Please read before loading firmware
Loading custom firmware onto any old synthesizer is a risk. While I've tested that this firmware does not touch the bootloader on my own Andromeda so that there is always a failsafe, please load this at your own risk. You are acknowledging that this is a beta!
- Install it correctly.
- Back up your patches, and keep a stock firmware SySex (below) on hand!
- If something goes wrong, please load into the bootloader and reload original stock firmware.
- Keep up with new updates.
LATEST RELEASE
A6Plus Andromeda 1.1.2
The first public Beta release of the firmware!
Changelog below.
Currently in Beta 1.1.2
A6Plus is an experimental work in progress!
Known Beta 1.1.2 issues:
The Vintage knob may lag the Arpeggiator if Chord mode is enabled. Vintage is currently disabled in Mix mode.
(Optimization coming in next update; Vintage knob recommended off while using Chord arp. Chord mode is very heavy on CPU.).
Oscillators and Effects can still clip, but less often than stock.
Envelopes may behave odd, looking into this.
Please read the changelog below (and inside the download), and read the install guide for loading this onboard the Andromeda.
Backup & safety net
Stock firmware
Before you flash anything custom, keep a copy of the original stock firmware so you always have a safe way back to factory settings. See the Install Guide.
Below is the OS v1.40.12 firmware that was the last full release firmware by Alesis.
Additionally, there is the OS v1.40.13b beta version that was never officially released (you'll have to find it on the internet yourself, search for it!)
All rights to Alesis in this firmware, this is official and not developed by me.
Version history
Changelog
Old versions will include Download buttons if you ever need to roll back.
A6Plus Beta 1.1.2
October 28th, 2026
- Fix for 'hanging notes' in 1.0 Beta.
- Experimental new Psuedo-Polyphonic Aftertouch support:
Per-key tracking: the A6 remembers the pressure of each held key, per MIDI channel, for up to 32 keys at once. - Highest key wins: the aftertouch value is always the highest pressure among the held keys, so two keys no longer fight. The harder-pressed key drives filter 1.
Lightening up: easing off a key, or releasing it, hands control to the next-highest key. When the last key is lifted, aftertouch goes back to 0.
Note: This feature is untested, so please let me know if it works! (I should really get a polyphonic aftertouch keyboard.)
Please note, your patches may sound slightly different. This patch adjusts the gain staging so 100% on both oscillators doesn't clip harshly like it used to, additionally the arpeggiator snaps to whole number increments, so you may need to adjust your BPM. Tweak accordingly!
A6Plus Beta 1.0
October 26th, 2026
- New "A6Plus" and "Settings" tab under the Global page.
- New stereo panning knob.
- Vintage knob mode, akin to a modern Prophet.
- Customizable random patch generator.
- New arpeggiator modes.
- Whole number BPM.
- Poly Pressure MIDI Input (received as mono aftertouch)
- Settings page for toggling stock/modded envelopes, tweaking gain staging.
- Bug fixes for jittery pots, CV glitches, envelope smoothing, and gain staging.
Please note, your patches may sound slightly different. This patch adjusts the gain staging so 100% on both oscillators doesn't clip harshly like it used to, additionally the arpeggiator snaps to whole number increments, so you may need to adjust your BPM. Tweak accordingly!