It’s been almost a month since a posted something here. I’m working on finishing some project between heat waves (I hate summer). But here’s a tinny update for those following this blog.
First of all, I added fonctionalities to the digital LFO. Now it can produce several functions: slow lfo, fast lfo, gated lfo (starts and stops with gates), attack-decay enveloppe, random with probality fonction (reduces the number of possible numbers, can also be a random gate or a pure “noise” with a kind of tone control), noisy kick (not very interesting considering the massive low pass after the dac, it looses all its punchness therefore it won’t stay) and the crunchy digital percussion heard on the previous soundcloud sample. I’ll certainly add more stuff in the futur for sure.
The tricky part is to indicate each modes which I’m currently doing using a dual led. Some modes make the led blinks, others offer plain color ect… In total I can put 7 or 8 modes with a single LED .However, a nice small 7 segments display would be a valuable substitute. There’s exist some very small cheap one.
The final incarnation of this module will offer 3 identical sub-modules. Two of each will use a dual Microchip DAC and the third one the built-in PWM output.It’s already a very handy module to have, but with a third channel it’ll be even more nicer. I’m working a 16HP panel to house it.
On the down side, I have 90% of the CPU free and it isn’t helping my OCD of efficiency and waste. An additional note, the first program used a wavetable/morphing for selecting the waveforms. But it was rather odd to use and not very interesting for that LFO application. I changed to a regular switch-like behavior of the wave pot. Note that I’m not very statisfied with that configuration either.
Despite its frankenstein adam’s look, it works very well and can do many things in a small format ! I also started the build of the digital VCO which be called for now on the “synthi-biscuit” from one of the most facist policeman on earth. Ten points if you pick up the reference ! I had to think about the way to browse through the waves and I decided to use two encoders for it. That way It’ll be easier to add more waves if needed. In this basic structure 32 waveforms can be loaded and browse through with a representation of 2X16 banks. The location will be expressed in hexdecimal format allowing 16 number with one 7 segment display. Once the dot of the 7 segment display is on, you’re into the second banks.
The DAC is an ugly one, a shift register followed by a R2R DAC from Bourns but that why it is so good !
Why is it in the plastic bag ? to avoid oxydation of the copper.
As I’m taking my time to design the circuit, it slows down the process. Other than that, I’ve been really dragged into software and programming. Which is actually a very interesting domain to bring to the modular synth. I don’t care about the typical “musician-friendly” dilema of analog-vs-digital. Both are great if used correctly, what matters is the result not the tools !
I also started to use KICAD instead of Eagles, so far it seems to be more intuitive and logical to use. And I’m not saying this because chauvinism, trust me.