Space / Time Control

Reference Manual – Software Version 1.1.0
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Introduction

Space / Time Control Software in Version 1.1.0

Space / Time Control (STC) is the analysis and control software for the Sillitoe Disk Mastering System (SDMS).

It enables precise and efficient cutting by supporting the cutting engineer through the following key steps:

This manual provides a reference for all software elements and settings.

For a step-by-step workflow guide, please refer to our tutorial videos at spacetimecontrol.com

STC is available for Windows and macOS. Most settings and features are identical on both platforms. When there is a difference, the platform specific information is marked with for macOS and for Windows.

Track List

Track List Section

The track list displays the arrangement of program tracks for one side of the record. Currently, only one side an be processed at a time.

Once tracks have been added, the header of the track list displays this information:

All timestamps and durations in STC are displayed in MM:SS.mmm format, where MM is minutes, SS is seconds and mmm is milliseconds. When entering a time, the parser will try to convert any input to a valid entry.

Each track entry is displayed in a collapsible list, showing basic track information by default and more details when expanded.

Managing Tracks

Adding Tracks

Tracks can be added to the track list by importing digital audio files using one of the following methods:

When adding a folder, all supported audio files within the folder and its subfolders will be imported.

Audio files are copied into the project. Changes made to the original files after import do not affect the tracks within the project.
Supported Audio Formats and Parameters
The first track added to the side defines the project sample rate. Mixed sample rates within a project are not supported.
BWF Cue Markers

If an audio file contains embedded Broadcast Wave File (BWF) cue markers, STC offers the option to split the file into individual tracks at the embedded cue positions on import.

Moving Tracks

Tracks can be reordered by dragging and dropping them within the list. Multiple tracks can be selected using standard selection methods based on the operating system.

Double-clicking a track will move the playhead position to the beginning of the track.

Deleting Tracks

Tracks can be removed via the menu command: Edit > Delete…

Deleting a track also removes its corresponding audio file unless other tracks reference the same file.

Splitting and Merging Tracks

In case a master file contains more than one track but no embedded cue markers, the file can be split into separate tracks manually.

Using the menu command Edit > Split Track will split a track at the current playhead position.

The command Edit > Merge Tracks allows to merge two or more selected tracks into one, if the tracks reference consecutive sections in the same audio file.

Splitting a track does not change the audio content but merely adds a visual track marker in the layout of the groove.

Track Information

Each track entry displays the following basic track information by default:

Clicking on the track title, allows to edit it.

Clicking the chevron icon > next to the track title expands the track info to reveal more details. Holding the or Ctrl key while clicking expands or collapses details for all tracks simultaneously.

Detailed track information

Track Settings

The expanded track view also includes two adjustable parameters:

Ensure proper fade-out in the master to avoid clicks when adding padding to the track.

Transport and Metering

Transport, Metering and Controls Section

The center of the main window contains the transport and metering section as well as auxiliary controls to open the Microscope View and the Application Settings dialog.

Transport Controls

Buttons for play, pause, seek and skip enable typical navigation and transport functionality. The red record button opens the Cutting Dialog to start the cutting process when connected to the SDMS.

A large timestamp displays the current playhead position in MM:SS.mmm format. Clicking the timestamp allows direct entry of a time value to reposition the playhead.

Using the arrow keys, the playhead can be moved in various intervals for quick navigation through the audio program as the following table shows.

Modifier Keys Arrow Keys
none none −1000 ms +1000 ms +10 smpl −10 smpl
Shift −100 ms +100 ms +1 smpl −1 smpl
Ctrl −10 ms +10 ms -- --
⌘ + ⇧ Ctrl + Shift; −1 ms +1 ms -- --
Alt Previous track Next track +1 revolution −1 revolution
Moving the playhead in increments of samples or revolutions is particularly useful when navigating in the Microscope View.

When starting playback, the master audio files are played back through the Monitor Audio Device selected in the Application Settings dialog. The selected audio device is also shown in the window's lower right corner.

Metering

The stereo level meter provides a real-time preview of the analog playback disk level based on the current cutting parameters.

Like the hardware meter of the SDMS Master Control, it combines:

The metering is calibrated to 0 dB = 5 cm/s Stereo (NAB).

The upper limit is +14 dB, with levels exceeding this threshold triggering bright red overload indicators. Clicking on the overload indicators resets them.

Layout Parameters

Layout Parameters Section

The parameter section provides control over key audio and groove layout parameters that vary on a per-project basis. These parameters are stored within the project file and will be recalled when a project is opened.

In disk cutting, groove width and groove depth are sometimes used interchangeably, leading to potential miscalculations. STC consistently uses groove width as the primary measurement, as it can be directly observed under a microscope. Due to the V-shaped groove profile, a groove's depth is always half of its width.

Record Parameters

The parameters in the RECORD section define the fundamental layout of the disk.

The functionality for the additional cutting speed values for half-speed cutting will be introduced in a future release.
When cutting, the Cutting Speed setting in STC must match the Turntable Speed setting on the SDMS Space / Time Control hardware module.

Groove Parameters

The parameters in the GROOVE & PITCH section define key parameters affecting the groove layout:

A track marker is automatically added before the end of each track, so that the next track begins at the end of the track marker. The track marker only increases the pitch of the groove for the time defined as Marker Time. It does not add silence between tracks or alters the audio signal in any other way.

Audio Parameters

Currently, STC provides two basic audio-related parameters:

If an elliptic filter is defined, it is applied to the monitoring audio signal on playback.

This first release of STC was designed with focus on optimal groove layout and cutting, leaving audio optimization to the mastering engineer. Future releases will include more built-in features for optimizing the audio signal.

Advanced Layout Parameters

Advanced Layout Parameters

Additional layout parameters are available in the Application Settings dialog.

Currently, these layout settings are stored globally for the application and are shared between individual project files. Keep that in mind when loading a project which may have used different layout settings when being saved.

Groove Processing

Any change to the track list or modifications to the audio and layout parameters trigger an update of the Virtual Groove with these processing steps:

  1. The master audio data is mathematically transformed into a geometric representation of the modulated groove.
  2. This groove is then shaped into a spiral, adhering to standardized geometric parameters such as record size, groove radius limits, etc. and user-defined layout settings such as basic width, marker time, etc.
  3. The dynamic pitch algorithm optimizes the spiral spacing to pack the groove as tightly as possible, maximizing the runtime of the side.
  4. The dynamic width algorithm adjusts the groove width dynamically, expanding it where stereo information would otherwise create an excessively narrow groove.

The result is a virtual, digital preview of the analog groove the SDMS hardware would cut, based on the provided audio data and lathe settings.

This Virual Groove is then analyzed for geometric and dynamic parameters for further refinement and optimization and can be observed in the Microscope View for a detailed inspection.

Groove Analysis

Groove Analysis

The lower section of the main window presents a waveform of the audio program alongside the results of the groove analysis, arranged on a horizontal timeline.

A playhead indicates the current playback position. Clicking anywhere in the waveform or analysis graph moves the playhead to that position in time. The playhead can also be dragged with the mouse or moved in predefined intervals using the commands in the Transport menu or keyboard shortcuts, see Transport Controls.

Zooming in and out along the timeline is possible using a scroll gesture (e.g., mouse scroll wheel) or the View > Zoom in | out | full menu commands.

Waveform

The waveform view provides a visual representation of the left and right audio channels of the digital master with left channel on top and right channel below.

The vertical zoom is fixed, and any signal exceeding value 0 dBFS is clipped in the display.

The global audio parameters Gain and Elliptic Filter do not change the waveform representation. Track-specific parameters Gain and Padding are applied to the waveform, making it possible to preview level adjustments directly in the waveform display.

Analysis Graphs

The results of the groove analysis are visualized as floating bar graphs, where each bar represents the range of values (minimum to maximum) for a specific time segment.

When zooming out, each bar summarizes a larger set of values, providing an overview of longer time spans. Zooming in increases the resolution, offering a more detailed view of how values change over time.

For some parameters, variations are displayed within the same graph, using different colors to distinguish them. The legend, which clarifies these variations, can be toggled via View > Show Graph Legend.

Each analysis graph has a fixed vertical range, optimized for its specific parameter to ensure comparability of analysis results on a common scale.

The displayed analysis parameter can be changed using the radio controls at the bottom of the window or through the View menu by selecting the desired parameter.

Analysis Parameters

Disk Level

Analysis Parameter Disk Level

The Disk Level parameter represents the analog disk level (PPM) that the groove will reproduce on playback. It is calculated and displayed separately for the left and right channels.

The reference level follows NAB standards, where 0 dB corresponds to 5 cm/s per stereo channel. This parameter matches the metering used in the SDMS hardware.

Stylus Velocity

Analysis Parameter Stylus Velocity

The Stylus Velocity parameter indicates the absolute velocity of a playback stylus moving in vertical and lateral directions combined during playback.

If velocity, and therefore acceleration, becomes too high, the stylus may lose contact with the groove, leading to distortion or skipping. Since velocity increases with both level and frequency, strong high-frequency audio signals such as cymbals or sibilance in a voice track are the primary causes of high velocities.

Whether a high-velocity section in the groove creates audible distortion or tracking problems depends on the material and the groove geometry at that specific location.

In general, high velocities at lower and mid frequencies tend to cause more tracking problems than those at high frequencies. To help with this distinction, the graph displays velocity for the full bandwidth as well as a filtered version for frequencies below 4 kHz.

Excursion

Analysis Parameter Excursion

Groove modulation depends on stereo phase relationships. A mono signal, where both channels are in phase, results in purely lateral modulation, while a mono signal with one channel inverted and thus opposite phase creates purely vertical modulation. Typical stereo signals, with continuously changing phase relations, generate a combination of both lateral and vertical modulation.

The Excursion parameter graph represents the lateral and vertical components of the stylus excursion during cutting and playback.

Extreme lateral excursions require more disk space and can lead to tracking distortion due to excessive stylus velocity and acceleration. Extreme vertical excursions require dynamic width compensation and can result in grooves that are both wider and deeper than normal.

Groove Width

Analysis Parameter Groove Width

For a purely lateral mono signal, the groove width remains constant at the basic width setting. When stereo content is present, the cutting stylus also moves vertically, which modulates the groove width.

The Groove Width parameter displays the result of this vertical modulation as modulated groove width, as well as the dynamic width compensation applied to maintain the groove above the defined minimum width parameter.

Extreme vertical modulation, such as that caused by strong out-of-phase low-frequency content, can create grooves that fluctuate between extremely narrow and excessively wide. This poses challenges during both the cutting process and later pressing.

While width automation can compensate for narrow passages, it will further exaggerate wide and deep sections. In such cases, an elliptic filter can help keep the groove within acceptable parameters.

Pitch

Analysis Parameter Pitch

The Pitch parameter represents the adjustments made by the dynamic pitch algorithm to optimize groove spacing and maximize disk runtime. By reducing the spacing between adjacent grooves, the system ensures that as much program material as possible fits onto the disk.

The parameter is expressed in lines per millimeter of disk radius (lpmm), where lower values indicate greater spacing between grooves.

This graph does not convey critical cutting issues but serves as a visualization of how the pitch dynamically changes across different tracks.

Land

Analysis Parameter Land

The Land parameter measures the remaining space between grooves after the dynamic pitch algorithm has been applied.

Like the pitch parameter, this information is primarily for visualization purposes and does not indicate any potential cutting issues.

Disk Capacity

Analysis Parameter Disk Capacity

One of the fundamental challenges in record cutting is maintaining the right balance between disk capacity and disk level. A louder cut provides a better signal-to-noise ratio but requires more disk space, limiting the total program duration that can be accommodated on a single side.

The Disk Capacity graph illustrates how each track gradually fills the disk, reaching the maximum capacity defined by the standard limits for the outermost and innermost groove diameters.

Output Level

Analysis Parameter Output Level

The Output Level parameter reflects the final digital signal level as it is sent to the SDMS Master Control's DAC.

This level is mainly determined by the combination of level calibration and gain settings. When using Sillitoe MMFB MKII heads, an additional Head Calibration EQ further affects the output signal level.

The graph provides a representation of the digital output level with all processing stages applied. To prevent clipping and distortion, STC enforces a strict upper limit of 0 dBFS on the output signal.

Calculating the output level requires more processing time than the other parameters. The output level parameter will therefor become available shortly after the other parameters have been calculated.

Microscope View

Virtual Microscope View

The most detailed inspection of the Virtual Groove is possible using the microscope view, which shows the calculated groove geometry with a sample-accurate resolution.

The geometric shape of the groove is overlaid with a color-mapped representation of the currently selected analysis parameter. The small circle in the center of the view indicates the current playhead position.

The Zoom of the microscope view can be toggled between 25x/50x/100x/200x, allowing for detailed inspection of the groove or a broader overview.

The Parameter List holds a list of all relevant geometric and dynamic groove parameters at the current playhead position.

Application Settings Dialog

Application Settings Dialog

The Application Settings dialog holds a list of settings which are shared between all projects, both new and loaded from a project file.

Devices

STC allows to select three different devices for audio and control signals:

Windows requires the selection of an Audio Driver. The tested and recommended driver is Windows Audio (Exclusive Mode). Other drivers may work but are not tested and supported.
When connecting a multi-channel DAC as Monitor Audio Output, currently the first two channels will be used for output by default.
If a device is displayed with the suffix value [unavailable] in the dropdown menu, please check your USB connection and ensure that both the SDMS hardware modules and STC are powered on.

Advanced Layout Parameters

See section Advanced Layout Parameters.

Lathe Calibration Dialog

Lathe Calibration Dialog

The Lathe Calibration dialog window holds a set of utilities to test and calibrate the software with the hardware of your individual lathe.

The various controls allow to manually send audio and control signals to your lathe and observe the results of the machine movement or test cuts.

For a step-by-step guide of how to calibrate your lathe, please refer to the calibration instructions or contact our support.

Manually sending audio and control signals to your SDMS can potentially damage your head or other automation systems. Use this dialog with caution.

Signal Source

The SOURCE section allows to select an audio source signal or a predefined sequence of control signals to be sent to the lathe.

For the predefined calibration signals, please refer to the respective calibration manuals for details: Pitch Calibration and Width Calibration.

Audio Signal Parameters

When a value of Sine tone or Noise signal is selected, the Signal section allows to define parameters for the audio signal.

Control Signal Parameters

The Control section allows to define parameters for the control signals sent to the lathe.

Trim Parameters

The parameters in the Trim section define the behavior of your particular lathe to the control signals sent by STC. Please refer to the calibration instructions how to find the correct values for your lathe.

After a successful calibration, please make a backup of all trim settings by taking notes or saving a screenshot of the calibration dialog.

Head Calibration

The Sillitoe MMFB MKII head requires a calibration EQ to be applied to the output signal to achieve a perfectly flat frequency response and best possible cutting results.

The head calibration EQ along with other calibration settings are contained in a .head calibration file created for your specific lathe during the initial setup process. Please contact our support to obtain your calibration file if you have not received it automatically.

To apply the head calibration, drag the .head file onto the Head section or select the file from the file dialog.

The head calibration will be copied and stored with the other calibration settings. When loaded successfully, the Head section will display the name and version of the calibration.

The head calibration filter is applied to all output signals sent to the Lathe Audio Output defined in the Application Settings dialog.

Signal Metering

When sending signals to the SDMS hardware from the calibration dialog, the metering sections display the current audio level and control signal values:

Lathe Controls and Lathe Information

The Lathe section displays information about the connected SDMS hardware modules and has basic transport controls to start and stop sending audio and control signals to the lathe:

When using the fast forward button to move the carriage, please make sure to select the carriage direction first using the hardware switch on the SDMS Space / Time Control hardware module. The speed of the carriage movement will increase in steps while holding down the

Next to the timestamp, information about the connected SDMS hardware modules is displayed:

If one or both hardware connections are lost, the device info will be change color to red and the transport controls will be disabled.

System Firmware

System Firmware

When the calibration dialog is opened and the SDMS hardware modules are connected, STC automatically checks for available firmware updates in the background.

If an update is available, an additional System section will be displayed, showing the current version number, the available version update and a button to download and apply the update.

Please close and reopen the calibration dialog after a successful update to make sure the new firmware is loaded and displayed correctly. In case the firmware update fails, please contact our support.

Cutting Dialog

Cut Project Dialog

Metering

The dialog shows three meters to monitor the cutting process:


The Pitch section also displays the current pitch automation phase with five status LEDs:


The Width section also features three status LEDs to indicate the current width automation state:

Lathe Controls

In the Lathe section, the cutting dialog has two buttons to control the cutting process:

The fast forward button can be used to move the carriage to the start position. The speed of the carriage movement will increase in steps while holding down the button.

When the record button is pressed, the cutting process will start automatically and the button will be displayed as Stop.

The timestamp next to the fast forward button displays the current cutting position and the total duration of the audio program.

A small link icon next to the timestamp indicates the status of the connection to the SDMS hardware modules:

Test Cuts

While the normal cutting process starts with the lead-in and then proceeds to cut the whole program, it is also possible to test cut only a custom section of the program.

After the head drop timeout, the audio and control signals will immediately be sent to the cutter head without a fade in. Make sure to start at a position with low level to avoid damage to the cutter head.

Manual Lock

If the Auto Lock setting is disabled in the Advanced Layout Parameters, the position of the lock groove has to be triggered manually:

The manual lock feature was added as an experimental feature to override the internal calculation of the lead-out and lock groove positions. If the internal calculation is accurate, the manual lock feature should not be used.

Miscellaneous

Keyboard Shortcuts

All menu commands have corresponding keyboard shortcuts that can substantially speed up the navigation through the application. The shortcuts are displayed in the menu bar next to each command.

Most interactive user interface elements have keyboard shortcuts assigned as well. The shortcuts are displayed as tooltips when hovering over the element.

License Handling

STC uses a personalized license file to activate the software. The license file is requested on first launch and stored in the user library folder. If the license file is lost, please contact our support to obtain a replacement.

The license is activated and validated in regular intervals with the STC license server. This happens automatically in the background and requires an internet connection and a valid system clock.

A purely offline licensing scheme is currently not supported. If you have such a requirement, please contact our support.

Project File Format

The .groove project file format is a binary container format that bundles audio files and settings. It should not be edited manually.

New versions of STC will maintain compatibility with project files from previous versions, but there might be issues with specific features. Project files saved with a newer version of STC might not be compatible with an older version of STC.

Log Files

STC writes a separate text file for each launch with debug and error messages to the user library folder. Each file is named with the current date and time.

The log files are useful for diagnosing issues and can be sent to our support team to help with troubleshooting. The log file for the current launch can be opened using the menu item Help > Show Log File….