched up
properly.