Use of LFO to control filter's cutoff frequency

If you have experience with analog synthesis you will likely be very familiar with the notion of manipulating a filter’s cutoff frequency with an LFO to give dynamism to the timbre of, for example, a saw tooth wave oscillatior. What I’d like to do is use an LFO and a filter to do the same to an audio track in ardour. But what I’ve tried so far doesn’t work. Maybe someone can advise?

I have an appropriate filter set up on a track, and as I experiment with the filter’s cutoff frequency I am getting exactly the kind of filter effect I am interested in. In a sense I want to automate this parameter, not with manual input or with drawn lines but rather with a sine wave, like that would be produced by an LFO. (Ultimately I’d want to use automation to control the frequency of the LFO, but a fixed frequency would be a huge step in the right direction).

However when I install the plugin called “LFO” that came with my Ardour installation as a plugin of that audio channel, it just shuts off the output; the output of the LFO seems to be stuck at 0.0 no matter how I manipulate the controls, but don’t know what correct operation is supposed to look like.

I also tried moving the LFO plugin to a separate buss but could not make that work either.

Can anyone advise? Should I be able to do this? Thanks!

The general name for this “modulation” and you can’t do it in Ardour at this time.

Ah! Ok, got it. Thanks Paul. I was wondering if it was even a doable thing.

There’s a Lua script to create LFO like automation. It can be useful though very limited.

1 Like

Is this similar to my question from a few weeks ago? Basically I wanted to use an LFO to control the Wah effect on a guitar part, and I did get it working though I’m having trouble reproducing it at the moment. I’ll give it a go tomorrow, but as far as i recall, it involved

1.) Enable a Generic MIDI Control Surface
2.) Set up an LFO on a MIDI track (with no synth) (QMidiArp LFO has controls for channel in/out, CC#, etc)
3.) Use MIDI routing to send the output of that track to Ardour Misc → MIDI Control In
4.) Put your filter on your audio track, add a midi port to that track
5.) Route Ardour Misc → MIDI Control Out to your audio track and
6.) Show the automation of your cutoff frequency and MIDI Learn. If memory serves (longshot) I may have had to use an expression pedal to get this to take.

That’s my memory, but I’m sleepy. Let me know if this is the right idea and I’ll see if I can get it working tomorrow.


This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.