Standard PWM on OP-1


I just got the op-1 and am trying to map out which engines have vanilla/familiar analog oscillators to start from. It looks like dr wave or dsynth is a promising candidate for plain square waves, triangles, saws…does anyone have their favorite engine to start with a plain old analog oscillator as a blank canvas, and how to “zero out” all the whacky parameters that these wild synth engines offer?

Also, i LOVE the pulse width mod sound when a synth starts as a square wave, and the pulse thins to zero, sounding like a square → saw → that rich staticky, buzzy breakup to nothing. Does anyone have a good technique for producing that on an op-1, even if it is roundabout and requires some of the effect modules?

Thanks for any help!

Dr Wave is definitely your best bet for analog-oscillator-style since AFAIK it’s the only one that actually gives you a waveform you can easily control: Blue controls waveshape + sample-rate-reduction (cycles through tri->saw->square IIRC, once clean and then once with SRR increasing then decreasing) so turn it until you get a nice non-SRR square; Green controls filter cutoff (lowpass cutoff sweeps low->high, then highpass cutoff sweeps low->high as you turn clockwise) set it to taste; Orange is some weird chorus effect, dial it full counter-clockwise to turn it off.

White is the control you want: it’s tricky to describe because it “bounces” at the extremities instead of wrapping like Green/Blue do. So, I don’t know which way you should turn it, but in one direction you’ll get a sync effect (the waveform repeats more than once per cycle), in the other direction you’ll get a pulse width effect (the waveform plays once but doesn’t fill the entire cycle, instead there’s some silence until the end of the cycle). That’s the region you want to explore.

You can modulate White to get a PWM-type effect, which works regardless of the waveform, and you even can get it right up to “0% duty cycle” for maximum buzziness.

You can also get a really ripping PWM-type sound by dialing in a lot of SRR with Blue (to the point where the wave is just a small number of horizontal edges) and then applying a small amount of modulation to Blue, which produces a sort of shifting stack of square waves. I’d start by moving Green to the center (lowpass cutoff all the way up, highpass cutoff all the way down), White to the center (neither <1 nor >1 waveform per cycle, instead exactly 1 which covers the whole cycle) and turning Orange off (full CCW). Then turn Blue until the wave turns into a heavily-SRR’d mess of horizontal edges, then play with moving the blue knob a bit to get a feel for how much modulation you need.

(note: the Dr. Wave graphics seem to only refresh when sound is playing, so you need to be pressing some notes while tweaking in order to get better visual feedback)

Pulse is another engine which can do PWM sounds. You want to turn Blue all the way (I forget CW or CCW, but basically open the filter all the way), tune Green/White to taste, and then you want to turn Orange counter-clockwise from the middle, which will gradually increase the depth+rate of modulation of the second pulse. (this is more or less audible depending on how Green/White are set). Or, you can sweep/modulate White to manually change the pulsewidth (in this case it’s the gap between two pulses, not the duty cycle of a rectangular wave, but it sounds similar).


I would offer that the OP-1 really isn’t a good device for “traditional” sound design. It’s a lot better for happy accidents and learning its quirky ways.

I started with it before I knew a lot about sound design, got some absolutely stellar results, went back and got a traditional subtractive synth, learned that, and since then I’ve had two modes of approaching the OP-1: trying to use what I’ve learned about traditional synthesis and being frustrated, or going back to twiddling knobs and having fun.

That said, your mileage may vary, and stick with it!! It’s a great little machine.

That’s super helpful, thanks!!! That phase to 0% duty cycle is exactly what i was looking for, is there away to assign an envelope to one of the knobs?

OP-1 definitely seems to be “one of those beasts”. Regardless, Im happy to see cuckoo demonstrate some 8-bit nes sounds which many people seem to actually find too much of OP-1’s (practical) soundscape to be limited to, but i love those sound palettes.

I love learning new instruments because you get thrown into something unfamiliar and don’t fall back to the familiar stuff you’ve already mapped out, so i am very excited that this synth seems to be designed around throwing you for a loop.

Plus, at the end of the day, “red means recording” has convinced me that there are some damn cool finished results you can get with this thing. Cheers!

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you can use any of the "LFO"s, but none is a plain envelope IIRC (except for the one in Element which uses the amp envelope as a mod source, which is fine but also limited).

You could try using the MIDI LFO with an envelope signal from a DAW, sadly not that easy/fun.

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