Analog Four MKII

It has run on an A4 with a Pi 5 and with a Pi 4, besides the emulator suites and flash rehearsals. What may come next for the A4: the Analog Four roadmap.

The Sidecar can drive an Analog Four MKII on OS 1.56. A track’s sound picks a Sidecar machine; that track’s trigs and knobs go to the Sidecar over USB, and the machine comes back over Overbridge, through stock’s own track inputs, into that voice’s analog path. So PLAITS or JUNO go through the A4’s filters, overdrive, amp and FX. No audio code is patched.

With no Sidecar, or with every sound OFF, the A4 sounds and plays as stock. What differs is the two knobs on the NOISE page, and a few short SysEx hellos on USB at each port-up.

What has run where

	on a real A4	emulator
Overbridge stream, machine through filter, drive and FX	Yes, 0 underruns, Pi 5 and Pi 4	Yes
The Sidecar’s first start into /.a4, and a swap with a Rytm	Yes	Yes
USB unplug and replug, an A4 restart with the Pi running	Yes	Yes
Clock and transport with CLOCK SEND and TRANSPORT SEND on	Yes, on an earlier build	Not checked
Chords from the sequencer and a step’s preview	Yes	Yes
MCH from OFF and back, machine on OSC1	Yes	Yes
OS2 on MACHINE	Yes	Yes
Locks and LFOs on the machine’s knobs	Yes	Yes
UP + YES, the Sidecar’s pages and MENU	Yes	Yes
UP and DOWN leave the octave alone	Yes	Yes
Going back to stock	Not on record	Rehearsed, no machine set
Recovery over MIDI DIN from a torn image	No	No

Not tried anywhere: a computer in Overbridge with a machine set, so keep every sound OFF for computer sessions.

What you need

• An Analog Four MKII on OS 1.56. Above 1.56 this is a downgrade: stop.
• The stock Analog-Four_MKII_OS1.56.syx. We never distribute firmware, stock or modified.
• A Sidecar on 0.4.0, on a Pi 5 or a Pi 4: both have run it.
• Your projects backed up with Transfer, and a MIDI DIN interface in hand.

Install

1. Build your firmware. On the patcher, pick the A4 build, drop your stock file on it, press Patch, then Save. It is done in your browser; nothing is uploaded, and the result is checked against the tested build.

   The same bytes come from the two .elemod files on the A4 mod’s release page (a4-v0.12) with elekloader’s command line. Use the lock file and version from the release, or the hash will differ:

   python3 -m elekloader.patch --stock Analog-Four_MKII_OS1.56.syx --mod core-0.3.elemod \
       --mod sidecar-a4-0.12.elemod --lockfile a4156.lock.json --version SA12 --out sidecar.syx

   Not on elekloader’s web page

   Don’t build the A4 firmware on elekloader’s web page. It has no lock file, so it picks other versions of the parts and gives a file nobody has tested on an A4. Use the patcher or the command line above.

   Check it before you flash. The patcher checks it for you. On the command line, run shasum -a 256 sidecar.syx; it must be:

   e9eab646102844518ff48e44864f42b2a555aadc2b8fd86b5eaabe2d772a1d71

   If yours differs, do not flash it.

   Never share the .syx you built: it contains Elektron’s firmware. Share the .elemod files instead.

2. Flash it. GLOBAL > SYSTEM > USB CONFIG: USB MIDI, connected to a computer. Send the .syx with Transfer as an OS update and press YES at UPGRADE OS NOW?. The A4 restarts.

3. Connect the Sidecar. Set USB CONFIG to OVERBRIDGE and connect the A4 to the Pi’s USB-A port. The first hello restarts the Pi once, into its own state folder /.a4. Samples, plugins and patch libraries stay shared with a Rytm’s /.rytm.

4. Clock. Turn on CLOCK SEND and TRANSPORT SEND on the A4 if you want the Sidecar’s synced LFOs and its transport. Without them it hears neither.

With a Rytm too: a box already streaming keeps the Sidecar, and the other waits. At a start with both attached, the Rytm takes it and the A4 waits.

Experimental: a stock A4 beside the Rytm. a4=1 in cmdline.txt takes an Analog Four MKII without the mod, in OVERBRIDGE mode on a USB-A port, and mixes its MAIN into the Rytm’s PRE pair, resampled to the Rytm’s clock (a4ch=N picks another A4 output pair, a4att=N lowers it by N dB, 6 by default). Audio only: no machines, no pages. Not for an A4 with the mod, which needs no option. It has not been run with both boxes streaming on hardware.

Pages

The OSC1 key steps two pages, OSC1 and NOISE. A sound with a machine turns both into the machine’s; a sound on OFF shows stock.

The NOISE page

Knob
A, B, C, E	Stock’s NOISE knobs, on the A4’s own noise
D, MCH	The machine: OFF PLTS JUNO DSY FM6 MD B2 U1 U2 U3 U4 U5. Stored in the sound, so kits, the sound pool and copy and paste carry it. Every sound starts OFF
F, OS2	ANALOG or MACHINE, below
G, H, I, J	Four more of the machine’s parameters, under its names. Empty where a machine has none

U1..U5 are what you put in those slots: on the A4 itself with the USER SLOTS page, or on the web page’s User machines tab.

A pick from OFF writes the machine’s defaults on its knobs and sets OSC1 LEV to 0, so the analog oscillator is out of the way. Turning on through the list keeps writing defaults as long as no knob has moved. From one machine to another with a knob moved, nothing is written. Back to OFF, the hidden values return to stock’s ranges; OSC1 LEV stays where it is.

The machine on OSC1

OSC1’s knobs are plain 0..127 dials with the machine’s names. A turned knob’s title says, for example, PLTS HRM. LEV stays the analog oscillator’s. A knob the machine does not read is empty, stock’s own hatched knob, and a turn does nothing.

Machine	TUN	FIN	DET	TRK	WAV	SUB	PW	SPD	PWM	NOISE G H I J
PLAITS	ENG	TUN	HRM	LPG	LEV	FM	TIM	MOR	DEC	FIN AUX TMD MMD
JUNO	PAT	-	CUT	DEC	REL	LEN	RES	ENV	ATK	-
DAISYSP	ENG	TUN	STR	EXC	LEV	XTN	BRI	DMP	INP	XDC FB OUT XP4
6-OP FM	PAT	TUN	TIM	LEV	LEN	-	MOR	DEC	LPG	-
MD, B2	CT1	ENG	CT2	CT6	CT7	CT8	CT3	CT4	CT5	TYP LEV
U1..U5	P1	P7	P2	P6	P8	P9	P3	P4	P5	P10..P13

Locks, LFOs and kit saves work on all of these, by stock’s own path. TUN and FIN are in no LFO or envelope list, so an LFO cannot jump ENG, and ENG cannot be modulated. The other lists keep stock’s names: DET in a list is HRM on PLAITS. NOISE G..J appear in the lists as PM1, FM1, ACC and AM1.

TUN and FIN are one word of the sound: a lock on either is one lock of that word. The word glides as stock’s does, so FIN’s value wobbles while TUN turns, and after a TUN lock the value glides back over the next steps.

A sound’s own LFOs reach the machine: a factory kit’s LFO on DET sweeps PLAITS HRM. Start from a cleared sound.

OSC2, NOISE A..C and E and the OSC 1&2 page stay stock’s. One exception: while NOISE J holds AM1, knob A of OSC 1&2 shows the machine’s name for it, as it is the same parameter.

OS2

Setting
ANALOG (default)	OSC2 and the noise stay the A4’s own
MACHINE	OSC2’s page goes to the machine, with its names, and NOISE G..J go empty. OSC2 LEV stays analog

MACHINE gives these on OSC2’s page, in the order TUN DET PW SPD PWM TRK:

Machine	OSC2
PLAITS	FIN AUX TMD MMD VEL GLD
DAISYSP	XDC FB OUT XP4 XLV XP5
MD, B2	TYP LEV
U1..U5	P10..P15

JUNO and 6-OP FM have nothing to give, so knob F is empty there and OSC2 stays stock’s. A flip writes no values: OSC2’s knobs bring what they hold. So PLAITS VEL reads OSC2 PWM, which is 0 on a cleared sound. On ANALOG, VEL, GLD, XLV, XP5, P14 and P15 stay at their defaults.

Chords

A chord on a step reaches the track’s machine whole, whatever KIT > POLY CONFIG says, so a mono track plays a Sidecar chord and takes no analog voice from another track. PLAITS, JUNO, DAISYSP, 6-OP FM and user machines that declare instances play it; MD, B2 and a mono user machine play one hit.

The Sidecar’s pages on the A4’s screen: UP + YES

Hold UP for a moment and press YES: the A4’s screen shows the Sidecar’s pages. UP + YES again leaves.

Key
LEFT, RIGHT	SIDECAR, SYSTEM, a page for each track with a machine, SCOPE, REC, USER SLOTS (LEFT once on SIDECAR)
YES	On SIDECAR: the MENU
NO	Back; on SIDECAR, leaves
Any stock page key	Leaves, and does its stock job

While a page is open only the arrows, YES, NO and the knobs that page uses are the Sidecar’s. The keyboard, track keys and transport stay stock’s. If the Sidecar goes away, the stock screen returns by itself within about a second.

While a Sidecar is connected, UP and DOWN do not change the keyboard’s octave on a parameter page, so UP + YES leaves it alone: use OCT+ and OCT-. In menus and lists UP and DOWN work as ever, and with no Sidecar they are stock’s. YES is the page’s while it is open, so a held trig’s note preview needs the page closed.

Limits

• 4 voices, one channel each. All of a chord’s audio is on that track’s channel, so it enters one analog voice and takes that voice’s filters and amp. That amp must be open. On a poly track, if the A4 gives none of the chord’s notes to that voice, the chord is silent while the notes play elsewhere.
• The A4’s amp envelope shapes the machine. A voice only sounds while the amp is open.
• Sample machines are not on the A4. Nor are the Rytm’s pages that need its pools, sequencer, send FX or project reports, machine names in the LFO lists, or the Sidecar following the A4’s project name.
• No FX channel in SCOPE. The A4’s stream has MAIN, the 4 voices and IN L/R.
• Text on the Sidecar’s pages is in the Sidecar’s font, not the A4’s.
• A restart of the A4 with the Pi running failed once to come back on USB: “A4 not connected” on the web page. A Sidecar restart cleared it. Cause unknown.
• Copy, paste and clear of a machine’s page take the shown knobs only.
• OSC1 LEV 0 is what keeps the analog oscillator out. With it at 0, SUB is silent, and AM2 and SYNC do not change OSC2’s sound: heard on a unit on an earlier build.

Heard on a unit: an accent trig plays the machine louder, and AM1 or AM2 with OSC1 LEV 0 changes nothing. Not yet judged: the dial feel of the wide knobs.

Back to stock

1. Set every sound’s machine to OFF and save. That takes TRK, WAV, SUB and AM1 back into stock’s ranges and PM1, FM1 to centre. A rollback with a machine still set is not rehearsed.
2. Send Analog-Four_MKII_OS1.56.syx with Transfer, as an OS update.

The other knobs keep what they hold, OSC1 LEV 0 among them.

If it will not boot: hold FUNC at power-on, press TRIG 4 for OS UPGRADE, and send the stock .syx over MIDI DIN (Transfer’s legacy mode). This route is the A4’s own and has not been rehearsed with this mod.