Put HALO on a reverb send with MIX at 100 % and feed it from several tracks — one shared shimmer bed glues a whole arrangement.
What HALO is
HALO is a shimmer reverb: a long, diffuse FDN tail with a +octave pitch-shift folded inside the feedback loop. Every pass through the loop climbs in pitch and gets reinjected, so a held note blooms into an ascending choir that grows over the original sound. The same engine as NEBULA, plus the octave-up loop that turns a tail into an endless rising halo.
Where it shines It shines on sustained material — pads, vocals, guitar swells, synth chords, drones and FX tails — anything you want to lift into something cinematic and ethereal. Honest note: this is algorithmic Shimmer (reverb + pitch in the loop), not a clone of any one box. It's a color effect first, so it earns its place on a send.
Up and running in five steps
- Drop HALO on a sustained sound, or on a reverb send bus to lift a whole group.
- Set the space with SIZE and DECAY — bigger and longer gives the shimmer room to bloom.
- Bring SHIMMER up until the rising octave is clearly singing over the dry note.
- Use DECAY high and TONE as the brake: if the loop builds too much, darken TONE to tame it.
- Dial MIX to taste — around 40 % on an insert, or 100 % on a send.
How the signal moves through it
The dry signal feeds a diffuse FDN — the same Schroeder allpass / delay-line network as NEBULA — whose scale and T60 are set by SIZE and DECAY. Inside the feedback path the tail is transposed +one octave (a splice/overlap pitch-shifter) and reinjected by the loop gain, so each cycle climbs and the choir stacks. SHIMMER sets how much of that transposed signal is fed back; TONE is a band EQ on the feedback that both colors the halo and keeps the loop on the edge without diverging. A slow ORBIT rotates the wet image (free in seconds-per-revolution, or locked to host tempo via SYNC). LOW CUT / HI CUT shape the whole output, IN PHASE collapses the wet to a mono-safe path, a soft limiter keeps the near-infinite tail clip-safe, and MIX cross-fades wet against dry. FREEZE latches the cloud so it sustains forever while you play over it.
Every control, explained
FREEZE
Latches the current cloud so the tail sustains forever.
Toggle (default off). Captures what's in the reverb and holds it; you can keep playing over the frozen bed without feeding new energy into the loop.
Catch a lush chord, hit FREEZE, then solo or speak over the held pad underneath.
ÓRBITA · FREE / SYNC
How the wet image's slow rotation is timed.
Toggle between FREE (the ORBIT RATE knob picks the speed) and SYNC (the orbit locks to a host-tempo DIVISION).
SYNC the orbit so the movement breathes in time with the track instead of drifting.
ORBIT RATE
Speed of the wet rotation in FREE mode, shown in seconds per revolution.
0.004–0.5 Hz, i.e. ~250 s down to ~2 s per turn (default glacial, ≈100 s). Logarithmic, so the whole knob travel is usable — no dead zone. Visible only when ÓRBITA is FREE.
Keep it glacial (60–120 s) for a cloud that drifts almost imperceptibly under a vocal.
DIVISION
The tempo-synced length of one orbit revolution.
Choice: 1/4 · 1/2 · 1 bar · 2 bar · 4 bar (default 1 bar). Always visible when ÓRBITA is SYNC.
2 or 4 bar reads as a slow, hypnotic sweep; 1 bar is obvious rhythmic motion.
MIX
Dry/wet blend of the effect.
0–100 % (default 40). Equal-power cross-fade between the dry signal and the shimmer cloud.
On an insert keep MIX around 30–50 % so the dry note stays present; push to 100 % on a send.
SIZE
The scale of the underlying space.
0–100 % (default 65). Sets the delay-line lengths / diffusion of the FDN — small room to vast cathedral.
Bigger SIZE gives the rising octave more room to spread before it stacks.
DECAY
Length of the reverb tail (T60).
0–100 % (default 75). Scales how long the base reverb — and the shimmer feeding off it — sustains.
High DECAY plus moderate SHIMMER is the classic 'grows forever' shimmer; pull it back for a quick sparkle.
SHIMMER
Amount of +octave signal reinjected into the loop.
0–100 % (default 55). At 0 it's a clean reverb with no shimmer; higher feeds more transposed tail back, so the ascending choir gets louder and more prominent.
If the shimmer sounds detuned or warbly, it's the pitch-shifter being pushed — ease SHIMMER back a touch.
TONE
Band EQ on the feedback — color and the stability brake.
0–100 % (default 45). Lower darkens the loop (more damping); higher keeps highs alive. It's not just color: it's the lever that holds the loop on the edge without runaway.
With DECAY and SHIMMER high, darken TONE to stop the highs from piling up into harshness.
ORBIT
Depth of the slow wet rotation.
0–100 % (default 40). Sets how wide the cloud rotates around the stereo field; ÓRBITA FREE/SYNC sets how fast.
A little ORBIT keeps the long tail alive and moving instead of sitting static behind the mix.
LOW CUT
High-pass on the plugin's output (dry + wet).
0–100 % → 20→500 Hz, logarithmic (default 0 % = off / transparent). Cuts lows from everything leaving HALO, so it's audible at any MIX.
Open it a touch to keep the shimmer cloud out of the low end and clear of the bass and kick.
HI CUT
Low-pass on the plugin's output (dry + wet) — the pair of LOW CUT.
0–100 % → 20k→1.5 kHz, logarithmic and inverted (default 0 % = off / transparent). Darkens the whole output.
Roll it down for a warmer, more vintage halo that sits behind the dry instead of glittering on top.
IN / OUT
Input and output trim.
−24…+24 dB each (default 0). Stage gain into the engine and compensate level on the way out.
Trim IN down a little on hot signals so the feedback loop has less energy to accumulate.
IN PHASE / mono-safe
Collapses the wet image to a mono-compatible path.
Toggle. Forces the wet to a positive phase correlation so the shimmer doesn't cancel when summed to mono.
Leave it on when the mix has to survive a club PA or a phone speaker.
Tips & tricks
01
02
FREEZE a chord, then play a melody on top: the held octave cloud becomes an instant ambient backdrop.
03
For an endless riser, automate SHIMMER and DECAY up across a build — the choir lifts into the drop.
04
Use TONE as a stability control, not just EQ: when high SHIMMER + DECAY starts to pile up, darken TONE to rein it in.
05
SYNC the ÓRBITA to 2 or 4 bar so the slow rotation locks to the song and the long tail breathes in time.
06
On vocals, set a low MIX (20–30 %) with a high LOW CUT so the shimmer floats above the voice without muddying it.
Troubleshooting
The tail builds up and gets harsh or runs away.
Bring TONE down to darken the feedback, and pull DECAY / SHIMMER back. TONE is the band EQ on the loop and acts as the stability brake — darker = less high-frequency build-up. The engine clamps hard so it can't truly explode, but lower settings keep it musical.
The shimmer sounds detuned, warbly or glitchy.
That's the splice/overlap pitch-shifter being pushed. Ease SHIMMER back and use clean, sustained source material — dense or percussive input stresses the shifter. On tuned, held notes the octave should sing cleanly.
I barely hear any shimmer.
Raise SHIMMER (it sets how much +octave is reinjected — at 0 it's just reverb), give it room with higher SIZE and DECAY, and make sure MIX is high enough. The choir needs a sustained source and a long tail to bloom.
It sounds thin or disappears in mono.
Click IN PHASE / mono-safe. The wide wet image and the orbit use stereo decorrelation that can partly cancel when summed to mono; IN PHASE forces a mono-compatible path.
Specs
Formats: VST3 · AU
Systems: macOS
Build: Universal (Apple Silicon + Intel)
Engine: Diffuse FDN reverb (shared with NEBULA)
Shimmer: +octave pitch-shift in the feedback loop
License: AGPLv3 · open-source