Rakarrack and wah automation

[Siv]

Hi all,

I am preparing a live audio demo for a Linux lesson, and I am going to use Rakarrack (among other software) with a few active effects; I am trying to understand if there is some way to automate the wah effect, given the fact that I don't have a midi pedal for it, in particular I'd like to "activate" the wah according to the song tempo. Searching the net, on some websites the automation functionality (of Ardour, QTractor and others) is cited, but there isn't a clear guide.
I suppose that some MIDI synth has to produce some kind of a wave, so the Rakarrack Wah parameter activates and deactivates, do you know what software is best (and how to do it)?

[holborn]

Hi ..

I think you need help

MIDI = Musical Instrument Digital Interface, is a comunication protocol between musical instruments, what MIDI is in fact is a sequence of numbers, what the musical instrument does is recognize certain numbers to do certain functions.

Rackarrack recognizes different messages but for control the Wah or other effect parameters , the mesage that you need is called: MIDI Control Mesage, they are various ways to generate this numbers, for example a synthesizer that has a modulation wheel send MIDI Control Mesage number 1 and also a value this value is the amount you move the "wheel".

For automatization purposes the best you can do is use a sequencer like Qtractor or Rosegarden, with this sequencers you can generate multiple MIDI Control Mesages with the values that you want in the position time that you want , is easy as paint a line with the mouse.

rakarrack has two different ways to recognize MIDI messages, a fixed table (MIDI Implementation Chart) that you can consult in the available help, or MIDI Learn where you can assign the MIDI Control mesage number for even each rakarrack parameter effect.

Also the git development version has ACI ... an analog control interface, that reads a audio (voltage) signal from a audio jack port, meassures the input level, and send this values to the selected MIDI Control Number, in this way you can control the Wah effect with a Microphone ... or whatever you want.

Good Luck

Josep

[autostatic]

And what about the JACK Transport option in the development version? You can set a tempo in QTractor or Hydrogen for example and have the Rakarrack Wah sync with it.

[StudioDave]

And what about the JACK Transport option in the development version? You can set a tempo in QTractor or Hydrogen for example and have the Rakarrack Wah sync with it.

Now that is just too cool.

[Siv]

And what about the JACK Transport option in the development version? You can set a tempo in QTractor or Hydrogen for example and have the Rakarrack Wah sync with it.

This is great!

[spekis182]

Also the git development version has ACI ... an analog control interface, that reads a audio (voltage) signal from a audio jack port, meassures the input level, and send this values to the selected MIDI Control Number, in this way you can control the Wah effect with a Microphone ... or whatever you want.

Does anybody know how to do that?

[ssj71]

This is a VERY old topic. IMHO it's better to start a new one, link the old one and ask your question.

There should just be a jack audio port under rackarrack for the ACI, I don't remember what it's labelled. I'm not sure about connecting an expression pedal to an audio interface, but assuming it doesn't break anything, you'd just connect it to an input of your interface and connect that input to Rakarrack in JACK.

Alternatively you can use something like my infamous envelope follower lv2 plugin for a similar result.

EDIT: you might want to be a bit more specific that asking how to do "that." Do you mean a mic? same story, but with a mic, and that's definitely safer for your audio interface.

[spekis182]

Hi

I apologize for the undefined question. What I wanted to know if there is someone who has actually DONE that, and can provide some tutorial or step by step instructions on how to use ACI. I've made an expression pedal, connected it to the computer, associated it to rakarrack aux in qjack. Now I don't understand what to do next.

Thanks in advance.

[ssj71]

ok, that was my first assumption. So the deal is it really depends on the audio interface. Expression pedals work by creating a voltage divider using the pot. This means the voltage and ground come from somewhere and the pedal makes a "middle" signal between the 2 depending on the pot position. Where the somewhere is is the hard thing. Audio interfaces are made to connect mics and instruments which actually *produce* voltages by converting mechanical audio energy into electrical energy. The interface has ground and a signal, you need ground signal and voltage. So you'll have to get a power supply or something to produce the voltage, and you'll have to google what a safe value is. Its possible some audio interfaces provide that functionality but I don't know of one.

So basically the big question is what audio interface you are plugging your expression pedal into?

EDIT: I just looked up my audient id14 and its input max is 12dBu which converts to sqrt(.6)*10^(12/20) = 3V rms. So you should probably look for something a little under 3v for headroom maybe 2.5vdc. But that's also assuming there's no HPF that would block a DC signal: it mentions 10DB in the bandwidth. :\

Once you have the signal in the computer the rest is easy.

[spekis182]

Hi
The pedal is connected to Computer's microphone port, which already has 4V supply on the ring. With turning the pot I'm able to put voltage from 0.69 to 3.21 to the jack's tip.

[ssj71]

Oh cool,

are you familiar with running jack? Connect the input from the mic to an scope program like x42-scope oscrolloscope, jack-scope etc (I've used a few, most are fine) and make sure you can see the signal rise and lower.

Rackarrack may need some setting to enable the ACI, but I don't remember.

[spekis182]

I don't understand how to use those programs. x42-scope is unable to connect to JACK server, and jack-scope simply opens an empty graph.

[ssj71]

this is a good article and may help:
http://libremusicproduction.com/article ... arted-jack

[spekis182]

I'm afraid I have to give up on this one. I managed to start the scope but qjackctl simply doesn't see the scope software and so it can't connect to it. Even if I solve this one it probably won't work anyway. Qjackctl can run only one hardware at the time but I need USB sound card for guitar and the integrated card for the expression pedal.

[ssj71]

it probably won't work anyway. Qjackctl can run only one hardware at the time but I need USB sound card for guitar and the integrated card for the expression pedal.

I believe that is indeed very difficult to configure (if not impossible). Sorry