Softpot Ribbon Controller

[Scott Stites]

Thanks Ian!

And the FET switch worked perfectly!! When set for no drop, there is no discernible difference in side to side motion of slide. Finger wiggle vibrato is dulled, but the hammer-on lag more than compensates for that. Now one can slide to any point, release, and not worry about detuning. Bend offset is no longer affected, because the first sample taken (when both initial and slide S&Hs take a sample simultaneously), there is no lag. The signal to initiate the lag comes from the flipflop controlling the gate. The gate goes high immediately after the first sample is taken, so any subsequent samples taken by the slide S&H are cushioned by the cap.

I've got it set up as a potentiometer control. If you don't want the compensation (and there are situations, believe it or not, that you may not), you simply dial it out. And you can dial it to just where you want it (narrower ranges will need less compensation).

Now, what situations would you choose to eschew the compensation? Well, the video of me jamming out that Antman posted a few posts back is one example -that was a simple gated signal from the ribbon controller. Gating the Appendage with no release time masks the detuning. Here you can have full minute finger wiggleage vibrato with no worrys. Introducing release time begins to expose the drop in pitch when the finger is removed. However, I plan to leave the hold switch in as well (it doesn't add any more parts other than a diode and could be left off at the builder's discretion). It's pretty easy to use (you just press the switch then release pressure), and allows a greater degree of expression. A nice feature of the hold switch is it allows one to pound out steps while sliding. There is a certain technique for avoiding the drop as well without using the hold switch or compensation, though it takes practice. For bug music, all of this is pointless.

For controllers, one would probably set-and-forget the lag time and not worry about the hold switch. This stuff is for if the touch ribbon is the main instrument board itself.

None of this, of course, affects the initial note CV.

Cheers,
Scott

[Scott Stites]

After playing with it since my last post....



This just puts it into the stratosphere!!!

[Scott Stites]

The detune upon release wasn't the squish factor at all. I just had to up the value of a component by about X1500.

Thing is, I fell in love with the action of this lag circuit that I put in, and will keep it. It really is pretty much like the legato function a lot of synths have (my SH-201 has it) - it's a mode of portamento that doesn't glide on individual notes, but if you press a key while pressing another key, the note will glide from one to the next.

Wha? Legato on a ribbon controller? Aren't they supposed to glide by design?

If you hammer-on with the Appendage, it will step to the hammer-on value. With this glide circuit, it will glide to the hammer-on value. It makes for a really nice sweep, and also is great for really deep vibrato that would require a wrist-snapping movement otherwise. And you can make a VCO sound like a l'il birdie with it, which is worth the price of admission alone.

[HL-SDK]

{jumps on the bandwagon}

I heard about this project indirectly from the sdiy list, and I'm surprised you all are still using just one sensor. Almost the first thing I thought of was a bank of 8-16, but not for doing CV work, for interfacing with pure data or max msp (too $$ for me).


Then I thought of multitouch and I feel that that may be out of my league - albeit infinitely cooler.

How about a sample and hold that keeps the value after finger has been released, so we don't have to use some sort of hold button, there is a switch that remembers the value of the softpot when finger is released.



Try perhaps lighting to go along with these, like LEDS underneath them?

I might get one of these to see if I can work out something

[Scott Stites]

[Scott Stites]

[RF]

[quote="Scott Stites"]

[Scott Stites]

Here are some samples of the evolushun:

Hypertrigger is a short demo of the hypertrigger function. Basically I'm just moving my finger over different areas of the ribbon and wiggling it up and down.

Hyper With Autolag is another demo of hypertrigger. All of the "slides" heard in this are actually the autolag. It shows up on hammer-ons.

Hyper Soft is hypertrigger again - I have a slower attack on the EG.

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Appendage_HyperTrigger.mp3
Description:	Hypertrigger example.	Download (listen)
Filename:	Appendage_HyperTrigger.mp3
Filesize:	307.88 KB
Downloaded:	1223 Time(s)

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Appendage_Hyper_With_Autolag.mp3
Description:	Hypertrigger with Auto Lag	Download (listen)
Filename:	Appendage_Hyper_With_Autolag.mp3
Filesize:	1.22 MB
Downloaded:	1188 Time(s)

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Appendage_Hyper_Soft.mp3
Description:	HyperTrigger with Soft Attack	Download (listen)
Filename:	Appendage_Hyper_Soft.mp3
Filesize:	1.05 MB
Downloaded:	1188 Time(s)

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[Scott Stites]

This is a sample that uses the dual pressure positional CV. Basically, if you apply two pressure points, the farther apart they are, the higher the voltage. I have the filter cranked pretty low, and the CV is controlling the cutoff (it's also modulating both VCOs). A hammer-on (widely spaced) cranks it on high (if you listen to the sample, you won't miss that ), a slide of the two pressure points away from each other increases gradually.

The two VCOs are controlled rather interestingly - one is controlled by slide, and one is controlled by slide and bend, so by moving the initial point up and down, the two VCOs detune proportionally.

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Appendage_Dual_Pressure_CV.mp3
Description:	Dual Pressure CV and stuff...	Download (listen)
Filename:	Appendage_Dual_Pressure_CV.mp3
Filesize:	3.57 MB
Downloaded:	1195 Time(s)

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[bugfight]

woohoo!
totally crazy.
i gots some ribbons now, can i wait or will i breadboard??
not that there's any shortage of projects to keep me busy...

[aetherpulse]

This really sounds like everything I ever wanted a controller for my modular to be! I must have two...
What's the best length of material to get? I probably should start sourcing this stuff to have ready when the circuit is ready for consumption...

[Scott Stites]

Here's the Appendage modulation input being modulated by a VCO, which it in turn is being modulated with the modulated slide and bend CV. This puts FM on the CV, which is being used to modulate two sine wave VCOs which are passed through the 2040 filter, which is controlled by the bend voltage. The Appendage is gating/triggering the EG, which is also controlling the filter and VCA.

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West_Coast_Appendage.mp3
Description:	Appendage FM	Download (listen)
Filename:	West_Coast_Appendage.mp3
Filesize:	7.65 MB
Downloaded:	1129 Time(s)

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[Scott Stites]

[mark_olson]

[numbernone]

Samples sounds so much like the ridiculous 1960's academic electronic music that I love so much.

Truly drooling in anticipation to build a few of these.

[fonik]

the softpots arrived today (50mm and circle type/iPOD style ). now that you incorporated the multitab feature i know i will have to order a 500mm type of softpot.

BTW are the softpots stickers? they look like they are but i don't know and don't want to damage them...

[Scott Stites]

Yes - the SoftPots have an adhesive strip on the back. Make sure you have something to stick them to before you strip it off.

As coincidence would have it, last night I did figure out how to allow the circuit to easily accomodate either 20K (500 mm) or 10K (less than 500 mm) SoftPots - it just requires an extra resistor for the smaller ones.

I tried it with a 100mm and a 200mm last night - it worked great! It was amazing sliding that 100mm and sending the modular from sub-aubdible to supersonic with a slight flick of the finger. Don't worry - you can scale the voltages.

Cheers,
Scott

[State Machine]

The samples are great Scott and have to agree with Numberone, I love the sound of the 1960's style electronic music and this definitely brings us there man !!! Good show !!!!. PS: I will reply to your PM's tomorrow at work

Bill

[bubblechamber]

really great samples. this is very cool and i can't wait to see the end result. keep up the amazing work.
david

[Scott Stites]

Well, I hope the craziness of the samples I produce doesn't give the impression that's all the Appendage is good for.

The thing is, it's ribbon controlled, and learning to play a ribbon controller for standard western tonality is much like learning a new instrument, like a trumpet or a cello. Obviously, quantization would make that process easier. Of course, that is not the only intended use of the Appendage - using it as an expression or gestural controller is very intuitive.

Using voltage as the source of the ribbon provides a very precise positional voltage when one point of pressure is applied. You can set the range so that you have a clear idea where octaves, steps, and so forth are. Using two points of pressure has a much more "west coast" feel. If you have two points that are an octave apart, pressing one or the other will produce a difference of one octave on the initial and slide outputs. Pressing both will produce an interval between the two octaves on the slide output. The bend output reflects this difference as the direct proportion between the two - so it will output something on the order of half a volt, up or down, depending on which side of the first point of pressure you apply the second point of pressure.

I've said little about it, but for some time now, the Appendage has been producing a fourth voltage I've come to call TFS (short for Two Fingered Salute, not the other meaning). This voltage reflects the distance between points of pressure in the form of a positive voltage. Using voltage to feed the ribbon, the response of this voltage is roughly logarithmic - it is not a linear relationship. The farther apart the two points of pressure are, the more sharply it will rise. It's a musically pleasing response, particularly when controlling a filter.

Using voltage to feed the ribbon allows one to hammer-on and hammer-off freely above and below the initial point of pressure. It also allows truly remarkable relationships between the initial, slide, bend and TFS outputs in ways I cannot describe - it would take a video to really demonstrate it.

There is another method of deriving voltages from the ribbon, and that is by feeding it a constant current source. There are advantages and drawbacks to this method.

The advantages are that hammer-on intervals and TFS have a direct linear relationship to their respective positions on the ribbon. The disadvantage is that it relegates one to low note priority. In other words, if one hammers on above the initial point of contact, the slide voltage will not change. It only changes if one hammers on below the initial point of contact. This does, however, provide a way to independently sweep a filter or some other parameter without changing the original pitch value by using the TFS voltage. The voltage method allows this with the initial note value, but the advantage here is that the original position can still slide and bend while independently controlling the TFS.

The point of this long-winded post is, I like both responses. Why does one have to choose between one or the other? The latest experimentation proves that one does not. The Appendage now on the breadboard provides two different operational modes, which I like to call "West Coast" (voltage fed) and "East Coast" (current fed). It's literally like having two instruments in one.

And - the left note priority of the "East Coast" mode? It can be either left or right note now, which was easy enough to implement, and which, in itself, provides some pretty cool things when using AutoLag.

All of this paves the way to true duophonic control of the Appendage, which will be realized on the optional second board I'm tentatively calling the "Control Freak". This second voltage will reflect the value of position two, complete with its own gate, trigger, intial, slide and bend outputs. It will be linear in East Coast Mode and non-linear in West Coast Mode. The control freak will allow you to control a large number of modules in surprising ways from a single controller.

I haven't even mentioned the control mechanisms concocted for the original board involving the S&H properties of the Appendage. These will tie the operation of the Appendage more intimately with the operation of keyboards, sequencers and nearly any module in a modular synth in a number of ways. But I probably should stick a fork in this post....

Cheerios,
Scott

[bugfight]

awesome news, esp providing both responses...
looking forward to playing with this.

no point in my trying to breadboard since you have gone way past the orig

meanwhile i can work on shortening the queue...
(and thus breaking a historical trend)

[bubblechamber]

this is looking better and better. thanks for all the work you're putting into this Scott.
i heard back from Spectra about samples, and they charge, with a 2 piece minimum. their prices are exactly the same as Spark.

[Scott Stites]

[blue hell]

[aetherpulse]

It sounds like you went inside my head, looked at everything I wanted a controller fo my synth to be, and then made it! I can't wait to build it.