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Prism – Manual

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The Concept

TDR Prism is a precise frequency analyzer with a focus on human perception. Among its flexible audio sourcing, decoding, and visual configuration possibilities, Prism features a wide range of spectral weighting/tilting methods, peak/RMS smoothing options, including human auditory filters, and real-time indication of auditory masking.

Prism is able to visualize and compare spectra from various sources, be it audio files, regular and sidechain inputs, or other Prism instances in the project.

A freely resizable user interface with fullscreen support offers comfortable insight into the spectrum. Screen magnification, automatic marker lines, and tone generator options further help inspect audio signals with ease.

Prism Controls

Filter Magnitude Display

This panel displays the frequency analyzer graph.

To magnify the view 4x, hold Shift. To scroll the graph on the horizontal axis, hold Shift and drag left or right.

Click the display to freeze the animation and examine the spectrum in detail. This action reveals a crosshair, enabling a detailed examination of the spectrum, including dynamic reference lines for all crossing points. To play a sine wave at the selected frequency, use Ctrl+click (Windows), Command+click (macOS).

Right-click on any blank area within the UI to open the standard context menu and access additional options. Click outside the menu to close it.

DC Level Indicator

This meter estimates the input’s DC level.

Note: Detecting DC in finite-length signals has limitations and may occasionally produce false positives.

Plot Legend and Configuration

The Plot Legend provides a compact overview of all visible plots along with their most relevant settings.

You can drag the legend to your preferred location. The toolbar’s “Legend” switch allows you to hide the legend entirely. There’s also an option to automatically hide the legend while inspecting the spectrum (i.e., when the left mouse button is pressed). This option, named “Inspection (Mouse Down): Hide Legend,” is available in the context menu.

Plot Configuration

Click to enter or exit the Plot Configuration panel. Alternatively, you can double-click the panel.

Plot Configuration Panel

The Plot Configuration Panel provides a range of configuration options. TDR Prism can display up to four plots simultaneously. Each plot can be independently sourced, decoded, detected, averaged, and styled.

The footer section also provides access to the overall analyzer precision/timing, a range of spectral weighting options, indication of auditory masking, and the vertical display range.

Plot Active

Select to display the plot. Deselect to hide the plot.

Plot Source

Defines the source of the plot:
  • Input: Uses the plugin’s main audio input
  • Sidechain: Uses the plugin’s audio sidechain input
  • Plugin Instances: Uses the main audio input from another TDR Prism instance
  • File: Uses an external audio file.
  • Show Calibration Slider: You can activate a plot calibration slider from this menu. This feature allows you to adjust the gain for the chosen plot source.

Plot Decoding

Defines the decoding method used for stereo sources:
  • LR Avg (Left/Right average)
  • Left
  • Right
  • Sum
  • Diff

Plot Detection

Defines the plot’s detection mode:
  • Peak
  • RMS

Plot Detection Timing

Controls the timing of the selected plot detection mode:
  • Fast: Provides a quick smoothing time.
  • Default: Offers moderate smoothing.
  • Gentle: Enables more smoothing.
  • Slow: Ensures strong smoothing.
  • Infinite: Integrates the input until manual reset (context menu).
With Peak detection, this parameter will control the peak decay time. In case of RMS detection, it will define the size of the RMS window.

Plot Spectral Smoothing

Controls the spectral grouping/averaging to be applied to the plot:
  • Raw: No smoothing applied
  • 1 Octave Smoothing: Frequency bins span 1 octave
  • 1/3rd Octave Smoothing: Frequency bins span 1/3rd of an octave
  • 1/6th Octave Smoothing: Frequency bins span 1/6th of an octave
  • 1/12th Octave Smoothing: Frequency bins span 1/12th of an octave.
  • Human: Human auditory filter model (ERB).

Plot Color

This option allows you to select a color for the plot.

Note: The options ‘Spectrum’, ‘Warm Spectrum’, and ‘Cold Spectrum’ allow the plot’s visual style to be displayed in a multi-color gradient.

Plot Style

Choose the visual style for the plot from the following options:
  • Line
  • Half Fill
  • Fill
  • Xray

Analyzer Precision

This defines the global spectral precision vs timing of the analyzer:
  • Low resolution (i.e. Fast timing)
  • Medium resolution (i.e. Moderate timing)
  • High resoution (i.e. Smooth timing)
Note: Temporal precision is generally inversely proportional to spectral precision. If a faster response is needed, select a lower precision.

Analyzer Weighting

A weighting curve is used to ‘weight’ measured values according to their importance in relation to some outcome. Prism supports several forms of weighting.

No Weighting

Flat transfer of all measured data.

No Weighting
White noise, no weighting

Slope (Tilt)

Linear weighting, at various slopes. These are useful in music production to visually linearize the naturally tilted frequency distribution of most music signals.

A slope of 3dB/Octave is equivalent to an inverse pink noise slope. A slope of 4.5dB/Octave is a commonly used starting point.

3dB/Oct tilt
White noise, with 3dB/oct Tilt

Cinema: X-Curve Weighting

The X-Curve, a slightly controversial standard, aims to predict the effect of large room acoustics in typical cinema applications. In other words, it helps preserve the overall frequency balance and intelligibility of dialogue across theatres. See ISO2969 for more details.

Prism implements the inverse X-Curve.

White noise, weighted by inverted X-Curve

Cinema: N-Curve Weighting

The N-Curve, a variant of the X-Curve, is suitable for very large-scale rooms.

Prism implements the inverse N-Curve.

White noise, weighted by N-Curve

Sound Pressure Level: A-Weighting

A standard audio weighting curve, primarily intended for use in lower level SPL measurements. For more information, please refer to the A-weighting article on Wikipedia.

White noise, A-weighted

Sound Pressure Level: B-Weighting

A standard audio weighting curve, primarily intended for use in moderate level SPL measurements. For more information, please refer to the B-weighting article on Wikipedia.

White noise, B-weighted

Sound Pressure Level: C-Weighting

A standard audio weighting curve, primarily intended for use in high level SPL measurements. For more information, please refer to the C-weighting article on Wikipedia.

White noise, C-weighted

Sound Pressure Level: D-Weighting

A standard audio weighting curve, developed to measure sound pressure levels of very high level noisy signals, particularly those produced by turbojet engines. For more information, please refer to the D-weighting article on Wikipedia.

D-Weighting has largely been replaced by ITU-R 468 Weighting.

White noise, D-weighted

Loudness: ITU-R 468

ITU-R 468 is a widely used standard for measuring noise in audio systems. The human ear exhibits different responses to tonal content as opposed to noisy content. This curve can be seen as the noise equivalent to the famous (pure tone) equal loudness curves.

ITU-R 468
White noise, weighted by ITU-R 468

Loudness: ISO 226

Inverse equal-loudness contour for pure tones at 80 Phon, as per ISO 226.

ISO 226
White noise, weighted by inverted ISO 226 (80 Phon)

Loudness: K-weighting

The K-weighting curve is used for program loudness measurements in the broadcast context, as suggested by ITU-R BS.1770 and used by EBU R-128.

White noise, K-weighted

Groove Geometry: Placement

Signal to disc groove placement.

White noise, disc groove placement

Groove Geometry: Velocity

Signal to disc groove velocity.

White noise, disc groove velocity

Auditory Masking

Activates the Auditory Masking visualization. Masked areas will then appear semi-transparent.

Note: This option has no effect on spectra imported/generated from external files (masking is largely a momentary effect).
Spectrum plot with Auditory Masking active. Semi transparent columns indicate which auditory bins are actively masked.

Auditory masking occurs when the perception of one sound is affected by the presence of another sound.

TDR Prism estimates auditory masking by using the mechanism described in ISO/IEC 13818-7 (AAC, i.e. Advanced Audio Encoding). While this is not a complete model of auditory masking, it provides sufficient accuracy for excellent lossy audio compression. Building on the same mechanisms, Prism can accurately visualize the masking predicted by lossy compression algorithms, such as the bands that these algorithms are likely to truncate.

Masking density provides a measure of the redundancy of an audio signal and its intelligibility. High masking activity is also known to induce listening stress and fatigue.

Details on the causes and effects behind auditory masking can be found in this Wikipedia article.

Analyzer Maximum

This setting specifies the maximum value for the analyzer in decibels (dB).

Analyzer Range

This setting specifies the analyzer’s vertical range in decibels (dB). Vertical range can also be changed using the mouse wheel over the analyzer’s vertical ruler area.



Use the undo/redo buttons to recall previous/next parameter changes. The exact event is shown in a tool tip. Please note that certain parameter changes are not tracked by this function (e.g. “Bypass”).

Preset Management

The preset drop-down list offers quick access to factory settings and user presets.

The next/previous buttons allow you to cycle through the presets.

Advanced preset management options are available from the context menu (Right-click).

Reset to Original state resets the currently active preset to its original state.

Save As New Global User Preset opens a dialog used to create User Presets. Note that these presets persist across sessions and DAWs (presets are saved on your machine). The total amount of user presets is limited to 20.

Overwrite/Rename Selected User-Preset allows to overwrite or rename presets.

Delete Selected User Preset allows to delete the current user preset.

Save As Default State replaces the plugins’ default preset with the current parameter state.

Revert Default State To Factory Setting deletes an overwritten default state.

Copy State (Ctrl+C) copies the current control states to the clipboard. This allows for applying control states (i.e. “presets”) across plugin instances and plugin hosts by using the Paste State command.

Paste State (Ctrl+V) pastes the control states from the clipboard.

Share State opens a dialog with additional preset sharing options via e-mail or internet forums.

A/B Control

A/B allows to compare two alternative parameter states.
A>B and B<A copies one state to the other.


This feature freezes the animation, allowing for a more detailed examination of the spectrum.


This function toggles the visibility of the Plot Legend.

Fullscreen Mode

This button enables the plugin’s interface to expand to full screen, facilitating precise adjustments and providing a more detailed view of the Filter Magnitude Display. To exit Fullscreen Mode, either press the Escape key or click the Fullscreen button again.


The dynamic help mode offers detailed information about the various elements of the user interface. Click “?” to activate the online help and move the mouse cursor over the control of interest. A small info bubble will appear displaying the function and details of the item.


The settings button opens a dialog which gives control over additional plugin options.

Slider allows for changing the behavior of knobs and control points in response to the mouse. Under Continuous Drag, knob and controller movement relies on mouse speed when Velocity is enabled. When Linear is enabled, knob and controller movement is proportional to mouse movement. Drag Sensitivity sets the linear sensitivity of the knob and controller movement further.

Plug-in controls, knobs, and control points can be adjusted using Left-click & drag (Continuous) and Right-click & drag (Stepped) by default. Mouse Configuration swaps the Continuous and Stepped behaviors between the left and right mouse buttons when selecting Invert Left/Right ButtonsNote that the default stepped values can be customized via the product configuration file. See “Local data” below for instructions on how to access this file.

Graphics allows for changing the interface size to a fixed percentage value between 100%, 125% and 150%.

Processing shows the plug-in latency and sample rate details. Highest quality rendering enables the option to always render at the highest Processing Quality, no matter what type is enabled in the Toolbar. See the “Processing Quality” subchapter for more details on these modes.

Registration offers access to offline and online product registration options. See the “Product Registration” chapter for more information.

Local Data allows for exporting and importing user preferences, presets, and keys, to and from other systems. Local data can also be deleted for all Tokyo Dawn Labs plug-ins using the Trash button.

In addition, the Folder button opens the Tokyo Dawn Labs local data folder containing all configuration files and keys. Note that these operations affect all TDR plug-ins, and not just SimuLathe REF.

Updates allows to Check for updates and to Download latest versionAutomatic Lookups can be enabled to Check for updates (once per day).

Help contains Documentation and Support links.

About shows the version number, build date, format, credits, and other information.

Context Menu

Standard Context Menu

Additional options can be accessed using the standard context menu. This can be opened by Right-clicking on a blank area anywhere in the UI. A click outside of the menu closes it.


The Analyzer feature offers further options for managing the spectrum animation in the Filter Magnitude Display:

Analyzer: Pause

This option halts the animation, allowing for a more detailed examination of the spectrum.

Analyzer: Reset Hold

This clears all Peak/RMS hold values. This effect is particularly noticeable in Infinite mode.

Analyzer: Reset Hold On Playback Start

This option clears all Peak/RMS hold values when playback starts. This effect is particularly noticeable in Infinite mode.

Analyzer: Inspection (Mouse Down)

The Inspection (Mouse Down) feature provides additional inspection options when you activate the crosshair on the Filter Magnitude Display:

Analyzer: Inspection (Mouse Down): Hide Legend

This option toggles the visibility of the Plot Legend when you activate the crosshair.

Analyzer: Inspection (Mouse Down): Freeze Plots

This feature pauses the spectrum animation, allowing for a more detailed examination when you activate the crosshair.

Analyzer: Inspection (Mouse Down): Play Tone with CTRL Key (Win), Play Tone with COMMAND Key (macOS)

This option activates a tone generator at the selected frequency when you press Ctrl+click (Windows) or Command+click (macOS) on the Filter Magnitude Display.

Analyzer: Inspection (Mouse Down): Tone Generator Mode

When you initiate the Play Tone with CTRL Key (Win) or Play Tone with COMMAND Key (macOS) feature, you have four modes to choose from:

  • Static Sine: Generates a static sine wave at the chosen frequency.
  • Dynamic Sine: Generates a dynamic sine wave at the chosen frequency.
  • Dynamic Noise: Generates dynamic white noise at the chosen frequency.
  • Bandpass: Enables bandpass monitoring at the chosen frequency.

Analyzer: Tooltip

Tooltip offers extra features that display the nearest musical note when you engage the crosshair on the Filter Magnitude Display:

Analyzer: Tooltip: Show Note

This feature displays the musical note that is closest to the frequency currently under the crosshair on the Filter Magnitude Display.

Analyzer: Tooltip: A4 Tuning

This option allows you to adjust the reference pitch of the note, typically set at 440 Hz. You can use this setting to accommodate various tuning standards.


This selection offers two quality modes for GPU performance:

  • Efficient: Ideal for systems with limited GPU resources.
  • High Quality: Ideal for systems with abundant GPU resources and when maximum detail is desired.

Fast Animations

This feature accelerates the spectrum animation in the Filter Magnitude Display.

High Contrast

This option slightly darkens the background of the user interface.

Plugin Size

Plugin Size provides additional options for adjusting the interface size of the plugin:

Plugin Size: Fullscreen

This feature allows the plugin’s interface to expand to full screen. To exit Fullscreen, you can select ‘Exit Fullscreen’ from the Context Menu, press the Escape key, or click the Fullscreen button on the Toolbar.

Plugin Size: Reset Plugin Size To Default

This allows you to revert the interface size of the plugin to its original setting, as defined under Defaults.

Plugin Size: Defaults

This option provides two additional settings:

  • Use This Plugin’s Size As New Default: This setting allows you to set the current size of the plugin as the new default size.
  • Revert To Factory Settings: This setting allows you to restore the plugin size to its original factory settings.

These options provide flexibility in customizing the plugin’s interface size according to your preferences.

User Interface Scale

User Interface Scale sets the on-screen interface size to a fixed percentage value of 100%, 125%, or 150%.


Instance allows for renaming the specific plug-in instance.

Control State Functions: Copy, Paste, and Share

Copy State (Ctrl+C) copies the current control states to the clipboard. This allows for applying control states (i.e. “presets”) across plugin instances and plugin hosts by using the Paste State command.

Paste State (Ctrl+V) pastes the control states from the clipboard.

Share State opens a dialog with additional preset sharing options via e-mail or internet forums.

Adjusting Plugin Controls

Resetting Controls to Default Preset Values

Any control can be reset to its default preset value. This default value is the value that is set in the Default preset.

To reset a control:
  • Alt-click (Windows), Option-click (macOS), directly on the control value.

Modifying Controls Using a Mouse Wheel

Many of the displayed values can be modified directly using a mouse wheel.

To modify control values using a mouse wheel:
  • Hover over the displayed value.
  • Scroll up or down using the mouse wheel.

Plugin Window Resize

Adjusts the interface size of the plugin by clicking and dragging the resize handle.

Copyright and Acknowledgements

Prism was originated by Vladislav Goncharov and Fabien Schivre

Documentation by Shane Johnson

Product evaluation and quality control by:

Ady Connor
Aleksi Vuolevi
Andrew Boult
Audiobomber | Castlemastering
Bob Olhsson
Cyril Meysson
Dax Liniere | Puzzle Factory
Dennis J Wilkins | Studio 12 Below
Diogo C. Borges
Eric Recourt
Greg Reierson
Gregg | Hermetech Mastering
Helmut Erler
Ilya Orlov
Janne Hatula
Jean Dante
Jeffrey Rippe
Jerry Anthony Mateo
Joe Caithness Mastering
Joseph Lyons
Justin Perkins
Laurent Sevestre
Michael Wynne
Miro Pajic
Murray Campbell | Beatworld
Niklas Silen
Nil Hartman
Pete Grandison
Resoundsound Mastering
Rich Prewett
Richard Pentrose
Robi Bulesic
Roland Löhlbach
Ruairi O’Flaherty
Sean Diggins
Sergey Makeev
Thaddeus Moore | Liquid Mastering
Titanio Studios
Valentin Zvukofor
Vitaly Zolotarev

Copyright © Tokyo Dawn Records. All rights reserved.

All other product and company names are trademarks or registered trademarks of their respective holders.

Published inProduct Manuals
Copyright © Tokyo Dawn Records