Disclosure: This page may contain affiliate links. Prices were checked on the date shown and may change.
An introduction to FLUX:: BitterSweet Pro, based on information from the maker and distributors: what it does, how to use it and who it may suit. It is not scored.
Frequency dependent transient designer, process only a certain part of the frequency spectrum, acting like a dynamic eq driven by Transients and/or Sustain.
— FLUX:: official site
What is BitterSweet Pro?
BitterSweet Pro (currently v3) is a transient designer from FLUX::. Transients are the attack portion of a sound and sustain is the tail that follows; the plugin lets you raise or lower each. It is the developed-further sibling of the company's freeware BitterSweet.
Its main feature is that it can process only part of the frequency spectrum. The maker describes it as acting like a dynamic EQ driven by transients and/or sustain: narrowing the frequency range makes it behave like a high-shelf, low-shelf or peak dynamic EQ.
On stereo material, a built-in M/S encoder lets you process just the mid or just the side. Dynamic gain runs from -100% (Sweet) to +100% (Bitter), while static gain and output gain span plus or minus 24 dB. A soft clipper sits at the end of the chain.
Two preset slots, A and B, plus a morphing slider between them can be automated from the host. It handles up to 16 channels of input and output and supports Open Sound Control (OSC).
Frequency-dependent processing
You choose the processed range within 20 Hz to 20 kHz. Raising the lower limit gives a high-shelf behavior, lowering the upper limit a low-shelf one, and setting both a peak one, so you could boost only the high-frequency attack of a snare.
Sweet and Bitter dynamic gain
Transients and sustain can be moved between -100% (Sweet) and +100% (Bitter), boosted or cut together or separately.
Filtered detector side-chain
Low-cut, high-cut and band-pass filters can shape what the detector hears, and the filtered signal can be auditioned alone.
M/S processing
Main, Center and Stereo modes process the full signal, only the mid, or only the side. The maker suggests Center for kick and snare and Stereo for panned rhythmic instruments.
Geek panel
Extra attack, hold and release parameters can be revealed for detailed envelope shaping.
A/B slots and morphing
Two full parameter sets can be loaded at once and blended with a slider, and the morph can be recorded as host automation.
Soft clipper and OSC
A soft clipper at the end of the path rounds off peaks. OSC support lets you control it from external devices.
Specifications
| Item | Details |
|---|---|
| OS | Windows 10 / 11 (64-bit), macOS 10.14.6 or later (Apple Silicon supported) |
| License | iLok.com account required (iLok USB key not needed) |
| Graphics | Windows needs a graphics card supporting OpenGL 2.0 |
| Type | Transient designer (frequency-dependent) |
| Channels | Up to 16 in/out |
| Frequency range | 20 Hz to 20 kHz |
| Dynamic gain | -100% (Sweet) to +100% (Bitter) |
| Static gain / output gain | plus or minus 24 dB |
| Speed | Fast / Medium / Slow |
| Frequency order | 6 / 12 / 18 / 24 dB per octave |
What is included and system requirements
- OS: Windows 10 / 11 (64-bit), macOS 10.14.6 or later
- An iLok.com account is needed for licensing
- A/B preset slots with morphing and a preset manager (Factory / User / Global)
- Built on the 64-bit v3 framework
How to use it
- Request the 30-day trial on the FLUX:: site, install it and authorize with iLok.
- Insert BitterSweet Pro on the track you want to process.
- Start with the full frequency range and move the dynamic gain to hear the change.
- Match the natural attack with the Speed setting (Fast / Medium / Slow).
- Narrow the frequency range and check that only the target band changes; use the audition buttons for the filters.
- On stereo material, switch the M/S mode to affect only the mid or the side.
- Open the Geek panel to refine attack, hold and release if needed.
- Load two settings into the A/B slots to compare them or morph between them.
Shaping drum attack and decay
You could try boosting snare or kick attack or shortening the tail. Narrowing the range may let you move only the high-frequency attack.
Adjusting guitar or piano resonance
Reducing sustain to tame a crowded tail, or increasing it for a longer ring, may be worth trying.
Processing only the center of a stereo source
The Center M/S mode may let you work on the attack of a centered vocal or kick.
Gentle adjustments on buses or the master
Used lightly, the dynamic gain could slightly change the energy of a whole mix.
Who it may suit
- People who want to shape transients per frequency range
- People who want dynamic-EQ-like behavior driven by transients
- People who want to treat mid and side separately
- People who like A/B comparison and morphing to dial in settings
Good to know before you buy
- An iLok.com account is required for licensing (the iLok USB key is not needed).
- USB displays are not supported. On Windows, a graphics card supporting OpenGL 2.0 and current drivers are needed.
- The official shop mentions a free 30-day trial.
- A 50% academic discount applies for students, teachers and schools.
- Subscriptions are also offered: All Plugins Pack at 14.95 USD per month and Complete Pack at 79.95 USD per month.
How it differs from similar products
We do not pick a winner; the official figures are placed side by side.
BitterSweetFLUX::、
The freeware BitterSweet is listed on the FLUX:: site as a free plugin. BitterSweet Pro adds a frequency range, M/S processing, a Geek panel and A/B slots, and is priced at 99 USD.
Price
$99 (FLUX:: official site, checked 2026-10-27). Prices can vary by region and promotion, so check the official page before buying.
See BitterSweet Pro on the product page
Sources: flux.audio shop.flux.audio minet.jp (checked 2026-10-27)
Comments