Subharmonic Oscillator on the 301

Has anyone had success building a subharmonic oscillator on the 301? I’m trying to make something like the mangrove oscillator or the 4ms dual looping delay as an oscillator with pitch divisions.

I’ve had limited results using Tap Tempo triggered by a fast sine. While adjusting the div parameter generates the undertone (?) series, I haven’t figured out a way to get the fundamental pitch to follow an incoming sequence reliably.

Curious to hear other people’s experiences with this…


I have tried it, after being inspired by one of loopop’s videos. I got stuck on that the EG units in the ER-301 currently have digital style envelope behaviors, where a new trigger will cause them to reset even if they have not completed their current cycle. This is different from how Maths behaves - it will complete its current cycle if it receives a new trigger midstream.

I’ve since added a new bespoke unit to Accents (Timed Gate) that has an option to ignore incoming triggers until it has completed its current cycle, but never got back around to seeing whether this might work as a square wave subharmonic osc. If it does, you could possibly also use Timed Gate as an intermediary trigger for a Skewed Sin or ADSR envelope so that you could shape the resulting wave form a bit more.

You could try that. It might work, but I haven’t had my head in it for a while, so not sure…

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Thanks Joe! I’ll check out Timed Gate and see if I can get something up and running.

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If you get something working I’d definitely be interested in hearing about it!

FWIW, this is what made me fall in love with the Serge DUSG…I love feeding one osc into each side of the DUSG and then sequencing each sides rise and fall times to create subharmonic variations, which in turn follow whichever sequence I have running through the main osc…

Tap Tempo is more for locking on to a consistent tempo/clock and then allowing you to create a new clock signal based on the implied tempo. It uses hysteresis to filter out jitter that might be in the incoming clock signal (common with external clocks). This means that it does not react to clock frequency changes quickly.

The Counter unit on the other hand simply counts pulses. So I would use that instead for dividing down an oscillator to create sub-harmonics. Just make sure that you set the Process Rate to ‘sample’.


By default, the Counter unit only processes it input at the frame rate (300Hz). Changing this option to ‘sample’ will have the unit process its input at the system rate (48kHz or 96kHz).


Following with great interest :heart:

Just reporting back that this works swimmingly.

I’ve got Sine Osc -> Counter (with process rate set to ‘sample’). Adjusting the ‘Finish’ parameter divides the pitches. Adding an envelope after allows for some timbral variation.

Very cool!


Ooh, exciting! Would you happen to have a unit where one could see what you did?

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Demo please! As a Mangrove user I’m very curious to hear how this compares.

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Here’s a quick video of how it sounds:

Patch notes: Sine Osc -> Counter -> Skewed Sine Envelope -> VCA -> Freeverb

Sine Osc V/oct receives CV from Eloquencer
Counter ‘finish’ is manually manipulated to divide the pitches
Skewed Sine Env ‘dur’ set to 2ms with a slow lfo modulating it slightly. ‘Skew’ is also modulated by an lfo.

I start off with a single note to demo the sound of the pitch divisions, then add a few more notes on the Eloquencer, all while moving the ‘finish’ parameter on Counter. Very fun to come up with new melodies and harmonic motion.


That sounds cool, and I it was easier than I thought! Always learning, with the ER-301.

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Tip: You can go in to the ‘finish’ control’s editor and reduce the range to something more useful (like 1 to 8) for this purpose.