Drones & Growth

[bugbrand]

Spurred on by all the vactrol talks in relation to phasers, I've been doing some developments --> The drone machine has four lofi oscillators with pitch and waveshape modulated by vactrol control (so thats 8 vactrol modulation circuits in all). The theory is for a machine that has oscillators running at audio or low frequency and where pretty much everything can feed back into itself -- although, of course, the vactrol control imparts some strangeness to the modulation behaviour. Its still in early stages (needs some additions - and works best within a modular setup rather than pure standalone right now) - sounds are pretty intense.!.




..first use of some lovely knobs I got off Ebay..
.. you can see the DIY vactrols on the rear shot - covered in black heat shrink..
[the four sections are the four oscs - the black knobs are Pitch and Shape, silver knobs next to those are modulation depth, switch is range (audio / low freq) and the silver knob next to that is rudimentary keytracking. Blue inputs are CV pitch & shape (..certainly nothing like 1V/Oct!) and green output is the section output. The additional holes are for a fourchannel mixer plus rate indicator LEDs for each osc.]

Oh yeahhhhhh, there's a lo-power dial that controls all the oscs! 'cos I wanted supersimple oscs (so as not to have to build four proper ones) I made use of the simple/standard hex 40106 inverter osc design -- so there's actually scope for two further oscs.!. The low power dial is a nice little circuit bend that starves the 40106 of power - so all the oscs go mighty wierdy!

I've also done a big update of my modular page - the system is growing!

[Uncle Krunkus]

Very nice,
you've sure been working hard on that modular layout. It's looking very 60s. Way cool!
The Frankenstein's Oscillator I'm working on should be a good drone source. Playing it in tune is one of those little details I'll work out later.
How do you do CV control for a 40106 oscillator? I reckon that could be a good source for the monster. At the moment I'm building it with a 555 carrier wave.

[bugbrand]

Thanks Uncle K - yeahyeah - at the moment I guess a lot of this design is to make its own sounds and, therefore, doesn't really as standard tune in to particularly normal tunings! Hands-on so you must constantly battle it into tune if you want to play with people --> chaotic, but powerful!

Yes, for CV i've just modified a Vactrol driver circuit snippet -> can accept a couple of CVs (one with depth control) and has an offset control too - this drives an Vactrol arrangement to produce a varibale resistance (the vactrol board has a preset pot on it so you can adjust the drive strength - for these boards its worked out best to tweak it to a range of about 1M to 5k) ,, hehe, it all needs some tweak&tuning really! These variable resistances just replace the pitch resistors in simple inverter based RC oscillators (..simplest design osc ever!) and the glide-time resistors in simple RC glide circuit (for the wave shaping -- rudimentary!)

[Scott Stites]

Very cool indeed!

If you haven't done so already, you can add a CD4070 and ringmodulate those bad boys (four digital ring modulators in a chip). Great for gong/vacuum cleaner/slamming trash can sounds.

Another source of a cool waveform is at the timing caps themselves - if you buffer that signal, you can get a rampoid type waveform out of each oscillator as well.

Cheers,
Scott

[bugbrand]

Yehaaaa - yes, I've used 4077s for quasiringmod in my weevil designs for ages -- haven't tried 4070s though they should be virtually identical (would sound the same) 'cos they're XORs and 4077s are XNORs. And, YESYESYES, that does make supreme sounds!

And, I'm thinking that the 4070/7 is a much simpler way of implementing the MS20 style ringmod - thats 3 4011 stages (if I remember right) which is probably combined/shrunken to a single 4070/7 gate?

Caps signals -- yeah, great idea, cheeeeeers, I've never tried buffering those for use before but its an obvious!