Glacial

Six-lane drum sequencer · Radish · Vulpus Labs

Glacial is paper wrapped round a slowly turning drum. The paper has six lanes. You place points in each lane, and as the drum turns, each lane's output follows the curve through its points. One turn of the drum takes anything from ten seconds to two hours, so a lane can be a filter that opens over twenty minutes, a pitch that drifts a few cents across an hour, or a level that rises and falls once a turn for as long as the patch runs.

The paper has no start and no end. It joins itself at a seam, so every lane is a loop, and a curve that crosses the seam is as smooth as one that does not. You can also take hold of the drum and turn it by hand, and it keeps turning a moment when you let go.

To begin: press TURN, click a few points into lane 1, and patch lane 1's output into something slow: a filter's cutoff, a VCA, an oscillator's fine tune. With RATE where it loads the drum turns once a minute, so you hear the whole curve every minute.

The paper

The paper runs down the module. Lanes are columns, numbered 1 to 6 beneath it. A point's place across its lane is its value: the lane's left edge is the bottom of its range, its right edge the top. A point's place down the paper is its place on the drum.

The red line across the paper a third of the way down is the playhead. What is under it is what the outputs are playing now. As the drum turns forward the paper scrolls up, so what is coming is always below the playhead and what has passed is above it.

The seam, where the paper joins itself, is the dashed line. Each time it crosses the playhead the drum has made one turn.

The darker strips beside and between the lanes are the drum's edge. Their ticks move as the drum turns, so you can see it turning even with nothing drawn.

A point stays on the paper, not on the clock. Its place is a fraction of a turn, not a time. Change RATE and the whole piece stretches or squeezes, as it would on a real drum turned faster or slower. Nothing has to be redrawn.

A lane with no points plays 0 V, and draws its line where 0 V is: down the middle of a BI lane, at the left edge of a POS lane.

Drawing

The pointer says what a press will do. Over a point it is a four-way arrow, and the point has a small square round it: a press picks that point up. Over an empty place in a lane it is a pointing hand: a click adds a point. Over the drum's edge it is a dragging hand: a drag turns the drum.

While you drag a point, it shows its value and its time: -2.50V 0:42 is -2.5 V on the lane's range, 42 seconds into the turn at the current RATE.

A point stays between its neighbours. Drag it past the next point and it stops just short; the order of the points round the drum never changes. It can be dragged across the seam if its neighbours allow. A lane holds up to 256 points.

The shape of a curve

Each point sets the shape of the curve that leaves it, towards the next point. Right-click a point to move on to the next shape:

The S-curve is the default because a slow straight sweep has a corner at every point, and on a filter or a pitch you can hear it.

RATE, ZOOM, TURN

RATE sets how long one turn of the drum takes: from 10 seconds, fully left, to 2 hours, fully right. The knob is exponential, so each part of its travel covers the same ratio of times. It loads at one minute. Hover over it for the time a turn takes, as Rate: 1:00 a turn.

ZOOM sets how much of the drum the paper shows: from an eighth of a turn, fully left, to the whole turn, fully right. It loads at a quarter of a turn. ZOOM changes only what you see; the outputs are the same at any zoom.

TURN runs the drum's motor. With it lit, the drum turns at RATE; with it off, the drum stops where it is. The GATE input does the same: the motor runs while TURN is lit or GATE is high.

REV and FWD: the switch beside TURN sets the motor's direction. FWD, down, where it loads, scrolls the paper up. REV, up, turns the drum backwards.

Turning by hand

Press on the drum's edge, beside or between the lanes, and drag. The drum follows your hand: drag up and the paper goes up, as if you had pushed it round. The outputs follow too, so turning by hand plays the lanes at whatever speed you move.

While your hand is on the drum the motor is ignored. Let go, and the drum keeps the speed your hand had and eases back to the motor's speed over about a second, or to a stop if TURN is off. A quick flick sends it spinning.

Inputs

GATE runs the motor while it is above 0 V, as TURN does. Patch a gate from a sequencer or a clock to let the drum turn only when something else is playing.

RATE is a CV on the drum's speed, through its AMT knob. AMT loads at its centre, where the input does nothing. At full right, each volt doubles the speed and each volt down halves it, up to five octaves either way: a one-minute turn goes as fast as two seconds or as slow as thirty-two minutes. Turn AMT left of centre to invert the CV.

RESET puts the drum back at the seam on each rise above 0 V. The small button beside it does the same by hand. Either one fires SEAM. While the jack is held high, the button does nothing more: the drum is already being held at the seam.

PHASE moves the drum from another module, through its AMT knob. It adds to wherever the motor and your hand have put the drum. AMT loads at its centre, where PHASE does nothing. At full right, 0 to +5 V takes the drum one whole turn forward, and 0 to -5 V one whole turn back. With TURN off, PHASE alone plays the drum: patch a slow LFO into it and the lanes scan back and forth; patch a ramp and they play through once per ramp. RESET does not undo PHASE: it puts the drum at the seam, and PHASE still adds to it.

Outputs

Lanes 1 to 6. Each lane has its output under it, and its RANGE switch above that:

• BI, up, where every lane loads: -5 to +5 V, the lane's left edge to its right.
• POS, down: 0 to +5 V.

SEAM gives a trigger, +5 V for one millisecond, every time the seam passes the playhead: once a turn while the motor runs, in either direction, by hand, or because PHASE moved the drum across it. RESET and the button fire it too. Use it to clock something once a turn, or to reset another Glacial so the two stay in step.

PHASE (the output) is where the drum is, as 0 to +10 V: 0 V at the seam, rising through the turn. It includes what the PHASE input adds. It is a ramp once a turn while the drum turns forward, and a falling ramp in reverse.

Jacks

Every input reads 0 V when nothing is patched.

Saving

The paper is saved with the patch: every point, its value and its shape, in every lane. It is saved with each variation as well, so one Glacial can hold several pieces and you can move between them with the variation selector. The knobs and switches are saved by Voltage Modular, as on any module.

Notes

Nothing moves? The motor runs while TURN is lit or GATE is high; GATE can run it with TURN unlit. If the drum is turning but an output is flat, look at that lane: an empty lane plays 0 V. If the drum turns but PHASE seems to do nothing, look at its AMT knob: it loads at its centre, off.

The PHASE output is 0 to +5 V, unlike the lanes, so it can drive other modules' phase or scan inputs across their full range.

Very slow is the point. At two hours a turn the paper moves about one pixel every few seconds, and the drum is still turning: the PHASE output shows it creeping up. The playhead and the ticks on the drum's edge show it too, if you wait.

Points very close together are fine. If two are closer than the drum moves in one sample, the lane jumps straight from one to the next.

Starting points

A filter that breathes. RATE at about four minutes. In lane 1, four points: low, high, low, higher, all S-curves. Lane 1 into a filter's cutoff CV. TURN on.

Two oscillators beating. Two oscillators a few cents apart. Lanes 1 and 2 on POS into each one's fine tune, with a small amount. Draw lane 1 rising slowly through the turn and lane 2 falling; the beating speeds up and slows down as the two lanes cross. RATE at twenty minutes or more.

Hand-cranked. TURN off. Draw a steep curve in lane 3 with step shapes, into a VCA. Turn the drum by its edge: slowly for a rhythm, a flick for a run that dies away.

Scanning. TURN off, PHASE's AMT at full. A slow triangle LFO into PHASE. The drum sweeps forward and back over the same stretch of paper, and the lanes play it like a tape rocked under a head.

In step. Two Glacials at different RATEs. The first's SEAM into the second's RESET: the second starts again every time the first comes round.