Drift

[espiegel123]

I’ve been wanting to experiment with the influence of oscillator drift/instability in certain architectures and was wondering if people have thoughts about the best ways to do that. I’ve wondered if adding a bit of erratic drift to modulating signals (such as the modulator oscillator in a West Coast-style complex oscillator) would add some of that organic slightly unstable character that makes some Buchla patches seem real (if totally alien).

I’ve played around just a little bit by mixing in the output of a low-amplitude lfo to the pitch inputs but wasn’t sure if there is a better way. In order to avoid the drift being to regular, I used the LFO that has FM/AM.

I am still enough of a newb that I wasn’t sure how to modify the existing lfo’s to have a randomly changing frequency whose rate of change was controllable and smooth.

If someone could provide some hints about the components to use, this would probably be a good project for me to improve my skills.

[robertsyrett]

a tiny amount of noise or stepped randoms in there can make audulus sound like a dying analog synth as well. I think 50-60 hz stepped randoms sounds good, like maybe this imaginary piece of hardware has a dirty power supply and you hear the AC power affecting the pitch.

dirty power supply.audulus (17.2 KB)

[espiegel123]

Thanks muchly!

[RudigerMeyer]

Here are some threads from the old forum – along with some of the patches I managed to dig up:

Drifting Gateable Quantizer: http://forum-old.audulus.com/discussion/comment/12667#Comment_12667

BR Strange Drift Gateable Quantizer AB Demo RM.audulus (581.6 KB)

BR-RM Strange Drift Gateable Quantizer.audulus (77.8 KB)

RM Drift VCOs.audulus (422.7 KB)

Drift VCO: http://forum-old.audulus.com/discussion/comment/12522#Comment_12522

RM Drift VCO Reset Tryout.audulus (77.8 KB)

[RudigerMeyer]

For what it’s worth here’s also the old forum thread on tuning systems and a scale bender that I built a while ago: http://forum-old.audulus.com/discussion/1579/tuning-systems/p1

RM Scale Bender.audulus (122.9 KB)
RM Scale Bender Detuner Reset.audulus (278.4 KB)
RM Scale Bender Equal 7 Demo.audulus (1.0 MB)
RM Scale Bender Fraction Demo.audulus (1.0 MB)
RM Scale Bender Ratios and Fractions (Updated).audulus (390.5 KB)

[RudigerMeyer]

The scale bender gets at bit complicated though, and a more starightforward way to achieve some (slowly modulated) detuned thickening could be to use something like the Hordijk Frequency Shifter:

Hordijk Frequency Shifter

Here’s my first take on putting together a Frequency Shifter. Once again, one of Rob Hordijk’s NOVARS tutorials has provided the inspiration. Hordijk describes the frequency shifter as kind of luxury ring modulator – with the extra feature that it’s possible to split the upper and lower sidebands. In essence it’s a ring modulator and an all-pass filter network, with the filters making it possible to cancel out one of the sidebands through phase cancellations. The all-pass filter is somethin…

[stschoen]

Here’s a drift simulator I posted last year:

uDrift One per octave detune and drift utility module

[0] uDrift The uDrift is a small utility module for introducing some oscillator detune and drift when using multiple oscillators. It accepts a one per octave signal and will shift the output +/- 2 octaves and provides a +/- 50 cents detune range. The output will also drift over time with an adjustable rate and intensity. Handy for adding some warm and “fatness” to a sound. I/O Input Signal Range Notes [o%20input] 1 per octave pitch input Output Signal Range Notes [o%20out…

[espiegel123]

@RudigerMeyer and @stschoen: thanks muchly. I will be curious to experiment and see how these influence things. I am still an unclear on the degree to which little instabilities of certain synth hardware is responsible for their character or not.