Manual

CHOPPAH is an Amen chopper for the M-VAVE FM-1. A break is cut into sixteen slices, one on each white key, and plays in time while you rearrange it, roll it, reverse it, stop it like a tape and push it through effects.

1Install

Try it first: the emulator runs the same code in the browser, with sound, played with the mouse.

Install: open the install page in Chrome or Edge, connect the FM-1 by USB and press Install. While it writes, the FM-1 says UPDATING and DO NOT UNPLUG: CHOPPAH's slice mark fills in amber with the bar. When it is done, the page throws confetti. If the FM-1 runs M-VAVE's FM1 Open firmware, put M-VAVE's original firmware back first (M-VAVE's workbench, Restore original), then install CHOPPAH.

2The screens

At power-on CHOPPAH shows its mark, then the start screen: the loaded break drops in slice by slice while a light runs through the buttons, they all flash as it completes, and PLAY blinks green. After two seconds, or at once on any key, the slicer view opens. PLAY on the start screen also starts the break.

The slicer view, top to bottom:

• Header: play or stop, the break's name, the pattern (P1–P16; "P2>" while P2 waits for the loop's end), REC while recording, a level meter (left and right, what leaves after MASTER: amber from −8 dB, white near full scale), the tempo.
• Tabs: the button you pressed (as printed on the panel), then the page's parts as tabs, the one you are on lit: the button again (or ALGORITHM) goes to the next. On EDIT and FX the part edited shows at the right, "< SUB FX >". Opening a page, or turning to another part, says the same in the header for a moment: the button, then the part ("GLO PITCH", "EDIT KICK SUB FX", "FX SLOT 2 TREMOLO", "SEQ HAT"). The tabs sit right under the header on every page, tap tempo's too.
• The break: its waveform, the slice markers, the slice sounding lit, the playhead.
• Slice blocks: sixteen blocks, one per white key, each with its slice's waveform. The slice sounding is lit; a key held is outlined; a dot marks a key with a loop of its own (§3, key loops).
• Pads: the eleven black-key pads, lit while held.
• Knobs: the page's four knobs and their values.

The rules. ALGORITHM picks what you edit on the page (an FX slot, a drum's part, a SEQ lane, GLOBAL's part); on HOME (both its parts) and the MIXER, where there is nothing to pick, it is the break. PRESETS picks what goes in (an effect, a kick, a snare or hat sound); elsewhere it is the pattern. SEQ is where everything is sequenced (the break's steps and the kick, snare and hat lanes), EDIT where the drums' sounds are made (kick, snare, hat); the white keys play slices everywhere but SEQ, ENV (tap tempo) and ARP (overlays). SEL + ALGORITHM is the break and SEL + PRESETS the pattern on every page. A page's button pressed again is its next part. Press SEL alone and the strip lists its combinations (SEL again, or any other button, key or knob, closes it). The control map (§11) shows all of it at once.

The demo

Leave CHOPPAH alone for a minute while it is stopped (three minutes while it plays: the break plays on) and it goes into its demo, five scenes of eight seconds each, in time with the tempo (with the break's own beat while it plays):

• BARS: the mark's sixteen bars bouncing to an Amen beat, kick low, snare in the middle, hats high.
• WAVE: the break's waveform scrolling under a playhead, a slice chopped out of line on each beat.
• TUNNEL: squares rushing out from the name, a white one every second beat.
• WORMHOLE: a wireframe tube of twisting rings rushing at you, its far end bending round to a glowing core; it lurches forward on each beat.
• STARS: slice blocks flying out of the screen.

The lights play along: a light runs round the buttons, and the keys follow the bars, the playhead, the tunnel (outwards from the middle keys), swirl round with the wormhole or twinkle with the stars. Touch any key, button or knob and the page you left comes back. That touch only ends the demo: it doesn't play a slice or start the break.

3Playing

Tap tempo

ENV opens TAP TEMPO, which takes the whole screen: the tempo on an LED display, a metronome swinging in time (its bob lights on each beat, white on the bar's first; BEAT counts 1–4 while playing), this run's taps beside the display. Tap ENV again in time, or any white key (the keys flash on the beat). The tempo follows from the second tap and settles as you go on (the average of the last eight taps); each tap flashes the display and sends a ripple out from the metronome. Stop for 2 seconds to start a new count; a tap far off the pace starts a new count from the tap before it. K1 sets the tempo a BPM at a time, K2 a tenth, K3 halves it (left) or doubles it (right), K4 is the metronome's CLICK level, OFF (the start) up to 100 %: a short tick on every beat while playing, higher on the bar's first, dry over everything (not through the effects), kept with SAVE. Following an outside clock, it says EXT CLOCK and waits.

Key loops

Hold a white key and it loops: a window that starts in its slice plays again and again in time, until you let go (playing, the break carries on from there; stopped, it ends with the window). Held for a moment, the slice blocks give way to the key's view: its window zoomed to the screen's width, the part this repeat has played lit (from the right when it runs backwards), the playhead, the slice lines inside the window, this repeat's progress and a dot for each repeat. A quick tap plays the slice once and keeps the blocks.

While the key is held, K1–K4 set its loop, for that key only (SAVE keeps them; a key with a loop of its own has a dot on its block):

SEL while a key is held puts its loop back to one slice, no pitch, from the start, LOOP. With several keys held the last one pressed loops; let it go and the lowest still held takes over. Pads still work on top: REV turns the loop round, ROLL and FREEZE take it over while held.

Slice effects

Every slice can have an effect of its own, there whenever that slice plays: in the loop, from its key, in a roll. Hold the key and press FX: K1–K4 turn from its loop to its slice's effect (FX again turns them back; the knobs stay on the layer you left them on for the next key). A block whose slice has an effect shows its tag (LP, HP, CR, DR, RM, EC, VB; LV for a level alone). SEL while held resets the layer shown.

ECHO and VERB throw only that slice: put a DELAY (or a REVERB) in the FX chain with its SEND (MIX) low, and only the slices you marked ring out, the classic dub throw. (Without a DELAY slot, ECHO goes into the delay after the chain.)

4The pads

The black keys, left to right, act while held and combine. While a pad is held, the slice blocks give way to an animation of what it does, and K1–K4 tune that pad (the foot shows its settings; SAVE keeps them):

5Patterns and the sequencer

CHOPPAH holds 16 patterns. Each is the break's 32 steps (2 bars), each step playing the loop's own slice (LOOP, where the generator can move it), a slice of its own, or nothing; and three drum lanes of 16 steps (kick, snare, hat) that repeat every bar. PRESETS picks the pattern on most pages; while playing, the next one starts when the loop comes round (the header shows "P2>").

SEQ opens the sequencer. ALGORITHM (or SEQ again) picks what the white keys edit:

The upper strip shows the half's 16 steps (a number: its own slice; a dot: LOOP; a dash: off; a mark under it: hits or reverse), the step playing lit; the lower strip all three drum lanes.

REC records: while it is lit and the break plays, every white key you press (on HOME and the other pages where the keys play slices) is written into the pattern at the step it lands on, and so are MIDI notes: 48–63 as slices, 36 / 38 / 42 into the kick, snare and hat lanes. REC again stops. SEL + REC clears: on SEQ the lane shown, on any other page the whole pattern. SEL + ARP (a random pattern) writes into the pattern playing. SEL + SAVE undoes either (and FILL, CLR / 4X4 and COPY on a drum lane); press it again to redo. SAVE keeps all 16.

Overlays

ARP opens OVERLAY: sixteen effects on the white keys, over everything that plays (the break, the drums, the FX chain's tails). Hold a key and its effect comes in (a 5 ms fade, no click), let go and it goes; hold several and they stack. With LATCH on (K4) a press switches an effect on and the next press off, and what is latched stays on when you go to another page, so you can play slices on HOME through it.

The cards light while their effect sounds, a latched one is outlined amber, the one K1 tunes is outlined white, and the bar on each card is its amount (each keeps its own). The white keys light for the effects on.

They follow the tempo playing (stopped, they keep time by themselves). SAVE keeps the amounts and the knobs.

6The FX chain

FX opens the master effects chain: four slots in series, the break (through its DJ filter, with the kick when it goes through the chain) into slot 1, then 2, 3 and 4, then on to the drums when they go around the chain, the DUB pad's delay and the limiter. Each slot holds any effect (two of one are fine), with three settings, a mix and a bypass, and more knobs on two more parts (MORE and MOD, below). The screen shows the effect you tune as a live picture; under it the chain in order (yours lit, the bypassed ones dim), its modulator and its level in and out.

EQ's bands go −12 … +12 dB, flat in the middle; its K4 is not a mix but the mid's frequency. TAPE is a saturator after a tape machine: put it last in the chain to glue the break, or before CRUNCH for a dusty sampler.

MB COMP is a 3-band (multiband) compressor, and the one effect with a page of its own (below). CLIP squares the peaks off at its ceiling: soft rounds them, hard cuts them; below the ceiling it only adds its drive. MB COMP then CLIP last in the chain is a loud master; CLIP before a FILTER is a fizzy one.

DELAY is a stereo ping-pong: the echoes bounce left, right, left, each darker. Its K4 is SEND, how much of the sound reaching it goes in (the echoes come back at full), so with SEND low only throws ring out: the DUB pad, the the slices' ECHO. There is one delay (0.74 s at most: 1/2 at 162 BPM and up; slower, it holds the longest it can).

REVERB is a plate (after Dattorro's design: diffusers, then a modulated stereo tank): its MIX is how much reverb goes over the dry sound. The tail rings on after STOP. There is one: a second REVERB slot passes the sound on. Put it late in the chain to reverb the effects before it, or early to crunch or drive the reverb itself.

The chain starts as CRUNCH → FILTER → FLANGER → RING MOD, all bypassed: SEL + FX switches the focused one on. CRUNCH used to be HOME's K4; it is slot 1 now.

STOP fades the break out at once (a white key held keeps looping); the reverb's and the dub delay's tails ring on.

Each effect's view, MORE and MOD

Every effect (but MB COMP, which has its own page, below) has three parts, stepped by FX again: MAIN (its three settings and mix, as in the table above), MORE (its extra knobs) and MOD (a modulator that moves one of its settings in time). The tab bar names the part (< FILTER MOD >), the strip shows it lit.

The picture above follows the sound as you turn:

• FILTER, FLANGER: the response from 20 Hz to 20 kHz (the cutoff and resonance; the flanger's comb sweeping as it plays). EQ: its three bands, ±12 dB about the middle line.
• DRIVE, CLIP, TAPE, CRUNCH: a tone through it, the clean tone grey behind: rounded, squared, folded, stepped. PUNCH: two hits, their peaks held down. RING MOD: the tone times its carrier. TREMOLO: a tone under two of its cycles.
• REVERB: its decay over 3 s (0 to −60 dB), the pre-delay a gap. DELAY: its echoes, left up and right down, each quieter by the feedback.

Below: the chain, then the modulator's cycle with where it is now (the white dot) and what it moves, and the effect's level in and out.

Every MORE knob starts where the effect always was, so a saved sound plays as it did.

ENV follows the effect's own input: the louder the break hits, the further it moves (a filter that opens on every snare, a drive that bites on the kicks). S&H jumps to a new random place each cycle. The foot shows the setting it moves as the modulator leaves it.

MB COMP

The break is split into a low, a mid and a high band (by default at 200 Hz and 2.5 kHz), each pressed on its own and added back together; with nothing pressed the bands add back up to the sound untouched. Focus an MB COMP slot and the screen turns into the compressor:

• Above: its six parts as tabs, then the spectrum from 20 Hz to 20 kHz in the three bands' colours (low red, mid amber, high blue). The filled shape is what the sound goes through right now: a band being pressed dips, a band turned up with GAIN stands above the 0 dB line, and the dotted line shows where it would be with nothing pressed. The splits are marked with their frequencies.
• Below: each band's curve, input across and output up (−48 … 0 dB): flat at 1:1, bending at the threshold, the knee rounding the bend. The white dot is the band's level, riding the curve as the break plays. Beside it, the band's level in (the threshold marked white) and its reduction hanging from the top in amber, its peak held for a second. On the right, the ratio, the threshold and any gain as they act now; at the top, the reduction in dB.

FX again steps through the six parts, then on to the next slot; ALGORITHM still jumps straight to another slot (and an MB COMP there opens on AMOUNT). The tab bar names the part: < MB COMP LOW >.

The amounts are the knobs to ride while playing: each takes its band from untouched (OFF) to its own threshold and ratio, and the foot shows the ratio it reaches. The band parts set where full amount lands: by default −30 dB and 8:1, the low slow (10 ms in, 150 ms out), the mid at 5 / 100 ms, the high fast (2 / 60 ms). Half of a band's reduction at full scale is made back up by itself; GAIN adds or takes away more after it. Solo plays the one band alone, with no dry sound under it, to hear exactly what it holds while you move the splits. The page outlines the band whose part you are on.

7GLOBAL: MIDI, Bluetooth, pitch, Bluetooth audio, reset

GLO opens the GLOBAL page: the slice blocks give way to the state of MIDI, and K1–K4 set it (SAVE keeps it). GLO again (or ALGORITHM) turns to its second part, the pitch; a third time, Bluetooth audio (both below).

The panel shows Bluetooth's state (ready to pair, connected), the clock coming in (its tempo, where from, running or stopped), the clock going out, and a light for MIDI in and out on each port. The FM-1 has no MIDI out jack: MIDI goes out over USB and Bluetooth only. On an iPhone or iPad, Bluetooth MIDI devices never show in Settings → Bluetooth: connect from a MIDI app's Bluetooth MIDI page (GarageBand: a song's Settings → Advanced → Bluetooth MIDI Devices).

Pitch and snap (GLO twice):

It covers every pitch in semitones: OCT, a key's pitch, the roll's pitch a repeat, the freeze's pitch, steps. The tempo's own repitch, HALF, REVERSE's speed and the tape stop stay speed effects.

Bluetooth audio (GLO three times): CHOPPAH plays through Bluetooth headphones or a Bluetooth speaker.

While it streams, the FM-1's own speaker and headphone output go quiet and MASTER still sets the level. It is stereo, as the FM-1's own output: the ping-pong delay, the reverb and the flanger spread left and right. K3 while streaming is TEST L/R: a low beep on the left, then a high beep on the right, twice; if you hear both beeps on one side, the headphones or speaker are playing one channel. K2 while streaming is CODEC: JOINT (joint stereo, the default) or STEREO (plain stereo). If only one side plays, switch it and run the test again: some speakers decode one better than the other. Bluetooth audio runs late: 150–300 ms between a key and your ear, so it is for listening and showing, not for playing in time (use the FM-1's own output or USB for that). Bluetooth MIDI keeps working beside it on the same radio. Turning Bluetooth audio on starts the radio even when Bluetooth MIDI is off.

8The drums: kick, snare, hat

Three synthesised drums play under the break, in time with it (swing included), on the pattern's drum lanes (§5): their steps are SEQ's KICK, SNARE and HAT lanes; their sounds are made on EDIT. They go through the FX chain or around it together (MIXER GROOVE K2).

EDIT opens the drum edited last; EDIT again goes to the next: KICK → SNARE → HAT → KICK (the tabs show which). ALGORITHM turns through the drum's parts, PRESETS loads a built-in sound. The lower strip shows the three drums side by side, each with its waveform (one hit, drawn again as you change the sound), the one edited outlined, lit on its hits. The white keys keep playing slices.

The kick

A synthesised kick for gabber, hardcore and techno. ALGORITHM turns through its parts: MIX → SUB → SUB FX → PUNCH → PUNCH FX → GRIT → GRIT FX → CLICK → CLICK FX → MACRO → OUT (each layer's part is its LAYER knobs, its FX part its LAYER FX knobs).

The kick is four layers summed and pushed into a clipper:

INTENSITY is the drive into the clipper: low is a clean, round kick; past half the clip turns hard, the tail flattens into the long, distorted gabber kick. The page is laid out as the snare's and the hat's: the part's four settings as bars, under them the four layers' levels (the layer edited lit, amber with an effect on); the kick's shape is its box in the strip below. Its steps: SEQ's KICK lane (empty to start).

The snare and the hat

EDIT again from the kick: the snare, then the hat. ALGORITHM turns between its SOUND and SHAPE knobs, PRESETS picks a built-in sound. Their steps: SEQ's SNARE and HAT lanes.

MIDI notes 38 (D1) play the snare, 42, 44 and 46 the hat, also while stopped. SAVE keeps the drums with the rest. (ENV, which used to open SNARE / HAT, is tap tempo now: §3.)

9The mixer

LFO opens the MIXER: four channels side by side, each a fader with a level meter (FX shows the chain's four slots, lit: on). LFO again turns to GROOVE.

FX is how much of the chain you hear (the drums routed around it stay dry). Bring BREAK down to drop the break and let the drums run alone, then up again for the drop. HOME keeps the gate, FX and COMPLEXITY to ride (K1, K3, K4) and the DJ filter (K2), which filters the break alone: sweep it down and the drums stay full on top. The FLT pad throws it the same way.

10Pages and knobs

Gate (HOME K1) cuts every slice the loop plays short: at 50 % each slice sounds for half its length, then quiet until the next; down to 5 % for clipped, staccato chops; 100 % is off. It follows the tempo and the pitch, and the slice lit in the waveform shrinks with it. It covers the loop's slices, ratchets and the RANDOM pad; key loops (their LENGTH) and rolls keep their own; FREEZE holds the slice whole.

The generator rearranges the break as it plays: complexity is how often it jumps, anchor keeps the kick and snare on the beats, roll repeats a slice or takes the one next to it, fill breaks the rules in the last bar of a phrase; it is HOME's second part (HOME again). SEL + ARP writes a random pattern (ARP alone opens the overlays).

11The control map

12Saving

SAVE keeps the tempo, pitch, swing, generator, the FX chain, the break chosen, each key's loop, the drums, the mixer, the GLOBAL settings and all 16 patterns; SAVE is lit when something changed. A new version keeps what an older one saved: new settings start at their defaults. (Version 0.32 changed the layout: what 0.31 and older saved starts over at the defaults once; Bluetooth pairings stay.) GLOBAL's RESET ALL clears it all on purpose (§7).

13Troubleshooting

• No sound: turn MASTER up; press PLAY.
• A crash screen: press a key to restart. Two failed starts in a row start safe mode, which the installer can still reach.
• The install stops: press Install again; it finishes a write that was cut off.