The Temperance Movement

Live in Hamburg, Oct. 11th 2013
Let me begin by stating officially that radio programs in Germany are proper crap. You hear the same hits from the current artists all the time, and should one good guitar solo come during the middle of the song, it gets "edited" away. Never mind a guitar solo at the end of a song, that one fades into oblivion. Gary Moore's "Still got the blues" in german radio would last only about a minute twenty. Once, just once, did one DJ play "Hotel California" in its entirety, and stated at the end: "Whoever doesn't play air guitar at the end of this song... he has no soul!"

Getting started on STM32F10x with *buntu Linux

I've struggled every time I need to do an installation for developing STM32 microcontrollers under any *buntu Linux distribution. There are quite a few websites with information, at my first attempt I downloaded and compiled everything per hand. But if you just want to get started as quickly as possible and spend your time getting that LED to blink and not looking for compilers and libraries and installing program after program, I might be able to help. I'm installing and setting up a simple yet good enough development environment on a Linux Xubuntu 14.04, and it has worked on higher versions too.

My system runs using the arm-none-eabi GCC compiler for bare metal, that is, you program everything per hand. printf won't work this way, I haven't bothered to install the newlib and generating the correct library. To be honest, I'm not even sure how that works.

These instructions will allow you to program pretty much every STM32F10x controller around, and later on, we can proceed to the STM32F2xx family, but let's not get ahead of ourselves.

The first ARM based Guitar Amp in the World!

...unless I'm mistaken of course, but from what I've looked, no one has (yet) built a guitar amp based on the STM32 ARM microcontrollers. So, this one's the first!

I've been working on my DIY guitar amp for a couple of years, starting as early as 2012 or so I recall, with the cabinet.

While I could have gotten a good modeling amp (Line6, VOX, et al) I think they are way over the top for what I want. Too many effects, in the end, you fiddle more with the amp than with the guitar. But an all analog design while nice, can be modified only on hardware, and those are costly and time consuming iterations. No problem with that, but you also want to have decent results from time to time. The idea came to me then, 2011 actually, why not build a very simple input stage with some gain, pass it onto a microcontroller via a ADC, add some effects, and take the output out via DAC / Amp combination?

The Smokey Headphone Amp

I'll start by admitting that this is not my original design, but it's actually based on CMoy's Headphone Amp, as well asNwAvGuy's O2 Headphone Amp. It's a bit of a mix, taking the output stage of the O2 Amp with the sheer simplicity of the CMoy Amp, but adding an extra 6 dB amplification.

Goes like this. I wanted to try a headphone amp. My colleague at work eats and shares his mints with me, so I thought, "Give me one of the empty boxes, I'll build an amp out of it". So the box lay on my desk for ages, and I realised

a) it was too small

b) it would fit only one 9V battery

c) I'd have to do a surface mount design

Installation of a Linux RAID1 Server

A couple of years back, 2010, the PC I was working with at work was replaced. I asked around, what happens with the hardware? They told me the guy in charge of putting down the PC's gave them away in exchange of a donation for the local children's hospital, around 20 Euros usually. He said he didn't want to charge any more than that, it ensured that most of the PC's ended up being sold. That seemed like a pretty good deal to me, for a desktop by HP manufactured around 2005, with a 80 GB hard drive, 1 or 2 GB RAM and a CD drive.

The STM32F103 Audio Test Board

Allow me to introduce my DIY ARM based Audio Test Board. On the following pages you'll find a description of the board, how I came to it, what tools I used and in the end, all available downloads.

Brothers in ARM's

The idea for this board came to me a little over two years ago. I was working on my DIY guitar amp, and I was having trouble getting the right levels out of the guitar, into the preamp, the level of distortion, etc. Basically, the preamp was a big question mark on the design of the amp.

Then it came to me, just like Doc Brown when he fell off he toilet and invented the flux capacitor! What if I replace the preamp with a DSP?! I could do EQ and some distortion and change it on the fly (or with a few lines of code) if I wasn't satisfied. I had also read a book called "Digital Audio Effects" by Zölzer where some examples of overdrive and tube simulation algorithms where shown.

However, a DSP was not meant to be. I work home with Linux, and use Windows only if I have to do my tax returns. Development tools for TI or ADC on Linux were not well known to me at the time. What if I used a microcontroller instead? I had an Atmel lying around on a dev board, 66 MHz or so I think, but adding hardware to it would prove too complicated. Finally, after a conversation with a work mate, he recommended an ARM processor from STM to me, they ran at 72 MHz, and gave me an USB dev board from Olimex, since he didn't have the time to play around with it.

After a bit of fiddling on the dev board for some time, adding ADC's, DAC's and a serial interface, I decided it was time to build my own audio processing board.

Speakers: AFC Mk I

Last year (2011)I decided I'd build a pair of speakers. Last time I'd built a pair of speakers, it was 1999 during the students protests and strike in Valparaiso. I got a pair of tweeters and a pair of woofers, two capacitors, an 8 Ohm potentiometer and made a box around them. Ah, yes, I drilled a hole in the front. Sadly/luckily, there are no pictures of those monsters, but they kept me company until around 2005 when I moved to Germany.

This time, I'd do it right. I decided to build a "Picolino 2" from the german "Hobby Hifi" magazine, to replace the E 90 Northridge from JBL, which I never liked to be very honest. I'd have to give it a try.