Untamed the filter in the shop

A friend of mine send me a pcb for a 3350 Chip filter. This filter was based on the digisound 80-16. I was the start for me getting into a search for 3350 filters. This chip is used in the Sytron Syrinx and I really like the sound of it from what I could find. There isn’t much info on this chip and old filters that use it. But I did find someone that took the datasheet schematic and used it in his synth. PolyKit made a 8 voiced synth called the polykit-6 (check out his YouTube and GitHub).

I used his schematic as a base for the Untamed (with permission). Basically Untamed is the schematic from the datasheet of the AS3350 chip, with controls and a eurorack panel. It has it’s quirks but also a unique sound. I called this Untamed cause of the little quirks and raw sound that make it unique. I don’t think it tracks 1v/octave but it sounds awesome.

I would like to thank Polykit for his generosity and putting his work online. I will put the schematics up for everybody to look at. To comment on for further improvements and maybe come to a new module that is a bit more Tamed. The files for the pcb’s to order your own will be released after 10 sales.


Sample and Hold. First batch of dual YASH came in, testing it.

I didn’t have any sample and hold module in my rack. At first I didn’t think I needed one. But seeing a few video’s of what you could do with them I just wanted to have one. A sample and hold basically takes a voltage and when triggered it send the voltages to the output and keeps it at that level until next trigger,in theory. But being in a analog realm the capacitors used to keep the level at the output steady lose there voltage slowly and the voltage keeps dropping. This can be overcome making a digital sample and hold or just to use a quantizer and hope the next trigger will come before the next note is quantized. In practice the last option fits most purposes. So I decided to build a analog sample and hold.

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Untamed.. Something new, a filter prototype

I have been working on a filter design. The design is based on a new version of the cem3350 chip. The cem3350 was used in the Synton Syrinx, Rhodes Chroma and a few more synths. It hasn’t been used that much and the chip is somewhat of a niche filter. This chip is in production again by Alfa as the AS3350. That gives opportunities to design a filter based on this chip. The design isn’t complete yet but the pcb’s came in yesterday, so I was able to do some testing. Found out that the cutoff knob is reversed on prototype. I have been testing it together with the reverb I’ve posted about last week, to give you all a bit of a teaser of what’s to come.

The patch is Braids “VOWL” into the filter to the Reverb.

Daisy, kxmx bluemchen, reverb fx and installing dev-tools on M1 Mac

I was looking for more effect units in my rack. As I’m a big fan of DIY there aren’t that much choices. Lucky I found the kxmx bluemchen. A small module, open source and with a Daisy on the back. I did not know about Daisy and it took me on a journey. Oh I went into a rabbit hole last few weeks.

The website where you can find it advertise it as ” the go-to DSP solution for your next audio project.” I looks a bit like a Teensy or Arduino Nano. It took my interest. I soon found out it can do a lot more then your average Arduino. Daisy is made for working with audio it’s a digital signal processor (DSP). Meaning it can do a lot of things with audio signals. It can even be the source of a audio signal. They also sell T-shirt with the slogan “We make computers sing”. It took me awhile before all of Daisy landed in my head. But now I’m a big fan of this little micro processor.

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Building: The Thomas Henry Mega Percussion Synth (MPS)

Oh boy oh boy. This one is very special to me. I was in a bad period in my life when I started reading the Noise Generator Cookbook by Thomas Henry. Reading it gave me a lot of rest and I learned a lot from it. I didn’t know that much about noise, white, pink, red, blue and the noise in my head, it all started clearing up. In this book Thomas Henry writes about the Mega Percussion Synth (MPS). Back in those days a lot of schematics where based upon 15volt. I always wanted to have a MPS but never found the time and skill to transfer his design to eurorack (12 volts)

Then Haraldswerk released the MPS, and put the gerbers online for building one. Sadly it was still 15 volts and with banana jack. Not typical for eurorack. I wrote about this in the topic Haraldswerk posted on modwiggler. And I wasn’t the only one hoping for a 12 volt version with 3,5 jacks. That started a discussion and.. well

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Some site updates

I found a way to remove all those post about the modules in my rack from the frontpage. I think I have most of them written now. I might need to update a few of them while playing with the modules more and more. I thought the frontpage got a bit messy with all those post so glad to found a way of removing them. Next up all the panel files I made and adding them to the website. After that maybe record some sound samples. Maintaining a website does take some time but I still enjoy doing it.

Building: Erica Synths VCO.

I have a love and hate relation with Erica Synths DIY modules. Some are quite nice to build but most of them are just terrible to build. I makes me wonder why Erica has left the DIY scene. I’m glad the put the designs on GitHub for the modules that they call legacy DIY. But I think the support desk was just overloaded cause these modules are just a pain in the butt to solder and are prone to make mistakes on. I had the VCO in my drawers for awhile and it was time to build it.

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A lot of post about different modules

I have been posting different modules to this site and give a little bit of information on them. These modules are all in my rack and for the menu item “My Rack” I need them as separate posts. I tend to add more in the upcoming weeks as there is more in my rack ;). I might list a few as open for offers/sale. So if you looking for some DIY modules that can’t be bought as build modules and have seen them in my rack. Send me a email or thru the contact page if you want to buy any of the modules listed as open for offers.

If you want more information on them please let me know in the comments.

Small update: When writing a few post on haraldwerks modules I noticed I never put up all panel files. So more stuff to do adding panel files for some of these modules.

Hagiwo Quantizer: how does it work, a bit of background

The Quantizer made by Hagiwo is a Arduino based quantizer. Hagiwo published all files and schematics. The code is readable and not packed into a hex files. I have put my own twist on the design by replacing the DAC.

The original post and design by Hagiwo can be found here:


So lets take a look on how it’s build and how it works.

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