Some presets start by themselves

[andro]

Some CA2600 presents just start by themselves, and I can't see how to stop them either. There are quite a few, especially in the FX presets section. for example, Rising Signs. What am I missing in my understanding?

[utdgrant]

You're not alone!

Roger Powell recalls Zawinul’s initial experience with the 2600: “Joe came up to Boston to play at the Jazz Workshop. I met him and showed him the 2600. It took him a little time to pick up on some of its features. For instance, the 2600 lets you route the output either through the VCA [voltage-controlled amplifier] or directly from the VCF [Voltage-Controlled Filter]. If the output came from the VCF, the sound would always be on. After Joe had the instrument for a week or so, he called and said, ‘Hey, man, the sound is fantastic. Now tell me, how do you make it stop?’

[andro]

Such an authentic replica!

[andro]

CA2600 developers, anybody?

[UrbanCyborg]

The Rising Signs preset is a pretty complex setup, and is clearly designed to be self-running. If you're looking for a quick shutoff, toggle the AR Envelope Generator input from S/H Gate to Kyb Gate. I wouldn't know about the other presets you mention, not knowing which they are, but I suspect something similar is going on, and they're intended to self-generate.

Reid

[andro]

Useful. Thanks!

As a beginner, it was not something I expected, to have patches that just run with no 'start button'. When you say clearly designed, what do you look for to establish that?

[Steve W]

Thanks for prompting me to start looking into programming the CA2600. I have been wanting an excuse to do that for a while. So, I started with the Sound FX presets until I found one that was on from the get-go (aka free-running / self-generating). Here's what I have so far:

Ghost Delay

• Notice that Initial Gain on the VCA is not set to zero. If you want to use that sound triggered by the keyboard, (1) try moving the VCA's Initial Gain to zero and (2) try triggering the VCA with something, for example move either of the envelope generator sliders (AR or ADSR) up.

Reid (UrbanCyborg) has already shown us how to change Rising Signs so it is triggered by a keyboard gate and not from the sample and hold gate.

I found a couple of other free-running presets, but those would need different methods to try to turn them into keyboard triggered sounds (and more time to reverse engineer than I have time for at the moment).

As for what you are "missing" in your understanding of free-running presets I'd suggest looking for repeating or cyclical triggers and envelopes and then figuring out how to (1) disengage them and (2) use a keyboard trigger and an envelope.

I wouldn't know about the other presets you mention, not knowing which they are, but I suspect something similar is going on, and they're intended to self-generate.

[Steve W]

To Also Fro

• This is one that I was looking at. For starters, notice that the Electronic Switch is cycling between A and B.
  
  • A is the wave from VCO1. Try pulling out the cable going into A. Then put it back in.
  • B = not A (silence). There's nothing going into B! Try changing the Rate slider to alter the switch's cycle. So, the Electronic Switch is cycling through A (sound from VCO1) and not A (silence).
  • Notice that in addition to the A (VCO1) to not A (silence) cycle, there's a second sound.
  • The second sound is the wave from VCO2. The ADSR going into the VCA is shaping that sound. Try turning down the ADSR control slider that goes into the VCA. Then turn it back up so you can see the next step.
  • Try adjusting the rate slider for the LFO. That should tell you that the LFO is triggering the ADSR.
  • Try disconnecting the cable that goes from the LFO square wave to the -10V in the Voltage Processors section.
  Can you see where this is going?
  • Look at the Voltage Processors section. Find the cable that goes to the Gate In of the ADSR Envelope Generator. Pull the cable going into the Gate In.
  There's more going on, but this should be enough to show how the "To" and the "Fro" are being triggered. One uses the Electronic Switch. The other uses an LFO square wave by way the Voltage Processors section.
  
  As for deconstructing how the Voltage Processors section is being used and how to get the keyboard to alternate between To and Fro from a single keypress, I'll leave that to you (or someone else).

[UrbanCyborg]

Looks like SteveW spent a little more time digging than I did, although to be fair, I did have to read substantial chunks of the manual to figure out what was up with Rising Signs. As for why I said that it was "obviously" meant to be self-generating, well, maybe it isn't so obvious, but when I see heavy use of the Voltage Processor, Sample & Hold, and Electronic Switch sections in a preset that does run by itself, I consider that a pretty strong sign. The 2600 is potentially a fairly complex synth, allowing you to treat it to some extent like a modular; I believe that was one of the design goals of the original hardware, to be a cut-rate 2500 for people who couldn't afford the real modular. That means, of course, that you can set up things that aren't obviously based on the base control flow. That's where the power of the 2600 comes from, and also, its steep learning curve.

Thanks, Steve. Your posts got me thinking in some different directions.

Reid