ForTran 1.1.0.0

ForTran 1.1.0.0

A polyphonic additive/formant synthesiser for macOS, as a VST3 and an
Audio Unit. Originally a Cakewalk DXi written in 2003; this is the port.

New in this release

Portamento, and it is properly polyphonic. The Glide knob on the right of
the panel sets the time; zero is off, which is the default, so nothing you
saved before this sounds different.

Each new note glides from the nearest pitch of the chord that was sounding
when the current chord began, and each of those pitches is used once - so
C-E-G to D-F-A is three glides of a tone, moving in parallel, rather than
three notes fanning out of whichever pitch happened to be last. Notes struck
within 30 ms of each other count as one chord; further apart than that and
each note glides from the one before it, which is what a played line wants.

The glide is constant time - every glide takes as long as the knob says,
whatever the interval, so a chord change arrives together - and even in
semitones, so an octave down sweeps at the same rate as an octave up. The
knob is squared like the envelope times: its centre is 500 ms of a two-second
maximum.

Universal binary. 1.0.0.1 was built for Apple Silicon only while its
installer claimed both architectures, so on an Intel Mac - or in any host
running under Rosetta - it installed cleanly and then loaded nothing. This
build is arm64 + x86_64.

What it is

Ten sine partials, each with its own level, phase, invert and ADSR; ten
formant envelopes over them; a sweepable filter with four switchable shapes
(low pass, high pass, comb, grass); amplitude and filter envelopes; vibrato,
tremolo and a per-harmonic LFO; sixteen voices.

Installing

Download ForTran-1.1.0.0.pkg and open it. The installer offers the two
formats separately:

/Library/Audio/Plug-Ins/VST3/ForTran.vst3
/Library/Audio/Plug-Ins/Components/ForTran.component

Quit your DAW first - a running host holds the old copy open. Signed with a
Developer ID and notarised by Apple, so it installs without any
Privacy & Security detour. Installing over 1.0.0.1 replaces it; your projects
and their settings are untouched.

Requires macOS 10.13 or later.

Two things that will look like bugs and are not

• The Level knob starts 20 dB down. The 2003 original ran hot enough to
  clip a dense chord. The top of that knob's travel is exactly the original's
  level, so nothing is lost - it is one turn away.
• The pitch wheel covers a whole octave either way, not two semitones.
  That is the DXi's own law, kept deliberately.

Known gaps

• Program change does not select the waveform. In the DXi the MIDI patch
  number chose sine, square or saw; this port is sine partials only.
• The output ladder's corner moves with the sample rate. Its coefficients
  are constants the original never scaled, so the same patch is more than an
  octave brighter at 96 kHz than at 44.1 kHz. Reproduced rather than fixed;
  the Ladder switch takes it out.
• Glide time is latched at note-on, like everything else a voice reads, so
  moving the knob does not retime a glide already under way.

Everything deliberate about the port - every deviation from the original and
why - is in PORTING-NOTES.md.

Uninstalling

A .pkg never will, so:

sudo rm -rf /Library/Audio/Plug-Ins/VST3/ForTran.vst3
sudo rm -rf /Library/Audio/Plug-Ins/Components/ForTran.component

Checksum

<paste: shasum -a 256 installer/ForTran-1.1.0.0.pkg>

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Copyright 2026 A. E. Cobley. CC BY-SA 4.0.
VST is a trademark of Steinberg Media Technologies GmbH.