My first module, Grendel (quadruple digital LFO module)

Today my first module was published by the VCV Rack team called Grendel!

Grendel is highly inspired by the Batumi from XAOC. It is a fully voltage controlled, quadruple digital LFO module with a couple of nice features. Each oscillator can be used independently or in one of the 3 other modes: quad, phase and divide. For each oscillator, there are sine, square, saw, ramp and triangle waveform outputs available. Voltage control is possible for each oscillator’s frequency, phase and reset.

You can find it here: < VCV Library - RPJ Grendel>

Documentation can be found here:

By the way, my next module is almost ready for release and will be called ’ Lady Nina’ . Do we see a pattern here?


Let me see…


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Hmmm maybe a Marillion connection here!? Like the idea of the phase option/divide, not tried it yet but hope it lives up to the description above, I’m sure it does. Thanks for making this and the ‘Lady Nina’ sounds interesting any more info on that, i.e. what does it do etc?

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This can do some lovely self-modulation. I can hardly wait to see what “Lady Nina” turns out to be.

Sorry meant to ask is this in the VCV library yet?

first sentence of the original post answers your question and theres also a link.

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Thanks persy and now added it to my collection of wonderful modules!

This is very cool. Welcome to VCV development.

I just tried it out. I have a couple of small suggestions to this otherwise excellent module.

I find the inverted knob at the top confusing and a little hard to use. I think a normal knob would fit quite easily with just a little re-work.

The knob at the top also has no tooltip. Would be nice to either turn off the tooltip or instead of saying “#5: 1” say “mode: quad”.

The CPU usage isn’t excessive compared to many of the LFOs, but it could be much lower. I suspect you are doing every calculation on every sample. If so, that’s necessary for a VCO, but it is not necessary for an LFO, as the frequency is so much lower.

Anyway - nice module!

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Thanks for testing, and also thanks for your comments and suggestions. They make sense and should be easy to implement.

So everyone, look out for a new version soon.

how about a switch/toggle or even a button w/ 4 indicator LED’s or 4 buttons? personally, im not a fan of knobs for switching between modes. admittedly i havent tried this particular module yet so im just spitballing here.

haha - I’m not a great UX designer. I know what you mean, but I have to confess I just use knobs as selectors all the time, although usually only when I’m space constrained, like in my Basic VCO.

When there is room, I generally prefer a drop down selector, like this:

I think there’s no “rule” for what’s best. I agree that knob as a selector is kind of lame (and the real reason I do it is because it’s easy!). It’s not great because you may not know what all the allowable setting are, it’s not visually obvious until you try it.

Sometime I also use a knob, but put a label next to it:

But in this case (Grendel) the labels make it pretty clear. I think it’s fine. That’s my arbitrary opinion, anyway/

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As a user I far prefer knobs as selectors where possible because it’s the easiest thing to map to a (usually MIDI) hardware controller. Even buttons are problematic because you can’t always tell their state by looking at the hardware, but knob position is a good physical reminder.


A new version 1.0.1 with a standard knob and tooltips as suggested by Squinky.Labs is on its way. It can be downloaded from my repo here (Windows only), or you have to wait until it will be made available through the library.


Just got the update from the library. Nice update.