strata

the walls remember

20 HP

A reverb in a stone cellar whose walls keep whatever's played loud enough, and play it back later, on their own, a little more worn each time. ERASE doesn't empty them: what you erase is pressed down a layer, and up comes what was erased before, older, lower and slower.

The STRATA panel: black, gold dots of a vaulted stone cellar seen from the top of its steps, the steps running up from the foot to a wall of stone blocks under the vault, the wall a window of bare circuit board in five courses of dressed stone over a course of rough bedrock. ERASE, a lit button, under the name above the wall; LEFT and RIGHT in at the top corners, WAKE and ERASE either side of the wall, SOAK and HAUNT under them with their own jacks, WEAR's knob under SOAK's, ROOM the big knob in the middle between the ROOM and WEAR jacks, SPEAK out across from WEAR, and along the foot LEFT out, GHOSTS out and RIGHT out; dashed white rings round WAKE, ERASE and SPEAK. strata at the top, daylight noise at the bottom.

Turn a knob: drag it or tap either side of it, roll the wheel over it or use the arrow keys; a double click puts it back. ERASE is a button: press it and the walls stop saying what they're saying, and something older comes up. The patches step on by themselves until you touch anything.

What you hear is a slow, dark rack: drums and a bass straight to the speakers, and a lead through STRATA that plucks under the SOAK line and now and then screams over it. It's all made in the page as you listen.

example patches

The walls, the room, the replays and every out here are STRATA's engine as it's designed, running in your browser. The drums, the bass, the lead and its screams are a stand-in for the rest of a rack.

What the walls keep

Anything that reaches the SOAK line is written into the stone: the moment itself, from just before it crossed until it falls quiet, three seconds at most. Later, at a time of their own choosing, the walls play one back, darker and further off, into the room.

SOAK: how readily the stone keeps things. Fully left only a scream gets in; at noon anything loud; at full every breath.
HAUNT: how often the walls speak by themselves, from never, through one every few seconds at noon, to eight a second, over each other.
WEAR: how much each hearing wears its recording. Fully left the walls keep everything for good; at full a moment is heard twice, thinner each time, and gone.
WAKE, a gate in: the walls speak now.

Digging

The wall has layers. The top row is the face, where new moments go. Under it are four strata of what's been erased, newest first, each one three semitones lower and slower than the one above. Under everything is the bedrock, made by the room from nothing but its own noise before you played a note.

ERASE, a button and a gate in: whatever the walls are saying is wiped. The face is pressed down a layer, and the walls speak at once from the layer under that: what you erased the time before. Press it again with the face bare and you dig on, down to the bedrock, which can't be dug past.
The very first ERASE, before anything was ever erased, goes straight to the bedrock.
The wall's blocks glow while they hold a recording, brighter in the row the walls speak from, and light up while theirs plays. ERASE's lamp is dark while the walls speak from the face, and burns brighter the deeper you've dug.

The room

ROOM: the cellar, from a small cold cell (a third of a second) to a crypt that goes on and on (forty seconds) and gets darker as it grows. Everything the walls play back rings in it too.
SOAK, HAUNT, ROOM, WEAR, CV in: each added to its knob.

What comes out

LEFT, RIGHT: what came in, untouched, with the room and the ghosts added to it. There's no mix knob.
GHOSTS: the replays alone, through the stone but without the room, to send somewhere else.
SPEAK: a trigger each time the walls speak.

Inside

One board sits 10 mm behind the panel with everything on its front: the jacks, the knobs, ERASE, the 92 LEDs and the whole circuit, the USB-C in a notch in its left edge. Each block of the wall has its own row of white LEDs in a cell of a black printed baffle, so a block that speaks lights only itself. An RP2350 runs the walls and the room on both its cores; what the walls keep is held in 8 MB of memory beside it.

The STRATA panel after an ERASE: the face's blocks dark, the stratum under it holding, one block of the next speaking bright, ERASE's lamp lit; its knobs and jacks on.

Drag it or use the arrow keys to turn it; click it to take it apart.

Specs

Format

Width: 20 HP
Depth: 20.8 mm behind the panel
+12 V: about 77 mA dark, 115 mA in usual play, 275 mA with the wall at its brightest (estimated)
−12 V: about 5 mA (estimated)
+5 V: not used
Controls: a big knob, 3 knobs, a lit button

I/O

LEFT, RIGHT in: audio, ±5 V (clips past ±10 V); RIGHT takes LEFT when it's empty
WAKE, ERASE: gates, high past about 0.9 V; safe to ±12 V
CVs: SOAK, HAUNT, ROOM, WEAR: ±5 V sweeps a whole knob, added to it; safe to ±12 V
LEFT, RIGHT out: audio, what came in with the room and the ghosts, never past 4.5 V
GHOSTS: audio, the replays alone, never past 4.5 V
SPEAK: trigger, 0/5 V, 10 ms each time the walls speak

Engine

Brain: RP2350, both cores, at 48 kHz
The walls: 23 blocks of up to 3 s each, mono, 16 kHz, in 8 MB of memory; the bedrock three pieces of 4 s
The room: 0.35 to 42 s to fall 60 dB
Light: 92 white LEDs, 125 frames a second
Power cycle: the walls wake holding nothing over a new bedrock; only the calibration is kept