square oscillator for volume?


I’ve been using Ardour off and on for a while, but have started to
get more serious with it recently. (Thanks for the fantastic DAW!)

I am having some trouble with a few things I hope someone can help
out with. The first challenge is that I have a clip that I’m trying to
have come in and cut out (volume) going along with a square oscillator.
In other words I want the full volume for a bit, then cut all the way out
a couple times a second.

I’m sure there is an easy way to do this, but because I’m not sure what
technical term that might be it’s limiting my ability to even search the forums.

What I THINK I want is are options to choose the type
of wave I want (square, sine, saw), the frequency (in sec or ms), strength to
apply (dry/wet?), and what to apply it to (volume).

I tried picking some plugins from the oscillators category, but that leads
to another challenge… None of the plugins (2 channel) I tried give me what I
am looking for… and some of the plugins didn’t have any controls at all!
So, now I’m also curious as to if there is a place/page which lists all the
LV2/LADSPA plugs available for Ardour, and what they are good for, and/or
how to use them. For example the “Wave Terrain Oscillator” seems to cut
the volume of my left channel EXTREMELY low… but doesn’t seem to do
anything else, and doesn’t have any controls in the plugin window,
so what’s it good for? Obviously I just don’t know how to use it, but where
do I go to find out how/when to use all these?

As for the square oscillation… I COULD open the Fader automation, and
manually set marks for full volume and 0 volume, but I’ve not seen a way to
copy/paste automation marks, and doing it manually 3 times a second over
a 10 second clip just seems obnoxious.

Thanks for any help! … on either or both questions!

Hmm probably the best way to do that would be to write your own plugin, I am not aware of any that do this at this time. Sorry. But the good news is that that probably isn’t to difficult to write a plugin for.


A couple years ago I tried to get this effect on my guitar amp. I pulled the board and speaker out of the cabinet and stuck a piece of wire across a computer fan. I put the computer fan in the circuit between the speaker and the board.

like ### [amp]






[fan] |##/#|##|


######| ###|
######### |


######### |

I turned the fan on, and the amp on really low. It sounded sweet, so I cranked it up and hit a chord. Instantly, the board went supernova.

I still don’t have an amp.


I’ve wanted a plugin / function that will do this for quite a while. You can get the same effect by drawing in the fader automation, but that’s a ridiculous pain in the ass. Through hours of searching I came up with a few vsts that looked like they could provide that functionality… but I don’t think they could tempo sync with ardour, even if you get them to work. I forget any names.

I may write one. But yeah, if you want anything other than a frustratingly barebones selection of plugins, you might do better to use Ardour on OSX or Reaper on Wine, which seemed to work surprisingly well with most vsts I tried. I didn’t test Reaper thoroughly.

That, or somehow find time to learn to write plugins. I suspect that’s infeasible for most musicians.

rock808, I was able to create a patch for ALSA Modular Synth in just a few minutes that does what you need. It uses an LFO connected to a couple of VCA modules to achieve the effect.

Copy and paste this into a file, and name it something.ams. Then load it into ALSA Modular Synth, and connect it to your Ardour track using an insert.

Module 17 1 44 35 0 0
FSlider 1 0 16384 0 0 16384 1
FSlider 1 1 16384 0 0 16384 1
FSlider 1 2 16384 0 0 16384 1
Module 7 2 633 417 0 0
ColorP 0 0 2 4 250 200 50 180 180 180
ColorP 1 0 2 3 250 200 50 180 180 180
FSlider 2 0 16384 0 0 16384 1
FSlider 2 1 16384 0 0 16384 1
FSlider 2 2 16384 0 0 16384 1
ComboBox 2 0 0 1
Module 2 3 332 308 0 0
ColorP 0 4 3 5 250 200 50 180 180 180
ColorP 2 1 3 1 250 200 50 180 180 180
FSlider 3 0 16384 0 0 16384 1
FSlider 3 1 0 0 0 16384 1
FSlider 3 2 16384 0 0 32768 1
FSlider 3 3 0 0 0 32768 1
FSlider 3 4 16485 0 0 32768 1
Module 2 4 336 75 0 0
ColorP 0 4 4 5 250 200 50 180 180 180
ColorP 2 0 4 1 250 200 50 180 180 180
FSlider 4 0 16384 0 0 16384 1
FSlider 4 1 0 0 0 16384 1
FSlider 4 2 16384 0 0 32768 1
FSlider 4 3 16384 0 0 32768 1
FSlider 4 4 16384 0 0 32768 1
Module 3 5 98 262 0 0
FSlider 5 0 18018 1 -150902 75451 1
FSlider 5 1 0 0 0 102940 1

When you load it, it should look like this:



Thanks!! … and so quick!

However, even though I’m a pretty sharp guy (some times)…
this is not one of those times apparently… :wink:

What is this “ALSA Modular Synth” you speak of… A “yum search”
does not pull up any package like that. Is this some part of Ardour?

And that graphic you’re showing doesn’t look like anything I’m
familiar with. Is that part of this ALSA Modular Synth?

I take it PCM input would be a mic input to the sound card, and PCM out is
going in to a track on Ardour?

(I’m using Fedora 15 - if that helps)


EDIT - ahh… yes… so “ams” is an additional package that doesn’t seem to be
in the standard repos (not even rpmfusion?!), but after adding in the Planet CCRMA
repos, it looks like I’m getting ams installed now.

EDIT2 - ok… last edit for the day… I’ve got the .ams file loaded, but I guess I’m too new
to inserts to know how to set it up. I’ve got a track with a sine wave clip and a couple
plugins in the top pre-fader section. Where does the send go? What should the input/outputs be?
I THINK I’m noticing that ams is getting the sound, but the LFO freq does not do much,
as I’m looking to get the same effect as you’d expect by breathing out of your mouth and tapping
your palm up to your mouth a couple times a second. Also, it seems that the controls on ams
do not take affect until I disconnect and reconnect the send, but I need to be able to adjust
the frequency using some automation control that would get applied real time. Perhaps I’m
not doing something correctly?

I would use an “insert” on the channel to send the signal to AMS and receive the output. Connect the insert’s output to the PCM input on amsynth, and connect the amsynth PCM output to the insert’s input. (An insert interrupts the signal flow through the channel, unlike a send, which does not interrupt the signal.)

If you need to control the LFO frequency using automation, that makes things considerably more complicated. I have to think about that.


Unless I’m misunderstanding, I think the effect you’re looking for is called tremolo. It uses an LFO to modulate the gain of an amp. Doing a quick search on my box, there’s the TAP Tremolo plugin, although that does not let you control the waveform.

If you can’t find a suitable LADSPA plugin, let me know. I have all the code lying around to write one in less than an hour, I’m sure.

I also have an old, terribly written jack program that can do it with the LFO synced to tempo (using jack_transport). I guess that would work as an insert (like ams above), but adds the additional (minor) complication of jack_transport.