MonoMiK - Analog meets digital

Published on Mar 19, 2015 Michael Kukat

"It's been a while since my last video, especially since my last video about the MonoMiK. This monster project was boxed for several years and didn't see power because i was busy writing an operating system for it and didn't have lots of spare time in general.

Okay, i also got distracted with other stuff that i can do with this operating system like SD card to SCSI adapters, MFM to USB bridges and some other crazy shit :)

But finally, the basic bits are there and i decided to switch back to this project. Working on it since several weekends, today was the moment to put the new digital control part together with the existing analog synth stuff.

The MonoMiK is a real analog synthesizer, just the control part is digital. So you have all those knobs for changing the parameters, they don't go through the CPU, they are directly connected to the synth modules. But you can still store them by some tricky override mechanism. At least this is planned.

To avoid tons of switches for waveform selection and configuration of the routing matrix, there is a touch screen with a GUI where those controls go. And here, you see the first test of how those things work together. It's the prototype of what will get a PCB during the next weeks.

Using circular DMA and some fancy tricks on the STM32F207, this generates 80 analog control voltages without using any CPU power, i plan to control oscillator synchronization using the STM32 timers also, which allows very fancy features for this synchronization, there is a lot more to come.

I hope you don't need to wait too long for the next part. Just wanted to say i'm back :)"

I created a new MonoMiK channel label for these moving forward. A quick search on MonoMiK will bring up previous posts.

MonoMiK Demo 1 Part 1

YouTube via MusicMiK
Welcome to a more complete demonstration of my current DIY synthesizer project, the MonoMiK. I needed a bit more to carefully test the latest module, which consists of the waveform selectors and the sub oscillators for the VCOs. The setup uses one VCO module (2 VCOs), the new VCO mixer module (waveform mixer and sub oscillator per VCO), the ladder filter module (only transistor ladder used in the video) and the envelope modules.

MonoMiK Demo 1 Part 2

click here and scroll for more videos by MonoMiK previously posted here on MATRIXSYNTH.

MusicMiK Site Updates

You might remember MonoMiK from these posts. MiK wrote in to let me know he has found a new host and made updates to his site which will include info on the MonoMiK as well as his other projects. You might also remember him from this how to repair a KORG Poly-61 post.

"after taking down my website a while ago, i found a new hoster this year and took the opportunity to give the site a whole face-lift. During this, i also rewrote the articles about the Poly-61 repair. I sent you the link to the old pages a year ago:

http://matrixsynth.blogspot.com/2008/01/how-to-repair-poly-61.html

I fixed the bad structure of the old document and added some minor information about the inner workings of the Poly-61, besides this, more repair stories will appear as time allows. All the other things can also be found there, like more information about the MonoMiK including the blog about the development: http://www.mik-music.org/MonoMiK"

MonoMiK Moog VCF test

YouTube via MusicMiK. Click here for all posts featuring MusicMiK's work.
"The VCOs for my new project are built, now the filters have to be developed and built. So why not take a first snapshot of the Moog style LPF sound, while it's still on the breadboard?
The light delay impression comes from the two audio tracks not being perfectly synchronized - iMovie didn't give better results here.
Schematics for the VCO are on my website, those for the VCF follow after build and test.

http://www.mik-music.org/tiki/MonoMiK

The sound of this video in better quality: http://www.mik-music.org/tiki/tiki-do..."

MonoMiK VCO config GUI prototype

YouTube via MusicMiK. Click here for all videos in the series.
"This is the first prototype version of one of the configuration screens for the MonoMiK. You see the VCO configuration, where you can select one or more of the 6 basic waveforms, which are mixed on the output, select the sub oscillators of VCO1/2, the noise mode (icons not yet designed), the ring modulator mode (icons also not yet designed) and the sync/pitch tracking settings.
Besides sync on/off, you can also select the sync source, which doesn't just handle sync between VCOs, but also sync to external sources, noise, the ring modulator and a digital signal from the CPU, if i get this implemented with the performance i have.
Synchronization can be configured to trigger when the source is less than or more than a specific signal voltage level, while the level can also be configured in those screens.

The touch screen driver is not yet optimized, usability with finger input might get improved, and there are lots of other screens to be implemented. This is just a small peek at how everything might look when completed.

The whole GUI and hardware drivers are written in C++ and runs on an ATmega168 clocked with the internal 8MHz oscillator currently."

MonoMiK DIY synth mechanics

YouTube via MusicMiK. You can find more previously posted here.
"Building a DIY synthesizer not just involves all this interesting electronics, there is also a lot of mechanics to do. As i want to create a lot of documentation for the current project, the MonoMiK, i had the camera running during my 6 hours of mechanics work today and created a video from it.

This is most of the inner frame holding the modules later and giving the synthesizer stability and some sort of electric shield."

MonoMiK - the CV generator system

Published on Mar 21, 2015 Michael Kukat

"As promised - let's go a bit into tech details.

Introduced by a quick overview of the analog boards, this video mainly describes how all those control voltages are generated.

80 CV channels, -10V to +10V (plus some headroom for software-base offset correction), 16 bits resolution, update rate 1KHz. Done with very simple external hardware plus some tricks in the MCU to run everything off DMA.

So this is the most important thing of the digital control part. I use designs like this since the MiK-one and i never made any bad experience with them. Maybe not perfect for measuring equipment but totally sufficient for musical purposes.

Now the next video might take a while. Going back to finish the PCB for this and hacking some more software. GUI stuff and so. Need to add the rotary encoders and see if my plan works for them."

4-wire touchscreen on AVR

YouTube via MusicMiK. Touchscreen interface for his MonoMiK DIY synthesizer.
You can find previous posts featuring MusicMiK here.
"I found this display at one of my usual electronics dealers - the one who specialized in selling industry surplus stuff. This display is available for 6,95 EUR, while neither the touch panel nor the EL backlight are mentioned in the offer, i just suspected the touch panel because the characteristic 4 lines going away in the photo of the offer.

The display uses an LC7981 controller, which is obsolete, but quite okay, the touch panel is a resistive 4-wire touch panel. I connected this via 4 protection resistors to an ATmega88, Port C0-C3, while the software uses those port pins as either digital outputs to provide the voltages or as analog inputs to sample the output of the panel. Quite an elegant and simple design.

Before you ask - Pollin Electronic, order number 120346. Currently, 778 are in stock, i think, the 10 units i just ordered are already substracted :)"

MonoMiK ladder VCF module test

YouTube via MusicMiK. You can find prior videos here.
"After you have seen the breadboarding videos of the two ladder filters, you can now see the final test of the assembled filter module with both filters in direct comparison.

Higher quality audio track and more about this here:
http://www.mik-music.org/tiki/tiki-vi..."

No-longer-accidental Polysynth

YouTube via MusicMiK. follow-up to this post. Be sure to see the second vid below.
"Day #2 of this. Another 4 hours or so. Cleaning up the breadboard with immediately creating new chaos on the clean surface. But now, i can put everything of the voice onto it.
The goal is to have the complete synth, reduced to 1 voice, but the rest as in the 8-voice version, on the breadboard before soldering everything together. This is how development is done most efficiently, in my eyes. It's just a bit complicated to get everything on a breadboard, if the circuits get a bit more complicated.

Anyway - i hope, you like it, the project now has a name - PolyMiK (even if the MonoMiK and the MiK-one still are incomplete :), and i'm looking forward to get good progress in this thing."

PolyMiK breadboard sound demo

"Okay. Added the ring modulator and the OTAs for feedback (resonance) and the VCA.
Things to do - some tricks for offset handling of the multiplexed exponential converter, will give a bunch of trimpots i think.
Need to make sure that i have enough buffer caps for the power, as i have some sync effects i don't want, but all in all, the result is quite okay for less than 12 hours i spent up to now.
More to follow the next weekends.

By the way - in the last video, i forgot the filter capacitors. Thanks to all those stray capacitance of a breadboad, it worked anyway :)"

MonoMiK - basic digital control test

Published on Mar 21, 2015 Michael Kukat

"Weekend, DIY time. Fixed some issues seen in the last video, so i could successfully verify the analog part now and see if my digital control stuff works as intended.

Running all 4 VCOs in parallel, through the transistor ladder filter, making some noise. Most LEDs work fine now, the prototype construction still has some minor issues and i need some more time to dive back into where i left off some years ago.

And due to the positive feedback on the last video, and a general feedback that people find my videos educating and inspiring, the next one will be about some tech stuff of this digital control."

MonoMiK ADSR demonstration

YouTube via MusicMiK. You can see the previous videos by MusicMiK posted here.
"It took quite a while due to vacation and some stress the last weeks, but finally, i soldered this module together. This was sort of much more difficult due to the very compact layout i needed so save some space in the overall construction behind those modules.

As usual, you can find more information about the project and the schematics for the modules via the blog: http://www.mik-music.org/tiki/blog1"

MonoMiK EMS VCF test

YouTube via MusicMiK. You can find more previously posted here.
"The next filter is completely developed now, it's an EMS-style diode ladder filter.
A lot of the circuitry surrounding the filter core is the same as on the transistor ladder filter, just some levels are a bit different and the resonance control works completely different."

OpenSoundControl breadboard feat iPhone

YouTube via MusicMiK

"Another quick hack...

Saturday afternoon - started to implement a chip driver for the ENC28J60 and basic IPv4 stuff. Sunday evening, ICMP (ping) and ARP worked fine, and even if the job used up most of the time yesterday and today (Tuesday), i had a working simple TCP socket this morning.

This evening, it took about 2 hours to hack together UDP support and some simple OSC message parsing.

So all in all - IP and OSC are really simple to implement, all this should also be no problem with an AVR MCU, and if i optimize memory usage, even a small ATmega168 or so might do the job. Everything is coded in C++ and with all the display stuff with graphics routines and lots more of garbage in the firmware, i currently get about 37KB code size on the ARM7TDMI used in this setup.

Imagine what's possible. Sure, OSC-MIDI is easy going. But how about controlling your home using the iPhone? Turning on and off the lights, studio gear, anything. I think, i will soon throw away the remote controlled power outlets and make a 19" 1U rackmount unit with some OSC features to control power of my gear.

Maybe the MonoMiK even gets more than MIDI. USB is quite sure, Ethernet would be also interesting now. A true analog synth with Ethernet? Why not? :)

Sorry for the blurred overall image, my camera can't re-focus during video and i set the focus for the details."