Software Programmable Guitar Effects? (Weird)

[XaiuM]

Hello everyone,

I had one crazy idea I just thought of, but I don't even know where to begin to look.  I was thinking how I could add a custom effect to my guitar, and then I thought that perhaps I could use a programmable chip.  Like I would write code and program that into a chip and then put that into the back of my guitar.  In doing this I could have as many effects as I wanted.  Crazy I know, anyone have any material I can reference?  I have access to a programmable chip, I think the main obstacle would be software related.  How do I program something to sound like a phaser for example?  This forum seems mostly geared towards the hardware end, but it seemed a decent place to discuss the idea.  I don't really think this is *too* far fetched, as I am currently working on my own all-tube amp and I think the obstacles would be software related, not hardware.

[Kilby]

Hi,

theres been an indepth article in one of this years UK guitar mags (can't remember which one).

The effects are standard effects removed from their cases (phase 100 and fuzz-factorys mostly).

The microprocessor comes in for the midi info to the digitech whammy and the lasers.

Apart from that they are analogue effects in the 'Matocasters' as they have been christened.


Hope this Helps,

Rob

[XaiuM]

This isn't exactly what I was thinking (or I don't think it is).  It's not simply taking a regular pedal and putting it into a guitar, I'm thinking having the actual effect be done in software.  Like the signal is unaltered until it hits the chip which modifies the tone according to how it is programmed.  Are you saying that Matt Bellamy's Manson guitars have this?  I know they have stompbox type effects innererds actually in the guitar, but that is done by hardware, I was thinking by software, unless that is how the whammy is operated?

[ExpAnonColin]

The "magicstomp" is about as far as you're going to get... software based patch editing that's pretty complex for a multipatch pedal.

You could probably do it, but I think it's safe to say that only a few people here actually know much at all about digital things... Peter comes to mind.

-Colin

[niftydog]

Interesting concept.

DSP isn't easy to deal with, ask the guys who manufacture those hokey multi-effects floor units!

What sort of chip are you talking about?  It has to be pretty damn fast to cope with audio sampling rates! Even so, you really want a dedicated DSP chip.

you have seen this? If you've got the download speed or the time, watch the promo video.  Cool stuff. I want to own a Magic enabled PA system! Forget that heavy multicore...

Not exactly what you're talking about, but perhaps splurging on a development board and software would at least point you in the right direction.  The first hurdle (AD conversion) is overcome, and perhaps this technology will be expanded in time to include software based effects programming for guitar.

[Kilby]

What I'm saying is that the only software controlled stuff in his guitars are the lasers and the control pad for the whammy that translates the signal from whammy control surface to midi which is then output.

Yes you could put a dsp/software solution into the guitar as that's basically what line 6 did with the variax except they chose to emulate guitars rather than effects.

However you will end up with serious trade off issues including physical size and weight, processor speed, available memory, power consumption, number of simultainious effects.

Even the editing of patches would either require a lcd / menu / button setup or connecting a PC and uploading them, neither of which you would not want to do mid gig (especially if you are like me and had some experimental settings or code installed earlier in the day)

Perhaps a hybrid solution may be better;

analogue distortion, overdrive, boost and amp simulation style effects (perhaps make those FX as modular boards).

Digital for time based and some modulation effects.

Therefore you are saving your processor cycles for things which are less practical for onboard analogue solutions.

Just a thought,

Rob...

[XaiuM]

After thinking about this idea more I had two ways that this could be worked.

1) Go from Signal ->A/D converter -> FFT (sort out the lows, mids, highs) -> software (Thinking I could boost different frequencies much like a wah) -> D/A -> amp

2) What about a non-linear circuit?  For example, you have a sine wave, any old sine wave will do.  What you would do is apply a certain mathmatical function to it.  IE you could square the wave.  Obviously this would make the sine wave all positive since a square of a neg. is pos going back to math.  With a software programmable chip you could chose the numbers of the equation.  So let's say you write an equation like ax+bx^2+cx^3+dx^4.  The x represents the signal from the guitar, you would simply pick a, b, c, and d. In effect this would distort the signal.  Not like distortion distortion, distortion as what goes in is not the same as what comes out (The signal has changed). My point is that maybe instead of simply trying to program software to make a "wah" sound or a "phaser" sound you could make your own sounds with the function.  This function, and it's inputs would be able to be changed, allowing for all sorts of fun.  I'd like some way of testing functions on sounds.  That is,  I want to know which ones are musically pleasing.  If I could get a point to point wave into my computer, then I could use something like Mathcad to apply the equation, and play the output in some way.

[les_chupacabra]

Start Here...
http://shoko.calarts.edu/~glmrboy/musicdsp/music-dsp.html

[Peter Snowberg]

I've written several effects in software exactly as you describe.

The hardware was based around the Motorola DSP56001 and DSP56002 mostly with A/D, D/A, and a little SRAM.

Until recently, getting enough DSP horsepower for a reasonable cost was the hard part. Now you can get inexpensive DSPs from companies like http://www.wavefrontsemi.com and cheap A/D and D/A to go with them. These are the chips at the heart of all the new Alesis effects boxes.

This works well for many effects, but when it comes to distortion, the analog way is still the best IMHO. Analog circuits have a "feel" to them in many cases that a simple digital simulation just won't copy. You might be able to get a phaser program running easily, but getting one that sounds better than a Small Stone is another story.

For more reading.... check these papers out:
http://www.stanford.edu/~dattorro/EffectDesignPart1.pdf
http://www.stanford.edu/~dattorro/EffectDesignPart2.pdf
http://www.stanford.edu/~dattorro/EffectDesignPart3.pdf

One of these days I'll introduce my DIY DSP stuff, but I don't have enough money or time to complete the development right now.

Take care,
-Peter

[XaiuM]

Any idea on what the AL3101/2 DSP-1K could do?  Seems like from my brief googling of those Motorola chips they are discontinuing, or have discontinued them.
I'll have to go through all this info, thanks for a place to start.

[Gilles C]

You could start by playing with this kind of software, and see if you can learn something from them.

http://guitarfxsoftware.com/links.htm

http://guitar-fx.org/

If I had the need, I would use a PC on stage. I would them use a midi controller to change the effects.

[chumpito]

Can I ask what chip you're going to use?  I'm looking to do something like this without having to pay too much.

If you look here someone suggested Microchips dsPIC's.
http://diystompboxes.com/sboxforum/viewtopic.php?t=21013&highlight=

[Arn C.]

XaiuM,
     I bought a Casio WK-3500 Keyboard for my fiancee last year and I downloaded a bunch of files to add to it for extra sounds.  They are DSP files.  

Here are some examples:

dsp_cmpdsdly.ckf
dsp_crn_flan.ckf
dsp_fz_phase.ckf
dsp_metal_2_.ckf

These are just a few, there are many more!

Peace!
Arn C.

[toneman]

2 all---

Great links stompboxers!!!

LOTS of good readin' in thare....

2all gday
tb

[smoguzbenjamin]

DSP is something that I find interesting, but I just don't have the time to get into it, I'm busy with the end of this school year. Maybe I'll have some time this summer to do some serious reading though. I heard that digital delays aren't that hard to do

[Gilles C]

A little bit more...

http://st.karelia.ru/~smlalx/download.htm

Having the sources can help  

[les_chupacabra]

By far the easiest to understand book or material I've read.

This one is pretty good too but I'd start with the one above.