Synthstick Idea

[Cliff Schecht]

I'm going to build a version of the synthstick into a guitar. I've already gotten the oscillator working and have decided upon a few mods and cool ideas.

1)The entire thing will be built into a guitar and mounted on a stand for easy use.
2) The frets are going to be pulled from the fretboard and I'm going to make this my contact area using a guitar string as the conductor.
3) Selectable sweep range (Input cap)
4) on/off switch
5) a separate kill switch for cutting out the signal (Buckethead style)
6) I might build 2 into one neck and see what I can do with that and maybe use a blend knob on there to play with cool sounds.
7) If I plan it out right, I should be able to match the actual fret markers up with where the notes should be, but this might be implausible with the addition of a sweep range switch. I was talking with my dad about it and theoretically it makes sence, being that both are just square functions.
Internal power so that it doesn't need but one cord going to the amp.

Does anybody have any other suggestions to make this thing any cooler? I have pretty high expectations for this one.

[Cliff Schecht]

Done!

I ended up not using the tone control rotary switch, but aside from that everything worked great and it looks cool as shit. This is easily the coolest, most useless thing I've built so far. I'm looking forward to jamming with it tomorrow I'm gonna wait a little while on the sound clips, as I'm thinking of just doing a collection of clips of all of the different pedals I've built, but I'll have some pics posted as soon as my image hosting website is back up.

[whythisreason?]

Sounds like a lot of fun! would love to see how it looks... 

[trevize]

can't wait to hear samples/ see pictures!

[Cliff Schecht]

I had a jam with this thing earlier, so I'll get some of that up later. This thing was great for creating all sorts of weird soundscapes. Alright here's pics:

[Transmogrifox]

That really got me thinking now.  You could make it useful as a guitar and synth most easily with a microcontroller.  Six strings and 22 frets would form a note selection matrix.  You would have a current sensing device for each string (and you'd have to rebuild the bridge so you could conductively isolate each string), then you'd add a current sensing device for each fret.  The combination of fret and string would give you the note information while you could still use a pickup for an audio output which you could put through an envelope detector to gather velocity and sustain information.  This information could be coded to MIDI format and sent to a MIDI synth, or even into Reason on the PC.  You could actually use this to make a "smart" ring modulator.  Keep your guitar tuned well, and this thing would find out what notes you were playing, and it would change the carrier with the notes to bring out certain harmonies or some kinds of pitch shift effect.

I would probably use optical isolators for the current sensors for the conductive path through the strings to the frets.  You would have an opto-isolator binary output for each of the 6 strings, and on the other end a binary output for each fret.  This would produce a 6x22 modulo 2 matrix that you could process to extract note information.  Might have to do something cheesy to deal with the open string condition--but it couldn't be any more cheesey than a monophonic synth.

I need to think on that one for a while

[Cliff Schecht]

I was trying to keep it simple by just using the simple oscillator design. I do want to think of a way to use each fret as part of the conductor, somehow get resistors connected to the frets and tune each one to the proper value, ie pushing down on the fifth fret gives you an A. It would be unreasonable to try to separate that into six strings, even with the microcontroller idea. You would probably have to build a new neck from scratch or make a strange custom fingerboard to get the job done.

Or you could scrap the guitar pickup all together and get rid of a more compliacated part of what you were talking about. The matrix idea alone would be enough to get a lot of usefullness out of and if just this is used, the guitars tuning won't matter. I don't personally know how to program microcontrollers yet, but my father and I were talking about using some of the PIC or Domino microcontrollers he has to make a more complex version of what I threw together. I definetly like where this is going though and if I can find a good excuse to learn to program PIC chips or whatever, I'm in.

One other thing that just popped in my mind is that if you did do the matrix system, after getting through designing a custom bridge system, you could use the matrix to jump around between different effects depending on what string you are playing on, where you are on the neck, etc...

[Transmogrifox]

Kinda like the MIDI guitars and guitar synth ideas--different effect for different strings.  I think what the MIDI guitars do is to employ a piezo element on each individual string and do a little frequency analysis on the incoming signal to detect the frequency.

You can still do the analog synth idea, even with the six strings, though the circuit gets more complicated.  You would still probably want to do the matrix detection scheme using optical isolator chips so you could get a clean logic "1" or "0" for each note.

What you'd do is set up an array of AND gates--one gate for each note output.  For instance, to get the low "G" note, you would have Fret 3 logically ANDed with String 6.  The B (3rd of the G chord) would be Fret 2 ANDed with String 2.  You would thus have an array of 120 AND gates to give a logic "0" when the note is off, and a logic "1" when the note is active.

For the more simple solution, you could get an analog synthesizer and remove the keyboard and replace each note trigger with the logic output from your synth stick.  You would have to use an array of OR gates to combine repeat notes from each string in order to fit into a 49-key synth.  Use the logic outputs to produce a trigger, and envelope follower (or multiple) to produce some velocity.

I realize this is still very complicated since it is the eqivalent of building a polyphonic analog synth.  The microcontroller would simplify the logic array that would be required to do this by brute force.  Furthermore, a microcontroller could directly convert it to a MIDI signal so you could use a MIDI synth without having to do a complicated hack on an analog synth. 

The most simple solution is to do what you're doing and make a 1-string machine all analog style.

The neck on the device I'm speaking about would not be very complicated at all.  You could cut a channel along the edge of the fret board with a rotary tool, and pack a bunch of small-guage wires in there, soldering one to each fret.  You could actually put a channel on each side of the fretboard to make it less tightly packed.

If you wanted to remove the fretboard, you could cut a channel for a 22-wide ribbon strip and leave a tab up at each fret location.  Drill a hole under each fret where the tab sticks up and you have electrical contact when you replace the fretboard.  Push down a string and it shorts to the fret--and there it is.  I realize it will short at least 2 frets at once, so one would have to add some more provision, yet, to prevent two notes playing at once.  This can still be done without a microcontroller, but gets to be much more complicated.

The other option you don't have, is that you don't have a continuous flow from note to note.  It's either an F or an F#, and you can't glide through the frequencies in between.  Not a worse scenario than a keyboard

I like the idea that maybe one day I can play Reason through a DIY MIDIfied guitar.

I'm looking forward to audio clips

[Cliff Schecht]

http://www.purevolume.com/cliffsjams

Audio! Like I said in the pictures topic, this was an impromptu thing with a guitarist on drums. It still grooves though. Enjoy!

[Khas Evets]

I want one! Did you manage to get the frequency to line up with the frets?

[Cliff Schecht]

Kinda, but not in the way you would think. I was hoping to be able to cover Eruption or something, but it doesn't work out perfectly. I need to play with more cap values.

[A.S.P.]

NICE - respect!

[Khas Evets]

I wonder if this could be modified to output CV, allowing you to interface with other analog synths. I don't know much about synths, so I'm just guessing this is possible.

[Harry]

That's pretty interesting. Possibley the strangest song I've ever heard. Sounds like a weezing horse or maybe an elephant blowing it's nose.

Here's an idea; Install a pickup and have the signal control an led, so it lights when a signal is sent with varying degrees of brightness based on loudness (there was a post on this recently on how someone did this I think). Then have a ldr against the led (photo-coupler) and use this to control the oscillator's volume level. That way you can hit the strings for a more guitar sound. I think that the that would work backwards though, when you hit the strings volume decreases, so again someone with brains could figure it out perhaps.

[Cliff Schecht]

I've had a lot of different people recommend that, but half of the work of building this thing was ripping out the frets, sanding the fretboard radius flatter and getting the stick tape down cleanly, as well as the VHS. There's foam underneath the strings, so nothing is able to ring out. I could see playing with ideas in the future, but for now this thing is staying as is, except for some new strap buttons.