How to Render Different Starting Phases from a Free-Running Synth LFO

Separate three questions: how fast the LFO runs, whether notes reset it, and whether its phase follows the host transport. A rate displayed in hertz answers the first question; it does not establish the other two.

Ableton Operator illustrates note-independent operation: its manual states that enabling LFO Retrigger restarts the cycle at the same position on each note, while disabling it makes the LFO free-running. Ableton Live 12: Live Instrument Reference

Other instruments use different rules. In u-he ACE, LFO2’s Free reset setting runs continuously as a monophonic modulation source, while Gate resets it per voice on each note. The manual also specifies that Sync frequency mode resets the LFOs in synchronization with the host. These are separate controls with interacting behavior. u-he ACE user guide, LFO2

Even a disabled Retrigger switch may leave a phrase-level reset. Output Arcade, for instance, describes its Off setting as Phrase Retrigger: the first note resets the LFO, which then runs continuously while that note is held. Output: LFO Modulation

Before recording, identify the documented behavior of your instrument. A workflow that depends on the LFO advancing through silent gaps requires continuous operation across those gaps.

Start with a diagnostic copy of the patch. Choose a periodic waveform such as a sine or triangle, set a slow rate, and apply an audible amount to one destination, such as filter cutoff. Temporarily simplify other modulation so that you can follow one repeating movement.

Use this listening sequence before arranging a batch of renders:

1. Hold one note through several cycles and identify a recurring landmark, such as maximum brightness.
2. Release it, wait briefly, and play another note without stopping playback.
3. Repeat with different waiting intervals.
4. Stop and restart the transport, then repeat the test.
5. Export the same short phrase twice and compare the modulation movement.

Treat these as separate observations. If every note begins with the same sweep, investigate note or phrase retrigger. If note entries vary during playback but repeated exports match, use a continuous audio capture for your variations. Neither result alone establishes how another synth or DAW will behave.

Keep pitch, velocity, note duration, and patch settings constant during the test. Listen for the timing of the slow modulation movement; differences in the audio waveform alone do not establish a different LFO phase.

For useful alternate takes without exact phase targets, continuous recording gives you a straightforward way to preserve the movements you hear. Use one synth instance and let it process the entire sequence without stopping or reloading the patch.

Build a sequence of identical notes or phrases at different entry times. Leave sufficient space for each release, and vary the gaps so the entries do not repeatedly fall at the same position in the modulation cycle. Confirm with the earlier test that the LFO advances between those entries.

Record the synth output to an audio track in one pass. In Ableton Live, the documented whole-set resampling method is to create an audio track, select Resampling under Audio From, set Monitor to Off, arm the track, and record into a clip slot. Because this captures the set output, isolate the intended synth and its processing before recording. Ableton: How to render audio in real-time

After recording, divide the take into separate regions. Align each region to its own note onset, preserve its attack and release, and audition the regions from their new beginnings. Keep the long original recording so that trimming remains reversible.

This produces recorded variations whose starting movements you can compare directly. Label them by audible behavior—such as “rising,” “near peak,” and “falling”—unless you have established a phase reference that supports numerical labels.

For a constant-rate periodic LFO that continues running, elapsed time determines relative phase advance. The following calculation is a timing model for planning note entries, not a measurement of a particular plug-in.

The cycle duration is T = 1/f, where f is the rate in hertz and T is seconds per cycle. To advance by a chosen angle, use Δt = (θ/360) × T. A quarter-cycle advance therefore requires a delay of T/4.

For an illustrative LFO rate of 0.5 Hz, one cycle lasts 2 seconds:

Relative phase advance	Additional entry delay
0°	0 seconds
90°	0.5 seconds
180°	1 second
270°	1.5 seconds
360°	2 seconds; the same cycle position

When notes need more room, add complete cycles to the intervals. In this example, entries at 0, 4.5, 9, and 13.5 seconds advance by successive quarter cycles while leaving 4.5 seconds between attacks. Record all four in one continuous pass, then trim each recording to its note onset.

These are relative phase offsets. Without a known reference, the first entry could begin anywhere in the cycle; the later entries are positioned relative to it. To target absolute starting positions, establish a documented reset before the sequence or use a resettable LFO with an explicit starting-phase control.

The calculation assumes a stable rate and uninterrupted phase progression. If rate modulation, note-dependent speed, or resets are active, the simple timing relationship no longer describes the sequence. Validate the resulting movement before labeling the files.

Use an explicit starting-phase control when you need repeatable, named positions rather than variations collected from continuous operation. This changes the setup: enable the reset behavior required by that control, then render the same phrase at several phase settings.

For example, Ableton Simpler resets its LFO to the Offset value on each new note when Retrigger is enabled. Its manual explicitly states that Offset has no effect when Retrigger is disabled. Turning the knob in free-running mode therefore will not select a new starting phase in that instrument. Ableton Live 12: Simpler LFO

In ACE, LFO2’s Phase control defines where its waveform starts when reset. Its Gate setting supplies a per-note reset. Together, those controls provide a documented basis for deliberately selecting starting positions. u-he ACE user guide, LFO2

Render one setting at a time while keeping the MIDI phrase and all other parameters fixed. Audition the complete phrase as well as its first note: introducing per-note resets changes the modulation relationship between successive notes, so this method may produce a different musical result from the original continuous LFO.

Work through the symptom before changing the patch extensively:

Symptom	Check or next action
Every note begins with the same movement	Check note and phrase reset settings.
Entries differ live, but separate exports repeat	Capture the variations within one uninterrupted recording.
A phase knob makes no audible difference	Check whether it requires an enabled reset.
Evenly spaced notes repeat the same movement	Check whether the interval equals a whole number of LFO cycles.
Variations sound different but their phase is unclear	Simplify other modulation and compare recurring sweep landmarks.

Adding silence before a phrase is only useful if the instrument actually processes and advances the LFO during that interval. Test the result; an earlier export boundary by itself does not establish a different phase at the note onset.

Likewise, a random waveform or random starting-phase option is unsuitable for constructing a deliberately ordered quarter-cycle comparison. For that task, use a repeating waveform and either a verified continuous timing relationship or a documented phase reset.

Export the captured audio regions using consistent boundaries relative to each note onset. Keep the same output routing and processing for every version, and allow enough duration for the intended release or effect tail.

In Ableton Live, Render Start and Render Length define the exported range, and a time selection in Arrangement can populate those values. The Rendered Track chooser determines which output is written. Check these controls for each variation so that the file represents the intended region and signal path. Ableton Live 12: Managing Files and Sets

Reimport the files, align their note onsets, and compare the first modulation movement and its continuation. Retain variations that offer a useful difference in the phrase, and preserve the source patch, MIDI sequence, and continuous recording alongside them.

For natural alternate takes, capture different note-entry positions during uninterrupted playback. For exact repeatability, use a documented phase-and-reset combination. In either case, the finished audio files are the reference for the starting movements you selected.

• Live Instrument Reference — Ableton Reference Manual Version 12
• ACE user guide — u-he
• LFO Modulation — Output Help Center
• How to render audio in real-time — Ableton
• Managing Files and Sets — Ableton Reference Manual Version 12