Modular Synth Reconfigured

Mostly pics for now, it took me ages to fit the new power supply & test, did have other things to do today…

A 1 minute video of the testing

This is what the (mostly) analog (moderately) modular desk looks like now. Loads of lovely rack space!

These two are modules I put together myself. First was the one on the right, two attenuators (a pot, I probably DC blocked so a couple of caps too) and two amplifiers (a couple of op amps each. I believe I used kcad for the schematic, should be around somewhere, but was pretty much datasheet stuff.

The one on the left, dual low pass gate, was very experimental. Vactrol-based, entirely passive. Surprisingly useful for very few components. The front panel was also a (failed) experiment.

This is just a passive switch box I made to quickly change monitoring setup. Included here because the front panel technique is the one that has worked the best. Design on computer (I used LibreOffice Draw, it’s good for block diagrams etc). Do a rough printout to use as a template, cut/drill 3mm aluminium to match. Do a high quality printout on glossy paper. Laminate. Cut out and glue to the aluminium, cut out the holes with a scalpel.

This is the Chatterbox, something I put together just before I started looking into modular. ESP32-based with decent 2-channel DAC, has MIDI in, and I even got WebSockets over Wifi going so it could be controlled from a web page. The ESP32 also has Bluetooth support, but I haven’t played with that yet).

Although I love the look, the case took way longer than I’d have liked to get together. Eurorack time!

It also revealed loads of little issues, eg. those push switches are hard work.

A bigger issue was that my code got messy. I’m not very experienced with C++ and the dual cores of the ESP32 did my head in a bit.

So next I made a version of another old idea, the Dreamachine. Like the Chatterbox this needed some controls and some DSP (for modulating the lights and generating white/pink noise for audio). My main aim was making a reasonably solid code framework. Instead of analogue pots I used rotary encoders and added a little display, only used the internal DACs.

I’ve got most of the coding done. The main frameworky idea was to have ESP32’s core 0 running all the UI code, core 1 doing the DSP. This seems to be working nicely, should be a good basis for other synthesis on the ESP32.

(The cable connects the device to an battery pack attached underneath).

I’ve got a bunch of analog and digital modules at various stages of design. More on those another day.

Out of Service

I managed to kill my main blog this week, it might take me a little while to get going. For now I’ll just point the links on my home page here.

For any poor soul interested in how I got to this :

Early Rise and fall

I did blog very regularly, it looks like 2003-2013, at dannyayers.com, on a blogging engine I wrote. The Internet Archive seems to have captured most if not all of that, but I’m pretty sure I’ll have a (RDF) data dump around somewhere.But the real world interfered, my motivation (and finances) were tidal, usually ebbing. To mix metaphors, I lost that domain name for want of a nail. I subsequently blogged occasionally somewhere here on wordpress.com (I should have the data for that somewhere too).

He is risen!

But 3 or 4 years ago I got around to getting my own virtual server again. Took a while to get it together, I lost another couple of domain names along the way. I wasn’t really thinking about blogging at the time, it was more to host services for my HKMS project(s).

Then a year or two back a friend asked me to look at reviving an old WordPress plugin (SparqlPress). Because the idea was very (sem)webby, as well as a local install of WordPress it made sense to also have one live online. I had no future plans for it so just looked for the quickest way of getting it up and running. XAMPP seemed to fit the bill, a bundle of Apache + MariaDB (MySQL) + PHP + Perl. It was very easy to set up, WordPress on top took no time.

I used that while developing SparqlPress2. It only really covers the minimum requirements for modernising the original, but is far from being properly useful. The underlying idea, of exposing the WordPress data as Linked Data, is good for both the blogger and the Web at large. I do plan to have another look, I’m sure there’s a better way of doing the architecture, but I need to think of that first.

Then I thought, as I have this WordPress install, I might as well start using it for blogging.

…and down again

If all you want is to get WordPress up and running quickly, consider XAMPP. But if you think you might ever want to use any of its components for anything else, don’t. I’ve used Apache a good few times in the past, and even though it’s .conf setup is an absolute nightmare, it seemed to make sense to use it as the entry point on my host, pointing/proxying to my other services. Which would have been fine, but XAMPP deviates from the standard Apache setup. Its filesystem locations are different and even the way the dread .confs are organised is different. I was pretty certain that at some point I’d screw up.

So as of a few months ago I’d decided to swap XAMPP for a more standard install of the necessary components. A few days ago I noticed the blog was broken.

But I’ve got a lot of other things on my plate right now and it still doesn’t seem a high priority. If I get the urge to blog, I can do it here.

I’ve just started using ChatGPT 4 as a coding assistant. Even though I’m not yet used to creating optimal prompts, it’s been incredibly good. Much faster than my usual approach of googling for something similar to what I want and tweaking it, googling at every error…

So I think I’ll build another blog engine as part of HKMS, same basic approach as the other bits. The data lives in an online SPARQL store, browser JS using templating for building requests, formatting responses.