Best practices for slowly rolling oscillators?

I often try to dial up nice slowly rolling (unsynced) horizontal bars with my oscillator (DWO3) and it works well enough. But after a little bit it always starts speeding up and I need to adjust it again to get it back to the nice and slow range. Is that just how it always is when using an unsynced oscillator? Are there any tips and tricks to keeping the roll stays slow? Are some oscillators just better at it than others?

Your suspicions are exactly the case. Analog oscillators’ tuning will drift as the temperature of the components change. Some modules are certainly better than others in maintaining their tuning as temperature changes.

Best bet is to let your system warm up for at least 30 minutes before you do your critical fine tuning of your scrolling oscillators. Patching a separate module that generates a DC offset into the FM input can sometimes help with more accurately setting a slow scroll. A wider diameter knob is particularly useful here.

I’ve had installations running for 8+ hours at a time where the slow scroll was an integral part of the aesthetic and the longest I got away with without a retune was ~3 hours.

The only way to guarantee a consistent scroll speed is using a digital oscillator. LZX’s Scrolls does this particularly well for video synthesis but I’m sure there’s plenty of other well-designed digital oscillators in the Eurorack world that have solid cores and won’t drift once tuned.

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I’ve made a precision voltage source with a Bourns multiturn potmeter just for this.
The prototype is ready to be tested. I might have some time to do that today.

Jack output details:
trimpot 1 sets the 5v input to a 0v to 5v range (set to 1v for video purposes)
trimpot 2 sets the ‘trimpot 1 value output’ to a 0 to 1v range (set to 0.5v for example)
so then :
jack1 : -0.5v
jack2: +0.5v
jack3: -1v
jack4: +1v
jack5: variable voltage 0 to 1v or -1 to +1v (selectable with the switch)

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My thought has been that this would probably be best achieved by using a vertical ramp and multiplier to generate the bars, and then use an LFO to offset (and thus shift) the bars.

The issue then is the wraparound for the lfo, which will be more or less noticeable depending on how precise you can get the LFO amplitude

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In my own experience Xaoc’s Zadar (adjustable to have a 1v output and loopable) can scroll at a consistent rate. You’re locked in to the millisecond values it jumps to, so it isn’t 100% flexible in this regard but there are lots of usable spots. Note it does not take 1v sync, so scrolling only. (I haven’t yet tried to amplify the VC’s sync outs to 5v to see if it’ll catch.)

A big +1 to this–it’s a dream to fine tune things with a larger diameter knob. (In the audio realm Livewire AFG and Malekko Wiard/Richter Oscillator come immediately to mind. And Music Thing’s Control for DC signals.)

Oh cool! I’m interested to see more dedicated DC offset modules in video.

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The prototype works and is ready for release.

Here is an example picture with a large vintage knob :skull:
The module name is “JOG”

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Funny you should mention this. I never let my system warm up before jumping in. lol. I’ll have to give it a try sometime! (Though I’m sure there have been times I’ve been using my system for a while and tried getting a slow roll. Can’t remember if those times had better stability or not.)

That’s awesome compared to what I’m seeing. I’ve only gotten away without retune for a matter of minutes. Hopefully all the advice in this thread will help with that.

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I find VH.S Baja works great for a slow scroll and doesn’t drift as much as other oscillators. Just like DWO3, you use the CV input attenuator for fine tuning.

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Let’s see some video!! Sounds awesome.

I use a BSO Triple Video LFO and getting consistent scrolling is the bane of my existence. I can maybe get it steady for a minute tops. However, I kind of just embrace it - it’s analog, after all. Sometimes I lightly tap the face of the knobs in time with the music until it gets back to the speed I want :smile:

I was thinking about trying to use a Teensy 4.0 with the audio library to make a digital oscillator with controls like “how many bars” (e.g. integer multiples of 60Hz), “how fast does it scroll” (some range between like +/- 10% of 60Hz), etc.

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An analog oscillator at megahertz range is just going to drift, no way around it. The fact that these are as stable as they are is amazing.

One idea is to use one or more frequency doublers, so the source oscillator can run at a lower frequency. If the drift is constant, it will be less as a proportion of the slower oscillator. I haven’t tried this but it seems logical.

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“I was thinking about trying to use a Teensy 4.0…”
I use an Electrosmith Daisy Patch for exactly this. 4 free running oscillators with adjustable waveform, amplitude, multiplier, etc… It can even produce 1 clean cycle of a vertical or diagonal bar (in SD) before we’re above 20khz then it’s just a mess. Even that can be used as a nice chaotic/noise texture in the right patch though… Makes nice lava-lamp-ish blob shapes when mixed together…

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Very cool! Do you use the daisy for other purposes?

If the goal is stable LFO or audio rate oscillators, there are many digital modules from which to choose. For LFO, Ornament and Crime immediately springs to mind.

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Synth Tech E350!
Rock solid timing, beautiful waveforms, can sync to 1v signal too

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I’m interested to see this! PDO can do some cool stuff sync-ed, I wasn’t aware of the E350’s sync-able-ness.

I have a polygon sketch that works really well for XY stuff. Has a base freq, number of sides, rotation angle, spin, starry-ness in/out, twist, etc… basically the same as our (trowaSoft) polyGen VCV Rack module. Will be really fun when I have a chromagnon and a laser to play with! :wink:

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It would be interesting to see how well this works. There are very slight differences between 60hz sources. Your Teensy clock could well be not exactly 60 hz. Some people run their systems at 50hz, too.
But yeah, analog LFO’s always drift. The Triple LFO seems to drift more than the Baja. It’s a nightmare when you have a few of them creating a complex LFO motion and then something changes but you can’t be sure which one of the LFOs it actually is.

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All you need to fix that is just one encoder per scrolling LFO :wink:

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