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Building the Anymix21
Categories: Synkie, video

The Anymix21 is a 12 channel analog video mixer based on the paradigm of classic audio mixing desks.

I’ve been dreaming of this since we were on our Baltic Tour with Biblioteq Mdulair in 2017. Thanks to Corona I finally found enough time to seriously consider digging into the project and started actively developing and building.  Thanks go to Max Egger for his support. He helped a lot debugging and was the only one that could grasp the size and interest of the endeavour.  I knew from the beginning that this was going to be a long and complex project. Most of its parts we’ve developed and tested separately on the Synkie before. But will they work as intended when put together?
If one channel works, can it scale up to 12 ? Finally we can only know when the whole thing is built. But building it is a HUGE undertaking.

I’ve spent the last four months completely immersed in this project, working days and some nights almost non-stop and was much too excited to talk or write about it. Many hurdles overcome have long been forgotten. There are probably some traces of them in the Github repository (that still needs some more cleaning up) and in these following (random) pictures of the process.

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Testing one channel Nov 2020

Around the end of November 2020 I thought I’d have finalised the design of one channel strip.

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First set of vm010 PCBs came accidentally with soldermask where the qfn44 atmega should go, had to scrape it off delicately with a screwdriver. Amazingly enough it reflowed well and worked.

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Test rig, Dec 2020. Test rig proved to be unreliable and needed too much debugging itself, I finally abandoned the idea.

Dec 2020: I think I've more or less found the design for the support structure.

Dec 2020: I think I’ve more or less found the design for the support structure. (wink wink, continue dreaming ;-)

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Dec 27th, 2020. Another test setup. Max has already convinced me that the current design will be much too error prone and tedious to build. There are just too many cables to solder for each channel strip. Multiply that by 12 and start crying…

Before I start another complete redesign (we’re about at stage 3 here already) I need to know if the system could work with a mix bus the width of the whole mixer. Before that, I always tried to keep the actual mixing part of the system as tight as possible, but that meant bringing the individual signals to the compact mix-unit via cabling.

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The grey cable simulates a mixbus of 60cm length.

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To be able to check for crosstalk we need four outputs. The output module is not finalised. So that means building 4 Microsynkies first..

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Results seem promising. Let’s start over.

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2 Jan 2021: The new electronics call for a rework of the structural design. Space will be constrained. It’s a back and forth between PCB design and 3D work. Impossible to be sure all the parts fit inside without some physical mockups.

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14 Jan 2021 – the new 1xx-series boards have arrived from China.

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16 Jan 2021 – vm101 looks beautiful and first tests are promising. Thanks to the four layer board signals are very stable and clean, no crosstalk anymore between the four mixing channels. I also spent much time and effort trying to design the symmetric power supply topology.

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The new boards call for a new test rig. As the main board and the bus connect at a 90 degree angle in space I go for a 3D cube.

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The new channel strip is crammed but much cleaner and easier to build. No cables to solder or crimp.

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The LCD control board is too wide and has to fit diagonally.

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3 Feb 2021 – Yet another test rig. This time everything is flattened out. Much easier to make measurements and swap out modules this way. vm129cpu needs rework, genlock handling is bad, vm120-outputs need rework, but the new channel design works really well !!

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13 Feb 2021 – Three channels built and working. Waiting for the new versions of the master PCBs to arrive. Time to build more channels.

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The new case

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26 Feb 2021- Three more channels finsished

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The master module is really crowded, but it fits and it works.

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That’s it for the moment. I’ll put this thing through some real world testing before building the remaining channels. Things look very good at the moment and 6 full channels are already really nice to play with, but I also already know I absolutely want all twelve of them. It takes about 1-2 days to solder, test and assemble one channel. Maybe this summer I can find some time to finish this – but first let’s rock it !IMG_1342

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