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Main :: ToneCore Development Kit

The RollerShifter - A guitar arpegiator
by PsiKTrOn on 2009-04-24 05:30:05.5900


I just want to introduce my first guitar effect designed with the line6 ToneCore Dsp Kit.

It's a guitar arpegiator. It converts the sound of the guitar into an arpeggio.

You just have to play one note or a chord and the RollerShifter will change the pitch of the the sound to create an arpeggio.

Here is the link of the demonstration video:


Re: The RollerShifter - A guitar arpegiator
by roblof on 2009-04-24 06:52:57.7460

Cool! Tnx for sharing...

Reminds me of some fx in the boss gt-6.

Re: The RollerShifter - A guitar arpegiator
by abrant on 2009-04-24 19:45:15.6000

Sounds good, I wasn't sure if this dsp could do pitch shifting that well. Do you have an plans for releasing it?

Re: The RollerShifter - A guitar arpegiator
by vignesebastien on 2009-04-29 07:33:38.8240

Nice one !!

In what language did you manage to create this effect and what's your technique to pitch shift ?


Re: The RollerShifter - A guitar arpegiator
by richfiddler11 on 2009-04-29 19:13:04.9360

Nice  Job!! Very cool effect!!

If you don't mind my asking, about how many hours work does this represent? How was the learning curve and do you have a programming/DSP background?

Thanks for sharing the video & good luck.


Re: The RollerShifter - A guitar arpegiator
by PsiKTrOn on 2009-04-30 03:12:24.9960


Thank you very much for your feedback.

I programmed the DSP in assembly language.

But, first, I wrote it with a high level simulation environments. I used Matlab.

Matlab is very adapted for the development part.

Then I translated the code into assembly.

This way of developing take more times but split the problems. In the Matlab part I tuned the DSP code to obtain the right sound.

And in the assembly part, I only had to solve assembly problems like writting in the external memory,...

I cannot evaluate clearly the development time. I received my kit for Christmas. But I only spent a few hours by weeks on it.

I'm a phd student in electronic. This background helps me for the development of the effect.

Have a nice day.

Re: The RollerShifter - A guitar arpegiator
by ricksox on 2009-04-30 13:31:41.1720

Amazing dude!!! I am really impressed! I would buy this pedal in a second!!! Nice job!


Re: The RollerShifter - A guitar arpegiator
by roblof on 2009-04-30 15:08:14.3530

Care for sharing it? It would be nice to view the code for this one!

Re: The RollerShifter - A guitar arpegiator
by jonsonnenberg on 2009-05-04 13:18:47.0410

I love it.  -especially the disjointed sounds as well as the octave shifts that you are getting. That is pretty advanced.


How did you use Matlab to help program the pedal?  Did you also use Simulink?

What is your goal with this?  Do you want to sell the code or modules?, work for Line6?, or share some of your secrets so we can learn from your creativity?

either way,  great job!

Re: The RollerShifter - A guitar arpegiator
by PsiKTrOn on 2009-05-12 08:21:27.5190


I didn't use Simulink because it's too different from the final code.

I develloped a code that works like the DSP. The advantage is that you can use all the features of Matlab (loading and writing wav file,...) to tune exactly the sound I wanted.

Then, I just converted all the code into assembly.

The most representative example is that i had to calculate the frequency of each note. In matlab, this take one line. In assembly i head to implement a look-up table which reprensents an important task.

I already shared things, I posted on the old forum how i use the external memory. And how i convert easily my code into a step by step debug code.

I think that the full code is hard to understand because due to storage capacity  of the program memory, I had to optimize it a lot.

I hope this will help you.

Re: The RollerShifter - A guitar arpegiator
by DarkZenGuitar on 2009-08-19 06:33:44.3990

Wow! Fantastic job. What's really impressive is the amount of function you programmed. Certainly no one trick pony!

Now, Line 6 just has to put that in my XTL and I'll be very happy....

Hey, Line 6-make a model pack of stuff like this!

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