API Legacy AXS User manual

\
Discrete
Mixing and Recording Console
OPERATOR’S MANUAL
V2.0
Written for Automated Processes Incorporated
by Daniel Pfeifer 2017

8301 Patuxent Range Road
Jessup, MD 20794 USA
301-776-7879
http://www.apiaudio.com

Table of Contents
About this Manual............................................................................. 6
Introduction ..................................................................................... 7
Features .................................................................................................7
Configuration Options.............................................................................8
Channel Features....................................................................................8
Central Facilities.....................................................................................8
Console Configuration ...................................................................... 9
Mainframe and Channel Slots .................................................................9
Channel Bucket.......................................................................................9
Upper 200 Slot....................................................................................9
Lower 200 Slot.................................................................................. 10
624 Bus Assignment Module Slot ......................................................... 10
500 Series Equalizer Slot .................................................................... 10
968 Input Module Slot........................................................................ 10
948 Fader Bay................................................................................... 10
Master Bucket ......................................................................................11
Patch Bay .............................................................................................11
Optional Work Station-Producer’s Desk................................................11
Channel Signal Path Architecture ................................................... 12
Channel Input Selection .......................................................................12
Channel Output Routing .......................................................................12
Direct Output.................................................................................... 12
Multitrack Buses ................................................................................ 13
Stereo Program Buses........................................................................ 13
Panning............................................................................................ 13
Session Signal Flow..............................................................................13
Small Fader to Multitrack .................................................................... 14
Large Fader to Multitrack .................................................................... 15
Signal Flow Block Diagram ...................................................................15
Fader Bypass........................................................................................15
Channel Strip Overview .................................................................. 16
Channel Input................................................................................. 17
Upper 200 Slot......................................................................................17
212 Mic Preamp................................................................................. 17
205 Direct Input................................................................................ 18
Channel Input Patch Points ..................................................................19
Channel Signal Processing.............................................................. 21
Lower 200 Slot .....................................................................................21
225 Compressor/Limiter ..................................................................... 21
235 Noise Gate/ Expander .................................................................. 22
215 High-Pass, Low-Pass Sweep Filter .................................................. 24
500 Series Equalizer Slot......................................................................24
550A Discrete 3-Band Equalizer........................................................... 25
550b Discrete 4-Band EQ.................................................................... 26
560 10-Band Graphic Equalizer............................................................ 27
565 Filter Bank.................................................................................. 28
Channel Signal Processing Patch Points ...............................................28
Channel Insert Patch Points................................................................. 29
Lower 200 Slot Patch Points ................................................................ 29

Channel Faders and Controls .......................................................... 30
968 Input Module .................................................................................30
Small Fader Path Controls................................................................... 31
Large Fader Path and Channel Routing Controls ..................................... 33
Large Fader ...................................................................................... 35
Auxiliary Sends ................................................................................. 36
Channel VU Meters ............................................................................ 37
Large Fader and Small Fader Peak Indicators......................................... 38
Channel Output Routing and Bus Assignment................................. 39
Channel Direct Output ..........................................................................39
624 Bus Assignment Module.................................................................40
Channel Patch Bay.......................................................................... 41
Master Bucket................................................................................. 44
Master Channel Routing Controls.................................................... 45
Stereo Return Modules 1-6............................................................. 47
Stereo Return Signal Flow ....................................................................48
Stereo Return Controls.........................................................................49
Stereo Return Patch Points...................................................................50
Stereo Program Bus Masters and Master Faders............................. 51
Stereo Program Bus Master and Master Fader Signal Flow...................51
624SM Stereo Program Master Module.................................................52
Stereo Grand Master.............................................................................52
2500C Stereo Bus Compressor .............................................................53
946 Stereo Program Master Faders ......................................................53
Main Stereo Meters...............................................................................53
Stereo Program Master Patch Points ....................................................54
Multitrack Buses............................................................................. 56
Multitrack Signal Flow ..........................................................................56
624M Multitrack Bus Masters................................................................56
Multitrack Patch Points.........................................................................57
Auxiliary Buses and Masters........................................................... 58
Auxiliary Signal Flow............................................................................58
Auxiliary Masters 1-12 .........................................................................59
Auxiliary Master Patch Points...............................................................59
Monitor Control .............................................................................. 62
Control Room Monitoring......................................................................62
Control Room Monitor Source Selection (MONITOR SELECT) .................... 63
Control Room Speaker Selection and Controls........................................ 64
Studio Monitoring.................................................................................65
Monitor System Patch Points................................................................65
Solo Modes and Controls ................................................................ 67
Solo Modes ...........................................................................................67
Solo Controls ........................................................................................68
Talkback......................................................................................... 70
Talkback Controls.................................................................................70
Talkback Patch Points ..........................................................................71

Oscillator........................................................................................ 71
Oscillator Controls................................................................................71
Oscillator Patch Points .........................................................................71
VU Meters and Peak Indicators....................................................... 72
VU Meter Bridge ...................................................................................72
Channel VU Meters and Peak Indicators...............................................72
Channel Peak Indicators.......................................................................73
Main Stereo Meters...............................................................................73
Stereo Return Meters ...........................................................................74
Auxiliary Master Meters........................................................................74
Power Supply Voltage Indicators .........................................................74
Patch Bay ....................................................................................... 75
Normals................................................................................................75
Patch Bay Overview..............................................................................75
Channel Patch Bay................................................................................76
System Patch Bay.................................................................................78
Stereo Return Patch Points.................................................................. 79
Stereo Program Master Patch Points..................................................... 79
2500C Stereo Bus Compressor Patch Points........................................... 80
Multitrack Patch Points ....................................................................... 80
Auxiliary Master Patch Points............................................................... 80
Monitor System Patch Points ............................................................... 83
Talkback Patch Points......................................................................... 84
Oscillator Patch Points ........................................................................ 84
Phase Reverse (polarity inverter)......................................................... 84
Appendix ........................................................................................ 85
API 2500C Stereo Bus Compressor.......................................................85
Setup Documents ........................................................................... 91
2500C Setup Sheet ...............................................................................91
205 Setup Sheet...................................................................................92
212 Setup Sheet...................................................................................93
215 Setup Sheet...................................................................................94
225 Setup Sheet...................................................................................95
235 Setup Sheet...................................................................................96
550A Setup Sheet.................................................................................97
550b Setup Sheet .................................................................................98
560 Setup Sheet...................................................................................99
624 Setup Sheet.................................................................................100
968 Setup Sheet.................................................................................101
Legacy AXS Block Diagram .................................................................102

Legacy AXS API
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About this Manual
This manual is presented in several sections. Section one, “Introduction” provides a summary of the
console features and attributes. Section two, “Console Configuration” provides an overview of various
console configurations and along with a description of the available pre-delivery customization options.
Likewise the rest of the manual is organized according to the various console systems such as “Channels,
Multitrack Buses, Program Masters,” and so on.
Sections one and two are useful to all users, and should be read thoroughly before purchase and
delivery. Experienced engineers may get up and running quickly by simply checking the graphic
overviews at the start of the sections. If you are new to API consoles and multitrack recording, it’s
recommended that you read the entire manual at least once and keep it at the console for reference.
NOTE: This version of this manual does not contain information regarding console automation.
Console automation will be addressed in a separate manual or new version of this one
sometime in the near future.

Legacy AXS API
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Introduction
Thank you for choosing the API Legacy AXS discrete analog recording and mixing console. The Legacy
AXS console continues API’s commitment to our world-famous analog signal path. Offering an expanded
and powerful feature set, the Legacy AXS is designed to meet the needs of today’s audio professionals.
Since the introduction of the first API Legacy Series console to Green Street Studios in Manhattan in
late 1989, API has delivered over 75 Legacy Series consoles around the world. The astonishing statistic
is that virtually every Legacy built is still in service.
We continue the API Legacy with the Legacy AXS Recording and Mixing Console. Featuring the traditional
API analog signal path, the AXS also offers a new and powerful feature set, all at an attractive price for
today's studios, artists, engineers and producers.
The Legacy AXS combines a traditional, easy to use in-line input/output architecture with flexible
customization options and superior sound quality. The Legacy AXS is built to the same exacting
standards of reliability, sonic performance, and investment grade audio of the API Legacy, Legacy Plus,
and Vision consoles, setting the standard for modern recording consoles.
Features
32 to 80 channels
API's discrete signal path with transformer outputs
Numerous preamp and signal processing options
VPR Alliance 500 Series compatible slot for EQ
Six assignable stereo line-level returns
Twenty-four multitrack summing buses
Three independent stereo program buses and assignable Grand Master
API 2500C stereo bus compressor
Extensive routing features for parallel compression and stem mixing
Twelve auxiliary buses
Onboard or remote full patch bay (only 32 thru 64-channel consoles can be onboard)
Highest quality finish and wood trim
Comprehensive automation system
Optional DAW/producer's desk
Configured to client specification

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Configuration Options
•Mainframes:
o32 to 80 channels (in 16-channel buckets)
oChannel Width: 1.5"
oChannel bucket Width: 24"
•500 Series equalizer slot on each channel
oVPR Alliance compliant
•Dual 200 Rows on each channel:
oUpper slot for preamp
oLower slot for optional signal processing
oPre or post EQ lower 200 slot routing option (specified when ordered)
Channel Features
Dual signal path architecture: Two independent audio paths:
o Large Fader: 100mm automated fader
o Small Fader: 45mm fader (non-automated)
Line In or Preamp Out input sources on both fader paths
Alternate Line Input source for Small Fader path
Upper 200 slot preamp options (as specified):
o 205 Direct Input
o 212 Microphone Preamplifier
Lower 200 slot signal processing options (as specified):
o 215 Sweep Filter
o 225 Compressor
o 235 Noise Gate
500 Series slot and equalizer/filter options (as specified):
o 550A 3-band parametric EQ
o 550b 4-band parametric EQ
o 560 10-band graphic EQ
o 565 Filter Bank
o Compatible with any VPR Alliance approved 500 module (except preamps)
40-600Hz, 12dB/8va high-pass sweep filter in the Large Fader path
50Hz, 12dB/8va fixed high-pass filter in the Small Fader path
Balanced Insert in each path
Phase reverse (polarity inverter) in each path
Twelve auxiliary sends and buses: 6 mono, 3 stereo
Channel VU metering for: Large Fader, Small Fader, Direct Output, and Multitrack Bus
Peak indicator in each path (globally set)
Central Facilities
Three control room monitor systems: stereo/surround MAINs and stereo ALT 1 & ALT 2
Two stereo studio monitor systems
Four stereo and two surround external playback sources
Comprehensive stereo program and cue send monitoring
Individual CUT control of all control room monitors (LEFT, RIGHT, CNTR, SURL, SURR,
LFE)
Monitor calibration level trim controls
Comprehensive cue and talkback systems
Solo System: Independent/Linkable AFL, PFL, and Solo-In-Place for Small and Large
faders
API 2500C stereo Bus Compressor
Routable Sine-wave oscillator
Four USER buttons (toggled contact closures on D-connector)
As with all API products, The Legacy AXS Console offers the same exacting craftsmanship featured on
all API large format consoles, including a unique 5-year warranty on all parts.

Legacy AXS API
9
Console Configuration
Each Legacy AXS console is built to meet the specifications determined by the owner when the console
is ordered. With a flexible design, the console may be configured in many ways. Beyond frame size,
users may configure each module with their preferred pre-amp and signal processor setup to include a
variety of preamp, equalizer, filters, and dynamic processor possibilities.
While workflow, capacity, and patching may vary by configuration, the basic operational premise of all
Legacy AXS consoles is the same.
Mainframe and Channel Slots
The Legacy AXS console mainframe comes in a variety of frame sizes consisting of a master bucket and
two or more 16-channel channel buckets. The smallest frame size is 32 channels and the largest
accommodates 80. The patch bay for consoles with frames for 32 thru 64 channels can be mounted
onboard the console or externally. The patch bay for console frames over 64 channels must be externally
mounted.
Channel Bucket
There are several module slots associated with each 16-channel bucket in the Legacy AXS mainframe.
Certain module slots can be fitted with optional components.
From the meter-bridge to the armrest, the slots are in the following order (see Channel Strip Overview
below):
Upper 200 slot (preamps)
Lower 200 slot (signal processing)
624 Bus Assignment Module slot
500 Series EQ slot
968 Input Module slot
948 Large Fader bay
The Bus Assignment slot can only be fitted with the 624 Bus Assignment Module.
The Input Module slot can only be fitted with a 968 Input Module.
The 200 slots and the 500 EQ slot offer customization options for inputs and signal processing.
Configuration of the upper 200 slot, lower 200 slot, the 500 EQ slot allows the user to customize the
console for their desired workflow and use. The upper 200 slot may be configured with one of two
preamp options, while the lower 200 slot may be fitted with one of three dynamic processors or filters.
The 500 EQ slot can be fitted with one of four API EQ and filter options or any VPR Alliance approved
500 Series module (except preamps). Any or all of the slots may be left open for future expansion.
Configuration options are specified by the user in consultation with API engineering staff before the
console is built at API.
Upper 200 Slot
The upper 200 slot is designed to house the channel preamp. The upper 200 slot is typically fitted with
the API 212 Microphone Preamplifier module. Alternately the upper 200 slot can be fitted with an API
205 Direct Input. Most consoles are fitted primarily with 212 Mic Preamps, but usually include at least
two 205 Direct Inputs to increase versatility and tonal variance when recording electric instruments.
The output of the preamp installed in the upper 200 slot is internally routed to the Small Fader path
input by default. The preamp output can be routed to the Large Fader path input on individual channels
by engaging the FLIP button on the 968 Input Module or globally by engaging the FLIP button in the
Master Section. The input to the Small Fader path will switch to the channel LINE IN (multitrack return)
when FLIP is engaged. The output of the upper 200 slot preamp cannot be directly routed to both fader
paths simultaneously.
The microphone input to the upper 200 slot preamp is available on patch as MIC PREAMP INPUT. These
patch points are fed from the MIC TIE-LINE patch points via a full-normal connection.

Legacy AXS API
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Lower 200 Slot
The lower 200 slot is designed to house additional channel signal processing and is typically fitted with
an API 225 Compressor-Limiter.However, API provides two additional 200 Series signal processing
module options:
215 Sweep Filter
235 Noise Gate/Expander
In the standard configuration, the lower 200 slot signal processor (COMP) is located pre-EQ in the Small
Fader path. The lower 200 slot (COMP) can be moved to the Large Fader path on individual channels by
engaging the COMP LRG button on the 968 Input Module or globally by engaging the COMP LRG button
in the Master Section. Engaging the COMP BYP button in the Master Section will bypass the lower 200
slot (COMP) on all channels.
An internal link inside each 968 Input Module can be programmed to place the lower 200 slot (COMP)
post-EQ instead of pre-EQ in its assigned path.
The signal processor in the lower 200 slot may be accessed using the COMPRESSOR INPUT, SIDE CHAIN,
and COMPRESSOR OUTPUT patch points.
See the 200 Series signal processor descriptions in the “Channel” section later in this manual.
624 Bus Assignment Module Slot
The channel bucket contains dedicated slots designed to support API 624 Bus Assignment Modules. The
624 module handles assignments to Multitrack and Program Buses from the channel Large and Small
Fader paths. It also facilitates pan-pot activation in each path. The assignment module slots can only
be fitted with API 624 Bus Assignment Modules.
Multitrack Bus outputs and access to the program bus signal flow are available in the System patch bay.
500 Series Equalizer Slot
The 500 Series slot on each channel strip is intended to house the channel equalizer (EQ). This 500
Series slot complies with VPR Alliance standards so it can accept any API or VPR approved 500 Series
module except preamps. This slot is not designed to house a preamp and does not have a 48v power
supply for phantom power.
The 500 Series EQ slot is typically fitted with one of four API equalizer or filter modules:
550A 3-Band EQ
550b 4-Band EQ
560 10-Band Graphic EQ
565 Filter Bank
The 500 Series EQ slot is assigned into the Large Fader path by design. The EQ can be routed to the
Small Fader Path by engaging the EQ SM button on the 968 Input Module.
968 Input Module Slot
The channel bucket contains dedicated slots designed to support API 968 Input Modules. The 968 is the
main channel module and contains the Large and Small fader paths, internal channel routing, and
associated controls. The 968 modules also contain the channel auxiliary sends. The input module slots
can only be fitted with API 968 Input Modules.
Access to the channel signal flow is available in the Channel patch bay.
948 Fader Bay
Bays for 948 Fader Modules are located at the bottom of the channel buckets. These bays contain two
8-channel fader modules that support the 16 channels in the bucket.

Legacy AXS API
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Master Bucket
The master bucket of the Legacy AXS contains routing and controls for buses, summing, outputs,
monitoring and other central console controls. From top to bottom the sections include:
•Program Meter Bridge
•2500C Stereo Bus Compressor
•624M Multitrack Masters
•624SM Program Bus Masters
•265 Auxiliary Bus/Cue Send Masters
•Six assignable Stereo Returns
•Master Section
•946 Program and Group Master Faders and automation controller.
Patch Bay
All consoles include fully integrated, fully balanced TT (bantam) patch bays that provide access to the
signal flow of various console and studio systems. In the standard configuration the “Channel Bay”
contains 14 patch points in the channel signal flow. The “System Bay” contains patch points for program,
multitrack, & auxiliary buses, stereo returns, 2500C Bus Compressor, monitoring, cues, effects, and
external studio audio devices.
Patch bays for consoles with frames for 32 thru 64 channels can be mounted onboard the console or
mounted externally. Patch bays for consoles frames larger that 64 channels must be externally mounted.
Optional Work Station-Producer’s Desk
An optional producer’s desk can be specified at the time the order for the console is placed. The
producer’s desk is designed to support a DAW workstation and/or work surface to help integrate analog
and digital audio workflow. Because the producer’s desk is built into the frame, it must be specified
before the console is built.
FOR A CONCISE AND CONSISTENT DESCRIPTION OF THE CONSOLE, IT IS NECESSARY TO ASSUME
ONE OF THE ABOVE CONFIGURATION CHOICES HAS BEEN MADE.
FOR THE REMAINDER OF THIS MANUAL IT IS ASSUMED THAT THE UPPER 200 SLOT IS EQUIPPED WITH
A 212 MIC PRE, THE LOWER 200 SLOT IS EQUIPPED WITH A 225 COMPRESSOR, AND THE 500 SERIES
SLOT IS FITTED WITH A 550A EQ.

Legacy AXS API
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Channel Signal Path Architecture
From top to bottom, the following channel bucket components described above make up a complete
Legacy AXS channel strip:
•Upper 200 slot: preamp
•Lower 200 slot: signal processing
•624 Bus Assignment Module
•500 Series Slot: EQ
•968 Input Module
•948 Fader Module
The Legacy AXS is a “dual-channel” or “in-line” console. Each channel strip provides two independent,
discrete audio paths for multitrack recording. One path routes microphones to a multitrack recorder and
the other path is for mixing the multitrack return. After recording, both audio paths can be routed to
the program buses to provide additional inputs during mix-down. On the Legacy AXS these audio paths
are referred to as the Small Fader path and the Large Fader path.
Channel Input Selection
There are two primary choices of input sources, Preamp output and Line In, and one Alternate Line In.
Preamp: This is the output of the preamp installed in the upper 200 slot.There are two modules
available to serve as a preamp:
212 Mic Preamp
205 Direct Input
Feeds the Small Fader Path by default
Line In: This is the output from the multitrack recorder interfaced with the console.
A -6 dB TAPE PAD can be engaged at the Line In
Feeds the Large Fader Path by default
Alt Line In: This is an alternate line input for the Small Fader path, replacing the Preamp output.
Feeds the Small Fader path input when the ALT button is engaged
The default input for the Large Fader path is Line In and the default input for the Small Fader path is
the Preamp output. Each input source cannot feed both paths simultaneously, so the Preamp, Line In,
or Alt Line In can only feed one path at a time.
Engaging the FLIP button will swap the input sources between fader paths, so the Preamp will feed the
Large Fader path and the Line In will feed the Small Fader. Engaging the ALT button will switch the
Small Fader path input to the Alt Line In for recording or mixing additional line level sources. If the ALT
and FLIP buttons are engaged, the Alt Line Input will feed the Large Fader path.
There is a FLIP button in the Master Section to reverse the inputs between the Small and Large Fader
paths on a global basis. There is also a master SM ALT LINE button that routes the Alternate Line Input
(ALT LINE INPUT) to the Small Fader input console wide. The master ALL CLR button clears all FLIP
and ALT buttons globally and restores normal channel inputs.
Channel Output Routing
The Small Fader and Large Fader paths have access to all output assignment possibilities. The output
possible assignments are:
Direct Output
Multitrack Buses 1-24
Stereo Mix Bus A, B, and C
Direct Output
Only one path can be assigned to feed the Direct Output at a time
The Large Fader will normally feed the Direct Output.
The Small Fader will feed the Direct Output when the DIR SM switch is engaged. This will defeat
the Large Fader signal to the Direct Output.
The pre-EQ and Insert signal of the selected fader path will feed the Direct Output when the DIR
PRE switch is engaged.

Legacy AXS API
13
Multitrack Buses
There are twenty-four (24) Multitrack Buses which feed the Active Combining Amplifiers (ACA).
The Large Fader or Small Fader can be assigned to any of the 24 Multitrack Buses in the 624 Bus
Assignment Module.
Only one audio path, Small Fader or Large Fader, can be assigned to the Multitrack Buses at a
time.
The default source for the Multitrack Buses is the Large Fader.
The Small Fader can feed the Multitrack Buses by pressing the 24 button on the 968 module.
This will defeat the Large Fader signal to the Multitrack Buses.
There is a TRIM control and on/off switch for each ACA output.
Stereo Program Buses
Both paths, Small Fader and Large Fader, can be assigned to any and all stereo Program Buses,
A, B, and C.
Program Bus assignments are made for both fader paths in the 624 Bus Assignment Module.
There are two sets of STA, STB, and STC switches at the bottom of the 624 module. The left set
of switches is for the Small Fader (as indicated by SM below the switches). The right set of
switches is for the Large Fader (as indicated by LG below the switches).
Panning
Pan-pots are not engaged by default in the either fader path. Each path has its own pan-pot,
which must be engaged to be active.
Panning assignments are made for both fader paths in the 624 Bus Assignment Module by using
the two PAN switches.
The left PAN switch is for the Small Fader (as indicated by SM). The right PAN switch is for the
Large Fader (as indicated by LG)
Session Signal Flow
For those familiar with other in-line recording consoles, one fader path functions as an “mic” or “channel”
path and the other fader path functions as a “monitor” or “mix” path. The fader used for each function
depends on the selected signal functions. The operational controls allow for both paths to be used for
either function.
Each path can provide a different function during the various types of recording sessions. The signal
routing of input and output of each path is handled by the 968 Input Module and the 624 Bus Assignment
Module.
Multitrack Recording and Overdubs: In a typical multitrack recording session, the channel strips function
as follows:
Record Path (channel path, input path, mic path): One fader path carries the signals from the
microphone preamp, DI, or other input source to the multitrack recorder (DAW).
o Routed via Direct Outputs or the 24 Multitrack Buses.
o Signal processing is often recorded to the multitrack so filters, EQ, and dynamics are
assigned to the record path as needed.
o The fader used for this function (Small or Large) is determined by the user.
Monitor Path (mix path, return path): The other fader path is used to mix signals from the
multitrack recorder (DAW) to the stereo Program Buses for monitoring.
o The fader used for this function (Small or Large) is determined by the user.
Stereo Mixing: In a typical mixing session, the channel strip functions as follows:
The Large Fader path is the main mix path.
The Small Fader path can also be used to route additional returns from multitrack recorders
(DAW) or other sources such as effect units to the mix.
Signal processing is often applied to channels contributing to the mix, so the compressor and
EQ are assigned to the Large or Small Fader paths as needed while mixing.
Stereo Returns are used to return mix stems and effects unit outputs.
The channels and stereo returns contributing to the mix are routed to one or more of the three
stereo Program Buses, A, B, C.
The three stereo Program Buses, A, B, C can be summed in the Grand Master Program Bus.
The 2500C Stereo Bus Compressor can be patched to any of the stereo Program Buses.

Legacy AXS API
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Default AXS Signal Flow: With no routing buttons engaged, the default channel signal flow is as
follows:
•Small Fader path:
oInput: output of the preamp (upper 200 slot)
oSignal Processing: Lower 200 slot (COMP)
oOutput: Assignable (Direct Output, Multitrack Buses, & Program Buses)
•Large Fader path:
oInput: INPUT (normalled to the MULTITRACK OUTPUT)
oSignal Processing: 500 Series EQ slot
oOutput: Direct Out & by default and assignable (Multitrack Buses & Program Buses)
This default channel signal flow can be altered determined by changing the positions of the channel
routing buttons labeled in BLUE:FLIP,ALT,COMP LRG, and EQ SM and the Direct Output routing
buttons: DIR SM and DIR PRE.
FLIP: Swaps the Large and Small fader path inputs when engaged:
•Large Fader source: Preamp output
•Small Fader source: Line Input
•Illuminates when engaged
ALT: Switches the Small Fader path input to the Alternate Line In (ALT) when engaged:
•Replaces the preamp output with the Alt Line In as the Small Fader path source
•Illuminates when engaged
COMP LRG (Compressor Large):Moves the lower 200 slot signal processor (COMP) to the
Large Fader path
•Illuminates when engaged
EQ SM (Equalizer Small):Moves the 500 Series EQ slot to the Small Fader path
•Illuminates when engaged
DIR SM (Direct Small):Routes the Small Fader to the Direct Output
•Disengages the Large Fader path from feeding the Direct Output
•Illuminates when engaged
DIR PRE (Direct Pre):Routes the selected fader PRE signal to the Direct Output
•The Direct Output is fed post-COMP, pre-EQ & Insert instead of post-MUTE
•Illuminates when engaged
While either configuration is appropriate, most engineers will choose to use the Small Fader path as the
“Record Path” to route microphones and other sources to the multitrack recorder and use the Large
Fader path the “Mix Path” to monitor the multitrack return via the Program Buses. Using this method,
the console will be in a basic mixing configuration when tracking is completed. Many engineers also
prefer to have the multitrack sends on the small faders and use the large faders to mix the multitrack
returns.
Small Fader to Multitrack
To use the Small Fader path as the “Record Path,” an output to the multitrack recorder must be assigned.
The Direct Outputs provide the most direct audio output path and are normalled to the Multitrack Inputs
in the standard configuration, so the Direct Output is often used when recording single source to a single
track. Engaging the DIR SM button will route the Small Fader path to the Direct Output post the MUTE
switch. If no console EQ or further gain adjustment is needed, also engaging the DIR PRE will route
the Small Fader path signal to the Direct Output post-COMP and pre-EQ.
If two or more sources are to be summed together before being sent to the multitrack recorder, the
Small Fader path must be routed to one or more of the twenty-four Multitrack Buses in the 624 Bus
Assignment module. The Multitrack Buses are fed from the Large Fader path by default, so the 24 button
must be engaged to reroute the Small Fader to feed the Multitrack Buses, followed by the desired bus
assignment(s). If odd-even stereo panning is to be employed, the PAN button in the Small Fader section
of the 624 module (SM) must be engaged.

Legacy AXS API
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In this configuration, the Large Fader path will be used to mix the multitrack returns and must be
assigned to a stereo Program Bus for monitoring. Assign the Large Fader path to the desired stereo bus
by engaging the STA, STB, or STC and the PAN buttons in the LG section on the 624 Bus Assignment
module.
Large Fader to Multitrack
If it is preferable to use the Large Fader path as the “Record Path” to route sources to the multitrack
recorder, engage the FLIP button to route the output of the 200 slot preamp to the Large Fader path
input. The Direct Output and Multitrack Bus matrix are fed from the Large Fader by default, so only the
desired multitrack bus/pan-pot assignments need to be made. If odd-even stereo panning is to be
employed, the PAN button in the Large Fader (LG) section of the 624 module must be engaged. If no
console EQ or further gain adjustment is needed, also engaging the DIR PRE only will route the Large
Fader path signal to the Direct Output post-COMP and pre-EQ.
In this configuration, the Small Fader path will be used to mix the multitrack returns and must be
assigned to a stereo Program Bus for monitoring. Assign the Small Fader path to the desired stereo bus
by engaging the STA, STB, or STC and the PAN buttons in the Small Fader (SM) section on the 624
Bus Assignment module.
NOTE: The multitrack recorder may alternately be fed from the Multitrack Buses by patching the
BUS OUTPUT patch points to the MULTITRACK INPUT patch points.
Signal Flow Block Diagram
The block diagram below indicates the signal flow through the Small and Large Fader signal paths. A
more technical and detailed signal flow diagram is available in a separate document in the appendix of
this manual.
The features of each path are shown in the order in which they occur within the path. The diagrams
assume the following:
A 212 Preamp is installed in the upper 200 slot
A 225 Compressor/Limiter is installed in the lower 200 slot
A 550A Equalizer is installed in the 500 Series EQ slot
FLIP, ALT, COMP LRG, EQ SM, DIR SM, and DIR PRE are in default positions (not engaged)
Pan-pots are engaged
Auxiliary Sends, 0dB Fader Bypass, solo sends, and VU meter are not included
Fader Bypass
The faders in both signal paths can be bypassed allowing the audio to pass at unity gain (0dB) when
the console is used with DAW automation and as a control surface. The Fader Bypass for the Large Fader
path is handled via the console automation package. The Fader Bypass for the Small Fader is engaged
globally by engaging the 0dB SM (0dB Small Fader) button in the master section. This option is not
available on individual channels and is not shown in the diagram above.

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Channel Strip Overview
Upper 200 Slot
•212 Microphone Preamplifier (standard configuration)
•Optional 205 Direct Input Module
Lower 200 Slot - May be fitted with one of three processor options:
•215 Sweep Filter
•225 Compressor/Limiter (standard configuration)
•235 Noise Gate/Expander
624 Bus Assignment Module
•Routes Small Fader or Large Fader to Multitrack Buses 1-24
•Routes Small Fader and Large Fader to stereo Program Buses (STA, STB, STC)
•PAN switch to engaged the pan-pot for both faders
oLeft/Right panning to stereo Program Buses
oOdd/Even panning to Multitrack Buses
500 Series EQ Slot
Receives lower 200 slot output (COMP) when engaged (standard configuration)
•500 series equalizers:
o550A 3-Band EQ
o550b 4-Band EQ
o560 10-Band Graphic EQ
o565 Filter Bank
•Any VPR Alliance approved 500 Series module (except preamps)
968 Input Module
Channel Controls
•Input Selection: Input FLIP and ALT Line In to Small Fader
•-6dB Line In Pad In/Out
•Signal Processing Routing: COMP LRG and EQ SM
•Output Routing:
oDirect Output Routing: DIR SM and DIR PRE
oSmall Fader to Multitrack Buses: 24
•Auxiliary Sends 1-12: Level, Pan, ON/off
oPre-fader Routing
oAux Send 5-12 from Small Fader
Large and Small Fader Controls (on both paths)
•Input TRIM
•Ø: Phase Reverse: Polarity inverter
•FILT: High-pass Filter In/Out: Sweep on Large Fader, fixed on Small Fader
•INS: Insert Return In/Out
•Pan-pot
•45mm Small Fader
•SOLO
•Solo and channel routing SAFE mode
•MUTE
948 Large Fader
•100mm long-throw automated resistive Large Fader

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Channel Input
The channel has three audio input sources:
•Preamp Output: The output of the preamp in the upper 200 slot (typically 212 Mic Preamp)
•Line Input: Balanced line input, normalled to multitrack (DAW) returns
•Alternate Line Input (ALT): Alternate balanced line input
The Large and Small Fader paths can accept only one audio source at a time.
The output upper 200 slot Preamp is the default source the Small Fader path. The Line Input is the
default source for the Large Fader. The inputs to the paths can be swapped on individual channels by
engaging the FLIP button on the 968 Input Module. This will route the Preamp output to the Large
Fader and the Line Input to the Small Fader. Engaging the FLIP button in the Master Section will swap
fader path inputs on a global basis.
The Alternate Line Input can replace the Preamp output as the source for the Small Fader path. This
provides additional balanced line-level inputs for recording and mixing. Engaging the ALT button on
the 968 Input Module will route the Alternate Line Input to the Small Fader path on individual channels.
Engaging the SM ALT LINE button in the Master Section will route the Alternate Line Inputs to the
Small Fader paths on a global basis.
The Alternate Line Input can be routed to the Large Fader by engaging the ALT and FLIP buttons on
individual channels or console-wide by the SM ALT LINE and FLIP buttons in the Master Section.
Upper 200 Slot
The upper 200 slot is designed to house the channel preamp. Two API 200 Series preamplifier modules
are available for installation. Only the upper 200 slot is wired to accept a preamp, so only one preamp
can be installed in each channel strip:
212 Microphone Preamplifier (standard configuration)
OR
205 Direct Input
212 Mic Preamp
Features
•Wide range GAIN control
•-20dB Pad
•48V phantom power switch
•Mic input transformer
•LED output Meter
•Uses API 2520 Op-Amp
•All discrete circuit
•Transformer coupled inputs & outputs to +28dBu
The tone of the 212 Mic Preamp finds its roots in the classic API 2488 series all
discrete recording consoles, best known for the famed "LA" sound. This same mic
preamp design is packaged into a compact module with features like a continuously
adjustable Gain control and a 5-segment LED meter.
An audio chain is only as strong as its weakest link. Often, emphasis is placed on obtaining the highest
quality microphones, while neglecting the integrity of the mic preamp. The API 212 incorporates the
same circuit as the legendary API console input modules, dating from the 1970's up to and including
the Model 1608, thus preserving its sonic qualities. This mic-pre articulates high frequencies with great
detail, while delivering the big sounding, warm bottom end that API is famous for. Whether it's a live
performance or the private setting of a studio session, the 212 will capture every nuance of the
moment.
The 212 Mic Preamp’s all discrete circuitry features the API 2520 op-amp and input and output
transformers. A -20dB pad is provided, allowing the level feeding the mic transformer to be reduced
by 20dB, while keeping the proper load on both the mic and transformer. 48V Phantom power can be

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locally switched ON or OFF via the front panel switch. An LED meter indicates output level in dBu. The
low noise floor, together with a clip point over +28dBu, makes this preamp suitable for the most
extreme applications requiring the highest quality audio.
The controls for the 212 Mic Preamp function as follows:
GAIN: Sets the preamplifier gain across a 55dB gain range
METER: The 5-segment LED meter indicates the mic pre output level in dBu
48V: Provides 48 Volt Phantom Power to the MIC PREAMP INPUT and MIC TIE-LINE patch points
•Illuminates when engaged
-20:Inserts a -20dB pad
•The level feeding the mic transformer is reduced by 20dB, while keeping the proper load on both
the mic and transformer
•Illuminates when engaged
205 Direct Input
Features
•Wide range GAIN control
•Hi-Z ¼” input, like a tube amp
•Thin < > Fat TONE Control reduces low end mud
•BRIGHT Switch boosts the presence
•-20dB PAD lowers the input level
•100 K LOAD switch changes the tone of instruments
•5-segment LED Meter shows output level
•Transformer coupled output to +28dBu
•All Discrete Design
The API 205 Direct Instrument Input is specifically designed to accept a guitar or
bass direct into it, without any loading on the pickups. The Gain Control is used to
normalize the instrument's input level, up to a +4dBu output level. With the use
of the unique TONE control, the low end "mud" can be reduced. Turning on the BRIGHT switch adds
clarity, like the bright switch on any amp. The combination of these two functions may eliminate the
need for any EQ on the instrument when recording, keeping the signal pure.
The input is designed specifically to load a pickup the same way that a tube guitar amp would, retaining
all of the tone, and minimizing the loading effect on the pickup. This minimal path eliminates the need
to use a standard direct box, which more times than not only converts the signal to a balanced mic
level output, which still requires a mic input, equalizer, and fader to get the signal to a recordable level.
The 205 is capable of boosting any instrument to a hefty line level without additional amplifiers. With
the 100 K LOAD switch, the tone of the pickup can be altered slightly, which tends to darken the high
frequency content. The BRIGHT switch adds a treble boost in the same manner that most instrument
amplifiers do, clarifying the instrument and adding presence to it without the need for outboard
equalization. When inserting an instrument with an internal preamp or a line level instrument such as
a sampler or a keyboard, the 205 has a -20dB PAD switch to drop the level without loading, thereby
retaining the full range of the 205 and its features.
Also, the output of the 205 can be fed to multitrack or the input of a guitar amplifier. The artist can
then be in the control room while the instrument amp is isolated in the studio. The 205 Direct Input
makes use of the 2510 and 2520 op-amps and therefore exhibits the reliability, long life, and uniformity
characteristic of API products.
The controls for the 205 Direct Input function as follows:
IN (in/out switch): Activates the module
•Illuminates when engaged
Hi-Z IN (¼” input jack): Instrument input jack
•High-impedance

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•Unbalanced
•Blue illumination
-20 PAD: Inserts a -20dB pad at the instrument input
100K LOAD: Engages a 100K Ohm input load
•Changes the tone of the pickup and tends to darken the high frequency content.
GAIN: Sets the preamplifier gain from -40 to +20dB
TONE: Adjusts the tonal characteristics of inputs signal
•Adjusting the TONE control between “Thin” and “Fat” control can reduce “muddiness”
THIN: -12dB at 150Hz
FAT: Flat (+/- 0dB)
BRT (Bright): Activates a +6dB at 8kHz presence boost.
•The combination of the TONE and BRT functions may eliminate the need for any EQ on the
instrument when recording, keeping the signal pure.
METER: The 5-segment LED meter indicates the 205 output level in dBu
•Capable of boosting any instrument to a hefty line level without additional amplifiers.
Channel Input Patch Points
Depending on console configuration, there will be input patch points for 32, 48, 64, or 80 channels in
the bay. In the interest of space, patch points for only 8 channels are shown below.
MIC TIE-LINE: Studio microphone outputs
•Full-normal to MIC PREAMP INPUT
•Breaking output: Inserted patch cord will replace studio tie-
line connection
MIC PREAMP INPUT: 212 Mic Preamp inputs
•Balanced, low-impedance, mic-level input
•Full-normal from MIC TIE-LINE patch points
•Breaking input: Inserted patch cord will replace normalled
connection
•Not used with 205 Direct Input Module
CAUTION: The MIC PREAMP INPUT patch point will carry 48-Volt phantom power when the 48V
button is engaged on the associated 212 Mic Preamp. Care should be used and 48V
should be always be disengaged before patching to these points.
MULTITRACK OUTPUT: Multitrack recorder returns
•Half-normal to LINE INPUT
•Outputs split if patched
LINE INPUT: Main line-level inputs
•Balanced, low-impedance, line-level input
•Half-normal from MULTITRACK OUTPUT
•Breaking input: Inserted patch cord will replace normalled
connection
•ALT LINE INPUT: Secondary line-level inputs
•Balanced, low-impedance, line-level input
•Alternate input to the Small Fader path
•Half-normal from owner specified source (optional)
•Breaking input: Inserted patch cord will replace normalled
connection

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Patch points for alternate external sources (such as virtual instruments, extra DAW returns, etc.)
normalled to the ALT LINE INPUT patch points are not provided in the standard configuration. However,
the ALT LINE INPUTs are available via a multi-pin connector on the back of the patch bay to allow
normal interfacing to these points.