Saturday, October 20, 2018

A MIDIbox SEQv4 enclosure

Please note, this guide may be incomplete... for example, config files are not yet attached, and there is no build guide for the TPD.  I'm not sure I finished the Breakout Box build guide, but I'm posting this now due to some requests.  If anything is unclear, feel free to comment below or email me at

A basic how-to guide:
How I built enclosures for my personal SEQv4 system.  

This is not the ONLY way to house a SEQv4, but it's what I'm using for my first build.  The design can still be customized to suit your own build parameters, but this will hopefully provide a head-start for anyone else looking for an enclosure option.  Search the MIDIbox Forum for other solutions.

The template I worked from was that of the MONGBOX, an acrylic case designed by forum member Mongro1 which took its cues from the Wilba front panel.  He was also very helpful throughout my learning process, so cheeers, mate!  If you aren't following my hardware selection (two midi_io, one quad_IIc, line driver, rectangular LEDs), then you may prefer to use his case design as it is slightly more compact, or you could still use mine and simply remove the cut-outs and graphics for the options you omit.  

Both the Mongbox and the Longback have STM32 Core ports (Audio, 5V USB, SD Card) on the left side panel.  If you are planning or willing to omit some MIDI ports and/or the Line Driver, you might be able to edit the design to fit your Core against the back panel.  Since I only use the USB port for updates and not power, I was OK with leaving the Core to the side.

A laser-cut acrylic (or other material) case is typically assembled using a "tab and slot" design which connects all sides of the enclosure keeping it square.  You still need to fasten at least two opposite sides (the ones with slots) to keep the case from falling apart.  I may have gone a bit overboard with my fasteners, a few more than in the original Mongbox, but I wanted to make sure my build was rigid and that pushing the buttons and encoders would cause minimal flex to the CS Board and the acrylic itself.

Mongro1 and I both used the services of Ponoko for our laser-cutting.  You simply upload an .SVG file to their website (find my .svg files below), choose a material and color, and you should receive your order in about 2 weeks (unless you pay extra for faster service).  Keep in mind that the original Mongbox and all my enclosures are designed for 3mm thick material!  If you want to use a thinner material, you will want to change the size of the slot cutouts and maybe the side panels as well, depending on how you change the slots. 

Before you go any further, make sure you are aware of the possible module options for the SEQv4 project.  What MIDI modules are you using?  Will you want to have CV/Gate/Trig outputs?  Do you want a TPD (track position display) module, or a BLM (button/LED matrix)?? .... I made the mistake of deciding to add the TPD module after my Breakout Box was already designed and assembled.  So I designed an enclosure just for the TPD based on the TPD front panel layout, and modified the side of my Breakout Box to allow me to connect the TPD to the DOUT board.....  Now (actually, for this post) I have designed another two versions of a Breakout Box which includes the TPD, one for placement on the left and one for on the right, whichever suits your setup.  I'll probably order one of those soon, and I have a bad feeling that I'm not yet finished...

Design Files

Choose whichever case or combination fits your needs, or expand on these designs to support the options or components you include in your build.  Click the titles to download the .svg files.  I used Inkscape to edit and create these files, it's free.  If you have a special request that you'd like to include, I may be able to customize a design for you or help you navigate the software on a novice level.    

SEQV4 Enclosure (Longback)

This is equivalent to the main sequencer case I built for myself which includes STM32 Core, Wilba CS Board, power switch and inlet, one Quad_IIc_MIDI, two MIDI_IO, and a Line Driver Transmitter.  I called this design the "Longback Remix" because the original Mongbox design's rear panel was made of two parts, and I needed to have a "longer", single-piece rear panel to fit all my MIDI ports. This case is taller and deeper than the original Mongbox, has some modified/additional graphics, and a different cut-out pattern.  This design uses 2x5mm rectangular LEDs for all except the "Beat" LED.  I will add another version of Longback with 3mm round LED holes.  You will need to order a clear acrylic sheet for the LCD window, find that file below.  Scroll down to see build guide.

This design, using the same material, would cost $111.77 (shipping included) from Ponoko if I ordered it today, 3/25/18.  That's $27.50 for the acrylic,  $84.27 for machine costs, and free shipping for orders over $100.  I thought it must be more expensive to get the long front panel cut when positioned at an angle because the machine has to move considerably between almost every single laser burst. But I uploaded a version of this design with NO front panel cutout and it only made a difference of $1.77!  You can reduce machine costs by removing unnecessary graphics, ordering when they have discount offers (black friday), and/or by purchasing Ponoko's "Prime" service ($39/mo for discount on machine cost).  You might be able to save $10 if you ordered two cases within one month, but you'd have to order both at once to get free shipping on both, so you'll have to compare scenarios to determine if Prime is right for you.  

Breakout Box (Basic)

I built this external case to house and power my CV/Gate/Clock/Trig signals (AOUT_NG and DOUT modules).  It connects to the main sequencer via a DB25 cable using the Line Driver Receiver port. There are two DIN Sync ports which are internally wired to the first two clock and start/stop signals.  Power switch and inlet drive the AOUT_NG board via a MFOS Wall Wart PSU, the DOUT chain gets its power from the Line Driver.  I had some PCBs fabricated for the outputs to minimize any point-to-point wiring necessary to assemble the box.  I will add links to these PCB files if you want to use the same sockets.  Otherwise, you will want to design your own PCBs accordingly. This case is the same height and depth as the Longback above, so pairs nicely side-by-side, but it is still rather cramped within.  You can simplify the build and any custom PCBs by eliminating the LEDs and driver circuits.... but I wanted immediate and constant verification that the signals were active.  This design does not give external access to the trimmers of the AOUT_NG, the top panel must be removed in order to calibrate before fastening shut!  Scroll down to see build guide.



This was the first TPD case I made which connects to the "basic" Breakout Box.  The design includes new sides for the Breakout Box, although only one is required.  You will need to order a clear acrylic sheet for the display windows, find that file below.  Scroll down to see build guide.


Breakout Box w/ TPD (left hand)

This case combines my basic Breakout Box with my TPD case into one enclosure!  This one is intended to sit to the left of the SEQv4 case, as in my current studio, the analog gear is on the left half of the room.  Below is a right-handed version of the same case.  Please note that I have not yet had a version of this case fabricated, so I cannot say that it is error-free.  Double-check the layout and order at your own risk.  I will get one made for personal use soon and will confirm or correct the status of the design.  Feel free to omit or replace the added graphics!


Breakout Box w/ TPD (right hand)


Fastening, fitting, and graphics-ing :
applies to all these enclosures

Fastening - Well...dang.  I know I read somewhere that the PCBs from MIDIBox Shop were 2mm thick, and that's the way I've designed my cases. I never actually verified.  They are closer to 1.5mm...  The difference is noticeable in a few places, especially where two PCBs are stacked.  Stand-offs that stack up to be too tall can be filed down (you may need to add an extra washer to make it tall), or you can measure your stand-offs and PCB and adjust each case design accordingly.  That's not too difficult, I can send you an edited file if you give me a measurement. 

I've already made the height inside my current cases 49mm (about 0.5mm taller than some of my stand-offs until I get around to fixing that), making the outside 55mm.  This gives just enough room in the case so that the headers and ribbon connectors on the CS board and LCDs do not conflict with the PCBs mounted on the base of the enclosure.  It's possible to use straight pin headers, no need to fit right-angle headers...which is great because I had already soldered in the straight pins long before I started to plan my case!  

All hardware is M3 unless otherwise noted.

I ordered an assortment of stand-offs and some 1mm nylon washers which, when combined in different ways, allowed me to sandwich the PCBs wherever necessary and still be in-line from bottom to top panel.

For example, starting from the bottom, I could stack a 37mm stand-off, the CS Board (2mm), and a 10mm stand-off. 37+2+10=49.  Or three 1mm washers (3mm), a MIDI_IO PCB (2mm), another washer (1mm), a 6mm stand-off, and a 37mm stand-off.  Or a 20mm, 24mm, three washers, and a get the idea. 

See this nearby image for an example of different stand-off combinations.  This photo shows the basic Breakout Box, but the stand-offs are the same ones used in my SEQv4 and TPD cases.  I spy both black and white 1mm washers, 37mm aluminum threaded female stand-offs, 24mm brass female stand-offs, an assorted case of various nylon M+F stand-offs...all of which came from  You might be able to find them cheaper elsewhere.  I recommend that you use all metal stand-offs if possible and that you use Lock-tite on any joints you want to stay together permanently otherwise you may find that a joint inside the case begins to loosen when trying to remove a screw from the top or bottom panel!  I will upgrade my cases to remove any nylon stand-offs at some point.

I purchased the black M3 flat head screws for the top panels, the black M3 pan head screws for the bottom panels, and the lock-nuts for fastening PCBs from a local hardware store.  I just bought what I needed at different stages of my builds, not all at once.  I required a variety of screw lengths: for example, some need to go through the acrylic, the spacers, a PCB, and a nut (3+3+2+4=12mm), while some needed only to get through the acrylic and into a stand-off, but not too far into the stand-off as some are not fully-threaded (I think the brass were fully threaded, but the aluminum and nylon had a max depth of 6mm).  

Now that my build is finished and this guide exists, you can add up exactly what you need to order and source them for less than I paid.  Don't underestimate the cost of the fasteners.  You may choose to reduce the number of stand-off/stiffeners in your build to a minimum to save some money and simplify assembly.  I will add lists and layouts for how mine are assembled with each guide below (next time I open the enclosures). You can always select some other method to fasten your enclosure, just edit the design files accordingly. 

Fitting - On the cases I've made so far, the holes for all the M3 fasteners on the top panel were counter-sunk (using the tool shown and a drill press with a digital depth reading) so the screw heads are flush with the acrylic.  This isn't necessary however. If you are happy to use pan-head or cap-screws, you need not modify the fastener cutouts. 

As there are so many small cutouts to deal with when assembling the front panel and CS board, and because I chose to use flat topped LEDs (whose square edges are rather unforgiving) throughout this build, I found it helpful to bevel the cutouts on the underside of the front panel to guide the LEDs into place.  I used this Dremel tool on the rectangular LEDs and a countersink on any round LEDs (Beat LED, Breakout Box).  I only went down about 1mm, so there is still plenty of material left around the cutouts.

Graphics - You'll notice that the lines and text on my acrylic cases are white.  I did this using a Lacquer-Stik... I just rubbed it into the etch and then wiped off the excess using 90% isopropyl alcohol.  It's a bit awkward getting the diluted paint out of the cutouts, so be careful when wiping the excess off.  Make sure to keep the lacquer stik sealed up well between uses to prevent it drying out.  Remove the paper from the surface of the acrylic before you fill the etch or you will have too much paint to wipe away easily.  

Another option is to use a bi-color acrylic.  You can use acrylic that is one color on the surface, but another color below that is revealed when etched.  I chose not to use this type because it was only available in a gloss finish, and I preferred to use acrylic with a matte finish.  

Yet another option, if you have access to a laser-cutter, could be to select a sheet of "etch-colored" acrylic (in my first case, that's white), and paint that sheet your desired panel color before you cut and etch (in my first case, that's matte black, but you could choose literally any color or design).  The laser will cut through the layer of paint and into the colored sheet.  I've seen some detailed eurorack panels like this, so this may be worth experimenting with if you can DIY. 

Build Guides...

SEQv4 Mongbox (Longback Remix) build guide (sort of)

I'm not even sure where to begin!  If you're here reading this, you must have some idea of what it's all about, so I don't want to repeat myself.  As you can see by this photo, I managed to squeeze my Core, 8 MIDI outs, 4 MIDI ins, and a line driver transmitter into my enclosure...along with the control surface and LCDs...and there's still so much room for activities! 

Not bad.

I started with a few prototypes made out of laser-cut wood with the help of Sean Pendleton.  I quite liked them!  The etching/cutting burns the wood slightly, so text shows up without being filled with paint, and cuts have a sort of reverse-vignette appearance - I'm sure there's a word for it.  My first attempt didn't turn out quite right because of a scaling issue when loading an SVG into Inkscape which was made in Illustrator.  Mongro1 helped sort out that issue and uploaded a file named "mongbox_scale corrected".  This is the file I built my Ponoko case from.  

There were still some issues when trying to load my edited Inkscape files into Corel, the software Sean was using at the laser-cutter.  Text I added to the design was being stretched to a zero-point (maybe), however Mongro1's "_scale corrected" file loaded without issue, if I remember correctly.  Ponoko accepts Inkscape files and verifies upon upload, so I figured I would prove the design somewhere that anyone could access. If you are happy to copy my same build, you just have to upload the relevant SVG file above to Ponoko.  Be sure to review an image of the design before you commit if you choose another fabricator.

PCB Spacers - 
(see Bottom Panel Fasteners image below)

All the PCBs on the bottom panel are supported by three 1mm washers as spacers, except for the Core (which has only two 1mm washers for a 2mm space) and the Line Driver Transmitter which has 0.25" unthreaded, nylon spacers.  I can't recall exactly why the Core has a shorter spacer, perhaps to give a bit more room between the STM32F4 and the headers on the bottom of the CS Board.  Next time the case is open, I will try and give a better answer and verify that the others are all 3mm.  All the pan-head screws on the underside of the case also had a nylon washer between the screw's head and the acrylic.  

Mounting Hardware - 
(see Top Panel Fasteners image below) 

Ideally, you will want the LCDs and CS board to stay mounted to the top panel when opening the case so you aren't fighting all the LEDs every time you want to look inside (as shown in the photo nearby).  However, because I used some nylon stand-offs, it is sometimes difficult to remove a screw from the panel without turning the stand-offs inside the case. Use all metal stand-offs and lock-tite where appropriate for better results.

I mounted the LCDs and CS Board to the front panel using 10mm stand-offs which held the LCDs even with the underside of the panel and gave me a good height for the switches and buttons I used.  These have two possible "levels": if you push the cap down hard, it will click a second time onto the switch and have a lower profile.  

Two of the PCBs have parts which protrude through the side panels: the Core's audio socket and the Line Driver's DB25 port.  These are a bit awkward to install.  You may want to put the screws through the bottom panel and secure them with tape, turn over and install washer/spacers onto screw threads, put PCB part through panel cutout, and lower PCB onto screws and panel into slots at the same time. This makes a few of the nuts difficult to hold when tightening the fasteners as the panel is very close to the nut.  I used a pair of pliers with a curved jaw at the end for some locations (shown poorly in nearby image).

coming soon : count list of stand-offs and other hardware.

Ribbon Cables - If you began with my parts lists from my previous post, then you should have all the connectors and ribbon cable you need to assemble this enclosure.  You can see that I labeled the ribbons in my case to make breakdown and rebuild easier.  Remember to make the ribbons that connect to the LCDs and CS Board to the Core and Line Driver long enough so that you can remove the panel enough to connect/disconnect the headers.  It is very important to align pin 1 of each connector on a ribbon and that the connector be on the appropriate side at each end to allow a manageable flow of ribbons between stand-offs.  This will likely require a twist or two in some ribbons.

Core J2 and J17, bottom right
Power - It's perhaps not necessary to add a power switch and receptacle, you can instead power using the USB connection to the Core.  However, I do not know the full power draw of my SEQv4 System (SEQv4, DOUT Chain/LEDs, TPD, LD_Rx) and didn't want to risk trusting every random USB supply.  I also don't want to risk damaging the port on the STM32F4 by frequently using that connection or by it taking a knock during use.  The power inlet I installed is easily replaceable should it fail, and the switch allows me to leave it plugged in when not in use.  Power comes through the switch to the 5V DC convertor and on to the Core Board's J2.  

You must also remove the USB Power jumper from the Core Board's J17.  I suppose it is possible to add a switch to select between external power and USB power, but I would not toggle back and forth while powered.  I would likely recess the switch so it could only be actuated deliberately. 


Breakout Box (Basic)

This is the first expansion I made for the SEQv4, but not entirely from scratch, of course.  The enclosure is based on the Longback in terms of size, shape, and construction and contains several boards from the MBHP (MIDIBox Hardware Platform), several that I made specifically for this case, and a MFOS PSU for the AOUT_NG.  You should decide if you plan to include the TPD at this point as that will affect your side panel and BOM (by one part). 

The layout of the PCBs on the bottom panel is shown below. 

Bottom panel layout

The top panel is used to mount the PCBs with output sockets and LEDs, as well as PCBs for the bipolar switch option for the AOUT_NG.  Of course, you can eliminate the switches (and just use the jumper settings on the AOUT_NG), and you can modify the front panel to omit LEDs or to fit whatever sockets and switches you prefer.  You can eliminate the PCBs altogether and do all your wiring point-to-point.  It would be a LOT cheaper!  I went to these lengths for my own build to make the final assembly as simple as connecting ribbon cables.  

The sockets I used were Cliff Electronics CL1384, the same type used in Doepfer modules until they switched to Cliff's FC681375V.  I already a had a large enough stock of CL1384 sockets on-hand, so I designed the boards to use these.  I might redesign the output boards at some point to use the FC681375V or another perpendicular socket.  That might save a few millimeters inside the enclosure and allow a wider selection of caps for the MFOS PSU, and the threads/nuts on the FC681375V (and even FC681375VH) are a smaller diameter than the CL1384 and might lead to a neater front panel.  The CL1384 is also available with gold contacts as the CL13845G.  Note that the 3mm acrylic used for this enclosure is the maximum thickness you should use with any of these Cliff sockets.  With the CL1384 sockets used in my case, the nuts rest slightly higher that the mouth of the socket, so a jack with a wide and flat diameter may not fully insert.

The Bipolar option boards were designed to use these push-button switches, and the panel is cut to use these switch caps.  There isn't a lot of "throw" to the push-button, in other words, the difference between the "Up" and "Down" positions is rather short. I would consider a different switch if I were to redesign the PCBs and panel, probably with LED indication of selected mode.

Top panel layout

PCB Spacers -  I use the same 1mm washers and 0.25" spacers in the Breakout Box that I used in the Longback enclosure.  The DIN Sync board has 3mm of washers between the bottom panel and the PCB, the Line Driver Receiver has 0.25" spacers, and the AOUT_NG, DOUT, and MFOS PSU all have 2mm of washers.  

Mounting Hardware - As shown in the top panel description above, with the exception of the bipolar switch boards, the other top panel-mounted PCBs are fastened using the nuts provided with the 3.5mm Cliff sockets.  The switch boards are mounted with 15mm threaded stand-offs. It was necessary for me to sand/file the sides of the stand-offs to fit between the switch bodies, but if you buy 4.5mm hex stand-offs rather the 6mm I had on-hand, you may not have a problem.  

The fasteners that hold the enclosure together are the same types and sizes used in the Longback as well.  Below is a diagram showing the layout and descriptions of the various stand-off combinations.  

Ribbon Cables -

There are quite a few ribbon cables crammed in here.  We've got three 16-wire connectors for the AOUT_NG, one 10-wire connector for power to the LED drivers, and four 10-wire connectors for the DOUT shift registers (one of which continues on to the DIN Sync board). 

I made a mistake on the layout of the first DIN Sync board, but used it anyway in my personal case.  I corrected the error by twisting 8 of the ribbon's wires just before the connector (see photo).  I have corrected the error on the board design (and removed the diodes you might notice is some pics here) and will share that fabrication file if anyone wants to include the DIN Sync outs.    

The DOUT shift registers are shown sequentially from right to left in this image, so you might consider its layout to be upside down compared to the top panel layout.  It is important to edit the config file appropriately.  With my top panel layout and the DOUT's orientation, you would make the Clock outputs SR n, the second set of Trigger outs SR n+1, the first set of Trigger outs SR n+2, and the Gate outs SR n+3.  See my own config file if using my same hardware options.  


Power -

The Line Driver Receiver, DOUT, LED drivers, and part of the AOUT_NG are all powered via the +5V on the DB-25 cable attached to the SEQv4 enclosure.  However, the AOUT_NG also requires -/+12VDC which is provided by the MFOS Wallwart PSU.  The MFOS is powered by an AMIGO 12VAC/1200mA supply, model AM-121200A.  The power inlet and switch are the same used in my Longback enclosure. 



  1. Excellent pictures and a world class write up, exceptional stuff Nick

  2. The svg file for the enclosure isn't working mate

    1. If it’s more efficient to communicate directly, send me a friend request on FB, or we can use WhatsApp, or just email directly rather than through the comments section. I will still comment with whatever solution we find in case others experience the same issue. I can email the file directly when I get home to make sure the filesharing host is not corrupting the data.

  3. The download doesn’t work? Or the SVG won’t load into your software? What software are you using? I’m using Inkscape 9 (iirc) and tried this file before posting, works for me. If you are using Inkscape also, and it loads but looks like there’s nothing there, go to View->Display->Outline and you should see the complete design. Let me know how you get on and exactly what is failing.

  4. the filesharing host is reporting the file as not there old chap,

    1. I uploaded the files to my Dropbox and changed the links accordingly.

    2. Really appreciate it Nicholas

  5. Please note that the SVG file for the transparent windows is not yet included. You will probably want to order this at the same time that you order the enclosure design to save on shipping costs. Also, Ponoko offers free shipping for orders over $100, so depending on the material you select for the enclosure, ordering the windows at the same time may push you over that qualifying mark ( although this offer may be location dependent).

  6. We are tied directly into the sate’s renewal database which allows us to process your request almost instantly. buy essays modulare Bauweise

  7. Great case, I have made one in yellow. Thank you so much for sharing.
    Could you tell me the partnumber of the DC power inlet?