Reverb Foundry HD Cart User manual

Document version 1.0
October 2017
USER GUIDE

Page 1
TABLE OF CONTENTS
Introduction 1!
Installation 2!
Plug-in Overview 2!
Preset Management 3!
Fundamental Controls 3!
Master Controls 4!
Character Controls 4!
Low Controls 5!
Advanced Controls 6!
Reflections Controls 7!
Supported Channel Modes 9!
INTRODUCTION
HD Cart is a high-density reverb plugin modelled after one of the most sought after and
expensive reverb units of all time. It was next to impossible to walk into almost any
professional recording studio in the mid to late 1980s - and for many years after - and not
have one be in the room somewhere. So many of the most cherished and well-known
recordings of all time owe a large part of their ambience and overall sound to this iconic state
of the art (at the time) processor.
One of the expansion cartridges for this unit contained the only algorithm to ever fully take
advantage of its considerable dual-board processing capabilities. This amazing program was
capable of being used in quadraphonic, 5.0 surround or high-density stereo reverb modes.
The surround mode takes a stereo input and produces four-channel quadraphonic output
(5.0 is also supported in this plug-in via a recommended routing patch). The HD mode mixes
the quad outputs down to a two-channel stereo reverb, resulting in denser, richer audio unlike
any other reverb processor.

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INSTALLATION
Reverb Foundry requires an Intel or AMD processor and approximately 50 MB per plug-in
format to be installed.
The plug-is is authorised via iLok (an iLok 2, iLok 3 or computer based iLok location is
required for activation). Before installing the plug-ins, please install the iLok License Manager
(http://www.ilok.com) and redeem your activation code to your iLok account. Then move this
license to an iLok or computer based location (or right-click and activate it from the available
licenses tab later).
A single license can be remain activated in two different locations concurrently. This could
mean two different iLoks, an iLok and computer based location, or on two different
computers. These must all be associated with the same iLok account and you can move
licenses between devices as required using iLok License Manager.
To install the plug-ins just run the installer packages and follow the guided instructions to
install the plug-in formats you need. All stereo and surround modes are supported by all plug-
in formats (host support for these modes may vary).
PLUG-IN OVERVIEW
The plugin is split into the following areas:
• Presets management:
o Factory presets
o Settings that affect the behaviour of the factory presets
o Storage or retrieval of custom presets
• The fundamental controls of reverb time and dry/wet mix
• Five control groups accessed via tabs:
o Master: control over the filtering and gain of the reverb and reflections
o Character: basic control of room characteristics
o Low control: fine control of the low frequency room behaviour
o Advanced: a selection of advanced algorithm controls
o Reflections: timing and frequency characteristics of the early reflections
• Metering of the input, output and early/late reverb component levels

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PRESET MANAGEMENT
You may select factory presets by clicking on the preset name in the main plug-in window to
show a list, or by moving between presets using the chevron icons (< >).
Preset initialisation options are provided in the menu:
Initialise preset
with enhanced
recirculation
Controls whether a preset is initialised with the enhanced recirculation
mode on or off. On provides a higher quality sound (this is the default)
and off provides a more authentic sound as per the original algorithm.
See the advanced tab section for more details about this control.
This does not affect user preset recall.
Initialise preset
with front/rear
at mid
The original device has duplicate presets for high density mode and
surround mode. This control means the presets are only needed once,
and you can choose whether it is instantiated as a high density (mid)
position or a frontal position.
This does not affect user preset recall.
Initialise with
100% wet mix
Controls whether the plug-in initial preset comes up fully wet (send mod)
or with a mid-valued dry/wet balance (insert mode).
This does not affect subsequent factory or user preset recall.
Further options are provided to enable the user to save and recall customised presets, these
can be freely shared with other users.
FUNDAMENTAL CONTROLS
Reverb Time
The decay time of the reverb is determined by the room damping amount (i.e. how much the
walls reflect or absorb energy) and its size (controlling the time taken for a soundwave to
reach the next wall after a reflection).
The reverb decay time shown on the master panel to the left indicates the time taken for the
initial reverb to decay to a point 60 dB lower than its initial loudness. Manipulating the master
dial controls the damping of the room which is the most natural way to control a reverb time.
The range of this value is determined by the size control (available on the character tab), so
when changing the room size naturally the decay time of the room is affected by these new
dimensions.
Sometimes in order to change the perceived size of the room it can be better to modify the
spread control with affects the perception of reflections within a space.
Dry/Wet Mix
Controls the basic contribution of dry and wet signal to the output.

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MASTER CONTROLS
The master controls affect filtering and gain of the reverb and early reflections. Whilst in a
real room a reverb’s initial wall reflections and late reverberant field are contiguous, artificial
algorithms typically allow them to be controlled individually as this is musically very useful.
Reverb Level and Roll-off
The late reverberant field level and filtering are modified using these two controls. The filter
uses a shallow 6 dB/octave low-pass model.
Gain
The output level of the entire plug-in.
Reflections Level and Roll-off
Similar to the late reverb controls. Although the original device did not allow control over the
filtering of the entire early reflections section, an additional 6 dB/octave low-pass filter is
provided here so that the tone of the initial reflections can be managed more effectively.
CHARACTER CONTROLS
This section provides basic control over the reverberant room characteristics.
Pre-delay
Allows time between the onset of the late reverberant field and the early/dry signals. Proving
some space between the diffuse reverberant field, early reflections and dry components can
improve the intelligibility of vocals and other performances.
Diffusion
Low values of diffusion simulate a very reflective environment (for instance a tiled or low
complexity rooms). High values represent environments that scatter the sound around more
(for instance furnished or complex spaces). With low diffusion values one may hear more
individual reflections within the reverb tail. The diffusion control affects the early and late
reverb equally.

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Spread
The effect of the spread parameter is to change the perceived size of the room by modifying
its initial reflective characteristics. Larger spread values cause noticeable pre-delays in some
components of the reverb which tends to make the room sound larger. Hence it is often a
more effective way of changing the perceived size of the room than using the size control
itself.
Size
The volume of the room is controlled by the size. This affects the total reverb time, the tone
of the room (small sizes tend to have a resonant quality to them) and the perceived
dimensions. Due to the extreme nature of this control it is often more acoustically satisfying
to modify some combination of spread and reverb time.
Spin Rate (Modulation)
In order to reduce the effect of resonances within the algorithm the spin control modulates
the reverb in a manner similar to a chorus, but without any of the audible phase effect
commonly associated with chorusing. This control relates to the wander control on the
advanced tab which affects the amount of movement; spin controls the speed of the
movement.
LOW CONTROLS
This section provides fine control over low frequency reverb behaviour.
Bass Decay and Frequency
Some rooms naturally have a much longer low frequency decay time than others. The bass
control time allows this to be specified as a factor of the reverb time. For example, a reverb
time of 1 second with a bass decay of 1.5x will decay for around 1.5 seconds below the
frequency selected.

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Low Boost, Frequency and Pre-delay
A delayed, low-pass filtered and boosted reverb component can be supplemented to the late
reverberant field. Like spread, this can be useful in creating a sense of space for longer delay
times. Without delay this can be used to add extra weight and body to the tone of the reverb.
ADVANCED CONTROLS
This section provides high frequency, recirculation, balance and wander control.
Treble Decay and Frequency
The time for high frequencies to decay can depend on room characteristics such as the
reflectivity of the surfaces. A tiled room and some plates will exacerbate the decay of high
frequencies, but in typical rooms the highs will tend to decay away more quickly than the
majority of the reflections at low and mid-range frequencies.
Recirculation
An enhancement of the original algorithm provides a new reverb topology never heard before,
even for users of the original expansion cartridge. Originally comprising two distinct reverbs
combined at a late stage, it can be modified by interconnecting them at key points within the
algorithm resulting in a more spacious higher quality reverb.
The enhanced mode is the default mode of operation, but for more authentic reverbs the
default operating mode can be changed per-preset or globally by modifying an option in the
presets menu.
Front/Rear
The HD Cart algorithm is inherently a surround algorithm, but it was designed so that it could
also facilitate very high-density reverbs by combining the front and surround output
components. This parameter controls the balance of the master (front) and surround (rear)
algorithm output levels.
• Mono/stereo modes: determines the contribution of front to rear reverb level, with the
mid-point presenting the maximum high-density reverb mode.
• Surround modes: determines the relative level of the front/rear output levels.

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Wander (Modulation)
Modifying the amount of modulation within the algorithm allows the user to change the
liveliness of the room. Small quantities are recommended. This parameter works in concert
with the spin control.
REFLECTIONS CONTROLS
Affects characteristics of the early reflections (timing and filtering). Two sets of modulated
reflections are provided, one for the front outputs and one for the rears.
Front Delay
The front reflections can only be defined in terms of their initial reflection time (although they
are also affected by the spin rate and the master’s filter roll-off).
Rear Level, Delay and Frequency
The rear reflections can be positioned relative to the fronts in time and level, and can also be
subjected to a shallow 6 dB/octave low-pass filter.
If the Front/Rear control is set to the front you will not hear the rear reflections; they can be
heard if it is set to the middle (high density mode) or to the rear.
Spin Rate (Modulation)
To reduce the effects of colouration from static delays, a rate of modulation is provided to
control the speed of movement of the early reflections.
Rear Stereo Width
The rear early reflections can be collapsed to mono. This and is how the original hardware
presented its rear reflections when in HD mode (in surround mode the rear and front
reflectiosn are stereo). In plug-in surround modes, or in stereo modes when a wider stereo
image is desirable, the rear reflections should be run in stereo.
The icon below the delay dial is used to set mono mode (a single circle) or stereo mode
(conjoined rings).

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Page 9
SUPPORTED CHANNEL MODES
HD Cart can operate in the following channel topologies where they are supported by the host
and audio configuration.
Inputs
Outputs
Topology
Mono
Mono
Mono
Stereo
Mono
Quad
Stereo
Stereo
Stereo
Quad
HD Cart
Reverb
Processor
L
R
Inputs
L
R
L
R
Mono Input Mono Output
+
Main Outputs (Front)Surround Outputs (Rear)
HD Cart
Reverb
Processor
L
R
Inputs
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Output L
+
Output R
+
Mono Input
HD Cart
Reverb
Processor
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Output L
Output R
Output L (surround)
Output R (surround)
L
R
Inputs
Mono Input
HD Cart
Reverb
Processor
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Output L
+
Output R
+
L
R
Inputs
Input L
Input R
HD Cart
Reverb
Processor
L
R
Inputs
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Input L
Output L
Input R
Output R
Output L (surround)
Output R (surround)

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Stereo
5.0
Quad
Quad
5.0
5.0
Notes:
• In mono and stereo output modes, the mix of the main outs and surround outs is
controlled by the Front/Rear control in the advanced panel.
• In mono and stereo output modes, the level of the main outs and surround outs is
controlled by the Front/Rear control in the advanced panel.
• The 5.0 modes are configured as per the original operation manual guidance.
HD Cart
Reverb
Processor
L
R
Inputs
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Input L
Output L
Input R
Output R
Output L (surround)
Output R (surround)
+x
-4 dB
Output C
HD Cart
Reverb
Processor
L
R
Inputs
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Input L
Output L
Output R
Output L (surround)
Output R (surround)
Input L (S)
+
Input R
Input R (S)
+
HD Cart
Reverb
Processor
Main Outputs (Front)Surround Outputs (Rear)
L
R
L
R
Output L
Output R
Output L (surround)
Output R (surround)
+x
-4 dB
Output C
L
R
Inputs
Input L
Input L (S)
+
Input R
Input R (S)
+
Input C