TWINFOLD is a stereo imager that keeps the mono sum unchanged whether you widen or narrow the stereo image. It processes only the left-right difference (Side), so the mono sum stays the same. It comes as the free edition TWINFOLD and the upgraded edition TWINFOLD Pro, which adds independent 3-band control, RECOVER, STEREOIZE, AUTO WIDTH and listening modes. This manual covers both. Features only in the Pro edition are marked “Pro only”.

Free vs Pro

In the free edition, the BANDS and PRO TOOLS panels show a “PRO” badge and cannot be operated.

1. Overview

With a typical stereo imager, the wider you make a sound, the more it tends to thin out on mono playback through phase cancellation, and the lead in the center can disappear. TWINFOLD applies all width processing to the left-right difference (Side) only and never touches the center (Mid). However boldly you shape the stereo field, the mono sum stays exactly as the original (except when RECOVER reinforces the center in the Pro edition).

• Mono sum guaranteed: Processing applies only to the left-right difference (Side), so the mono sum stays the same.
• Independent 3-band width (Pro only): Splits the sound into three bands, LOW / MID / HIGH, and adjusts the width of each one independently.
• Drag-to-set crossovers (Pro only): Drag the frequency lines on screen left and right to set the crossover frequencies.
• Tight low end: BASS MONO removes the stereo content below a set frequency and gathers it in the center, preventing muddy lows and phase problems.
• RECOVER (Pro only): Naturally makes up the energy lost in narrowed bands with gain on the center (Mid).
• STEREOIZE (Pro only): Builds a natural, wide stereo image from mono sources or narrow tracks without touching the mono sum.
• AUTO WIDTH (Pro only): Analyzes how wide the input is and automatically sets the overall width so the phase correlation reaches the target (TARGET).
• MONO / SIDE listening modes (Pro only): One click lets you hear mono playback (MONO) or only the stereo difference (SIDE).
• Full metering: An auto-zooming vectorscope, an overall phase correlation meter, per-band phase correlation readouts (Pro only), and a MONO LOSS meter that constantly shows how much the level drops in mono.
• Low-latency mode: The ZERO LAT button at the top right removes latency completely, so you can use it comfortably while recording or playing live.
• Preset management & A/B comparison: Factory presets (7 in the free edition / 14 in Pro) and A/B comparison. Saving, removing, exporting and importing user presets (.twinfold) is Pro only.
• Mono track support: Works on stereo tracks, and can also be inserted on a mono track to widen it to a stereo output.

2. Requirements

3. Installation

Installation (Windows)

1. Extract the downloaded ZIP file.
2. Copy the TWINFOLD.vst3 folder (TWINFOLD Pro.vst3 for Pro) to the following location:
   C:\Program Files\Common Files\VST3\
3. Launch your DAW and run a plugin rescan (if you copy the file while your DAW is running, the change may not take effect).

Installation (Mac)

1. Extract the downloaded ZIP file.
2. Copy TWINFOLD.vst3 (TWINFOLD Pro.vst3 for Pro) to ~/Library/Audio/Plug-Ins/VST3/ and TWINFOLD.component (TWINFOLD Pro.component for Pro) to ~/Library/Audio/Plug-Ins/Components/ (~ is your home folder. In Finder, choose Go → Go to Folder and paste the path to open it. Create the folder if it does not exist).
3. Open Terminal (Applications → Utilities → Terminal), paste the following three lines one at a time, and press Return after each.
   Free edition:

   cd ~/Library/Audio/Plug-Ins
   xattr -dr com.apple.quarantine VST3/TWINFOLD.vst3
   xattr -dr com.apple.quarantine Components/TWINFOLD.component

   Pro edition:

   cd ~/Library/Audio/Plug-Ins
   xattr -dr com.apple.quarantine VST3/"TWINFOLD Pro.vst3"
   xattr -dr com.apple.quarantine Components/"TWINFOLD Pro.component"

4. Launch your DAW and run a plugin rescan (if you copy the files while your DAW is running, the change may not take effect. If the AU does not appear in Logic Pro or another DAW, restart your Mac).

Uninstalling

[Windows] Remove the TWINFOLD.vst3 folder (TWINFOLD Pro.vst3 for Pro) you copied. To also remove your user presets in Pro, remove %APPDATA%\Tonecraft Tokyo\TWINFOLD Pro\ as well.
[Mac] Remove the TWINFOLD.vst3 and TWINFOLD.component (TWINFOLD Pro.vst3 and TWINFOLD Pro.component for Pro) you copied. To also remove your user presets in Pro, remove ~/Library/Tonecraft Tokyo/TWINFOLD Pro/ as well.

4. The screen

Header (top row)

• Logo & version: The logo and product version (v1.1.0) are shown at the top left of the window.
• PresetBar: Choose a preset. Saving (SAVE), removing (DEL), and exporting or importing preset files (.twinfold) from the menu are Pro only.
• A / B / COPY: A/B buttons to flip back and forth to compare two settings, and a COPY button that copies the current settings to the other slot.
• ZERO LAT: Turns low-latency mode on and off. When lit, latency is zero.

InfoBar (top strip)

• Located just below the header. Hover the mouse over a knob or button to see what it does and how to use it, in Japanese or English depending on the OS display language.

SCOPE panel (left)

• Vectorscope: Plots the stereo image (width and placement) of the output in real time. It smoothly zooms to the best scale for the level (Auto Zoom); the current zoom is shown at the bottom right. The frame lights up while the MONO / SIDE listening mode (Pro) is on.
• Phase correlation meter: Shows the phase correlation of the left and right output channels from −1.0 to +1.0. +1.0 means fully mono, 0.0 means uncorrelated (stereo), and negative values mean there is out-of-phase content. When AUTO WIDTH (Pro) is on, a marker (Lime) shows the target.
• MONO LOSS meter: Constantly shows, in dB, how much the level drops when this stereo audio is summed to mono. 0 dB means no loss. The colors green (−2 dB or above), yellow (−2 to −4 dB) and red (below −4 dB) let you see at a glance when too much width will make it quieter in mono.

WIDTH panel (center)

• WIDTH: The large knob for the overall stereo width. In Pro it works as an overall multiplier on the width of each band (LOW / MID / HIGH), and when AUTO WIDTH is on, the automatically calculated width is overlaid faintly and the value in the center follows it.
• BASS MONO: A toggle that makes only the low end mono.
• FREQ: A knob that sets the upper frequency limit for BASS MONO.

BANDS panel (center right, Pro only)

In the free edition it shows a “PRO” badge and cannot be operated.

• Band width display & per-band correlation: Shows the width setting of the LOW / MID / HIGH bands as bar lengths, and the phase correlation of each band in its section.
• Crossovers (LO X / HI X): Drag a band line left or right with the mouse to change its frequency (double-click to return to the default).
• LOW / MID / HIGH knobs: Control the stereo width of each band separately.

PRO TOOLS panel (right, Pro only)

In the free edition it shows a “PRO” badge and cannot be operated.

• RECOVER: Makes up the level lost in narrowed bands with gain on the center (Mid).
• STEREOIZE: Adds a natural stereo feel to mono sources or narrow images.
• AUTO WIDTH & TARGET: Turns automatic width on and off, and sets its target phase correlation.
• Listening modes (MONO / SIDE): Mutually exclusive buttons that let you check, in one click, how it sounds in mono (MONO) or hear only the spread content (SIDE).

OUTPUT panel (bottom)

• OUT: Sets the final output level of the plugin.
• BYPASS: Bypasses all processing in the plugin.

5. Knobs and buttons

• WIDTH (0 .. 200 %, default: 100 %)
  Sets the overall stereo width. 100% is the original width, 0% is fully mono, and 200% emphasizes the stereo feel. In Pro it is multiplied with the width of each band (LOW / MID / HIGH). Processing applies only to the left-right difference (Side), so the mono sum stays the same.
• BASS MONO (off / on, default: off)
  Turns on or off the function that removes the stereo content of the low end and gathers it in the center.
• FREQ (40 .. 300 Hz, default: 120 Hz)
  Sets the upper frequency limit made mono while BASS MONO is on. The knob uses a logarithmic scale.
• OUT (-12.0 .. +12.0 dB, default: 0.0 dB)
  Sets the final output level.
• BYPASS (off / on, default: off)
  Bypasses the plugin’s processing. When on, the unprocessed original sound is output.
• ZERO LATENCY (off / on, default: off)
  Switched with the ZERO LAT button at the right end of the header. When on, the plugin’s processing latency becomes zero, so there is no delay while recording or playing. When on, the phase of the stereo content shifts slightly, and BASS MONO works slightly more gently.
• LO X (Pro only) (100 .. 1000 Hz, default: 250 Hz)
  Sets the crossover frequency where the low (LOW) band meets the mid (MID) band. You can also drag the line on screen directly.
• HI X (Pro only) (1000 .. 10000 Hz, default: 4000 Hz)
  Sets the crossover frequency where the mid (MID) band meets the high (HIGH) band. You can also drag the line on screen directly.
• LOW (Pro only) (0 .. 200 %, default: 100 %)
  Sets the stereo width of the low band (below LO X) separately.
• MID (Pro only) (0 .. 200 %, default: 100 %)
  Sets the stereo width of the mid band (LO X to HI X) separately.
• HIGH (Pro only) (0 .. 200 %, default: 100 %)
  Sets the stereo width of the high band (above HI X) separately.
• RECOVER (Pro only) (0 .. 100 %, default: 0 %)
  Makes up the energy lost in narrowed bands with gain on the center (Mid). Because it adds gain to the Mid, the level in mono playback changes too (up to +6 dB). It has no effect on bands that are being widened.
• STEREOIZE (Pro only) (0 .. 100 %, default: 0 %)
  Builds a natural spread from the center and adds it to the stereo content (Side). It turns fully mono sources or tracks that lack width into a rich stereo image without harming the mono sum. It does not affect the lows below FREQ.
• AUTO WIDTH (Pro only) (off / on, default: off)
  Analyzes how wide the input is and automatically sets the overall width so the phase correlation reaches the target (TARGET). While it is on, the automatically calculated value is overlaid faintly on the WIDTH knob.
• TARGET (Pro only) (0.0 .. 0.9, default: 0.5)
  Sets the target phase correlation used while AUTO WIDTH is on. A marker (Lime) is shown on the correlation meter.
• MONO / SIDE (listening switches) (Pro only)
  Monitoring buttons that temporarily switch the output so you can check it (only one can be on at a time). MONO outputs the mono sum of left and right (L=R), and SIDE outputs only the stereo difference. They are not saved in DAW projects or presets.

6. Presets

The free edition includes 7 factory presets (F01–F07), and Pro includes 14 (F01–F14). F08–F14 are Pro only.

• F01: DEFAULT — Initial state. Keeps the stereo balance of the original as it is.
• F02: GENTLE WIDE — WIDTH 125%. Adds a natural, modest spread.
• F03: WIDE — WIDTH 160%, BASS MONO 120 Hz. A standard spread together with a tight low end.
• F04: EXTRA WIDE — WIDTH 200%, BASS MONO 150 Hz. A bold, wide sound with tight lows.
• F05: TIGHT LOW END — WIDTH 100%, BASS MONO 180 Hz. Tightens the lows while keeping the overall width.
• F06: NARROW — WIDTH 60%. Narrows the stereo image and pulls it tightly toward the center.
• F07: MONO — WIDTH 0%. Fully mono output.
• F08: AIR LIFT — LOW 80%, HIGH 150%, BASS MONO 120 Hz. Brings out the air in the highs while keeping the lows clean.
• F09: MIX BUS — WIDTH 110%, LOW 70%, HIGH 125%, BASS MONO 100 Hz. Improves the clarity and spread of the whole mix.
• F10: FOCUS CENTER — LOW 50%, MID 80%, HIGH 110%. Tightens the lows and mids to strengthen the core in the center.
• F11: NARROW + RECOVER — WIDTH 40%, RECOVER 50%. Narrows the stereo width while RECOVER firmly makes up the thinning.
• F12: MONO TO STEREO — STEREOIZE 60%, BASS MONO 120 Hz. Expands mono material into a natural stereo image.
• F13: AUTO WIDTH — AUTO WIDTH on, TARGET 0.5. Automatically keeps a steady stereo feel as the dynamics change.
• F14: AUTO SAFE — AUTO WIDTH on, TARGET 0.7, BASS MONO 120 Hz. A safe setting that puts mono compatibility first.

Saving and managing user presets (Pro only)

In the free edition, saving (SAVE) and removing (DEL) are disabled. Keep your settings and automation in your DAW project file.

• SAVE: Saves the current settings as a user preset under a name you choose.
• DEL: Removes the selected user preset.
• Export / import: From the PresetBar menu you can export presets as .twinfold files or import external files. Useful for sharing across computers or projects.
• Preset folder:
  [Windows] %APPDATA%\Tonecraft Tokyo\TWINFOLD Pro\Presets\
  [Mac] ~/Library/Tonecraft Tokyo/TWINFOLD Pro/Presets/

7. A/B comparison

The A and B buttons in the header let you flip back and forth to compare two settings by ear.

• Slot A is active when the plugin opens.
• The first time you press B, the settings of A at that moment are copied to B as they are. After that, you can adjust each slot independently.
• The button of the active slot lights up in cyan.
• Pressing COPY copies the settings of the current slot over the other slot.
• Choosing a preset updates only the currently active slot.
• Note: When you save a DAW project, only the settings of the slot active at that moment are saved. The contents of both A and B are not kept in the project. BYPASS and ZERO LATENCY are not affected by A/B switching.

8. Tips

• Checking mono playback, and the RECOVER exception:
  TWINFOLD’s basic processing applies only to the left-right difference (Side), so the mono sum stays the same. However, RECOVER (Pro only) is the one exception. To make up the level lost when narrowing, it adds gain to the center (Mid). So turning up RECOVER also raises the level in mono playback.
• Natural depth for mono material with STEREOIZE (Pro only):
  Apply STEREOIZE to guitar, vocals or acoustic instruments recorded in mono to give them stereo spread. The original sound is kept as it is on mono playback.
• Setting the BANDS crossovers (Pro only):
  You can drag the lines in the BANDS panel (LO X / HI X) left and right directly with the mouse. While watching the per-band correlation shown in each section, you can easily do mastering moves such as “keep the lows (LOW) well correlated and widen only the highs (HIGH)”. Double-click to return to the default.
• Accurate monitoring with MONO / SIDE (Pro only):
  Press MONO to instantly hear how it will sound on a mono speaker or a smartphone. Press SIDE to monitor only the stereo difference, so you can hear exactly which sounds in which bands (reverb, doubled parts and so on) are spreading.
• Over-widening the highs and pre-echo:
  Widening the highs heavily may cause a slight ringing just before attacks. If that bothers you, turn on ZERO LAT.
• Using the MONO LOSS meter:
  The tone of the mono sum itself does not change, but when you widen the stereo image a lot, the share of mono in the total stereo energy goes down, and mono playback can feel relatively quieter (thinner). As long as the MONO LOSS meter stays in the green range (−2 dB or above), the level difference in mono is hardly noticeable.
• Keeping the kick and bass centered:
  On the mix bus or in mastering, we recommend turning on BASS MONO and setting FREQ to around 100–140 Hz. It prevents low-end phase cancellation on club systems and large speakers and keeps a punchy bottom end.

9. Notes

TWINFOLD (free edition)

• This product is distributed free of charge (freeware) “AS IS”, without support.
• The source code is proprietary and not public.
• All copyrights to this product belong to Tonecraft Tokyo.
• Modification, reverse engineering, redistribution, and resale of this product are prohibited (please download it from the Tonecraft Tokyo official website and BOOTH).
• Free for both commercial and non-commercial use.

TWINFOLD Pro

• This product comes with no support and is provided as is.
• No refunds are provided.
• The source code is proprietary and not public.
• Copyright for this product belongs to Tonecraft Tokyo.
• Redistribution, resale, modification, and reverse engineering of this product are prohibited.
• Only the purchaser may use this product. Transferring or sharing it with third parties is prohibited.

10. Disclaimer

• This product is provided “AS IS”, without warranty of any kind, express or implied, including but not limited to merchantability, fitness for a particular purpose, and non-infringement of third-party rights.
• Tonecraft Tokyo is not liable for any damages arising from the use of, or inability to use, this product, including but not limited to loss or corruption of project files or audio data, equipment malfunction, lost working time, or lost profits.
• Operation is not guaranteed for every combination of DAW, operating system, and hardware.
• Specifications may change, and the product may be discontinued, without notice.
• Use this product at your own risk. Back up your projects before important work.

11. Licenses

• VST is a trademark of Steinberg Media Technologies GmbH.
• This product uses JUCE.
• Noto Sans JP / JetBrains Mono — SIL Open Font License 1.1