Sample Circulator 2

s3g Sample Circulator 2 is a compact file-or-capture stereo loop instrument descended from the original CRCLTR v1.0.1 Gen/Oopsy firmware engine. New instances open in the flexible Dual model, while Classic remains available for the original loop relationship.

Load a mono or stereo file into either slot, or replace, overdub, and punch its live stereo captures; choose an editable window, direction, rate, and join for each loop; then move between them manually or with periodic, ramped, stepped, or random motion. It is intentionally simpler than Sample Rings: two stereo loop slots, one crossfade, and stereo-only I/O.

Sample Circulator 2 interface with two loaded stereo loop sources, aligned live vertical playheads across their four waveform lanes, playback switched on, the A and B crossfade position at the midpoint, and loop, capture, output, and crossfade controls — Live Sample Circulator interface. The vertical playheads cross both stereo loop slots in real time while the A/B field at left shows their equal-power midpoint blend.

Workflow

Insert Sample Circulator on a stereo REAPER track.
Route the stereo output to the main speakers or stereo monitor path, set Blend toward the loops, and begin playback. Another effect may precede that destination when its build matches the stereo bus.
Press Load A or Load B, or drop a file directly on the matching waveform lane. Dropping two files together assigns the first to A and the second to B. For live capture instead, route the source to the plug-in's left and right inputs.
Choose Loop 1, Both, or Loop 2 with Record Target, then choose Replace, Overdub, or Punch.
Set Record to RECORD and hold it for the desired capture time, or hold MIDI C2.
Return Record to Idle to close the loop and restart its playhead.
Drag the S and E markers on either waveform, or use the matching sliders, to queue each loop's next start and end; then choose direction, rate, and Seam or Duck join.
Choose a Crossfade Motion and Fade Shape, then set Position manually or set the automated motion Rate.
Balance the live source and loop crossfade with Blend.

A record hold shorter than 100 ms is discarded without changing an existing loop. The first 100 ms is kept in a pre-roll buffer, so a valid hold retains its beginning.

Waveforms and MIDI Buttons

The waveform panel draws normalized grayscale left and right envelopes for loaded files and embedded captures, so quiet material remains legible. Mono files are duplicated to both stereo lanes. Grab either thin S or E marker to edit the same Start or End parameter shown by the sliders. During playback, the solid markers move immediately while dashed markers retain the active window and NEXT WRAP shows that the edit is queued. The reader finishes its current pass, adopts the latest window at wrap, and uses a short boundary handoff to prevent a click or cursor seek. An edit made while stopped is ready before playback resumes.

Files decode in the background. During playback, a replacement becomes audible only after the complete loop is ready. Files longer than the 32-second slot capacity are truncated; sample-rate conversion preserves their duration and pitch up to that limit.

The vertical graph at the left borrows the Sample Lanes path display and follows the waveform order directly: cool blue A is at the top, warm amber B is at the bottom, and violet marks the region where both loops contribute. Its gradient changes with the selected gain law. A horizontal line and center handle show the current mix, while the arrow shows travel toward A or B. In Manual mode, drag the graph vertically to set Position directly.

Motion choices are Sine, Trapezoid with endpoint holds, bounded Random Walk, constant-speed Triangle, repeating A-to-B and B-to-A ramps, Sample & Hold, and Square. The clock follows Loop A's selected window and rate when available, falls back to Loop B when A is empty, and uses a neutral one-second cycle when both captures are empty.

Fade Shape is independent of motion. Equal Power retains the original law; Linear is constant-sum; Wide and Tight change the shared region; Smooth eases both ends; Full Overlap brings both loops to unity at center; Deep Dip strongly attenuates the center; Plateau holds a stable equal-power blend; and Cut makes a narrow, smoothed handoff. These shapes apply only to the A/B circulator mix: each loop's Seam join retains its own short equal-power End-to-Start crossfade.

MIDI note	Button	Behavior
C2 / 36	Record	Momentary capture gate: note-on begins the hold and note-off closes the loop.
C♯2 / 37	Play	Toggles both loop readers between play and pause.
D2 / 38	A Reverse	Toggles Loop A playback direction.
D♯2 / 39	B Reverse	Toggles Loop B playback direction.

Controls

CLAP control	Original mapping	Meaning
Loop 1 Rate	1	Loop 1 playback rate, 0.25x to 2.75x.
Loop 2 Rate	2	Loop 2 playback rate, 0.25x to 2.75x.
Crossfade Motion	3	Manual, Sine, Trapezoid, Random Walk, Triangle, A-to-B Ramp, B-to-A Ramp, Sample & Hold, or Square.
Position / Rate	4	Loop position in Manual mode. In motion modes it maps 0.25x to 4x relative to Loop A, falling back to Loop B when A is empty.
Blend	5	Equal-power mix from source audio to the loop crossfade.
Input Gain	6	Gain into the record path, followed by soft tanh saturation.
Output Gain	7	Final gain followed by soft tanh saturation.
Record	FSU / button / gate	Momentary record gate.
Record Target	Switch 1	Loop 1, both loops, or Loop 2.
Record Monitor	Switch 2	During Replace capture, pass the source through the Loop 1 slot, remain silent, or pass it through the Loop 2 slot. Overdub and Punch keep the established loop audible.
Record Mode	New	Replace makes a new loop, Overdub adds input while retaining the selected amount of old audio, and Punch writes new input directly into the existing loop.
Feedback	New	Amount of existing loop retained on every Overdub pass.
Start / End	New	Independent normalized playback window for each loop, editable from its slider or by dragging the S/E waveform markers. A live edit is queued until the next wrap and handed off smoothly. In Classic mode, A selects within its original half-capture source and B selects within the full capture.
Reverse	New	Independent signed playback direction for each loop.
Join	New	Seam, the default for both slots in new instances, uses a short equal-power End-to-Start wrap crossfade inside the selected window. Duck uses a raised-cosine edge window.
Playing	New	Pauses both readers without clearing either capture.
Fade Shape	New	Equal Power, Linear, Wide, Tight, Smooth, Full Overlap, Deep Dip, Plateau, or Cut gain law for the A/B mix.
Load A / B	New	Loads a mono or stereo audio file into either loop slot; drag-and-drop on a waveform selects the same destination.
Clear Loop A / B	New	Momentary erase buttons that independently empty either loaded or captured loop without entering record or changing the other slot.

Loop Models

Dual gives both slots complete independent captures with their own start/end window, direction, rate, and join. Each slot can contain approximately 32 seconds at the current session sample rate.

CRCLTR Classic retains the original relationship: Loop 1 reads the first half of its capture while Loop 2 reads the complete capture. Each loop still uses its current Start, End, direction, rate, and Join controls. Older CRCLTR sessions select Classic automatically.

Sample-Rate Behavior

Rates, timing constants, and recording behavior adapt to the session sample rate, so loop durations remain consistent across sample rates.

Storage and Recall

Sample Circulator stores both stereo loops inside the host project whether they came from files or live capture, so reopening a session does not depend on the original files remaining in place. If the session sample rate changes, the loops are resampled during recall to preserve their duration.

Older CRCLTR sessions reopen in Classic mode. The loops, playback windows, directions, rates, joins, crossfade settings, and play state otherwise return with the project.