TWINFOLD is a stereo imager that keeps the mono sum unchanged whether you widen or narrow the stereo image. It processes only the difference between left and right (Side), so the mono sum stays the same.
1. Overview
With a typical stereo imager, the wider you make the stereo image, the more likely it is to thin out on mono playback, or for some sounds to cancel each other out and disappear. TWINFOLD applies all width adjustment to the difference between left and right (Side) only and never touches the center (Mid). However boldly you widen or narrow, the tone and level on mono playback match the original exactly.
- Mono sum guaranteed: Processing applies only to the difference between left and right (Side), so the mono sum stays the same.
- Simple width control: A single
WIDTH knob sets the overall spread.
- Tight low end:
BASS MONO removes the stereo content below a set frequency and gathers it in the center, preventing muddy lows.
- Clear visual feedback: A vectorscope that zooms smoothly with the input level, a phase correlation meter, 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.
- Factory presets & A/B comparison: 7 presets and A/B switching.
- 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
| Item | Details |
|---|
| Supported OS | Windows 10 / 11 (64-bit), macOS 11 or later (Apple Silicon / Intel) |
| Plugin format | Windows: VST3 / Mac: VST3, AU |
| Supported hosts | DAWs supporting VST3 or AU |
| Input channels | Stereo or mono |
| Output channels | Stereo |
| Sample rate | Depends on the host (DAW) |
| Screen size | 960 × 600 px (fixed, not resizable) |
| Screen language | Japanese / English (follows the OS display language) |
| Latency | Yes (compensated automatically by the DAW; none with ZERO LAT on) |
3. Installation
Installation (Windows)
- Extract the downloaded ZIP file.
- Copy the
TWINFOLD.vst3 folder to the following location:
C:\Program Files\Common Files\VST3\
- Launch your DAW and run a plugin rescan (if you copy the file while your DAW is running, the change may not take effect).
About warnings on Windows:
Because the software is not code-signed, Windows SmartScreen may show a warning when you download or first run it. Click "More info", then choose "Run anyway" to continue.
Installation (Mac)
- Extract the downloaded ZIP file.
- Copy
TWINFOLD.vst3 to ~/Library/Audio/Plug-Ins/VST3/ and TWINFOLD.component 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).
- Open Terminal (Applications → Utilities → Terminal), paste the following three lines one at a time, and press Return after each.
cd ~/Library/Audio/Plug-Ins
xattr -dr com.apple.quarantine VST3/TWINFOLD.vst3
xattr -dr com.apple.quarantine Components/TWINFOLD.component
- 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).
About security warnings on Mac:
This plugin is not notarized. Unless you run the commands above in Terminal, macOS shows "is damaged and can't be opened" or "cannot be opened because the developer cannot be verified", and the DAW will not load the plugin. The commands only remove the quarantine attribute (a mark) that macOS adds to downloaded files. Run them again whenever you reinstall the plugin for an update. If nothing is shown and the prompt moves to the next line, it worked.
Uninstalling
[Windows] Delete the TWINFOLD.vst3 folder you copied.
[Mac] Delete the TWINFOLD.vst3 and TWINFOLD.component you copied.
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: Select and manage presets. The current preset name is shown in the middle.
- A / B / COPY: A/B buttons to switch between two settings and compare them, 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.
- Phase correlation meter: Shows the phase correlation between 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.
- 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.
- BASS MONO: A toggle that makes only the low end mono.
- FREQ: A knob that sets the upper frequency limit for BASS MONO.
BANDS and PRO TOOLS panels (right)
- In the Free edition, the right-hand section shows a "PRO" badge and its controls are disabled. Independent 3-band width, RECOVER, STEREOIZE, AUTO WIDTH and the MONO/SIDE listening modes are available in TWINFOLD Pro.
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 level of the stereo content (Side). 100% is the original width, 0% is fully mono, and 200% emphasizes the stereo feel. Processing applies only to the difference between left and right (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. It keeps the kick and bass steady in the center and prevents phase problems in the lows.
- 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.
6. Presets
TWINFOLD includes 7 factory presets.
- 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.
Settings not included in presets:
The BYPASS and ZERO LATENCY settings are not stored in presets. Switching presets never changes the bypass state or the latency mode unexpectedly.
* In the Free edition, saving (SAVE) and deleting (DEL) presets are disabled. Keep your settings and automation in your DAW project file.
7. A/B comparison
The A and B buttons in the header let you switch between two settings and compare them 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.
- Selecting 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:
Try switching to mono playback with your DAW's utility or similar. TWINFOLD processes only the difference between left and right (Side), so the mono sum stays the same. However much you emphasize the stereo feel, you don't have to worry about vocals or the kick receding or disappearing in mono.
- 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.
- 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.
- 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.
About TWINFOLD Pro
For more detailed mixing and mastering, an upgraded edition, "TWINFOLD Pro", is also available. TWINFOLD Pro adds the following:
- Independent 3-band stereo width (LOW / MID / HIGH)
- RECOVER, which makes up the level of narrowed bands in the Mid
- STEREOIZE, which builds natural stereo from mono sources
- MONO / SIDE listening to check only the mono sum or the Side content in one click
- AUTO WIDTH, which automatically tracks a target spread
- Per-band phase correlation display, and dragging the crossover lines with the mouse
- Saving, deleting, exporting and importing user presets (.twinfold)
9. Notes
- 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 official website and BOOTH).
- Free for both commercial and non-commercial use.
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