Midibox SeqV4 Build

Hardware Sequencing

MIDIbox Sequencer V4 was a great electronics project that was fun to build and very creative to use.  Listen to this tune using it for backing tracks with played stuff on top. No computer sequencing was used, just the SeqV4 with seemingly endless knob twiddling and button pushing: In Memory Of My Robot

Pulling A Plan Together

A very careful and considered look at the MIDIbox SeqV4 Website and forums is necessary in order to make sure you get the right parts. The Midibox processor card uses an LPC1769 Expresso Board. Schematics are not generally available but the idea and the circuitry is very straightforward. Different boards and control panels are designed by different contributors. There are also many ideas for enclosures too, ranging from highly expensive Aluminium extruded enclosures to low cost laser cut clear or coloured perspex.

Parts Ordering

Parts were ordered from a number of sources: Smash TV for the PCBs and processor board parts & Mouser for front panel electronic parts. Kits for different areas of the design are available from “SmashTV” on his website: AVI ShowTech Website

Here is a parts list of some important items, it contains a useful list because switches, button caps, encoders and knobs are quite awkward to work out.  SeqV4-OrderedPartsList


Note that the latest version of the LPC1769 Expresso Board has a connector that has moved and it is necessary to hard wire some connections rather than use a socket. However once installed, it isn’t necessary to remove anyway.

Processor Board Build & Set Up

The Processor board was built first, all parts were socketed so wasnt necessary to initially build up on an anti-static mat.


Initial testing of the CPU board and loading it with software to get the SD Card interface working so that sequencer software can be loaded on it. The Website instructions have to be followed very carefully, but it is a great piece of software engineering as it has an amazing array of drivers for accessing its functions that even include MIDI over Ethernet.



Front Panel

Building the huge front panel is great fun. The lighting of the LEDs is very much trial and error because it depends on the LED types chosen. I decided to use turned pin DIL sockets to house the resistors on the rear of the board. This way, different resistors can be tried out without dismantling the whole panel again.



Initial Testing

Testing out for the first time with a Roland D110 sound module and a portable speaker was a great moment. It is so much fun messing with the multi layering of different instruments and sequences.



The forum contains many enclosure ideas. There is a zip file that can be downloaded that has CAD data for a laser cut Perspex enclosure: Laser Cut Enclosure. Using Razor Lab to provide the material in any colour, mark up and cut the panels online is easy. RazorLab Website

Inkscape was used to edit the CAD file and remove all of the 3mm fixing holes on the rear panel, these are not required if glue is used to hold it together. Another area of adjustment was for the LCD windows;  the CAD data was adjusted to only score the windows outlines and not cut them out. This is achieved by changing colour of the line data that represents the LCD window framing.

The Case was glued together with superglue with the exception of the front panel. The front panel easily friction fits very tightly whilst allowing it to be removed easily later on.

A recommendation once the panels are glued together, is to remove the “blooming” caused by the laser cutting process and super glue with T-Cut car bodywork polish.

When entering your order at RazorLab, almost any colour of material can be selected and using Inkscape it would be straightforward to add any further graphics or symbols to enhance the appearance and give it a “custom” look and feel. Even wood is an option.



MIDI Port Upgrade

Adding an extra 4 MIDI ports was easy. A PCB & parts kit from SmashTV is available and shown in picture below. It also adds DIN Sync to connect to Roland Drum Machines.



Eventually, the unit got fully installed in my set up in a nice high position above the keyboards and easily accessible for twiddling the next riff! It was used to sequence all keyboards at one point making a lot of noise. It had the power to sequence all keyboards through all ports without missing a beat.



More Pictures….



All images Copyright © 2020 Super Synth Projects, Guy Wilkinson

See www.MIDIbox.org for more information and licence agreements.