frequency shifter

How to play

• The pages, along the top: the OB, Rings, the Drums, Stages, FX and Mix, each the whole of the instrument while it's open (Tab, the next; Shift-Tab, the one before). Play (or space), the tempo, the key and the scale are there on every page.
• Each synth has its own sequencer, and the drums theirs; play (beside the tabs, or at the start of its bar) starts every one that's switched on, together. Each has its sequencer on/off in its bar; off, its steps are dimmed, and touching one switches it on. The OB's sequence, Rings', a beat: all at once, or just one.
• The sequencer: drag up and down across the steps to draw a melody, in key. Each step's button goes off, note, chord; ×1 above it repeats the note 2, 4 or 8 times in the step's time (R on a step); the ~ makes it fluctuate: a note or two either way, in the scale, different each time round (F). Dice makes a new one: the melody, and a few steps repeated or fluctuating, where it sounds right. Octave moves the whole sequence up or down (two either way).
• Chords: one touch, a whole chord, strummed. Swipe across them; on a computer, A–L and Q–P. Keys: click, touch, or play along the middle row, A to ' (sharps above); Z X change octave. They play the synth whose page is open (or the last one that was).
• The OB is an OB-X or an OB-Xa (the switch at the top), each with its own programs, picked as on theirs: a group, then a program, 1 to 8 (1–8). The OB-X has 32 (groups A to D); on the OB-Xa, press the group buttons together for its 15 groups (A, B, AB, C, AC ... ABCD), 120 programs. Below, its front panel, section by section, as each had it: control, modulation, oscillators, filter, the two envelopes, and the bend and mod levers' switches. The OB-X has X-MOD, two noise levels and KBD tracking; the OB-Xa, F-ENV (the filter envelope on oscillator 2), 4 POLE and TRACK. A lit lamp: it's on. Your moves stay with the program until you pick another.
• Rings is a resonator: a bell, a plate, a string. Try each model (1–6), then the sliders. Click one and use ↑ ↓ to nudge it.
• The drums are a DMX: eight voice cards, three sounds each, each card one sound at a time (so a closed hi-hat cuts an open one off). Each card has its level, its tuning (half an octave either way; the sound gets longer as it goes down, as on the real one) and its pan. DX loads the DX's sounds onto the cards the DX had; the second toms, tambourine and rimshot stay the DMX's. The pattern: a row a card, sixteen sixteenths; click a step and it plays the row's lit button (pick another above, or by its row); swing pushes every second sixteenth later, as the DMX's did. A–K play the eight cards, and a MIDI keyboard plays them on its drum notes. Dice makes a new beat: one of a few grooves (straight, half-time, four on the floor, boom bap, electro), a little different each time, never just hits at random.
• Stages: six segments, each a ramp, a hold or a step (press its name), with its level, its time (a step's: how long it glides) and loop. Link puts neighbours in one group. Each group moves a slider you pick, on the OB or Rings, by its amount (either way), starting again on its own (free), each step, each bar, or each note that synth plays. Alone, a ramp's a decay (looping, a wave), a hold's a pulse; a run of steps is a step sequencer. Random fills it all; drift changes a little of it each time round.
• FX: four effects, side by side, in a pedalboard's order, each on or off; under each, a slider for each instrument: how much of it goes to that effect (the distortion: through it, so all the way is all distorted). What goes through the distortion carries on into the chorus, delay and reverb as much as that instrument sends to them. The distortion is an overdrive (warm, the lows kept clean), an amp (a high-gain guitar amp: tight, the mids pushed) or a fuzz (after the Big Muff: saturated, the mids scooped), with a guitar speaker cab after it (most of what makes Rings' strings sound like a guitar through an amp); drive (its level stays about the same as you turn it), tone, level. The chorus is after the Juno-60's: I slow and wide, II faster, I+II a quick shimmer. The delay is a tape echo: its time in note values with the tempo (sync) or in milliseconds, feedback (past three-quarters it sings on its own), level, tone, and wow; ping-pong bounces it left and right. The reverb is a plate. Switched off, the delay and reverb ring out.
• Mix: a strip each for the OB, Rings and the drums: level (its meter beside it), balance, and a mute (how much of each goes to each effect is on the FX page). Double-click any slider to put it back.
• A MIDI keyboard: plug it in, press MIDI at the top (and allow it), and it plays what the keys play: how hard you play, the sustain pedal, pitch bend, and the mod wheel (vibrato, on the OB). Chrome, Edge or Firefox; not Safari.

After Mutable Instruments' Rings and Stages, by Émilie Gillet (their code is MIT-licensed). The OB is a port of OB-Xf, after OB-Xd (GPL-3.0; its source, oberheim.js, is free under the same license), with programs from its library (CC0) by Saif Sameer, Aleksey Zhehanov, Black Sided Sun, Ocean Swift, Artur Rembe, Vincent Zauhar, Fedir Tkachov, EvilDragon, 0.5°, John Valentine, Pebblestream and Den Rize (and a few of ours, after Saif Sameer's "It's an OB-X!"). The drums play the DMX's and DX's sound chips the way their voice cards did. The reverb follows Jon Dattorro's plate (Effect Design, Part 1, 1997); the chorus, Roland's Juno-60; the delay, Roland's RE-201 Space Echo. Oberheim, OB-X, OB-Xa, DMX and DX are Oberheim's names, and Juno-60 and Space Echo Roland's; this isn't theirs.