Source Audio ATLAS COMPRESSOR SA 252 User manual

SA252 Atlas Compressor User Guide
1
Atlas Compressor User Guide
Welcome
Thank you for purchasing the Source Audio Atlas! The Atlas is an all-in-one compressor pedal that
aims to be the ultimate destination for guitar or bass compression and a dive into the deep history of
compressor units. On the surface, the Atlas serves up six unique compressor circuits spanning from
classic stompbox compressors to expensive studio rack gear to ultra-modern and flexible dual-band
compressors.
Connect via USB to the Neuro Mobile App and Neuro Desktop Editors to transform the Atlas into a
DAW compression module with real time gain reduction readout displays and enough controls—such
as Threshold, Attack, Release, Makeup Gain, Ratio, Soft Knee Width, Clean Blend, and a Side Chain
Low-Pass and High-Pass Filters to fine-tune the Atlas Compressor to your exact specifications.
Parameter range controls allow you to set a custom range for each control knob so your tones will
always be in the useable range.
The Atlas Compressor is our love letter to compression and was a collaborative effort between our
trusted engineering duo of Jesse Remignanti (hardware) & Bob Chidlaw (DSP) and Christopher Venter
of SHOE Pedals, who has previously contributed on the ZIO and True Spring pedals. Plug in an Atlas
and experience the final word in audio compression.
—The Source Audio Team

SA252 Atlas Compressor User Guide
2
Contents
Welcome ................................................................................................................................................. 1
Contents .................................................................................................................................................. 2
Feature Overview .................................................................................................................................... 3
Connecting the Pedal .............................................................................................................................. 4
Controls ................................................................................................................................................... 8
ALT Controls .......................................................................................................................................... 10
Atlas Factory Presets ............................................................................................................................. 11
Stereo Operation & Signal Routing ....................................................................................................... 12
Preset Storage and Recall ..................................................................................................................... 13
External Control Options ....................................................................................................................... 14
Expression Control ................................................................................................................................ 15
Neuro Desktop and Mobile Editors ....................................................................................................... 16
The Neuro Desktop Editor ..................................................................................................................... 16
Graphic Equalizer Module ..................................................................................................................... 21
Parametric Equalizer Module ................................................................................................................ 21
Knob Assignment Module ..................................................................................................................... 22
The Neuro Mobile App — with New Direct MIDI-USB Support ............................................................ 24
Neuro Hub ............................................................................................................................................. 25
MIDI ...................................................................................................................................................... 26
USB ........................................................................................................................................................ 27
Specifications ........................................................................................................................................ 27
Troubleshooting .................................................................................................................................... 28
Frequently Asked Questions ................................................................................................................. 28
Rubber Feet ........................................................................................................................................... 30
Waste Disposal Notes ........................................................................................................................... 30
Warranty ............................................................................................................................................... 30
Version History ...................................................................................................................................... 31

SA252 Atlas Compressor User Guide
3
Feature Overview
Look Ahead Compression: When engaged, Look Ahead creates an imperceptible latency in
the signal that “looks into the future” and allows for an extra quick and smooth attack that
without any additional distortion or artifacts.
Side Chain Compression: Use the signal going to Input 2 to trigger the compression applied
to the signal going into Input 1.
Six Preset Positions: Use the Atlas’s three-position toggle switch and two preset banks to
save six easily accessible presets.
Stereo Ins and Outs: Create two entirely different compression presets and run them in
series, parallel or run each to a separate output.
Bass Optimized Mode: Each of the six onboard compression circuits can be reloaded and
optimized for bass guitar with a simple button press.
Growing Library of Published Presets: For quick and easy access to a world of great tones,
try sampling sounds from a vast collection of published presets created by the Source Audio
team and the ever-growing Neuro Community.
Unprecedented Sound Sculpting Options: The powerful Neuro Desktop Editor (free
download for Mac and Windows) and Neuro Mobile App (iOS and Android) offer maximum
sound exploration possibilities. Use Neuro’s DAW inspired editor to create custom Atlas
presets that can be burned directly to the pedal, saved to a private cloud-based library, or
shared publicly with other members of the Neuro Community.
128 MIDI Accessible Factory Presets: The addition of a third-party MIDI controller with USB
host provides access to any of the pedal’s 128 Factory presets.
Compact Design: The extruded anodized aluminum housing, with its slim profile and small
footprint, is built for the rigors of the road.
MIDI Capable: Connect the Atlas to the Source Audio Neuro Hub or a USB-MIDI Host and
access up to 128 presets with MIDI Program Change (PC) messages. Control many of the
pedal’s parameters with MIDI Continuous Controller (CC) messages.
USB Port: Class compliant USB-MIDI allows the Atlas to work as a plug-and-play device with
recording software running on Mac and Windows. The USB port offers connectivity to the
Neuro Desktop Editor as well as the Neuro Mobile App, providing access to deep editing
possibilities and pedal firmware updates.
Universal Bypass™: Select between analog buffered and relay-based True Bypass.

SA252 Atlas Compressor User Guide
4
External Expression Pedal Control: Make simultaneous, on-the-fly changes of up to three
parameters with an external expression pedal.
Connecting the Pedal
Power
To power the unit, connect the included 9V DC negative-tipped power supply to the jack labeled DC
9V on the back panel. The Atlas needs at least 160mA of current to operate as intended.
Warning: Using a non-Source Audio supply, especially an unregulated supply, could damage the unit.
A power supply with insufficient current levels may also cause noise or other unpredictable behavior.
Please be very cautious when using 3rd-party power supplies and refer to the power supply
requirements in the Specifications section of this guide.
Guitar/Audio Connections
Using standard ¼” mono (TS) cables, connect your guitar, bass, or other instrument to the INPUT 1
jack and your amp (or the next audio device in the signal chain) to the OUTPUT 1 jack. If you have a
second amp, connect it to OUTPUT 2.
When the power and audio connections have been made, Atlas is ready for use.

SA252 Atlas Compressor User Guide
5
Input Side Connections
INPUT 1
INPUT 1 is the primary input for guitar, bass, or other instruments. It can also accept line-level inputs
and will work in your amp’s effect loop. Connect it to your instrument or other audio source using a
mono (TS) 1/4” cable. Details about the appropriate signal levels are available in the Specifications
section.
INPUT 2
Use the secondary audio input for stereo sources or as the data connection to your mobile device
when using the Neuro App.
• INPUT 2 as an Audio Input: The tip contact on INPUT 2 acts as a secondary input for guitar, bass,
or other instruments. Connect your instrument (or the previous effect in the signal chain) using
a mono (TS) ¼” cable. The Atlas will automatically configure itself for stereo audio input. Other
routing options are available using the Neuro App. For more information about stereo routing,
refer to the Stereo Operation section.
• INPUT 2 as a Neuro App Data Input: The ring contact on INPUT 2 acts as a data connection for the
Neuro Mobile App. The Neuro App sends data to the pedal using your mobile device’s
headphone jack. Connect it to your mobile device using the included stereo (TRS) 1/8” to 1/4”
cable. It can also accept daisy-chained Neuro data from another Neuro-compatible pedal in the
chain, provided that a TRS cable is used. The audio signal (if applicable) will be on the tip contact
of the plug, and the Neuro App data will be on the ring contact. This allows audio and Neuro
data to flow on the same cable.

SA252 Atlas Compressor User Guide
6
Output Side Connections
OUTPUT 1
This is the primary audio output. Connect it to your amplifier, recording interface, or the next device
in your effects signal chain using a mono (TS) ¼” cable.
OUTPUT 2
OUTPUT 2 can act either as an audio output or a daisy-chain data connection for the Neuro App.
• OUTPUT 2 as an Audio Output: The tip contact on OUTPUT 2 acts as the secondary audio output.
It carries an audio signal when the Atlas is configured with a signal routing that uses stereo
outputs. Connect it to your amplifier, recording interface, or the next device in your effects
signal chain using a mono (TS) ¼” cable.
• OUTPUT 2 as a Neuro App Data Daisy-Chain Output: The ring contact on OUTPUT 2 acts as a data
connection for the Neuro App, passing data from the Atlas to the next Source Audio effect in
your signal chain. You can daisy-chain the Neuro App data regardless of whether OUTPUT 2 is
configured to output audio or not. Connect OUTPUT 2 to the next device’s Neuro App Data input
(usually INPUT 2) using a stereo (TRS) 1/4” cable. The audio signal (if applicable) will be on the tip
contact of the plug, and the Neuro App data will be on the ring contact. This allows audio and
Neuro data to flow on the same cable.

SA252 Atlas Compressor User Guide
7
Power and Control Connections
DC 9V (Power)
Connect to the included 9 Volt DC power supply. If you would like to use a 3rd-party supply, the
power supply must be regulated at 9 Volts DC (direct current), able to source at least 160 mA
(milliamps) of current, and the plug should have a tip-negative, barrel-positive polarity.
USB
Connect to your computer (Windows or Mac) or mobile device (Android or iOS) to the Atlas’s USB
port (denoted by the icon) using a standard USB mini-B cable. The Atlas is a class compliant USB
device, meaning that it does not require any custom drivers.
CONTROL INPUT
The 3.5 mm CONTROL INPUT port connects to external control devices such as the Source Audio Tap
Tempo Switch, Source Audio Dual Expression Pedal, and the Neuro Hub. For more information, refer
to the Expression Pedal Input and Neuro Hub sections of the User’s Guide.

SA252 Atlas Compressor User Guide
8
Controls
Footswitch
Click the footswitch to engage or bypass the pedal. Press + hold the footswitch down while the pedal
is bypassed to bank to Red LED (ALT) Mode for more presets.
Control Input / ALT Button
This small button located at the top of the pedal is used to enable or disable external control. It also
is used to control the ALT parameters on the surface of the pedal. Press + hold the ALT knob while
turning any of the control knobs to access their alternate parameters (see next page for ALT
Controls).
Engage/Bypass LED
The Engage/Bypass LED indicates whether the effect is bypassed or engaged. In ALT Mode (presets
4-6), the LED becomes red when the pedal is engaged.
Gain Reduction
By default, the Engage/Bypass LED also shows gain reduction by changing from green to red
whenever compression is being applied to the input signal. This feature can be turned off in the
Hardware Options section of the Neuro App and Desktop Editor.

SA252 Atlas Compressor User Guide
9
THRESHOLD Knob
Adjusts the decibel level at which the signal becomes compressed. Turn counterclockwise for a
lower threshold (earlier compression), or clockwise for a higher threshold (a hotter signal is needed
for compression to occur).
RATIO Knob
Adjusts the overall level of compression. Turn clockwise for a higher (flatter) ratio and ultra-
squashed dynamics. Turn counterclockwise for a lower ratio and more subtle compression
BLEND Knob
Adjusts the wet/dry mix of compression. Unlike MIX controls on other Source Audio pedals, the
BLEND control blends in clean signal as the knob is turned up. Therefore, 100% wet (compressed)
signal is at full counterclockwise on the BLEND knob, and 100% dry is at full clockwise on the knob.
OUTPUT Knob
Adjusts the overall output level (wet/dry mix) of the Atlas.
Preset Selector Toggle
Use the Atlas’s three-position toggle switch and two preset banks to easily access six different
presets. First Preset Bank (Indicated by the green center LED): default the center toggle switch
selects between three presets stored in the first bank of presets. Second Preset Bank (Indicated by
the red center LED): Pressing the ALT button on the topside of the pedal opens access to the second
bank of presets. After pressing the ALT button, the small LED at the top of the pedal’s face will start
to blink, indicating that the second preset bank is accessible with the toggle switch. Upon moving the
toggle switch the center LED will turn red indicating the current preset is drawn from the second
bank.

SA252 Atlas Compressor User Guide
10
ALT Controls
Pressing and holding the ALT button while rotating the control knobs will adjust their ALT parameter
instead of their normal parameter. Below are a list of ALT parameters and how they correspond to
the normal controls.
Makeup Gain (ALT THRESHOLD)
Adjusts the makeup gain within the compression signal. Makeup gain allows you to recover lost
output volume caused by heavy compression. The Makeup Gain control only affects your
compressed (wet) signal.
Tone (ALT RATIO)
Cuts (below noon) or boosts (above noon) the treble control in the parametric equalizer. By default,
the Treble frequency is set to about 4461Hz, but this frequency can be changed using the Neuro App
or Desktop Editor.
Attack (ALT BLEND)
Attack controls how quickly in milliseconds compression is applied to your input signal. Turn
clockwise for fast attack times and counterclockwise for slower attack times.
Release (ALT OUTPUT)
Release controls how quickly in milliseconds compression “let’s go” or stops being applied to your
input signal. Turn clockwise for fast release times and counterclockwise for slower release times.

SA252 Atlas Compressor User Guide
11
Atlas Factory Presets
The Atlas comes equipped with six hand-tuned presets found on the three toggle switch and three
ALT + toggle switch positions. Each preset has already been optimized for sound and feel out of the
box without needing to connect the Atlas to the app or editors. Below is a description of each factory
preset.
STUDIO: “Studio Snap” - A hard knee VCA style compressor that uses both Peak and RMS detectors to
create a dual-stage release and applies a dynamic EQ to enhance attacks.
OPTICAL: “Optical Rack” - A gentler and more relaxed compressor based closely on a studio rack mount
staple, the LA2A optical compressor.
DUAL: “Dual Band” - Based on modern digital processing, this is a two-band compressor that treats
frequencies under 333hz differently than those above. This allows for fewer compression artifacts and
an enhanced blooming sustain on chords or notes that ring out.
STUDIO (ALT): “Studio 76” - Based on the famous 1176, a studio rack mount FET compressor known for
its very fast attack times. This version has been optimized for use with guitar.
OPTICAL (ALT): “Cubic Zirconia” - A less clean optical compressor based on a popular, discontinued
yellow compressor pedal that used an LED to achieve its compression.
DUAL (ALT): “Dual Jangle” - A modern style dual band compressor that is aimed at enhancing
harmonics above 2000hz, but without adding additional harshness to pick attack. This works very well to
enhance 12 string guitars, Jangly strumming patterns, and arpeggiated picking techniques.
Optimized For Bass
The Atlas Compressor features an alternate set of factory presets tuned especially for bass. This
mode can be selected by holding down the CONTROL/ALT button while powering on the pedal. The
small green LED will blink once to indicate normal (guitar) mode and twice to indicate bass mode.
Release the CONTROL/ALT button to select the desired mode.
Most of the factory preset are the same name and description for bass. The noted discrepancies are
as follows:
• “Dual Band” has a frequency cutoff point at 82Hz for bass compared to 333hz for guitar.
• “Dual Jangle” for guitar is named “Dual Lookahead Bass” for bass. It is a modern style dual
band compressor that is aimed at evening out string to string balance and maintaining
dynamic consistency when switching playing techniques. This mode also uses the Atlas'
Lookahead feature. This allows for faster reaction by the compressor without the artifacts
usually associated with very fast attack times.

SA252 Atlas Compressor User Guide
12
Stereo Operation & Signal Routing
The Atlas is flexible for many different use cases due to its stereo INPUT and OUTPUT jacks. By
default, the Atlas auto-detects the cables connected to INPUTS and OUTPUTS 1 & 2 and engages the
appropriate Routing Mode. Stereo Routing can also be performed manually with the Neuro Editors,
select between “Mono In, Stereo Out” or “Stereo In, Stereo Out.”
There are four routing modes available when the Atlas is in its default Auto Detect mode. See
detailed descriptions of each Auto Detect mode in the sections below.
• Mono In, Mono Out
• Mono In, Stereo Out
• Stereo In, Stereo Out
• Stereo In, Mono Out
Mono In, Mono Out
This is the most common use case. Plugging the incoming signal into INPUT 1 with OUTPUT 1
connected to an amp (or the next device in the signal chain) produces a standard mono signal. Dual
processing effects are also mixed down a single output.
Mono In, Stereo Out
This is a very common use case that allows you to create some nice stereo imaging from a single
mono instrument input or use your Atlas as a splitter to send your signal to two separate outputs.
When the unit is bypassed in this mode, it will automatically switch to Soft Bypass mode to maintain
the bypass signal on the Channel 2 output. When Ch. 1 and Ch. 2 are linked, the output will be the
same for both channels. When they are unlinked, you can configure separate settings for Channel 2.

SA252 Atlas Compressor User Guide
13
Stereo In, Stereo Out
This mode should be your default selection for Stereo In, Stereo Out applications. Stereo In, Stereo
Out allows you to continue your stereo chain of effects. When Ch. 1 and Ch. 2 are linked, the output
will be the same for both channels. When they are unlinked, you can configure separate settings for
Channel 2.
Stereo In, Mono Out
This mode will accept stereo input on jacks INPUT 1 and 2. Inputs 1 and 2 are sent to Channel 1 and 2
respectively. When Ch. 1 and Ch. 2 are linked, the output will be the same for both channels. When
they are unlinked, you can configure separate settings for Channel 2. The outputs of the Channel 1
and Channel 2 equalizers are mixed and sent to OUTPUT 1.
Preset Storage and Recall
User Presets store all user editable parameters. This includes the knob positions, parameter settings,
frequencies, routing options, external control, and the full list of Neuro/MIDI accessible parameters.
Included in every preset are settings for either channel (Channel 1 [Mono] or Channel 2). After a
preset is recalled, you can always tweak the top-level controls in a performance situation by turning
the knob. The knob parameter will then “jump” to the current knob position as it is rotated.

SA252 Atlas Compressor User Guide
14
Recalling Presets
The first six User Presets are accessible via the onboard hardware or with an external footswitch in
the following ways:
1. Move the toggle switch to left, center, or right to access presets #1-3.
2. Press the ALT button while moving the toggle switch to access presets #4-6, or press + hold the
footswitch when the pedal is OFF for 5 seconds to access the Red LED (presets #4-6).
Recalling MIDI Presets
All 128 available User Presets are accessible with an external MIDI controller. MIDI controllers can be
connected via USB port at the top of the pedal, or through a Neuro Hub, which connected to the
CONTROL INPUT at the top of the pedal. All 128 User Presets can be recalled with the corresponding
MIDI program change (PC) messages.
Note: When recalling presets via MIDI PC messages, you may wish to queue up your preset with
effect bypassed. To do this, simply engage the preset, bypass it with the footswitch, then re-save the
preset normally. When recalled, the pedal will load the saved user settings, but the effects will be
bypassed until you engage the pedal.
Copying a Preset to a New Location Using the Neuro App
Using the BURN and SAVE AS commands in Neuro Mobile or Desktop Editors, it is possible to copy
presets to any location in memory.
Clearing all Presets
All 128 User Presets can be erased using the Factory Reset procedure. Warning: The Factory Reset
procedure resets the entire pedal back to the state in which it was originally shipped – this includes all
global settings and User Presets. A Factory Reset will not erase any firmware updates.
* * *
External Control Options
There are two main ways the Atlas’s Control Input port is utilized. Below are the possible used for
the Control Input port. Please note that External Switch Options is a global hardware setting.

SA252 Atlas Compressor User Guide
15
Neuro Hub: This configures the Control Input port to receive MIDI code signals from the Neuro Hub,
allowing the pedal to be added to Hub Scenes (which are controlled by PC messages) and allowing for
MIDI CC (Continuous Controller) control.
Expression: Using the Source Audio Dual Expression pedal, or an expression pedal connected to the
Neuro Hub, it is possible to map up to three parameters to be controlled via expression.
Expression Control
Use a Source Audio Dual Expression pedal to control up to three different parameters on the Atlas
per preset. Parameters include Threshold level, Output Level, Tone, Ratio, Blend, Attack, Release,
and many more.
Connecting the Expression Pedal
Connect a Source Audio Dual Expression pedal using a 3.5mm TRRS cable from the EXP pedal’s
Sensor Output to the Atlas’s CONTROL INPUT port on the pedal’s top panel. Press the CONTROL
INPUT button to enable External Control.
If you are not getting the desired results from your Expression pedal setup, go to the Hardware
Options section of the Neuro software. You’ll need to select “Neuro Hub/Expression” under “Control
Input Option”, and you may also need to calibrate your expression pedal. For more details, visit
Hardware Options.
Mapping Parameters
The quickest way to map parameters to your expression pedal is by connecting your Atlas to the
Neuro App or Neuro Desktop Editor. The Expression Control section is at the bottom of the Atlas’s
Sound Editor. Download the Neuro Desktop Editor and go to Devices > Show Offline Device Editor >
Atlas to view the full list of expressible parameters.
MIDI
The Atlas can also receive expression signal over MIDI. To do this, you need a MIDI controller that has
an expression input and is also compatible with the Atlas (this will be most MIDI controllers). Connect
your compatible expression pedal to your MIDI controller, and your MIDI controller to your Atlas via a
USB-MIDI Host. You can also achieve this with the Neuro Hub.
Using a Third-Party Expression Pedal
The Atlas’s Control Input uses a specific wiring to communicate with both the Dual Expression pedal
and the Neuro Hub. To use a third party expression pedal, please refer to the One Series Third Party
Expression Pedal Guide.

SA252 Atlas Compressor User Guide
16
Neuro Desktop and Mobile Editors
Like all pedals in the Source Audio One Series line, the Atlas Compressor features access to more
precise editing parameters, preset sharing, and added functionality via the Neuro Desktop Editor and
Mobile App. The Neuro Desktop Editor is available as a free download for Mac or Windows on the
Editors & Firmware page of the Source Audio website.
The Neuro Desktop Editor
The Neuro Desktop Editor is an excellent tool for creating and organizing highly customized presets
for your Atlas Compressor. The Desktop offers an advanced cataloging system for naming and storing
Atlas presets. The Desktop is also a tool for installing the latest updates to your Atlas’s firmware.
Downloading and Connecting the Neuro Desktop Editor
The Neuro Desktop Editor is a free download for Mac and Windows PCs. To download the Neuro
Desktop, go to the Source Audio Editors & Firmware page. In the Software tab select the appropriate
file (you have a choice between the Mac and Windows versions) and download it. You will also want
to download the latest One Series Pedal Firmware, which is located directly below the Neuro
downloads.
After the download process, connect your Atlas with a USB Type A male to mini type B male data
cable (Must be data-capable, not solely a charger cable). Connect the cable from the mini-USB port
on the pedal to the USB port on your computer. Once you’ve made the connection a blue box will
appear in the Connections field indicating that the Atlas is ready to be edited.
If a new firmware update is available, the Firmware Update icon (the arrow icon) will be framed in
yellow. When you click the arrow icon, you will be instructed on the updating procedure.
Neuro Desktop Editor User Interface
The Neuro Desktop’s user interface features three primary sections: Connections, Sound Editor, and
Presets.

SA252 Atlas Compressor User Guide
17
Connections
The Connections section is located on the left side of the Neuro Desktop Editor. This field displays all
connected One Series pedals. Each connected pedal offers the three options listed below:
• Firmware Updates: The arrow icon checks for any recent firmware updates to the connected
pedal. If an update is available, the software will provide instructions on how to proceed.
• Hardware Options: The gear icon opens the Hardware Options window. Each Source Audio
pedal has its own set of global hardware settings. The attached pedal will retain all hardware
option edits until either the option is changed, or a Factory Reset is performed.
• Open Editing Interface: The wrench icon opens the Atlas’s Sound Editor, revealing a deep set
of editing controls for creating custom presets.
Hardware Options
Clicking the gear icon in the Atlas’s Connections window opens the Hardware Options menu (see the
graphic below). Use the Hardware Options window to choose your pedal’s global hardware settings.

SA252 Atlas Compressor User Guide
18
The Atlas’s Hardware Options include the following:
• Preset/WYSIWYG Mode: Selects between Preset (all parameters are saved & recalled) and
WYSIWYG (the pedal’s physical knob positions override where they are set in the preset)
modes.
• Hardware Bypass Mode: Selects between True or Buffered Bypass.
• MIDI Channel: Selects the pedal’s MIDI channel (1 through 16).
• Power Up State: Selects between engaging or bypassing the effect upon the initial power up
of the pedal.
• Default Input Routing: Sets the default I/O signal routing mode. Descriptions of the available
routing modes are available in the Stereo Operation & Signal Routing section of this manual.
• Quick Bank Switch Using Footswitch (2 Seconds): Enabling this setting allows you to bank to
and from the secondary (red LED) bank of presets by pressing + holding down the footswitch
for 2 seconds instead of 5 seconds.
• Always use Main LED to display Gain Reduction: By default, the Atlas’s main (ON/OFF) LED
shows gain reduction by flashing red whenever gain reduction (compression) is being applied
to your input signal.
• Factory Presets Dropdown Menu: By default, the factory presets are tuned and optimized
for guitar, but you can also optimize the Atlas’s factory presets for bass.
• Pedal Input & Control Input Calibration (Accessible via the Show Expression Pedal
Calibration dropdown controls): In some cases, it might be necessary to adjust the
calibration range of an expression pedal to get the desired pedal response when using
expression control either through the Neuro Hub, a direct connection to the Source Audio
Dual Expression Pedal, or a 3rd-party pedal. To perform the calibration process, connect the
pedal and press the “Calibrate” button. Then rock the pedal back and forth to set the
minimum value and the range. When complete, press the “Stop and Set” button to retain the
new calibration values. Or press “Reset” to return to the default values.
Sound Editor
Selecting the Wrench icon in the Connections tab opens the sound editor for the Atlas Compressor.
Within the Atlas editor there are live gain reduction readouts for each channel that interact with
each relevant parameter. Additionally, the Atlas has two internal compressors, which doubles to
four in Dual mode. Using the Configuration dropdown menu, you can select between a wide variety
of configurations for these compressors, including Cascade B->A and Parallel compression.

SA252 Atlas Compressor User Guide
19
Configuration: Select how the Atlas’s onboard compressors are configured within the signal path.
Choose between the options below.

SA252 Atlas Compressor User Guide
20
Band Split Frequency: For dual mode only, this is the point on the frequency spectrum at which the
two bands in the Dual Band compressor are split.
I/O Routing Option: By default, the Atlas uses an auto-detecting routing system, but you can use this
menu to manually put presets into Mono In, Stereo Out or Stereo In, Stereo Out routing.
Crossfade: A pan knob between Compressor A and Compressor B.
Input 1 Gain: Use this control to boost or cut input gain for Input 1.
Input 2 Gain: Use this control to boost or cut input gain for Input 2. These controls are useful if you
are planning on using the Atlas’s inputs for different instruments with varied signal strengths.
Gate Threshold: Dial in an internal noise gate that cuts any signal noise below the decibel threshold.
Compressor A & B settings
Enable: Switches on this compressor channel. Use “Enable” to use Compressor A, B, or both.
Mute: Mutes this compressor channel.
Compressor Selector Dropdown: Select a premade compressor circuit. Select from a list of options:
Peak, RMS, Optical Rack Peak, Optical Rack RMS, FET Rack, FET Pedal, Vari-Mu, Fast Limit, Slow
Limit, Squish, Squeeze, Dual A, Dual B, and Expander/Gate.
Threshold: Adjusts the decibel (dB) level at which compression is applied. A lower threshold means
that compression is applied at lower signal levels, meaning that less pick attack is needed to trigger
the compression. This point is called the “knee”. Any signal lower than the knee will not be
compressed, and any signal with a level higher than the knee will be compressed.
Ratio: Adjusts the severity of the compression applied to your signal. As you increase this knob, you
will see the line begin to flatten at the knee.
Attack: Adjusts how quickly, in milliseconds, the compression is applied to your signal after playing a
note. Turn counterclockwise for fast attack times or turn clockwise for slower attack times.
Release: Adjusts how quickly, in milliseconds, the compression “lets go” of your signal after it has
been applied. Turn counterclockwise for fast release times or turn clockwise for slower release times
(more sustained compression).
Blend: Acts as a clean blend between the dry and compressed signal. Fully counterclockwise is
completely compressed—no clean signal. Fully clockwise is 100% clean, no compressor. Mixing dry
signal back into your compressed tone is what is known as “parallel compression” and is often
utilized in studios.
Output Gain: Adjusts the level of gain after the compressor. Increase for heightened overall output.
Output Gain cuts or boost the gain of both wet and dry (uncompressed) signal levels.