Hardware Synth Modifications

US Add-ons, expansions and hacks to enhance your gear 28/06/21

When you've owned a piece of gear for years its features become so familiar that using it becomes completely second nature, akin to using the force. While you can't teach an old dog new tricks - many synths, drum machines and effects have been investigated by electronic explorers to expand their capabilities, modify their features and upgrade their grey matter.

Some gear modifications have reached cult status, such as the excellent Tubbutec modifications for the Juno 6 and Sh101, as well as Harry Axten's TR trilogy of sound expansions for the Roland 505, 626 and 707 drum machines. But let's take a look at what else is available, with options for veteran modifiers and eager experimentalists alike...

Sequential Circuits Prophet 600
The Prophet 600 is a 6 voice analog synth released in 1982. While it was the first commercial synth to have MIDI, it also featured a Zilog Z80 CPU which by today's standards is fairly slow and sluggish to respond. Luckily, a reversible mod has been created by GliGli which uses a Teensy to replace the firmware allowing for increased resolution for sound parameters, faster envelope generators, a new LFO function generator, dedicated vibrato, unison detune and full MIDI control of parameters. All the info you need to pimp your prophet is here.

Korg Monotron
Pocket-sized synths have come into prominence in recent years, with Korg offering some neat and wholly customisable options. We'll look at Volcas later, but first here's the miniature Korg Monotron looking more like a minor Minilogue. It's got full-sized keys instead of a ribbon controller, added waveforms and CV/Gate controls all running through the glorious MS-20 filter. This more advanced modification is an early project from the aforementioned Harry Axten - who provides a full overview with schematics here.

Arturia Minibrute
The Arturia MiniBrute is a glorious monosynth which comes with a front panel correctly indicating controls for an Arpeggiator - but it can also perform as a sequencer using a unique SYSEX code detailed here. Sending the message using a program such as MIDI-OX (PC) or Sysex Librarian (Mac) enables you to convert your MiniBrute back and forth between the two states - for a really refreshing change! On the link above you'll also see a destructive Vibrato mod (replacing two components) which expands the LFO range into lovely audio/FM rates, shown here:

Korg Volcas (Various)
The Volca series has been a great success and they prove you don't need to spend thousands to have warm analogue sounds which can be chained together and played on the move. Most of the series have MIDI in but do not natively have any MIDI outputs. However, these are clearly marked on the PCBs inside the units and a small modification can result in a 3.5mm socket being installed fairly comfortably. Alternatively there are options for 5-Pin Din sockets with external mounts, if you'd prefer that - there's even a mod to have MIDI in on the Volca Modular!

Dubreq Stylophone
The Stylophone is a classic instrument which is often modified and offers a unique playback method ideal for slides and quick note movements. This modification turns the Stylophone into a MIDI controller, outputting notes each time a connection is made. It's a useful mod if you're in need of a mobile MIDI keyboard, with more details available here.

LTC1799 Modifications (Various)
Numerous keyboards, guitar pedals and drum machines rely on a simple timing component which is fixed to output a single stable playback speed. Replacing this element with an LTC1799 brings a massive range of pitch possibilities, allowing units to go from a deathly crawl to a shrill squeal in the full turn of a potentiometer. This is a simple modification which is an absolute must for any lofi keyboard fan, illustrated brilliantly by Simon The Magpie below.

Korg ER-1 Electribe
The Korg ER-1 is becoming a bit of a classic machine, alongside many of the Korg grooveboxes of that era. This unofficial modification from Electribe Shaman upgrades the firmware to support alternative samples, extended support for MIDI CCs and NRPNs, and is completely non-destructive as it's a firmware upgrade. Make your ER-1 sound like a 909, an 808, or even a 303 on both the Mk1 and Mk2 models - demonstrated and explained here by AudioPilz.

Korg MS-20
The Korg MS-20 is one of the most iconic synths ever made, and in recent years has been released in both a cut-down Mini model and a full size reproduction. There are some minor shortcomings in its design - the most notable being a lack of pulse width modulation, a sync function and no form of FM synthesis. Thankfully, this modification from YewTreeMagic adds all of the above plus a ring modulator, separate waveform outputs and two new input sockets for the mixer. Some of the mods are detailed here:

Yamaha DX7 Mk II
The world's best-selling keyboard is not safe from modification! The E! board Grey Matter upgrade consists of a single circuit board which can be fitted into the vacant slots of two native EEPROM chips - adding greater storage capacity (320 sounds as opposed to 32 on the original) and a tonne of features too long to list here. It has voice stacking, micro tonal control and an analogue-replicating feature which unifies each operator output level into one brightness control. Finally, a set of MIDI data filters are available for incoming and outgoing MIDI data. See the manual for all the possibilities!

USB Storage Devices (Various)
The days of using SCSI drives to back up samplers (read up on the painstaking process here) are behind us. In recent years the HxC Gotek revolution has made saving, storing and loading samples infinitely easier, with a simple USB drive replacing the floppy disc drives with a simple connection over standard IDE cables. As well as working for MPCs, Samplers, Synths and Keyboards - these mods are equally useful to those making music on Atari STs and Comoodore Amigas.

So, there are some of the best mods we know! It's important to emphasize that some of these mods will require a professional to be carried out and may invalidate your warranty. Working on electronic equipment can prove dangerous and some may view modifying classic gear as sacrilegious. When done correctly though, they can bring a new lease of life and sense of adventure to an old friend.

What mods have you done? Are there any you think we should know about?

About the author [midierror]: midierror makes nifty Max For Live devices, innovative music hardware, award winning sample packs and hosts a podcast speaking to people in the music world.