UNOFFICIAL FIRMWARENOT FROM ROLAND · COMMUNITY BUILDS
Community developers are writing their own custom firmware, also called alternative firmware, for the SP-404 MKII. This is a selection, not every fork or experiment: we list the projects with a working build and a real following, and check them every day. FW Radar doesn’t host these files and doesn’t send alerts for their versions: each link opens the developer’s page.
1 PROJECT · LAST CHECKED 3 NOV 2026
Get an email when new custom firmware for the SP-404 MKII is found
01BETA
DOOM OS
by Klangfeld Labs
A modified 5.52 firmware that adds a graphical pattern sequencer with piano roll, a mixer with per-track EQ, built-in instruments and kits, an arpeggiator, parameter locks, effect automation and undo. The stock interface stays: you open and close DOOM OS with a button combo.
Unofficial, not supported by Roland, still early: expect rough edges. Back up your data first. Running Roland's original 5.52 update puts the stock firmware back.
READ THIS FIRSTAt your own risk, and it may void your warranty. Read the developer’s install notes, back up your presets, and make sure you know how to go back: official 5.52 and how to install it →
Running one of these?Mark it in your rig: the SP-404 MKII won’t show as out of date, and you still hear about official updates.
What you get with a free account
An alert the day a new SP-404 MKII firmware ships, by email, Telegram or push
Your whole rig in one place, with the version each device is on
Used and new Reverb prices for your gear
A public rig page to share, if you want one
We check Roland's official download page for the Roland SP-404 MKII every day. One message per release. No spam, no newsletter.
We pick the ones worth trying: a build you can install and a real following, from GitHub stars and downloads or from the community. Forks that only rename a project or add a few presets stay out, and brand-new projects get a second look after their first week.
Does FW Radar track custom firmware versions?
We note the latest version each developer has published when we check the list, every day, but we don’t send alerts for it: alerts are only for official Roland firmware.
