A pitch trigger to adjust parameters

#1

Hi all, this is my first post received my Axoloti on Friday, @ WOW. !
Sorry if this is too much of a Noob question...
My main aim with it is as a Bass Guitar Multi Effects, I am not too concerned for now about the effects side of things as this will grow with me, what I am more interested in is how I will interface with it, one of the negatives for me when changing effects with pedals, is you have to get down on your knees and make adjustments, then test the sound, make more adjustments, then check again. What I would like to be able to do which may seem possible with the Axoloti, is to be able to switch on/off a parameter with a foot switch, and pluck a note on the Bass, and depending on wether this is above or below a certain pitch, the parameter will adjust based on a configurable time / step scenario, eg.. 5 point every second. This way you can here the effect as it changes.
This setup will completely define how I build my fully foot controlled unit, so it is something I am focused on achieving sooner rather then later.
Any recommendations on where to start for a setup like this would be appreciated.
Thanks..

#2

To add to the above, the only solution I have come up with so far is to get an external dev board like the Teensy 3.1 with an audio add on shield that has a library that can be used to detect frequencies, and then turn this into midi control. I am pretty sure I could build this up. But what I want to know is could this be incorporated into the Axoloti while running effect patches. Apologies if the first entry is a little vague.

#3

Hi Gavin

If you want to change effect parameters by pitch, then the detected pitch doesn't need to be very precise. It's something completely different than building a bass synthesizer, where you want to catch every litlle bend and vibrato of your fingers. Therefore something very simple could satisfy your needs. For example: Use a low pass filter to estimate the low frequency power of the note. Then use an overlapping high pass filter to estimate the high frequencies. Then you could create a signal: (high freq power) / (high freq power + low freq power)
This signal could then be used to change your effect parameter.

Or you could use a sweeping band pass filter to detect the lowest frequency
peak. I'm an axoloti beginner too, but I think this would be possible just with the axoloti.

#4

Thanks Jan,
I think your right, I'm thinking to complicated here, I've been thinking about analyzing the whole signal first, rather then breaking down as you suggest, this should be good place to start without taking away too many resources for the effects on the patch.
Thanks for the help.