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MIDIbox of the Week (MIDIbox SEQ of Gridracer)


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Can;t stop smiling since I finished my box last weekend :D

First of all, thank's a million, million times to all midibox members for developing and SHARING this

incredible piece of gear, very special thanks to TK of course!

Since I got my first MIDI gear in 1995 I always dreamed of "the ultimate hardware sequencer"

Over the years boxes have come and gone and I spend sometimes more or sometimes less time in my studio. I was pretty happy with my RS7000 but always had an eye on other SEQ's. I had the Manikin Schrittmacher and the Genoqs Nemo on my wanna try list, and I had on the very back of my mind that there was a site about a remarkable DIY SEQ on the net.

As I work in the automotive industry it became that since the end of 2008 I have more time to spend for

my hobby then the years before due to shortend working times. :( ??? :)

So the wish for THE sequencer became stronger than ever before and I was close to get a nemo.

BUT... then i recalled this DIY SEQ found it on the web again, started reading, reading, reading

and things developed.........


so since last weekend I have a grin on my face and this BOX on my desk:







Here some Info:

My "want to have it all" frontpanel as well as the rearpanel is from Schaeffer

The wooden box is made by a friend and carpenter out of ALDER wood which is oiled with FLAXOIL

My singlecolour BLM is a slight variation of the duocolour version, I only added a darlington array as sinkdrivers.

These are the buttons I use (more about them, read below):


All modules came as kits from MIKE

What i learned:

-reading is the key, if I had read more for example I could have avoided building my own bankstick e.g. ;)

I just overlooked that there is a PCB available, only no kit ...silly me.

-Switching polarity on the MIDI sockets is easy.... but also easy to sort out, just compare by using an LED

with some commercial gear.

-Optocouplers are lousy little bastards! >:( I became just anothert victim.. mine passed all tests, but messed up SW upload! My bugy opto even works fine on the thru port of the IIC module as the signal gets amplified, but messes up the midi in -> note numbers and Velocity values get randomly changed!

-The "melt isolation" wire i used on the matrix is tricky, it takes lots of heat to get a propper connection

so there is the danger to overheat the components. I fried 5 buttons, 1LED, 1Diode and had lots of non

conducting connections, whereas I had not a single problem on the PCBs.

-The buttons I use seem to have problems with production tolerances, I guess I was lucky to have only 2 or 3 "sticky / rough" blue ones while I had to repalace almost half of the yellow ones due to the bad feel.

If the buttons show up to be a cause of trouble I might disassemble them and use them as luxury cap system for tact swiches.

-ALPS encoder STEC16B04 743420 unequal VOITI + SOUNDWELL encoder ?

I got my encoders from www.distrelec.de and had to discover that they only decrease values when

connected as described. I got mine to work by switching ground and highest din pin.

-Watch the spec's of the displays, I had to use additional resistors and a different potentiometer e.g.

Finally, I hope I can give at least a little of all that I recieved back:



EDIT: fixed attachment tag

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  • 6 months later...

Now after some enjoyable months with SEQV3 here are some new pics from updating to V4 this week:



By the way, shortly after I had finished my SEQV3 I changed the resistors of the LEDs as I noticed

that they were much too bright:

I now use:

8,2KOhm !! for the blue non multiplexed LEDs

1,3KOhm    for the blue multiplexed matrix LEDs

470Ohm    for all red LEDs

(for all green and yellow LEDs i kept 220Ohm)

Now all LEDs look equal bright and are gentle to the eye, esspecially the blue ones do not spike out any more, which is clearly visible if you compare this new picture with my older pictures

on the beginning of this thread


some more pics:


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  • 3 weeks later...
  • 1 month later...
  • 4 weeks later...

Hi gjvti,

you do not have to modify the software.

You just have to assign the additional buttons and led's in the configfile:


In the file all buttons, LED,s and options are listed that are available without software change.

The file is included in the release package:


For the additional Buttons and LED's you will need additional DIN and DOUT modules.

Best Regards,


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  • 6 years later...

7 years have passed, time to post something new about my SEQ:

Since the optional step digits were released, i wanted to have them  too.

Finally this week I screwed my box apart and put :cencored: the frontpanel under the milling machine.

Luckily everything worked well, as same as gluing in the display glas and soldering the protoboard panel for the digits.

Only issue was that the pinout shematic Dout->Digits seemed to be wrong.

Thanks again TK, and everybody involved for this icredible piece of gear. :happy:

Best Regards, Gridracer



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