Turn the 12 pads into sample-start markers. Pick a track, open the CHOP page, and every pad plays that track's sample from its own start point. Record it live and each hit becomes an ordinary STA p-lock, so your patterns play back on stock firmware too.

Unofficial firmware mod for the Analog Rytm MK1, OS 1.73, built on gdeo607/rytm1_mods. Not affiliated with or endorsed by Elektron. Flashing modified firmware is at your own risk.

1. Select the track with the sample you want to chop. Use the normal pad mode, not chromatic or scale.
2. Press SAMPLE, let go, pause, then press SAMPLE again to open the CHOP page.
3. Turn CHP right to switch it ON. The selected track becomes the chop track.
4. Hit pads 1–12. The sample plays from markers 0, 10, 20 … 110.
5. To move a marker, hit its pad (or turn PAD), then turn STA (0–120).
6. Press REC + PLAY and play the pads. Each hit records a trig with an STA p-lock.
7. Turn CHP left to switch it OFF, and the pads are stock again.

Tip: make your loop 120 sixteenths long (7.5 bars). Then every STA value lands exactly on a 16th.

Good to know:

• Markers reset on power-off. They live in RAM, so re-chop after a restart. Recorded p-locks stay in your pattern.
• Pads all go to the chop track while CHP is ON, including TRK + pad. Turn CHP OFF to select other tracks with the pads.
• Pad pressure (aftertouch) still goes to the pad's own track.
• A quick double-tap of SAMPLE opens the stock sample list. Pause between presses to get CHOP.
• The build includes rytm1_mods' euclid accents and velocity humanise, but not SMP CUT. SMP CUT clashes with CHOP.

You build the firmware yourself from Elektron's own OS file. This repo never ships Elektron's code.

• An Analog Rytm MK1 on OS 1.73. The Rytm can't go back to an older OS, so update with Elektron's official 1.73 first.
• A Mac or Linux machine with git, make, a C compiler and Python 3.11+.
• m68k binutils: brew install m68k-elf-binutils (macOS) or sudo apt install binutils-m68k-linux-gnu (Debian/Ubuntu).
• Elektron Transfer (free, from elektron.se) for flashing.
• A DIN MIDI interface. Recovery works over DIN only, so have one before you flash.

Download Elektron's official MK1 OS 1.73 (Analog-Rytm_OS1.73_dist.zip) and unzip it. Check the .syx:

shasum -a 256 Analog-Rytm_OS1.73.syx
# 9115c3888354bb388f90410e0445cd312bf020593ed99f768a99e475d1d6157c

git clone https://github.com/gdeo607/rytm1_mods
cd rytm1_mods
git checkout 2fae7ce
git am /path/to/this-repo/mods/0001-chop/rytm1_mods-chop.patch
cp /path/to/Analog-Rytm_OS1.73.syx stock/Analog-Rytm_OS1.73.syx
make setup          # fetches and builds the firmware container tool
make chop           # builds + verifies; must end with PASS
make control        # stock code repacked, for your first flash

On macOS, if python3 is older than 3.11, add PY=python3.12 to each make command.

The end of make chop's output must show all three of these:

ok   null repack: stock .syx rebuilds byte-identically
ok   embedded bootstrap image unchanged (87,068 B) - recovery path intact
PASS

Then check your build is the same file this repo was tested with:

shasum -a 256 build/AR1_OS1.73_0000_0001_0002_0003.syx
# 3ea80d31dba5a6ea3c937d6feb68026907759a68c7557e31373f4d7bd1a2b00b

1. Back up your projects and +Drive in Transfer.
2. Connect USB, power on, and in Transfer > CONNECTION set MIDI IN and OUT to the Analog Rytm.
3. Control build first: drag build/AR1_OS1.73_control.syx onto Transfer > DROP and press YES on the Rytm. Check it boots and plays normally. This proves the toolchain on your unit.
4. Then CHOP: do the same with build/AR1_OS1.73_0000_0001_0002_0003.syx.
5. Don't power off during an update or during the first boot after it.

If Transfer refuses a file as "same version", nothing was written. Use the recovery route below to send it.

1. Hold FUNC while powering on.
2. Press TRIG 4 (OS UPGRADE).
3. In Transfer > CONNECTION, choose LEGACY OS UPGRADE, and send the stock Analog-Rytm_OS1.73.syx over DIN MIDI (not USB).

This route runs from the Rytm's recovery code in flash, which CHOP never touches.

Do not flash rytm1_mods' SMP CUT or RANDOM builds on an MK1. They use an MK2 memory offset that is wrong for the MK1.

• ✅ A pad hit plays from its marker on the first hit.
• ✅ Under live REC, the STA p-lock lands on the trig's step.
• ✅ The CHOP page draws and switches back to the sample page.
• ✅ No crashes or stuck notes under mashing and fast retriggers.
• ⏳ Reinstalling stock 1.73 over CHOP: not yet tried.

• gdeo607/rytm1_mods: the MK1 mod framework, symbol map and build/verify tooling that CHOP is built on.
• mischa85/elektron-firmware-tool (MIT): Elektron OS container tool.
• irpina/elekloader: mod loader.

Elektron, Analog Rytm and Overbridge are trademarks of Elektron Music Machines. This project contains no Elektron firmware.