Time to follow up on the software programmers post.
Retroaktiv MPG-50 ($555)
This seems to be the king of AJ controllers, costing 10x what I’ve paid for my AJ1. It has all the basic features, plus patch storage, plus way more: controlling two AJs at once for bitimbrality or 12 voice polyphony, crossfading between them, advanced modulation, random patch generation, and more, and more. Rack mountable. One day I’ll get one. Not today.
Synthark MSP-AJx/MSP-AJm/MSP-AJa ($256/$320/$448)
Three versions: the AJm adds MKS-50 specific patch controls, and the AJa (currently unavailable) adds an arbitrary waveform generator that can be used as an 8 stage envelope or as a 16 stage LFO. The AJx is the cheapest dedicated hardware AJ programmer out there.
Dtronics DT-300 (€309)
The DT-300 is a faithful recreation of the original PG-300 by Roland. It offers the same functionality, giving your AJ the controls it deserves, and not much more.
Volt PG300V/PG300A ($300)
Little is known about this one. It’s a customized version of Volt Controller One that doesn’t strike me as super convenient, as the six knobs are shared between 48 parameters over 8 layers without any visual feedback. Still way better than the original AJ interface though.
Stereoping CE-1 Alpha J ($540)
Again, a customized version of a universal retro synth controller. This time with 16 knobs and 3 layers, which still isn’t ideal in my opinion. You can change the overlay and control other retro synths, which may or may not justify the price to you.
Out of production
Roland knew the AJ interface sucked. They knew people would hate it. So they released the PG-300 to help those people and to score some extra cash. I see no point in hunting for it today now that we have lots of cheaper and often better controllers that haven’t spent 35 years in your grandpa’s attic.
MIDI Club JunoCTRL
It was a nice dedicated controller for those who love knobs. The oscillator select and envelope mode knobs were actually 6 and 4 position rotary switches, not just regular potentiometers. It even had chord memory. Looks like MIDI Club went out of business a few years ago though.
Novation ZeRO SL mk1/mk2 (discontinued)
It’s quite old, but that’s not necessarily a bad thing. It’s often dirt cheap, yet Novation still has parts for it (they have the best support overall). It has an Alpha Juno preset out of the box, no fiddling involved. Not as fancy and convenient as dedicated controllers, but much cheaper and way easier to find used.
Behringer BCR2000 (discontinued)
A versatile controller that is still quite popular (and way pricier than the Novation one). You can buy overlays to make it easier to use, and don’t forget to download the resource pack. Meanwhile everyone is waiting for the elusive BCR32 to be released.
If you know any other controllers, please let me know so that I could update the article.