MATRIXSYNTH: Skagmo


Showing posts with label Skagmo. Show all posts
Showing posts with label Skagmo. Show all posts

Tuesday, April 13, 2021

CB55 analog drum machine, 16HP eurorack build


video by Jon Petter Skagmo



CB55 is a DR55 clone pcb from circuitbenders.co.uk. You can find addtional posts featuring the CB55 here.

This one was built by http://skagmo.com

"CB55 analog drum machine (16 HP)

This one is popular to mount in Eurorack. I started off trying to make a 28 HP module, but i didn't see the needs for all the modifications/pots I planned, and I thought the module was too large, so I started over and made a narrow (16 HP) MIDI enabled module.
Based on the Circuitbenders CB55 analog drum machine PCB
Cut off the entire trigger conditioning circuit and drilled new mounting holes to allow the PCB to be placed vertically behind a Eurorack panel.
Designed a MIDI and sequencer addon with a PIC18, with a switch on the front panel to start/select predefined sequences, and a DIN-5 for MIDI in. This PCB also has the voltage regulators and power connector, as that was chopped off together with the trigger conditioning circuit.
In addition to the standard volume, tone and accent pots, there are individual volume pots and jack outputs for each of the voices.
Panel was milled from the rear side because I needed to machine some pockets for some protuding tabs on the potmeters, and then flipped over to do the engraving."



Thursday, January 02, 2020

Polynorth - a hybrid polyphonic synthesizer, part 2


Published on Jan 2, 2020 Jon Petter Skagmo

"Demo tracks start at 3:31. (I couldn't embed this in the video.)

A presentation of the new Polynorth prototype. Although I've actually spent a lot more time developing and optimizing the firmware than the hardware, this video will focus on the hardware."

Polynorth

Wednesday, July 31, 2019

Polynorth - a hybrid analog/digital polyphonic synthesizer


Published on Jul 31, 2019 Jon Petter Skagmo


via skagmo.com

"The Polynorth is my first attempt at designing a polyphonic synthesizer. It's got a completely analog filter section, combined with a powerful 200 MHz 32-bit microcontroller.

I've always wanted to build an analog polyphonic synthesizer, but they often end up being very large and complex because the size of the electronics pretty much scales linearly with the number of voices.

In many ways I think the filters are the hardest part of a digital synthesizer to get to "sound analog", so I figured out a good compromise would be to keep the filters analog and do all the rest with a microcontroller. The mostly digital architecture also has some important benefits:

- Flexible internal signal routing like a modular synth, but without a ton of patch leads
- More advanced modulation options (FM)
- Patch store/recall (including the routing)
- Much smaller size

I stumbled upon the SSI2144 filter, which is a modern remake of the classic SSM2044. It's very similar in many ways, but in a much more compact package and with better dynamic range, so a 6 voice synth could be made pretty compact. This is what kicked off the project.

The system architecture is explained in this block schematic."


See skagmo.com for additional details.
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